2. SEDIMENTOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OF …
Transcript of 2. SEDIMENTOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OF …
Larson, R. L., Lancelot, Y., et al., 1992Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 129
2. SEDIMENTOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OFLEG 129 SILICEOUS DEPOSITS1
S. M. Karl,2 G. A. Wandless,3 and A. M. Karpoff4
ABSTRACT
Siliceous deposits drilled on Ocean Drilling Program Leg 129 accumulated within a few degrees of the equator during theJurassic through early Tertiary, as constrained by paleomagnetic data. During the Jurassic and Early Cretaceous, radiolarian ooze,mixed with a minor amount of pelagic clay, was deposited near the equator, and overall accumulation rates were moderate to low.At a smaller scale, in more detail, periods of relatively higher accumulation rates alternated with periods of very low accumulationrates. Higher rates are represented by radiolarite and limestone; lower rates are represented by radiolarian claystone. Our limiteddata from Leg 129 suggests that accumulation of biogenic deposits was not symmetrical about the equator or consistent over time.In the Jurassic, sedimentation was siliceous; in the Cretaceous there was significant calcareous deposition; in the Tertiary claystoneindicates significantly lower accumulation rates at least the northern part of the equatorial zone. Accumulation rates for Leg 129deposits in the Cretaceous were higher in the southern part of the equatorial zone than in the northern part, and the southern sideof this high productivity zone extended to approximately 15°S, while the northern side extended only to about 5°N.
Accumulation rates are influenced by relative contributions from various sediment sources. Several elements and elementratios are useful for discriminating sedimentary sources for the equatorial depositional environments. Silica partitioningcalculations indicate that silica is dominantly of biogenic origin, with a detrital component in the volcaniclastic turbidite units,and a small hydrothermal component in the basal sediments on spreading ridge basement of Jurassic age at Site 801. Iron in Leg 129sediments is dominantly of detrital origin, highest in the volcaniclastic units, with a minor hydrothermal component in the basalsediments at Site 801. Manganese concentrations are highest in the units with the lowest accumulation rates. Fe/Mn ratios are >3in all units, indicating negligible hydrothermal influence. Magnesium and aluminum concentrations are highest in the volcani-clastic units and in the basal sediments at Site 801. Phosphorous is very low in abundance and may be detrital, derived from fishparts. Boron is virtually absent, as is typical of deep-water deposits. Rare earth element concentrations are slightly higher in thevolcaniclastic deposits, suggesting a detrital source, and lower in the rest of the lithologic units. Rare earth element abundancesare also low relative to "average shale." Rare earth element patterns indicate all samples are light rare earth element enriched.Siliceous deposits in the volcaniclastic units have patterns which lack a cerium anomaly, suggesting some input of rare earthelements from a detrital source; most other units have a distinct negative Ce anomaly similar to seawater, suggesting a seawatersource, through adsorption either onto biogenic tests or incorporation into authigenic minerals for Ce in these units.
The A1/(A1 + Fe + Mn) ratio indicates that there is some detrital component in all the units sampled. This ratio plotted againstFe/Ti shows that all samples plot near the detrital and basalt end-members, except for the basal samples from Site 801, whichshow a clear trend toward the hydrothermal end-member. The results of these plots and the association of high Fe with high Mgand Al indicate the detrital component is dominantly volcaniclastic, but the presence of potassium in some samples suggests someterrigenous material may also be present, most likely in the form of eolian clay. On Al-Fe-Mn ternary plots, samples from allthree sites show a trend from biogenic ooze at the top of the section downhole to oceanic basalt. On Si-Fe-Mn ternary plots, thesamples from all three sites fall on a trend between equatorial mid-ocean spreading ridges and north Pacific red clay.Copper-barium ratios show units that have low accumulation rates plot in the authigenic field, and radiolarite and limestonesamples that have high accumulation rates fall in the biogenic field.
INTRODUCTION
Siliceous deposits are enigmatic indicators of high-productivity sedi-mentary environments. They accumulate in several marine environ-ments, which are generally distinguished with the aid of lithologiesassociated with the siliceous deposits. Sedimentary and geochemicalcharacteristics of siliceous deposits are used to discriminate betweendepositional environments and define paleoceanographic conditions forthese deposits.
On Leg 129, several types of siliceous deposits were cored. Theresults of detailed sedimentological studies are presented in Ogg etal. (this volume), and diagenetic studies are presented in Behl andSmith (this volume). The known environmental conditions include
Larson, R. L., Lancelot, Y., et al, 1992. Proc. ODP, Sci. Results, 129: CollegeStation, TX (Ocean Drilling Program).
2 U.S. Geological Survey, Branch of Alaskan Geology, 4200 University Drive,Anchorage, AK 99508-4667, U.S.A.
3 U.S. Geological Survey, National Center, MS 990,12201 Sunrise Valley Dr., Reston,VA 22092, U.S.A.
4 Centre de Géochimie de la Surface—CNRS, Institut de Géologie, 1 rue Blessig,67084 Strasbourg Cedex, France.
initial deposition on a mid-ocean spreading ridge at moderate accu-mulation rates averaging 700 g/cm2/m.y. (Ogg et al , this volume),near the equator in the middle of the Mesozoic Pacific Ocean(Lancelot, Larson, et al, 1990). The sites drilled during Leg 129initially migrated southward from the equator, and subsequentlymoved northward across the equator and into the north Pacific basin(Lancelot, Larson, et al., 1990). Accumulation rates for siliceousdeposits in excess of 1000 g/cm2/m.y. characterize these equatorialcrossings (Ogg et al., this volume). Although we know the generaltectonic, paleoceanographic, and biologic setting of these siliceousdeposits, sedimentary, diagenetic, and chemical characteristics canhelp us define these environments more precisely and gain insightsinto circulation patterns and productivity cycles in the MesozoicPacific Ocean.
In this paper we focus only on the siliceous deposits. Our purposeis to examine changes in siliceous deposition at Leg 129 sites throughtime, and to identify significant factors affecting siliceous deposi-tion. We do not address general sedimentation at these sites becauseabundant turbidite deposition masks other paleoceanographic proc-esses, and because poor recovery limits our ability to assess therepresentativeness and relative proportions of lithologies cored at Leg129 sites.
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S. M. KARL. G. A. WANDLESS, A. M. KARPOFF
TERMINOLOGY
The classification of siliceous sediments and rocks in this paperfollows the definitions provided in the Initial Reports for Leg 129(Lancelot, Larson, et al., 1990). The term biogenic is applied when30% or more of the sediment is carbonate or silica from a biogenicsource. Pelagic biogenic ooze consists of 60% or more organisms.Transitional pelagic ooze contains 30% to 60% organisms, and at least40% silt or clay. Pelagic clay has less than 30% organisms.
There are several types of pelagic clay. Eolian pelagic clay con-tains detrital clay minerals and quartz crystals. Authigenic pelagicclay contains authigenic clay minerals, zeolites, iron oxides, andferromanganese micronodules. Volcanogenic pelagic clay containsglass, mafic minerals, feldspar, volcanic rock fragments, palagonite,and clay minerals derived from alteration of volcanic material. Pelagicclay in general may also contain fish parts and cosmic particles.Sediment samples were analyzed for clay mineralogy by X-ray dif-fraction (XRD) aboard ship and on the microprobe at the Universityof Strasbourg, France. The preliminary interpretations used for thisstudy did not discriminate species of smectite; Karpoff (this volume)identified dioctahedral smectite (d{060}=1.50Å), possible illite, andinterlayered illite-smectite.
The siliceous deposits studied include biogenic siliceous materialin various stages of preservation and recrystallization. Terms for silicaphases of samples used in this study are "field terms" based onproperties observed in core samples. Silica phases were not analyzedfor this study, but some samples correspond to samples analyzed byBehl and Smith (this volume). The term chert is used for siliceousdeposits recrystallized to opal C/T (cristobalite/tridymite) and cryp-tocrystalline, microcrystalline, or chalcedonic quartz. Chert has aglassy to waxy luster, smooth conchoidal fracture, and a hardness of6.3-7.0. Porcellanite has the same silica mineralogy plus more than10% clay. Porcellanite has a dull luster, matte surface, blocky fracture,and a hardness of 4.0-5.5. Radiolarite has less than 10% clay, a rough,sandy texture, granular fracture, and is soft to friable. Modifiers tothese terms are used to reflect the presence of components in excessof 25%. A clayey radiolarite has more than 25% clay. A "radiolaritewith clay" contains 10% to 25% clay.
Accumulation rates were calculated using fossil age determina-tions and stratigraphic thickness. Original rates of deposition orsedimentation are not known, because volume changes resulting fromdiagenetic processes have not been quantitatively determined. In thisstudy, high or low sedimentation rates are thus relative terms only.Accumulation rates less than 3 m/m.y. are considered low. Accumu-lation rates in excess of 10 m/m.y. are considered high. Because theocean is greatly undersaturated with respect to silica and dissolutiontakes place at the sediment-water interface, it is generally inferred thatlow accumulation rates reflect low sedimentation rates, and the con-verse is also true.
SAMPLE DESCRIPTION
Site 800
Unit I brown pelagic clay from the top of the sequence was notsampled for this study.
Unit II (Fig. 1) is late Campanian to Turonian in age, and consistsof 40 m of porcellanite and radiolarian chert (Lancelot, Larson, et al.,1990; Behl and Smith, this volume). Both phases are brown. The chertis patchy, cuts across sedimentary laminations, and increases inabundance downsection. All samples studied from this unit (Table 1)are composed of mottled brown and pale brown chert; the samplefrom Core 129-800A-7R has black Mn-oxide coatings on the surfaceof some bedding laminations.
Unit III is Turonian to early Albian in age and consists of 150 mof olive gray to gray radiolarian chert and finely laminated siliceouslimestone, with subordinate nannofossil chalk (Lancelot, Larson, etal., 1990). The silicification of the chalk and limestone is patchy and
discontinuous. Locally laminations are disrupted by burrows, andsome laminations are deformed. The chert contains up to 45% radio-larians, many of which are filled with opal C/T, chalcedony, and rarebarite crystals. The limestone contains up to 25% radiolarians as wellas foraminifers and locally abundant nannofossils. Limestone increasesdownsection. Replacement chert in the limestone forms bedding-parallel laminations and nodules with bedding-discordant, cuspate,convex-outward silicification fronts that grade from chert to calcare-ous porcellanite, which in turn grades to the host limestone. FromCore 129-800A-22R downward, volcanic clasts were observed andsmectite was identified by shipboard XRD analyses (Lancelot, Larson,et al., 1990). In Core 129-800A-23R clinoptilolite and smectite wereidentified in clayey radiolarite. These minerals are characteristic ofthe underlying volcaniclastic turbidite unit and indicate a gradationaltransition to that unit.
Samples from Unit III are composed of chert, radiolarian porcel-lanite, and porcelaneous radiolarite. Most samples are pinkish tobrownish green or gray, indicating transitional redox conditions.Samples from Cores 129-800A-13R and -24R contain black man-ganiferous streaks.
Unit IV is Aptian in age and consists of 221 m of volcaniclasticsand-silt-clay turbidites with intervals of pelagic radiolarian clay-stone. The turbidites are predominantly green, and the radiolarianclaystone intervals are typically brown. Turbidite sandstone is com-posed mainly of volcanic detritus, with minor, variable amounts ofcalcareous shallow-water biogenic debris or calcareous cement.Detrital claystone within turbidite beds contains volcanic glass,plagioclase, pyroxene, iron oxides, smectites, montmorillonite, cli-noptilolite, up to 25% radiolarians and up to 15% nannofossils. Thepelagic claystone, calcareous claystone, radiolarian claystone, andclayey radiolarite between turbidite beds are finely laminated andcontain up to 50% radiolarians, with subordinate volcanic glass, clayminerals, iron oxides, and rare plagioclase, pyroxene and volcanicrock fragments. Fractures in Core 129-800A-38R are coated withMn-oxide dendrites.
Samples studied from Unit IV are all from pelagic intervals exceptfor Samples 129-8OOA-26R-1, 135-139 cm, 129-800A-27R-1, 61-64cm, 129-8OOA-41R-1, 87-93 cm, and 129-800A-44R-1, 92-94 cm,which are claystones from the tops of turbidites sampled for compara-tive purposes.
Unit V is Barremian to Berriasian and consists of 48.5 m ofmassive to microlaminated clayey radiolarite and radiolarian clay-stone (Lancelot, Larson, et al., 1990). The unit is dominantly red orbrown, with rare green reduced zones. The radiolarite alternates withclaystone on a centimeter scale but radiolarite is the dominant lithol-ogy (60% to 80% of each core). Radiolarite layers contain up to 85%radiolarians. Some layers are bioturbated. Shipboard XRD analysesindicate the presence of smectite, zeolites, and feldspar. Manganeseoxides occur as lenses, as laminations, as accumulations aroundburrows or along redox fronts, as micronodules, as radiolarian fill-ings, and as fracture coatings. Fractures are also commonly filled withsilica. Samples studied from this unit are all from radiolarite layersexcept Sample 129-800A-52R-1,16-20 cm, which is a claystone withMn-oxide streaks.
Unit VI is Berriasian(?) in age and consists dominantly of doleritesills with minor amounts of recrystallized siliceous sediment trappedbetween sills (Lancelot, Larson, et al., 1990). The sample from thelowest sedimentary rock cored at Site 800 is from a chert lens betweendolerite sills. This chert is brown, red or bleached pink, and microlami-nated similar to the radiolarite of overlying Unit V. The sample studiedis massive brown chert with approximately 5% ghosts of radiolariansand 1 % opaque minerals. Iron staining is patchy in thin section.
Site 801
Unit I brown pelagic clay from the top of the sequence was notsampled for this study.
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LEG 129 SILICEOUS DEPOSITS
Unit Lithostratigraphy "Trends"
2 >S ESi
38.0
38.0
Pelagic brown clays• clays (smectites)• iron oxides• zeolites (phillipsite)
•deep-sea deposits <0.5
(mbsf)
40.2Brown cherts and porcellanites
• opal-CT;diagenetic quartz
•silica diagenesis <3
150.4
Gray radiolarian cherts and limestones
• discordant diageneticboundaries
• opal-CT & quartz• calcite• clays• clinoptilolite
•changes in pelagicinput, Ca -> Si
•diagenetic processes
Q .CD
Q
300 —
221.0
400 —
Redeposited volcaniclastics
- Turbidites- Debrites- Interturbidite pelagic sedimentation- Fluidized / grain flow deposits
volcanic glass; alteredplagioclasepyroxenegreen clay mineralszeolites: clinoptilolite
fractures- calcite-filled- green clay minerals- manganite
fine-grainedthinly beddedthin sequences
alteration ofvolcaniclastics
resedimentation
coarse-grainedmassive bedsbrecciasdebrites
<35
48.5Clays and radiolarites
• clays• opal-CT / diagenetic quartz
finely laminated(Milankovitch cycles?)
<4>2
500 —
46.4
Dolerite sills with minor chert• 3 intrusive units• aphyric and holocrystalline• smectite-dominated alteration
sediment bakedmetamorphismof sills
Figure 1. Core ages, lithologies, and units for Site 800, Leg 129 (Lancelot, Larson, et al., 1990).
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S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Table 1. Sample descriptions for Site 800, Leg 129.
Sample (cm)
129-800A-
6R-1, 67-697R-1, 2-58R-1,48-509R-1,30-33
10R-1, 13-1711R-1,7-1O12R-1, 30-3213R-1, 12-1414R-1, 110-11517R-1,68-7118R-1, 127-13023R-1,69-7024R-1,92-9524R-1, 68-7126R-1, 22-2626R-1, 135-13927R-1, 61-6427R-1, 110-11428R-3, 106-11030R-1, 125-12930R-2, 114-11831R-1, 12-1432R-CC, 10-1333R-7, 14-1834R-2, 139-14235R-3, 84-8836R-1, 110-11436R-4, 28-3241R-1,87-9342R-1, 41-4344R-1,92-9451R-1, 106-10852R-1, 16-2053R-1,32-3455R-1,76-8155R-2, 25-3056R-1, 8-1358R-1,37^2
Depth(mbsf)
40.249.259.468.878.387.997.6
106.9117.3144.9155.0201.2210.6210.8228.8230.0238.6239.1251.3267.2268.5272.1280.8296.6299.9310.2317.0320.7363.4369.0384.6450.7459.0465.2479.9480.9488.6507.2
Unit
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVVVVVVVVI
Age
late Campanianearly Campanianearly Campanian
early Campanian/TuronianTuronian
CenomanianCenomanianCenomanianCenomanianlate Albianlate Albian
early Albianearly Albianearly Albianlate Aptianlate Aptian
middle(?) Aptianmiddle(?) Aptian
early Aptianearly Aptianearly Aptianearly Aptianearly Aptianearly Aptianearly Aptianearly Aptianearly Aptianearly Aptian
Aptian(?) Barremian(?)Aptian(?) Barremian(?)Aptian(?) Barremian(?)Hauterivian/BarremianHauterivian/BarremianHauterivian/Barremian
BerriasianBerriasianBerriasian
• >
Samplelithology
ChertChertChertChertChert
PorcellanitePorcellanitePorcellaniteRadiolaritePorcellanitePorcellaniteRadiolariteRadiolariteRadiolariteClaystoneSiltstoneSiltstone
RadiolariteClaystone
PorcellaniteRadiolaritePorcellaniteClaystoneClaystoneClaystoneSiltstone
ClaystoneClaystoneClaystoneClaystoneSiltstone
RadiolariteClaystoneRadiolariteRadiolariteRadiolarite
ChertChert
Compactedthickness/time
(m/m.y.)
<3<3<3<36666666666
12<ct<3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 3512 < et < 352 < et < 42 < et < 42 < et < 42 < et < 42 < et < 42 < et < 42 < et < 4
Accumulationrate (g/cm2/m.y.)
6006306486601290133213801380143413681422147013621362
3192 <AR< 93103192<AR<93103240 < AR < 94503120 <AR< 91003168 <AR< 92402964 < AR < 86453060 < AR < 89253072 < AR < 89603216 <AR< 93803192 <AR< 93103240 < AR < 94503228 <AR< 94153240 < AR < 94503000 < AR < 87503300 < AR < 96253300 < AR < 96253120 <AR< 9100
532 <AR< 1064536 <AR< 1072518 <AR< 1036530 <AR< 1060530 < AR < 1060492 < AR < 984500 <AR< 1000
Unit II (Fig. 2) is Campanian to Cenomanian in age and 62 m thick.Poor recovery for this unit suggests a strong hardness contrast betweenlithologies recovered and not recovered. Recovered rocks were domi-nantly chert and porcellanite very similar to that of Unit II at Site 800.Minor recovered claystone suggests that much of the missing core mayhave been soft clay or claystone. The chert is pale to dark brown, andfinely laminated to banded, with alternating bands of pale brown chertand dark brown porcellanite. Some chert is bioturbated. Fractures arecommonly filled with Mn-oxide grains or dendrites. The chert containsup to 35% radiolarians and variable amounts of clay minerals. The unitis noncalcareous, except at its lower boundary, which is gradational tothe underlying turbidite unit: Core 129-801 A-13R contains calcareousradiolarian porcellanite; Cores 129-801A-14R and -15R contain tuf-faceous nannofossil claystone and chalk. The samples from Unit II(Table 2) are brown chert except samples from Cores 129-801 A- 12Rand -13R which are cherty porcellanite.
Unit III is Cenomanian to Albian in age, 92 m thick, and consists ofvolcaniclastic turbidites very similar to those of Unit IV at Site 800.Pelagic intervals are represented by radiolarian claystone, radiolarianporcellanite, radiolarite, chert, nannofossil claystone, and chalk. Theturbidites are dark greenish to bluish gray with beds up to 5 m thick, someof which contain shallow-water carbonate debris. The pelagic interbedsare mostly olive green to gray, and have discontinuous laminations orsparse bioturbation. The base of the unit consists of thin-bedded distal-facies turbidites with brown radiolarian claystone or radiolarite intervalsup to 1 cm thick, which is transitional to the underlying radiolarite unit.Samples studied from Unit III consist of pelagic gray to brown radiolarian
porcellanite and chert. For purposes of comparison, claystone fromthe tops of turbidite beds in Sections 129-801A-18R-2 and 129-801B-8R-2 were sampled, and a calcareous porcellanite from Sec-tion 129-801B-1 OR-1 was sampled. This latter sample contained10% limestone, 30% chert, and 60% porcellanite.
Unit IV is Valanginian to Oxfordian in age, 125 m thick, andconsists mainly of brown radiolarite with subordinate dark brownchert and porcellanite bands and nodules. The unit is subdivided intoan upper, chert-rich radiolarite with 10% or less clay, and a lowerradiolarite with 20% or more clay. Radiolarians comprise up to 90%of the radiolarite and up to 70% of the chert. Foraminifers are rare.Sedimentary structures include rare fine laminations, flasers, lamina-tions that grade to radiolarian clay, and rare bioturbation. Porcellaniteand chert zones crosscut these features. Black Mn oxides occur asgrains, microlaminations, and coatings on fractures. Interstitial Fe-Mn-oxide grains may comprise as much as 20% of some radiolarite.Shipboard XRD analyses indicate that hematite and smectite arepresent in addition to various phases of silica in cores from Unit IV.Samples studied from this unit are all radiolarite and chert. The samplefrom Section 129-801B-26R-CC contains Mn-oxide grains.
Unit V is Callovian in age, 18m thick, and consists of interbeddedred radiolarite and claystone. There is a distinct color change frombrown to red at the upper unit boundary. The layers of radiolarite andclaystone alternate on a centimeter scale, and average about 5 cm inthickness. Layer boundaries are gradational on a millimeter scale, asobserved in thin section, suggesting fluctuating depositional condi-tions. Radiolarite layers contain up to 25% clay minerals and rare
34
LEG 129 SILICEOUS DEPOSITS
8begin ^Hole 801A
Depth(mbsf)
I ?Lithostratigraphy i«
100 —
200begin ^Hole 801B
Q.
Q
300
400 —
500begin ^ -Hole 801C
63.8
Pelagic brown clayA = Dark reddish-brownB = Brown with light streaks• Clays (smectites)• Iron oxides/hydroxides• Zeolites (phillipsite)
< 1
Brown chert and po reel Ian ite
• Opal-CT; diagenetic quartz
126.5
Volcaniclastic turbiditesand minor pelagic intervals
Glass and altered glassPlagioclaseBackground radiolarian sedimentation
< 12>5
318.3
IV
442.9
Brown radiolarite
A = Brown radiolariteB = Brown clayey radiolarite(both with dark brown chert)
Fine-scale sub-horizontal bioturbationDecreasing clay content up-sectionAbundant Mn oxides (and micronodules)
<5
V461.6
Alternation of red radiolarite and claystone
VI
Basalt
Interbedded silicified claystone at 453 mbsfIntrusive and pillow unitsAphyric and holocrystallineHydrothermal deposit at 512 mbsf
590.9
Figure 2. Core ages, lithologies, and units for Site 801, Leg 129 (Lancelot, Larson, et al., 1990).
35
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Table 2. Sample descriptions for Site 801, Leg 129.
Sample (cm)
129-801A-
8R-9R-
10R-12R-80-1C13R-14R-15R-16R-
, 1-3,0-3,0-5, 22-250M, 21-26, 26-28, 24-26, 135-138
17R-1,28-3018R-2, 14-1719R-CC, 12-1620R-1.8-12
129-801B-
8R-2, 60-6310R-11R-12R-14R-15R-16R-
, 70-73,31-36, 64-70, 52-57, 19-20,40-43
17R-1, 34-3618R-1,37^019R-1,24-2620R-21R-24R-25R-26R-I27R-29R-31R-33R-33R-35R-35R-37R-
, 23-26, 12-13, 69-73, 49-53
:c.o^i, 104-107. 17-19, 18-20, 10-14,126-129,51-55, 123-127,7-10
39R-1,4-7
129-801C-
4R-1, 11-165R-4, 11-166R-1,31-34
Depth(mbsf)
60.670.279.599.0
100.0108.7118.5128.1139.0147.5158.6176.3176.5
254.8272.7282.0292.0310.8319.9329.6338.9348.2357.5366.7375.8393.3397.7407.0407.7416.4425.8434.9436.1444.8445.5453.6462.7
521.8535.8540.8
Unit
11II11II11IIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIII
IVAIVAIVAIVAIVAIVAIVAIVAIVBIVRIVBIVBIVBIVBIVBIVBVVVVI
VIVIVI
Age
CampanianConiacian-Santonian
ConiacianCenomanian/Coniacian
9
CenomanianCenomanianCenomanianlate Albianlate Albianlate Albianlate Albian
middle Albian
middle AlbianPre-middle Albian, post-Valanginian
Pre-middle AlbianPre-middle Albian
ValanginianValanginian
Berriasian/ValanginianBerriasianBerriasianBerriasian
late Tithonianlate Tithonianlate Tithonian
early Tithonianearly TithonianKimmeridgianKimmeridgian
OxfordianCallovianCallovianCallovianCallovianBathonianBathonian
> Bathonian> Bathonian
Bathonian
Samplelithology
ChertChertChert
PorcellaniteChert
PorcellaniteChertChert
PorcellanitePorcellaniteClaystoneClaystone
Chert
ClayPorcellanitePorcellanite
ChertRadiolarite
ChertChertChertChertChertChertChert
RadiolariteRadiolariteRadiolarite
ChertChertChert
RadiolariteRadiolarite
ClayClaystoneClaystone
Chert
QuartzQuartzQuartz
Compactedthickness/time
(m/m.y.)
33337
35 <ct< 125 < c t < 125 <ct< 125 <ct< 125 <c t< 125 <ct< 125 <ct< 12
5 <ct< 125 <ct< 125 <ct< 125 <ct< 12
444444444444441.31.31.31.39?
?9
9
Accumulationrate (g/cm2/m.y.)
687645669699
9
6571150 <AR< 27601145 <AR< 27491220 <AR< 29281145 <AR< 27491360 <AR< 32641360 <AR< 32641190 <AR< 2856
1385 <AR< 33241285 <AR< 30841285 <AR< 30841285 <AR< 3084
1112101610521064106410401032988101610921072101610161040354354358358?7
777
burrows. Color mottling, anastomosing clay seams, and patchy silici-fication within layers are diagenetic features. Mn oxides on fracturesare rare relative to the overlying radiolarite unit. Claystone beds aredarker red than the radiolarite beds, contain rare burrows, and lessthan 25% radiolarians. The red color indicates oxic conditionsthroughout the section despite high productivity. Shipboard XRDanalyses indicate the presence of hematite and smectite in addition tovarious phases of quartz. Samples studied from this unit include twosamples of radiolarite, one of claystone, and one of soft, unlithifiedCallovian clay (Sample 129-801B-35R-1, 51-55 cm, Table 2).
Unit VI is Bathonian in age, and consists of basalt flows withinterpülow sedimentary rocks. The basalt is interpreted to representbasement (Lancelot, Larson, et al., 1990). InterpiHow lithologies includechert, claystone, carbonate, tuff, and hydrothermal quartz. These sedi-mentary rocks are thermally recrystallized and some are laced with veinsof drusy quartz. The chert contains quartz-filled radiolarians. Samplesstudied from this unit include radiolarian claystone, chert, and threesamples from Cores 129-801 C-4R,-5R, and -6R of hydrothermal quartzand goethite (Karpoff, this volume).
Site 802
Unit I consists of brown pelagic clay (Fig. 3). Unit II consists ofMiocene volcaniclastic turbidites with intervals of brown pelagicclaystone, nannofossil claystone, and nannofossil chalk. No sampleswere collected from these units for this study.
Unit III is early Miocene to Paleocene in age, 75 m thick, andconsists of nannofossil chalk with minor amounts of claystone, por-cellanite, and nodular chert (Lancelot, Larson, et al., 1990). The chalkis thick-bedded, commonly graded, laminated and cross-laminated,and bioturbated. Clasts of claystone are common in the chalk, andmixed assemblages of Cretaceous through Oligocene nannofossilsindicate that this chalk is redeposited carbonate ooze. The brownclaystone contains clay minerals, zeolites, volcanic glass, iron oxides,radiolarians, and nannofossils. The claystone is extensively biotur-bated. Chert occurs as scattered nodules, comprising less than 3% ofthe recovered core. The chert has sharp, irregular contacts with thechalk, and often contains carbonate inclusions. The chert is clearly adiagenetic product derived from dissolution of siliceous plankton in
LEG 129 SILICEOUS DEPOSITS
Q.Φ
Cl
0
100
200 —
300 —
400 —
500
Co
re
in2R3R
4R5R
6R7R
9R10R
12R
14R15R16R
17R18R19R20R21R22R
23 R24R
25R
27R28R29R30R
31R
32R33R34R35R36R37R38R39R40R41R42R43R44 R45R46R47R48R49R
son5-lR52R53R54R55R56R
57R58R59R
Re
co
very
• • M
=
a
iP
60R 1blH ^™
Age
— , late Pliocene - Quaternary _
late Miocene - middle Pliocene
?
middle Miocene
early Miocene
? late Oligocene
early Eocene
Paleocene
late Campanian
Santonian
Coniacian
Cenomanian
? late Aptian
Lit
ho
log
y
_ _ _ _ _y v v v v
y v v v vV V V V VV V V V V
y v v v vy v V V V
y v v v vV V V V V
y v v v v
y v v v vV V V V V
y v v v v
1/ V V V V
' V V V V
' V V V V
' V V V VV V V V V
V V V V V
V V V V V^ V V V V/ V V V VV V V V Vif V V V V
f V V V VV V V V V
V V V V V' V V V VV V V V V' V V V V
' V V V V
i' V V V VV V V V Vf V V V VV V V V Vi' V V V V
^ V V V VV V V V V^ V V V V
lass*/ V V V V
>i \ S X \y y y y y
\ \ \ \ \y y y y y
\ x \ \ \
^ \ \ \ \y y y y /
\ \ \ \ \y y y y y
s x x •y. \y y y y y
\ X X X X
Un
it
1 14.6
II
160 6
B
237.4
III
329.9IV
349.2
V
460.0VI
469.9VII
497.1
V I I I - I X509.2
x
559.8
Ic LithostratigraphyojcCD
^ Pelagic brown clay
TuffVolcaniclastic turbidites
O
cb A : Tuff with pelagic clay
B : Tuff with calcareous claystone
oo and chalk
i n
en
CO
σ> Claystone
° Volcaniclastic turbidites
Claystone and radiolarite
<N Calcareous claystoneCM and radiolarian limestone
Claystone-volcanic turbidites
BasaltCO
o Pillow units• Sparsely microphyric and
hypocrystalline
Se
dim
en
tati
on
rate
(m
/m.y
.)
low
11
15
12
7
2-4
9
2
1.5
Figure 3. Core ages, lithologies, and units for Site 802, Leg 129 (Lancelot, Larson, et al., 1990).
37
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Table 3. Sample descriptions for Site 802, Leg 129.
Sample (cm)
129-802A-
33R-1, 116-12034R-1, 128-13235R-CC, 0-437R-1, 11-1538R-CC, 12-1539R-1, 10-1543 R-1,75-7852R-2, 125-13055R-1, 138-14156R-1,43^756R-2, 88-92
Depth(mbsf)
294.0303.6320.5330.0348.6348.8382.9462.6489.3497.5499.5
Unit
IIIIIIIIIIVIVIVVVIVIIVIIIVIII
Age
early Eoceneearly Eocenelate Paleocenelate Paleocene
late Campanianlate Campanian
SantonianConiacian/Cenomanian(?)
Cenomanianlate Aptian(?)late Aptian(?)
Samplelithology
LimestoneChertChertChert
MudstonePorcellanitePorcellaniteRadiolariteRadiolariteRadiolariteMudstone
Compactedthickness/time
(m/m.y.)
7779
1775.55.55.55.51
Accumulationrate (g/cm2/m.y.)
189717851785
9
9
18691869139113971397452
the chalk. Samples studied from Unit III (Table 3) include radiolarianlimestone with Mn-oxide micronodules and red chert nodules withminor chalk inclusions.
Unit IV is Paleocene to late Campanian in age, 19 m thick, andconsists of zeolitic pelagic claystone with subordinate nannofossilclaystone, porcellanite, chert, and calcareous siltstone and sandstone(Lancelot, Larson, et al., 1990). The claystone contains 15%-40%zeolites, 3%—10% radiolarians, and scattered Fe-Mn oxyhydroxides.The Fe-Mn oxyhydroxides are indicators of deep-water depositionand slow accumulation rates; they are not found in continental margindeposits or areas with high accumulation rates. The claystone is thinlylaminated and commonly bioturbated. Some beds are graded orcross-laminated, and some have convolute layers or flame structures,indicating that they were deposited as turbidites. The samples studiedfrom Unit IV include a millimeter-laminated chert nodule from chalk,calcareous radiolarian mudstone, and massive brown porcellanite.
Unit V is late Campanian to Cenomanian in age, 111m thick, andconsists dominantly of volcaniclastic turbidites up to 1 m thick.Pelagic intervals are represented by claystone containing up to 20%radiolarians and/or nannofossils, which gradationally overlies tuf-faceous claystone. The sample studied from this unit is a greenishgray, slightly calcareous porcellanite from the top of a turbidite bed.
Unit VI is Cenomanian in age, 10 m thick, and consists ofinterbedded brown claystone and radiolarite (Lancelot, Larson, et al.,1990). The claystone contains clay minerals, Fe-Mn oxides, zeolites,and radiolarians in layers up to 125 cm thick. Radiolarite occurs inbeds less than 4 cm thick and ranges from green to gray to brown.Contacts between layers are gradational in some places and sharp inothers. The sample studied from Unit VI is a centimeter-scale beddedbuff-colored radiolarite and reddish brown clay. Bedding contactswithin the sample are sharp, not graded, suggesting alternating depo-sitional conditions.
Unit VII is Cenomanian to late Aptian in age and consists of 27 mof radiolarian limestone, nannofossil chalk, calcareous claystone,clayey sandstone, radiolarite, porcellanite, and chert (Lancelot, Larson,et al., 1990). Beds are laminated to massive and vary from a millimeterto more than a meter thick. The unit boundaries are defined by theoccurrence of carbonate rocks at the top and the base. The samplestudied from this unit is a laminated radiolarite with rare Fe-Mnmicronodules, which is similar to radiolarite from Unit VI.
Unit VIII is late Aptian(?) in age and consists of 2 m of claystonewith thin interbeds of radiolarite (Lancelot, Larson, et al., 1990). Theclaystone is yellowish-brown, thinly laminated, contains Fe oxides,zeolites, Fe-Mn micronodules, and pyritized burrows. Sharp, dis-crete, plane-laminated beds suggest current deposition, whereasscour and grading in some beds suggest turbidite deposition. Radio-larite beds are 1-4 cm thick, comprising approximately 10% ofrecovered core. Some radiolarite beds are graded, with sharp contacts,suggesting turbidite deposition. Samples studied from Unit VIII
include millimeter-laminated radiolarite with radiolarian claystone,and radiolarian claystone.
PALEOMAGNETIC CONSTRAINTS ON LEG 129SITES
The Mesozoic Pacific Ocean, as reconstructed from magneticdata, was larger than the modern Pacific Ocean (Larson and Pittman,1973) but had a strong equatorial current and wind patterns thatapproximately resembled modern patterns (Kennett, 1982). Magneticdata were used to determine paleolatitudes for Sites 800,801, and 802(Lancelot, Larson, et al., 1990; Steiner and Wallick, this volume; Ogget al., this volume), providing geographic constraints for depositionof various lithologic units.
Site 800
The oldest sediments and sedimentary rocks recovered from Site 800are Berriasian, at which time the site was located at approximately2°S and moving southward on the Pacific plate (Ogg et al., thisvolume). This location would have been in the equatorial zone of highproductivity (Bostrom, 1976), during accumulation of the radiolariteof Unit V. The site migrated to approximately 13°S, and startedmoving northward during the Aptian. During the Albian when sili-ceous limestone of Unit III was deposited, the site was still south ofthe equator. Accumulation of the radiolarian chert of Unit II corre-sponds to subsequent transition of the site to north of the equator, andbrown pelagic clay of Unit I marks passage into the northern Pacificprovince of low accumulation.
Site 801
Site 801 was situated approximately 9° south of the equator duringdeposition of radiolarite and claystone of Unit V in the Callovian, andmigrated as far north as 1°S of the equator during deposition of theradiolarite of Unit IV in the Tithonian (Ogg et al., this volume). Thesite moved southward during deposition of the volcaniclastic tur-bidites of Unit III. During the Aptian, Site 801 reached 16° S beforemigrating northward. At this maximum southern latitude for thissite, radiolarite, radiolarian claystone, and calcareous claystone weredeposited between turbidite events as background sedimentation. Thesite crossed the equator during deposition of brown chert and porcel-lanite of Unit II in the Late Cretaceous. In the Maestrichtian, the sitemigrated north of 5°N, into the North Pacific Basin, where Unit Ibrown pelagic clay was deposited.
Site 802
Site 802 was situated slightly south of the equator during deposi-tion of radiolarite, claystone, and turbidites of Units V through VIII
38
LEG 129 SILICEOUS DEPOSITS
in the middle to Late Cretaceous (Lancelot, Larson, et al., 1990).Moving northward, it crossed the equator during accumulation of LateCretaceous to early Paleocene radiolarian claystone of Unit IV, andchalk of Unit III accumulated within a few degrees of the equator.Clay and turbidites of Units I and II were deposited north of theequatorial zone in the late Tertiary to Quaternary.
PALEOCEANOGRAPHIC CONDITIONS
The sequence of deposition at Sites 800, 801, and 802 indicatesthat the conditions of deposition were not symmetrical about theequator or homogenous in the equatorial province, nor were theyconsistent over time. Upwelling of nutrients caused by current shearbetween the northern and southern gyres in the Mesozoic Pacificresulted in high productivity in this zone of divergence at the equator(Heath and Moberly, 1971). Higher productivity results in higheraccumulation rates because biogenic material is exposed for less timeat the seafloor, and consequently less dissolves in corrosive, Si andCa undersaturated bottom waters (Berger, 1976). As a result of theseconditions, in deep water, higher accumulation rates are representedby radiolarite and limestone; lower accumulation rates are repre-sented by claystone. In the Jurassic, radiolarite was deposited betweenan unknown north latitude and at least 9°S, with slightly higheraccumulation rates closer to the equator; no evidence of calcareousdeposition remains, although calculated subsidence curves suggestSite 801 may have been near the carbonate compensation depth(CCD) (Ogg et al., this volume). In the Cretaceous, radiolarite wasdeposited between approximately 5°N and 16°S; calcareous biogenicmaterial was deposited between about 2°S to 10°S. Although sedi-mentary structures indicative of turbidite deposition were not ob-served in Cretaceous calcareous deposits cored, faunal evidence(Erba, this volume; Matsuoka, this volume) suggests at least some ofthe calcareous sediments were redeposited. These calcareous depos-its, recorded at Site 800 and in rare pelagic intervals between volcani-clastic turbidites at Sites 801 and 802, accumulated below the inferredCCD for the Cretaceous (see Ogg et al., this volume). Even if all ofthe Cretaceous calcareous sediments were redeposited, it is signifi-cant that calcareous material was available, since none was depositedor redeposited at shallower depths in the Jurassic. The distribution ofthis calcareous sedimentation (observed only for time intervals whenthese sites were located south of the equator) also suggests thatproductivity was higher on the southern flank of the equatorial zonethan on the northern flank. Accumulation rates for background sedi-ments in the volcaniclastic turbidite units could not be calculated, butthe presence of radiolarite in Cores 129-800A-42R and -43R, andCores 129-801B-8R through -12R, and calcareous claystone in Core129-800A-36R, during which time these sites were at their farthestsouth latitudes, suggests relatively high accumulation rates based onthe criteria mentioned above. In addition, accumulation rates werelower for the brown chert and porcellanite units (Units II), whichrepresent the equator crossings at Sites 800 and 801, than accumula-tion rates for radiolarite or limestone deposited south of the equatorduring the Late Jurassic and Early Cretaceous. Leg 129 data indicatesthat accumulation rates decline rapidly north of the equator (Figs. 1,2, and 3; Tables 4, 5, and 6; Ogg et al., this volume). This observationis in conflict with the curve of accumulation rates for other Pacificsites representing equatorial paleolatitudes plotted in Ogg et al. (thisvolume, fig. 11), and may reflect local variations in sedimentation oraccumulation rate, or differences in productivity and accumulationbetween Early and Late Cretaceous. The combination of factorscontrolling the presence of laminated, current-laid, bioturbated,pelagic, or turbiditic deposits of biogenic material at Leg 129 sites ispoorly understood in detail.
In the Tertiary background sedimentation north of the equator wasclay with less than 10% siliceous or calcareous biogenic material atvery low accumulation rates; we do not have data for this area of thePacific south of the equator during the Tertiary. The low accumulation
rates and low proportion of biogenic material for this claystone alsosuggest lower productivity in the Tertiary than for the same latitudesin the Late Cretaceous.
In the Late Jurassic to Early Cretaceous, the accumulation rate forbiogenic material in the equatorial divergence zone, which apparentlyextended several degrees south of the equator, was approximately1000 g/cm2/m.y. for Leg 129 sites; during the Late Cretaceous the ratefor the same calculated latitude was in the range of 1400 g/cm2/m.y.Immediately north of the equator, accumulation rates for non-redepos-ited biogenic material in the Late Cretaceous were less than700 g/cm2/m.y., and less than 200 g/cm2/m.y. in the Tertiary for Leg 129sites. North of the equatorial divergence zone, accumulation rates wereless than 300 g/cm2/m.y. in the Late Cretaceous and less than 200g/cm2/m.y. in the Tertiary.
Accumulation rates for background sedimentation may havechanged with respect to time and location during the Mesozoic andCenozoic for various reasons. Nonsymmetrical equatorial depositioninterpreted from Leg 129 stratigraphy may have been a function of(1) differences in relative vigor between the northern and southernPacific current gyres, (2) continent configurations and wind patterns,and (3) nutrient input differences between the arctic and antarctic.Factors affecting sedimentation of Leg 129 deposits over time includethe following: (1) small- and large-scale climatic changes that affectedthe width and productivity of the equatorial province (see Ogg et al.,this volume), (2) oceanographic changes in carbonate budget andrelative productivity of calcareous and siliceous organisms, (3) sub-sidence and heat flow on the flanks of the mid-Pacific spreadingridges, (4) local vs. regional intensity of the Cretaceous volcanicevents, and (5) frequency of turbidites that mask local depositionalconditions. Factors affecting accumulation, such as productivity, rateof deposition and burial, and corrosivity of bottom waters alsostrongly influenced the depositional sequence at these sites.
Pelagic clay minerals throughout the stratigraphic section at allthree sites are dominantly smectites (shipboard data and Karpoff,this volume) and may be dominantly authigenic clay minerals, asdescribed by Heath et al. (1974), or they may signify redistributionof volcanogenic material through time. Although the main episodesof volcanic activity in the vicinity of Leg 129 deposits occurredduring the mid- to Late Cretaceous and Miocene, as indicated by thevolcanic sills and volcaniclastic deposits, reworking of the volcani-clastic sediments by turbidites and bottom currents, as described byKelts and Arthur (1981), may have been an important process.
Jurassic
Homogenous radiolarite of Unit IV at Site 801 accumulated atapproximately 1000 g/cm2/m.y. under oxic conditions during the LateJurassic. Deposition was sufficiently rapid to prevent complete dis-solution of radiolarians but slow enough to maintain oxic conditionssouth of the equator. The diagenetic growth of manganese mi-cronodules, some of which are found inside radiolarian tests, suggeststhere was some period of exposure at the seafloor.
Cretaceous
Alternating pelagic claystone and radiolarite of Unit V deposited 2°Sto 10°S during the Early Cretaceous at Site 800 reflect changes inproductivity. This might be a consequence of changes in nutrient avail-ability, which can be enhanced during cooler global climates which forcestronger circulation between the poles and equator (Arthur et al., 1984).When these conditions are cyclic, they correspond to Milankovich cycles,and may contribute to depositional alternations such as were recorded atSites 800 and 801 (Ogg andMolinie, this volume; Ogg et al., this volume).Conditions apparently changed by the time Site 800 returned to the samelatitudes in the Late Cretaceous, at which time more homogenous radio-larian chert and limestone of Unit III were deposited at a greater accumu-lation rate than the alternating radiolarite and claystone of Unit V.
39
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Table 4. Silica contents (in percent) of samples from Site 800, Leg 129.
Sample (cm)
129-800A-
6R-1,76R-6R-7R-7R-8R-8R-8R-9R-
10R-10R-11R-12R-12R-13R-13R-14R-14R-17R-17R-18R-
1,37, 67-69,2-5,66
1,01,22,48-50,30-33,13, 13-17,7-10,30-32,37, 12-14,46, 101, 110-115,25,68-71,70
18R-1, 12118R-1, 127-13019R-1, 119R-1,3721R-2, 822R-1, 1923R-1,69-7024R-1.3024R-1,68-7124R-1,92-9526R-1,22-2626R-1, 135-13927R-1, 61-6427R-1, 110-11428R-3, 106-11030R-1, 125-12930R-2,114-11831R-1, 12-1432R-CC, 10-1333R-7, 14-1834R-2, 139-14235R-3, 84-8836R-1,110-11436R-4, 28-3241R-42R-44R-51R-52R-53R-
,87-93,41^3, 92-94,106-108, 16-20, 32-34
55R-1, 76-8155R-2, 25-3056R-1, 8-1358R- ,37-42
Depth(mbsf)
39.740.040.249.249.858.959.159.468.878.378.387.997.697.7
106.9107.2117.2117.3144.4144.9154.4154.9155.0162.9163.3182.9191.2201.2210.2210.6210.8228.8230.0238.6239.1251.3267.2268.5272.1280.8296.6299.9310.2317.0320.7363.4369.0384.6450.7459.0465.2479.9480.9488.6507.6
Unit
IIIIIIIIIIII11IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVVVVVVVVI
TotalSiO2
85.580.887.389.392.087.589.087.686.692.889.682.885.690.689.869.193.078.262.285.283.692.088.985.580.148.733.683.985.379.490.446.255.055.072.848.675.685.774.070.042.642.367.140.642.343.357.044.580.273.381.083.179.887.095.7
Percentage of sample
BiogenicSiO2
71.063.379.683.487.177.980.880.879.386.983.975.776.582.784.166.888.163.759.676.170.787.182.774.061.547.111.274.174.164.285.236.231.327.059.911.356.675.854.446.7
5.713.441.3
6.05.39.3
24.56.1
62.849.466.771.162.276.893.8
HydrothermalSiO2
0.00.00.00.00.00.00.00.00.11.00.40.00.00.00.10.00.00.00.00.00.00.00.00.00.50.00.30.60.40.00.00.41.41.71.12.31.00.80.00.64.12.72.83.03.35.93.27.80.00.00.40.00.00.00.0
DetritalSiO2
14.517.57.75.95.09.68.36.87.25.05.37.19.17.95.62.35.0
14.52.69.1
12.95.06.2
11.618.21.7
22.19.2
10.915.25.29.6
22.326.311.835.017.99.1
19.622.732.826.223.031.633.728.129.330.617.423.913.912.017.610.2
1.9
Percentage of total silica
BiogenicSiO2
83.078.491.293.394.689.190.792.391.593.693.791.489.491.393.796.794.781.495.889.384.694.693.086.576.896.633.488.386.880.894.378.456.849.082.223.374.988.573.666.713.431.661.614.812.621.442.913.778.367.482.385.578.088.398.0
HydrothermalSiO2
0.00.00.00.00.00.00.00.00.11.10.50.00.00.00.10.00.00.00.00.00.00.00.00.00.60.00.80.70.40.00.00.92.53.11.64.71.40.90.00.99.76.44.17.37.8
13.75.6
17.50.00.00.50.00.00.00.0
DetritalSiO2
17.021.6
8.86.75.4
10.99.37.78.35.35.98.6
10.68.76.23.35.3
18.64.2
10.715.45.47.0
13.522.73.4
65.811.012.819.25.7
20.740.647.816.272.023.710.626.432.476.962.034.377.979.664.951.568.821.732.617.214.522.011.72.0
Notes: Ratios and equations from Heath and Dymond (1977) and Bishoff et al. (1979). Detrital SiO2% = 3.3 (A12O3
= 1.74 [(Fe2O3 - 0.75 A12O3) - 0.32 MnO]; biogenic SiO2% = total SiO2% - hydrothermal SiO2%.); hydrothermal SiO2
In the Early Cretaceous, when Site 801 was 5° to 10° south of theequator, finely laminated to massive radiolarite of Unit IV wasdeposited. By the middle Cretaceous, when Site 801 was as much as16°S, pelagic and biogenic accumulation patterns were masked by theinflux of volcaniclastic turbidites, however relatively high accumu-lation rates are inferred from pelagic radiolarite beds preserved be-tween turbidite beds. When Site 801 migrated north of the equatorduring the Late Cretaceous, alternating pelagic clay and radiolaritemay have accumulated, but poor drilling recovery prevents verifica-tion of this hypothesis. Although the nature of bedding is not certain,
accumulation rates were low and the unit contains more clay than unitsdeposited at similar latitudes south of the equator. The Cretaceousdeposits from Leg 129 suggest that productivity was higher in thesouthern part of equatorial divergence zone than the northern part; alsothe southern part of the zone was apparently greater in breadth.
Tertiary
When Site 802 was in the northern part of the equatorial zone inthe early Tertiary, chalk turbidites of Unit III were deposited. These
40
LEG 129 SILICEOUS DEPOSITS
Table 5. Silica contents (in percent) of samples from Site 801, Leg 129.
Sample (cm)
129-801A-
7R-CC, 18R,1, 1-39R-1,0-3
lOR-1,0-510R-1, 1112R-1,22-2580-100M13R-1, 21-2614R-1,26-2815R-1,24-2616R-1, 135-13817R-1, 28-3018R-2, 14-1719R-CC, 12-1620R-l,8-12
129-801B-
8R-2, 60-631 OR-1,70-7311R-1, 31-3612R-1,64-70HR-1,2414R-1,52-5715R-1, 19-2016R-1, 40-4317R-1,34-3618R-1.2418R-1,37-4019R-1,24-2620R-1,23-2621R-1, 12-1324R-1.5424R-1,69-7325R-1, 125R-1,49-5327R-1.3027R-1, 104-10729R-1, 17-1931R-1, 18-2033R-1, 10-1433R-1.4333R-1, 126-12933R-2, 4835R-1,51-5535R-1, 123-12735R-2, 12035R-2, 14035R-3, 135R-3, 1937R-1.7-1039R-1,4-7
129-801C-
4R-1, 11-165R-4, 11-16
Depth(mbsf)
60.460.670.279.579.699.0
100.0108.7118.5128.1139.0147.5158.6176.3176.5
254.8272.7282.0292.0310.5310.8319.9329.6338.9348.0348.2357.5366.7375.8393.1393.3397.2397.7407.0407.7416.4425.8434.9435.2436.1436.8444.8445.5447.0447.2447.3447.5453.6462.7
521.8535.8
Unit
IIIIIIII11IIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVIVVVVVVVVVI
VIVI
TotalSiO2
90.896.783.989.890.576.382.884.186.079.675.478.976.982.988.6
89.558.077.177.482.585.282.993.192.485.491.095.591.892.885.390.785.984.796.893.792.792.868.781.483.783.764.674.556.364.866.769.891.894.8
81.111.4
Percentage of sample
BiogenicSiO2
84.595.472.784.583.658.371.272.977.264.958.864.460.973.182.4
83.625.858.959.166.774.569.189.187.773.285.293.786.786.874.684.274.672.695.690.388.288.338.364.269.370.730.549.812.330.434.240.184.990.4
53.63.9
HydrothermalSiO2
0.00.00.00.00.00.00.00.00.01.81.10.90.91.10.6
0.15.30.76.00.00.00.00.00.00.00.00.00.01.50.10.00.10.00.20.00.00.09.72.31.13.16.27.56.77.04.83.94.81.9
27.25.9
DetritalSiO2
6.31.3
11.25.36.9
18.011.611.28.8
12.815.513.515.18.75.7
5.826.917.612.315.810.713.84.04.7
12.25.81.85.14.5
10.66.5
11.212.1
1.03.44.54.5
20.614.913.39.9
27.917.237.327.427.725.72.02.4
0.31.5
Percentage of total silica
BiogenicSiO2
93.198.786.694.092.376.586.086.789.781.677.981.779.288.193.0
93.444.576.376.380.887.583.495.794.985.793.698.194.493.587.592.986.885.798.796.395.295.155.878.982.884.447.366.921.946.951.357.592.595.4
66.134.6
HydrothermalSiO2
0.00.00.00.00.00.00.00.00.02.31.41.21.21.40.6
0.19.20.97.80.00.00.00.00.00.00.00.00.01.60.20.00.10.00.30.00.00.0
14.22.81.33.79.6
10.111.910.87.15.65.32.0
33.552.1
DetritalSiO2
6.91.3
13.46.07.7
23.514.013.310.316.120.617.114.610.56.4
6.546.322.815.919.212.516.64.35.1
14.36.41.95.64.8
12.47.1
13.114.3
1.03.64.84.9
30.018.215.811.843.123.066.242.341.636.92.22.6
0.413.3
Notes: Ratios and equations from Heath and Dymond (1977) and Bishoff et al. (1979). Detrital SiO2% = 3.3 (A12O3%); hydrothermalSiO2% = 1.74 [(Fe2O3 - 0.75 A12O3) - 0.32 MnO]; biogenic SiO2% = total SiO2% - detrital SiO2% - hydrothermal SiO2%.
voluminous deposits have masked clues to depositional conditionsat this location in the Tertiary. Background sedimentation at theequator consisted of pelagic clay with less than 10% siliceous orcalcareous fauna and low accumulation rates. Sites 800 and 801 werenorth of the equatorial zone during the Tertiary, where sedimentationand accumulation rates were both extremely low, and pelagic claywas deposited.
GEOCHEMISTRY OF LEG 129 SILICEOUSDEPOSITS
Leg 129 sedimentary rocks were analyzed geochemically in orderto characterize various types of siliceous deposits. Trends in elementabundance were consistent between the three sites. Elements testedas key environmental indicators include Si, Fe, Mn, Mg, Al, B, P, Ba,
41
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Table 6. Silica contents (in percent) of samples from Site 802, Leg 129.
Sample (cm)
129-802 A-
33R-1, 116-12034R-1, 128-13235R-CC, 0-437R-1, 11-1538R-CC, 12-1539R-1, 10-1543R-1, 75-7852R-2, 125-13055R-1, 138-14156R-1,43^756R-2, 88-92
Depth(mbsf)
294.0303.6320.5330.0348.6348.8382.9462.6489.3497.5499.5
Unit
IIIIIIIIIIVIVIVVVIVIIVIIIVIII
TotalSiO2
45.595.894.888.965.470.077.873.276.370.778.8
Percentage of sample
BiogenicSiO2
42.195.293.286.343.653.862.249.856.944.561.9
HydrothermalSiO2
0.00.00.00.00.51.20.00.00.00.04.6
DetritalSiO2
3.40.61.62.6
21.315.015.623.419.426.212.2
Percentage of total silica
BiogenicSiO2
92.599.398.497.066.676.880.068.174.563.078.6
HydrothermalSiO2
0.00.00.00.00.81.70.00.00.00.05.9
DetritalSiO2
7.50.71.63.0
32.521.520.031.925.537.015.5
Notes: Ratios and equations from Heath and Dymond (1977) and Bishoff et al. (1979). Detrital SiO2% = 3.3 (A12O3%); hydrothermalSiO2% = 1.74 [(Fe2O3 - 0.75 A12O3) - 0.32 MnO]; biogenic SiO2% = total SiO2% - detrital SiO2% - hydrothermal SiO2%.
Cu, La, and Ce. Because some elements are characteristic of morethan one depositional environment, element ratios and partitioningequations have been derived to discriminate between environments(Bishoff et al., 1979, Leinen and Stakes, 1979; Leinen, 1981; Leinenand Pisias, 1982). Aluminum to metal ratios plotted according todefined fields in various diagrams (Bostrom, 1973, Karpoff et al.,1988; Karpoff, 1989) help to determine detrital and metalliferoussources of the sediments. A copper-barium plot discriminates betweenbiogenic and authigenic sources (Karl, 1982). Finally, rare earthelement (REE) patterns are compared in order to identify sedimentarysources and depositional trends.
Methods of Analysis
One hundred and one samples of siliceous rocks were chosen fromSites 800, 801, and 802. These samples were selected to representbackground sedimentation as well as depositional episodes, such ashigh productivity events or turbidite events. For example, in theturbidite units, both the fine-grained tops of turbidites and the pelagicinterval between turbidites were sampled for purposes of comparison.In the alternating chert/shale units, both lithologies were sampled.Statistically, however, each unit is represented overwhelmingly bypelagic deposits in this study. Poor recovery in general at Leg 129sites, and in particular for siliceous lithologies, limited our ability toadequately sample every unit.
Samples studied each weighed approximately 15 g and wereground to -100 mesh in a tungsten carbide mill. Tungsten carbidemills are known to contaminate samples in Co, Nb, Ta, and W; thiscrushing equipment was chosen because these elements were consid-ered less important than contaminating elements from other means ofcrushing. After crushing the samples were divided into three splits.One split was analyzed nondestructively for minor elements by X-rayspectroscopy, and by X-ray fluorescence for major elements (Appen-dix Tables A1-A3 and B1-B3). The precision of the minor elementanalyses is approximately 10%, and of the major elements is l%-2%.The second split was analyzed for Boron by quantitative emissionspectroscopy. Rare earth element compositions were determined onthe third split by induced neutron activation analysis (AppendixTables C1-C3). The samples were irradiated for 7 hr in the TRIGAreactor at the U.S. Geological Survey in Denver, and counted 4 timesover 8 weeks.
Thirty additional samples of siliceous rocks were analyzed formajor and minor elements by microprobe at the University of Stras-bourg, France (Appendix Tables Dl and D2). The precision of theseanalyses is about 2% for major elements and 10% for minor elements,
which is comparable to the analyses performed in the U.S. GeologicalSurvey laboratories. Consequently these data were plotted togetherwhere appropriate.
Results
Silica
The two main sources of silica in the ocean are detrital aluminosili-cates (both terrigenous and volcaniclastic) and biogenic tests (Bostromet al., 1974; Heath, 1974; Berger, 1976). Alteration of clays and volcanicglass, and hydrothermal emanations also contribute minor amounts ofsilica (Rona et al., 1980). Since the ocean is 98% undersaturated withrespect to silica (Berger, 1976), biogenic siliceous deposits only accumu-late under areas with high rates of deposition. High rates of depositionare controlled by the availability of nutrients, which are brought up to thephotic zone in regions of current shear, such as the equatorial divergence,or where winds and currents impinge on continental margins (Kennett,1982). Siliceous deposits in the modern Pacific Ocean accumulate nearthe equator, at high latitudes, and along the continental margins (Ber-ger, 1976; Keene, 1976; Jenkyns, 1978). At the equator, productivityis ultimately controlled mainly by climate, because temperature con-trast between the poles and equator during cool climates drives strongerwinds and currents. During times of low productivity, only pelagic clayaccumulates. The cyclicity of pelagic clay and siliceous deposits on acentimeter scale has been attributed cyclic climatic variations, orMilankovitch cycles (RCCG, 1986; Rea et al., 1991).
The siliceous deposits at Sites 800, 801, and 802 were depositedbetween 5°N and 15° S of the equator, and are dominantly biogenic.The central Pacific low-latitude paleo-location of these sites, withwinds from the east, resulted in a negligible contribution of terrige-nous material to this area during deposition of the sediments sampledfor this study. Illite and quartz grains signify terrigenous contributionsto siliceous deposits; the scarcity of illite and the lack of quartz grainsin Leg 129 deposits suggests most of the detrital sediments arevolcaniclastic. Interbedded volcaniclastic turbidites indicate an inter-mittent volcanic source. Reworking of volcanic detritus by bottomcurrents between volcanic episodes may have intercalated volcanicmaterial with the pelagic deposits. There was probably some contri-bution of silica from alteration of volcanic-derived clay minerals andglass in the volcaniclastic turbidite sections. At the base of Site 801,there is hydrothermal silica.
Partitioning ratios for elements representing the above sedimentsources were used to calculate relative proportions of these sources.Partitioning of silica, based on ratios and equations from Heath andDymond (1977) and Bishoff et al. (1979) (Tables 4, 5, and 6), shows
ODP SITE 800 (Fe% (XRF AND MICROPROBE))
LEG 129 SILICEOUS DEPOSITS
ODP SITE 801 (Fe% (XRF AND MICROPROBE))
-20
-60
-100
-140
-180
-220
-260
-300
-340
-380
-420
-460
-500
-540
-
- •— •
•
• •- •
•
•
-•
_
-
—
m
• ••
•
•
••
• •
••
• •
•
• • "•
•
• •
1
••
• •
• "•
1
1
II
IV
V
VI
0
-50
-100
-150
-200
-250
-300
-350
-400
-450
-500
-550
-
•••
•••
-
• •
•
-
•••
— • ••
••
_ • . 1••
•
—
•
••
•
•
• mm
m
m
i
•
•
• # •
•
•
•
1
1
II
IM
IV
V
VI
6
Fθ%
10 12 6
Fβ%
10 12
ODP SITE 802 (Fe% (XRF))
-250
-300 i-
-350
-400
-450
-500
-550
•
•
•
•
•
— • •
-
I I I I I
III
IV
V
VI
VII
VIII-IX
X
0 2 4 6
Fθ%
10 12
Figure 4. Iron contents of samples from Leg 129.
43
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
ODP SITE 800 (Mn% (XRF AND MICROPROBE))
-20
-60
-100
-140
-180
_ -220CO
£ -260
Φ -300Q
-340
-380
-420
-460
-500
-540
0.0
ODP SITE 801 (Mn% (XRF AND MICROPROBE))
-
• • •• •
— • • ••
•
X •
— ••
a• •
• ••
•
- ••
" ••
• •~ •
• •
•
1
II
III
IV
V
VI
0
-50
-100
-150
-200
-250
-300 f•
-350
-400
-450
-500
-550
-
•• •
• ••
•
••
•
X•
••
••
•— • •
••
•
• • •• •
••
•i•
-• ta•
m
1 , f , •
1
II
III
IV
V
VI
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Mn%
ODP SITE 802 (Mn% (XRF))
-250
-300
-350
-400
-450 -
-500
-550
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 O.f
Mn%
Figure 5. Manganese contents of samples from Leg 129.
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.J
Mn%
••
•
•
•
•
—• •
I I
III
IV
V
VI
VM
VIII-IX
X
44
ODP SITE 800 (Mg% (XRF AND MICROPROBE))
LEG 129 SILICEOUS DEPOSITS
ODP SITE 801 (Mg% (XRF AND MICROPROBE))
-20
-60
-100
-140
-180
_ -220CO
£ -260
S• -300
-340
-380
-420
-460
-500
-540
0
-50
-100
-150
-200
| -250
JS
g• -300Q
-350
-400
-450
-500
-550
1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8
Mg% Mg%
ODP SITE 802 (Mg% (XRF))
-
- • • •
••
_ •• •_ • •
• •• •
~• ••• •
- • ••
•• •
•
. •
- • •• •
I
1 1 1
1
II
III
IV
V
VI
-
•l•
•""
• •• •- • •
••
••
•••-• •1•
•• • •
• rt •
I
1 1 1
1
II
III
IV
V
VI
-300
-350
-400
•450
-500
.sen
•V
m
—
—
•
•
1 1 1 1 1
III
IV
V
VI
VII
V I I I -IX
X
0 1 2 3 4 5 6 7 8
Mg%
Figure 6. Magnesium contents of samples from Leg 129.
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
ODP SITE 800 (Al% (XRF AND MICROPROBE))
-20 -
• ••60 h • • •
-140
-180
_ -220m
1 -260
g• -300Q
-340
•380
-420
-460
-500
-540
IV
VI
ODP SITE 801 (Al% (XRF AND MICROPROBE))
-50
-100
-150
-200
-250
-300 \
-350
-400
-450
-500
-550
-
•• •
— • ••
••
••
• •
••
•
•••
— • ••
••
• • • •• •
••
• • • •
I
1 1
1
II
III
IV
V
VI
ODP SITE 802 (Al% (XRF))
-250
-300 =-
-350
-400
-450 -
-500
-550
•
•
•
•
•
— • •
1 1 1 1
III
IV
V
VI
VII
VIII-IX
X
Figure 7. Aluminum contents of samples from Leg 129.
46
ODP SITE 800 (P% (XRF))
LEG 129 SILICEOUS DEPOSITS
ODP SITE 801 (P% (XRF))
-20
-60
-100
-140
-180
-220
-260
-300
-340
-380
-420
-460
-500
-540
-
-—
••
-
••
•
•--
-
—
••
•-
1
•
•
••
•
••
•
•
1
••
•
••
•1
• ••
1
II
III
IV
V
VI
0
-50
-100
-150
-200
-250
-300
-350
-400
-450
-500
-550
a
-
—
-
—
•
••
•_ 1
•
-••
••
•
•
•
••
••
•
•
••
• ••
••
••
••
•
••
•
1 1
1
II
III
IV
V
VI
0.00 0.05 0.10
P%
0.15 0.20 0.00 0.05
ODP SITE 802 (P% (XRF))
-250
-300
-350
-400 -
-450
-500
-550
•
•
•
•
•
— • •
I I
III
IV
V
VI
VII
VIII-IX
X
0.00 0.05 0.10
P%
0.15 0.20
0.10
P%
0.15 0.20
Figure 8. Phosphorous contents of samples from Leg 129.
47
Figure 9. Boron contents of samples from Leg 129.
ODP SITE 800 (B ppm (MASS SPEC.))
-20 - I- i
-60 - • B 'I
-100 - m ••
• 1 4 0 : . in
-180 -
_ -220 - _
t -260 . . .c •S -300 - • •
* IV
-340 -
-380 - .
-420 -
-460 - ~~m • •~~
V-500 = —"
I I I I I I I V l
.540 I I I I I I I I I I I I I I I I I I
0 10 20 30 40 50 60 70 80
B ppm
ODP SITE 801 (B ppm (MASS SPEC.))
o I 1 1
i
-50 -•
•
-100 - • • • "•
-150 - a •
• •
-200 -_ III
| -250 - .•
JZ •
I" -300 - •Q •
•
-350 - • " u
• " IV
-400 - u • ••
• •-450 - . m r ~ V
—Ü
-500 - vi•
. 5 5 0 F I I I I I I I I I 1 I 1 I I I I I0 10 20 30 40 50 60 70 80
B ppm
ODP SITE 802 (B ppm (MASS SPEC.))
-250 | 1 1
-300 - a
m•
IV-350 . •
"5 _.Q •E~ -400 - Va.Φ
a
-450 -
• ~~vi~
VII
-500 — " i VNT
! ×_
X
-550 I—!—I—I I ! I I I—!—I I I I I I L J0 10 20 30 40 50 60 70 80
B ppm
Figure 10. Lanthanum contents of samples from Leg 129.
ODP SITE 800 (La ppm (INAA))
-20 - I_ B
-60 - jj• "_ m
-100 - m ••
-180 -
c • W = ' • ' * .•» • •
i -260 - . - ".£ •
I" -300 - %IV
-340 -
• .
-380 - •
-420 -
-460 - ~~" B ~ •• • • V
.500 =iI I I I I V l
. 5 4 0 I I I I I I 1 I I I I I I I 1 I I I I 1
0 5 10 15 20 25 30 35 40 45
La ppm
ODP SITE 801 (La ppm (INAA))
o | i
i
-50 = _ B
••
-100 - •• "• •
-150 - •
• •
-200 -III
1 -250 -•
J= m
g• -300 - •
•
-350 -u " •
- " • IV
-400 - m • ••
•• •
-450 - . ~~•~ *~ V•
-500 ~ v|
. 5 5 0 1 * 1 I I I I I I I I I I I I I I I I i
0 5 10 15 20 25 30 35 40 45
La ppm
ODP SITE 802 (La ppm (INAA))
-250 | 1 1
111
-300 - m
m
•
IV
-350 • •
^ •E"2 -400 - Vo.ΦQ
-450 -
• VI
VII
-500 = i • vüT[x_
X
-550 I — I — I — L J I—I I I I I | | I I | | L J
0 5 10 15 20 25 30 35 40 45
La ppm
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
that the silica at all three sites is predominantly biogenic, with a high(volcaniclastic) detrital component in the samples from the turbiditeunits. Thin section observations, microprobe, and XRD analysesindicate that the clay minerals at Sites 800, 801, and 802 are domi-nantly undifferentiated smectites, including rare montmorillonite,that are most likely volcanogenic. The apparent hydrothermal silicathat shows up in the turbidite units may in part be due to inadequaciesof the partitioning ratios, and to unaccounted-for excess iron that mayhave been concentrated and mobilized by diagenetic processes. Smallamounts of Fe and Al in biogenic material (Bostrom, 1976) are alsounaccounted for in these partitioning calculations.
Iron
In the modern Pacific Ocean iron is most concentrated in sedimentson the East Pacific rise and in areas of volcanic arcs (Bostrom et al., 1973).The accumulation of Fe in sediments near spreading ridges appears to beproportional to spreading rates, and probably has a magmatic source(Bostrom, 1973; Bishoff et al., 1980; Dean et al., 1989). Iron is carried inslightly reduced CO2-rich fluids, and is the first element to precipitate asamorphous oxides with amorphous silica, as the chemical environmentbecomes more oxidized at the seafloor, followed by Mn, Cu, and Ni(Bostrom et al., 1973; Lonsdale et al., 1980).
At Site 800, Fe is the most abundant in the volcaniclastic unit(Fig. 4), suggesting a predominantly volcanic detrital source. It de-creases upward in the overlying unit, possibly indicating a gradation-ally decreasing volcaniclastic contribution. The tops of Unit III andUnit II are apparently free of volcaniclastic detritus. The slight Feenrichment in Unit V may result in part from hydrothermal or diage-netic mobilization of Fe from the underlying dolerite sills.
Thin sections from hydrothermal deposits at the base of Site 801contain coarsely-crystalline quartz and iron oxides that are apparentlychemically precipitated. The sediments immediately overlying thebasalt contain amorphous iron and silica in addition to abundantradiolarian tests. At Site 801, Fe concentrations (Fig. 4) are generallycomparable to those at Site 800, especially in the turbidite unit, butthey are remarkably high in the basal and interpiU°w sediments. Thesevalues are consistent with moderate to fast spreading rates for thismid-ocean ridge (Lancelot, Larson, et al., 1990).
At Site 802, Fe concentrations are low in the chalk unit, and similarto Sites 800 and 801 in the volcaniclastic turbidite units (Fig. 4).
Manganese
The distribution of Mn in sediments in the modern Pacific Ocean ismainly associated with spreading ridges and seamounts, suggesting asource similar to that of Fe. However, the diagenetic behavior of Mn isdifferent from that of Fe. Manganese is very mobile in reducing environ-ments, and requires a more oxidizing environment than Fe to precipitate.At Sites 800 and 801, Mn may have been preferentially mobilized bydiagenetic processes and migrated up the section. Since bottom waters inthe central paleo-Pacific apparently were oxidizing, but since organicmatter could have reduced buried sediments, Mn may have movedupward through reduced sediments in the sedimentary column, andaccumulated at a redox boundary, which commonly occurs where thereis a change to slow depositional and accumulation rates (Drever, 1982).
At Site 800, Mn concentrations are highest in Units II and V(Fig. 5), the units with the lowest accumulation rates. Moderate Mnabundances in Unit IV may reflect a volcaniclastic source, or repre-sent pelagic intervals of low accumulation.
At Site 801, Mn is also high in the units with low accumulationrates (Fig. 5). The increase of Mn in Unit IV relative to underlyingUnit V may be due to diagenetic remobilization, since Mn is lowrelative to Fe in Unit V, but may be partly hydrothermal.
Manganese is very low in all units at Site 802 (Fig. 5) relative tounits at Sites 800 and 801, but is highest in the pelagic sedimentsoverlying the pillow basalt at the base of the hole.
The Fe/Mn ratios of ridge crest hydrothermal sediments is ap-proximately 3 (Bostrom, 1973; Bishoff et al, 1979). Fe/Mn ratios areconsiderably higher than 3 for all units at all three sites, suggesting,as did the silica calculations, that detrital Fe is a more significantsource of Fe than hydrothermal Fe, but also that remobilization of Mnmay be an important diagenetic process.
Magnesium
A major source of magnesium in marine sediments is maficdetritus from weathering of basalt or volcaniclastic material (Bishoffet al., 1979). A detrital source for Mg at all three sites is indicated bythe highest Mg values in the turbidite units (Fig. 6). Mg values arealso high in the basal units at Site 801, which could be authigenic Mgderived from seawater or detrital Mg derived from weathering ofbasalt at the seafloor. Carbonate rocks are another source of Mg, butMg values are similarly low in the limestone and radiolarite units atall three sites.
Aluminum
Aluminum in marine sediments is derived dominantly from detri-tal sources. This is supported by high Al values in the turbidite unitsat all three sites (Fig. 7). As with Mg, the high Al values in the basalsediments at Site 801 strongly suggest weathering of basement as onesource for these sediments. This hypothesis is supported by highFe/Mn values for Unit V at Site 801.
Phosphorous
Phosphorous is carried in some hydrothermal fluids (Bostrom,1973), but is mainly associated with biogenic debris in marine sedi-ments (Berger, 1976). Under more alkaline conditions, phosphate ismore mobile than iron, and thus tends to be enriched in more reducedsediments (Price, 1976).
At Sites 800, 801, and 802 the abundance of P is consistently low,but is highest at the base of the turbidite units (Fig. 8), which are morereduced than the other units. P is also relatively abundant in theradiolarite/claystone units at Site 801. Fish parts were observed in thinsections of chert, claystone, and volcaniclastic rocks from several units,and thus the likely source of P at all three sites is fish debris.
Boron
Boron is considered to be a biogenic indicator and is found mainlyin sponge spicules, which are associated with shallow-water deposits(Hein et al, 1981, 1982; Truscott and Shaw, 1983). No shallow-watersediments were drilled on Leg 129, and sponge spicules are extremelyrare, only observed in sandstone and chalk turbidites that were rede-posited from shallow water.
Boron concentrations are low in all units, and there are no strati-graphic trends (Fig. 9). Special effort was made to measure boronquantitatively. Results indicate that boron is not important in deep-water deposits. In fact, the lack of boron may be useful as a deep-waterenvironmental indicator.
Lanthanum
Lanthanum abundances in sedimentary rocks reflect total REEabundances because REE have very similar physical and chemicalproperties (Henderson, 1984). The source of REE in deep marinesediments is controversial, but generally assumed to be seawater, fromwhich it is adsorbed mainly onto authigenic or biogenic phases (Piper,1974). Eolian or other detritral sources are volumetrically less important.
La abundances in siliceous samples from Leg 129 are generallyhighest in the samples from pelagic units with the lowest accumula-tion rates, and higher in the pelagic samples with clay than in pelagic
50
Figure 11. Cerium contents of samples from Leg 129.
ODP SITE 802 (Ce ppm (INAA))
- 2 5 0 | •
III-300 - .
••
IV-350 — • •
M
-α •E~ -400 - VQ.ΦQ
-450 -
• ~~vT~
. v "-500 - — l • virT
. ix_
X
-550 ' 1 1 I I I I I 1 I 1 I L . _
0 10 20 30 40 50 60
CΘ ppm
ODP SITE 800 (Ce ppm (INAA))
-20 - I- •
-60 - • a "= •—
-100 - m " ••
-140 7 . • III
-180•
C - 2 2 0 = . — ' .2 m •E -260 - . . .JS - .
g" -300 *
" • • ,v
-340 -
-380 - .
-420 -
-460 - -
-500 = . "I V l
.540 I 1 1 1 1 1 1 1 1 1 1 1 1 1
0 10 20 30 40 50 60
Ce ppm
ODP SITE 801 (Ce ppm (INAA))
o | 1
i
-50 = β
••
-100 - • m • ".
.-150 ~ •
-200 -III
1 -250 - .
j= •
S" -300 = •
m
-350 - m " •
- . " IV
-400 - " ••
•. •
-450 - . ~~÷~~ ~~*~ V— a
-500 — vi
i
-550 L^J 1 1 1 1 1 1 1 1 1 1 1
0 10 20 30 40 50 60
CΘ ppm
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
ODP SITE 800 (Ce ppm/AI%)
-20
-60
-100
-140
-180
._. -220n
& -260
g• -300 rα
-340
-380
-420
-460
-500
-540
0 2 4 6 8 10 12 14 16 18 20 22 0 2 4
(Cβ ppm)/(AI%)
ODP SITE 802 (Ce ppm/AI%)
-250
-300
-350
-400 -
-450 -
-500
ODP SITE 801 (Ce ppm/AI%)
-
-
_
—
-
•
•
••
•
1
•
1 1 1
•
•
•
•
•
• •
1•
•
•
••
1 1
••
••
••
1 1
1
II
III
IV
V
VI
u
-50
-100
-150
-200
-250
-300
-350
-400
-450
-500
-550
•
— •••
•_ •
•
••
••
•_ •
••
•
• ••
•• •
•
•
I I ^ I I I I I
•
I I
I
II
III
IV
V
VI
8 10 12 14 16 18 20 22
Cβ ppm/AI%
-550
-
•
•
•
-
•
•
•J i •
I I I
III
IV
V
VI
VII
V I I I -IX
X
8 10 12 14 16 18 20 22
Cθ ppm/AI%
Figure 12. Cerium/aluminum ratios for samples from Leg 129.
52
ODP SITE 800 (AI/(AI+Fe+Mn) (XRF AND MICROPROBE))
LEG 129 SILICEOUS DEPOSITS
ODP SITE 801 (AI/(AI+Fe+Mn)(XRF AND MICROPROBE))
-20
-60
-100
-140
-180
_ -220
B. -260
I" -300Q
-340
-380
-420
-460
-500
-540
III
IV
VI
-50
-100
-150
-200
-250
-300 r
-350
-400
-450
-500
-550
-
-
—
-
-
-
•
-
1
•
•
•
• •
•
1
•
••••
••••
•••
•
•
•
•
•I
•• •
••
••
• ••
•
1
1
II
IV
V
VI
0.0 0.1 0.2 0.3 0.4 0.5 0.6
AI/(AI+Fθ+Mn)
ODP SITE 802 (AI/(AI+Fe+Mn) (XRF))
-250
-300 -
-350
-400 -
-450
-500
0.0 0.1 0.2 0.3 0.4 0.5 0.6
AI/(AI+Fβ+Mn)
••
•
•
•
•
— • •
-
I I I
III
IV
V
VI
VII
VIII-IX
X
0.0 0.1 0.2 0.3 0.4 0.5 0.6
AI/(AI+Fβ+Mn)
Figure 13. Aluminum/metal ratios for samples from Leg 129.
53
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
ODP SITE 800 (Fe/Ti VERSUS AI/(AI+Fe+Mn)) ODP SITE 801 (Fe/Ti VERSUS AI/(AI+Fe+Mn))
1000
100 -
10 -
1
1000
100 -
10 -
1
•,H
\λ \
Ii
i i
i i
i i
1
\
\ X\ A +
o \ .
X
s
0
+
•
"i 0
^ Δ B
1 \
UnitUnitUnitUnitUnit
B-T
1
IIII!IVVVI
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
AI/(AI+Fθ+Mn)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
AI/(AI+Fβ+Mn)
ODP SITE 802 (Fe/Ti VERSUS AI/(AI+Fe+Mn))
1000
100 -
10 -
- H
j\i\\\
i i
i i
i i
MI
i
E Unit III
* Unit IV
o Unit V
* Unit VI
• Unit VII
D Unit VII
D
1
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
AI/(AI+Fβ+Mn)
Figure 14. Plot of Fe/Ti vs. A1/(A1 + Fe + Mn) (after Bostrom, 1973). H = hydrothermal compositional end-member, T = terrigenous compositional end-member,
B = basaltic compositional end-member.
LEG 129 SILICEOUS DEPOSITS
samples without clay. There is also a subtle increase in the La contentsof samples upsection at each site. At Site 800, the lowest concentra-tions of La are in radiolarian chert and limestone of Unit III (Fig. 10).The highest concentrations of La are in claystone samples from thetops of turbidite beds, but high La concentrations are not restricted tothese beds. At Site 801, REE are virtually absent in the hydrothermaldeposits within the pillow basalt section at the base of the hole (Fig. 10).La concentrations in the rest of the section are lowest in biogenicsamples in Unit VI, deposited on basement, and highest in a claysample from Unit V near basement. La abundances are higher in thepelagic samples with clay than in the clay-poor radiolarite of Unit IV.At Site 802, La concentrations are lowest in the nannofossil chalk unitand the highest La "concentrations of all three sites are in pelagicclaystone of Unit VI (Fig. 10).
The relative abundances of La in the samples studied suggest thathigh La (and REE) concentrations correspond to high clay contents,and that clay from units with low accumulation rates have generallyhigher La abundances than clay associated with the volcaniclasticturbidites. There appears to be a possible detrital source of REEdeposited on basement at Site 801, and in the volcaniclastic depositsat all three sites, but an authigenic source for La and the REE seems tobe dominant in all units. A biogenic source for REE is also indicated,but appears to be subordinate to authigenic sources.
Cerium
Cerium is typically depleted with respect to the other REE indeep-water pelagic sediments. It is not depleted in shallow-waterterrigenous sediments (Shimizu and Masuda, 1977; Murray et al.,1990), and it is not depleted in eolian pelagic sediments in the Pacific(Olivarez et al., 1991). Toyoda et al. (1990) found that the negativecerium anomaly is mainly associated with sediments deposited atspreading ridges and equatorial divergence zones, in sediments withlow accumulation rates and relatively high REE contents. The deple-tion of cerium in deep-water sediments is thought to reflect thenegative Ce anomaly that characterizes seawater, which is conse-quently thought to be the source of REE in deep marine pelagicsediments (Bostrom et al., 1973; Piper, 1974; Henderson, 1984).Cerium is depleted in many pelagic constituents, including fora-minifers, pteropods, fish bones, diatoms, and radiolarians, and also inauthigenic minerals such as barite, phosphorite, phillipsite, and thevarious smectites (Piper, 1974; Toyoda et al, 1990). Cerium is notdepleted with respect to the other REE in illite or other terrigenousclay minerals, nor is there a cerium anomaly in volcanogenic clayminerals. Cerium is enriched in ferromanganese nodules, whichadsorb Ce from seawater, and may be responsible for the depletion ofCe in seawater (Piper, 1974). Ce is preferentially extracted (relativeto La and Nd) from seawater because it is the only REE that oxidizeseasily in seawater, and oxidized Ce is highly insoluble (Piper, 1974).
Ce concentrations for Leg 129 siliceous deposits (Fig. 11) aregenerally very similar to La concentrations, with the exception ofsamples rich in Mn and Fe-Mn oxides. This observation is consistentwith high Ce contents in Fe-Mn oxyhydroxides observed elsewherein the deep Pacific (Piper, 1974). The distribution of high Ce concen-trations supports a dominant authigenic source, ultimately derivedfrom seawater, for Ce. The negative Ce anomalies for sediments fromthe pelagic units also supports a seawater source.
Ce/Al
Since La and Ce abundances suggest a detrital source for some ofthe REE in units with detrital constituents, the Ce/Al ratio was plottedin order to test the proportion of Ce that is detrital relative to theproportion that is authigenic or biogenic. In general the ratio for allthree sites has a similar range. At Site 800 the Ce/Al ratio is higher inthe pelagic units and lower in the volcaniclastic units, suggesting
detrital sources of Ce are subordinate to pelagic sources (Fig. 12). AtSite 801, the Ce/Al ratio is highest in the brown chert and porcellaniteof Unit II, and the lowest of all three sites in basal Units V and VI,distinctly suggesting a detrital source for those sediments, and that Ceis not derived from this source (Fig. 12). The volcaniclastic depositsalso have a relatively low Ce/Al ratio. The Ce/Al ratios for samplesfrom Site 802 are highest in the dominantly biogenic units, andrelatively high for the pelagic interval sampled in the turbidite unit(Fig. 12). The ratio is lowest in the claystone sample from Unit VIII,which may include tuffaceous clay similar to the subjacent unit.
The variation in the Ce/Al ratio, and the trend of high values forsediments in pelagic units and low values for sediments in detritalunits suggests independent sources for these two elements, and sup-ports an authigenic or seawater source rather than a detrital source forCe and the other REE.
MULTIELEMENT PLOTS
Multielement plots are another method of visually partitioningsource components in sedimentary rocks. A few of these plots showinteresting trends.
Al-Fe-Mn
The ratio A1/(A1 + Fe + Mn) is an index of detrital claycomponent, and generally a ratio greater than 0.4 is considered toindicate a detrital source in marine sediments (Bostrom and Peter-son, 1969; Bostrom, 1973). All samples studied from Site 800 havevalues at or above 0.4 for this ratio (Fig. 13). At Site 801, only thelower part of the Unit IV radiolarite, and Units V and VI havevalues less than 0.4 (Fig. 13), suggesting the lack of a detritalsource. At Site 802, only one sample from Unit VIII has a valueless than 0.4 (Fig. 13). Because XRD and microprobe analyseshave detected only traces of possible illite in these units (Karpoff,this volume), and because of wind and current patterns in thePacific Ocean (Kennett, 1982) a terrigenous (eolian) source islikely to be a very small contributor to the high aluminum to metalratios for these sites. A plot of Fe/Ti to A1/(A1 + Fe + Mn)(Bostrom, 1973) better clarifies source components for Leg 129sediments. All of the samples from Site 800 fall in a general areabetween terrigenous and basaltic compositions (Fig. 14). At Site801, however, there is a distinct downsection trend toward thehydrothermal end-member as the position of the samples ap-proaches mid-ocean ridge basalt (MORB) basement, a reflectionof the high Fe contents of these sediments (Fig. 14). At Sites 800and 801, another discernible trend is that sediments with higheraccumulation rates fall closer to the basaltic end-member. Thesamples from Site 802 tend to plot closer to the basalt end-member(Fig. 14), which also coincides with higher accumulation rates.Samples studied from Unit VIII at Site 802 reflect a slight hy-drothermal signature, in support of previous observations of Mnabundance in that unit.
On a triangular plot of Al-Fe-Mn (Fig. 15), with fields defined byclay deposits from specific oceanic environments (Karpoff, 1989),the samples from Sites 801 and 802 fall on a trend from biogenic oozefor the upper units, to oceanic basalts for the lower units in each hole.This is consistent with indications from the single-element plots thatvolcanic detritus from the seafloor is mixed in with biogenic materialnear basement. The trend is not so pronounced for Site 800 where thehole bottoms in intrusive rocks rather than basement.
On an Si-Fe-Mn plot (Fig. 16) Leg 129 samples are compared withother types of oceanic clay deposits (Karpoff et al., 1988). TheLeg 129 samples fall on a well-defined trend between equatorialmid-ocean ridge sediment and north Pacific red clay, even thoughmany of these samples were deposited south of the equator. Appar-ently, sediments deposited in the vicinity of the equator and equatorial
55
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
divergence zones have distinctly less Mn than clay deposited in thesouthern or central Pacific.
Cu-Ba
Copper and barium in marine sediments are mainly derived fromdetrital, hydrothermal, and biogenic sources. In biogenic deposits,when detrital and hydrothermal sources can be shown to be negligible,the ratio Cu/B a can be instructive with respect to authigenic, biogenic,and biogenic dissolution residue source components (Karl, 1982).The authigenic contribution should reflect accumulation rates. Theboundary between the authigenic and biogenic fields is based on aCu/Ba ratio of 0.15, and the boundary between the biogenic anddissolution residue fields is defined by a ratio of 0.02.
At Site 800, brown chert and porcellanite of Unit II and pelagicclay from between the volcaniclastic turbidite beds of Unit IV fall inthe authigenic field (Fig. 17). Alow accumulation rate was calculatedfor Unit II (Table 1), but the authigenic signature of the pelagic claysfrom Unit IV indicates a slow rate of accumulation for backgrounddeposits which is masked by thick turbidite deposits. Samples fromthe limestone-chert and radiolarite units fall in the biogenic field aswell as the authigenic field. Only one sample from the siliceouslimestone suggests a high rate of biogenic dissolution, or poor pres-ervation of biogenic ooze.
At Site 801, samples from the radiolarite units fall mainly in thebiogenic field; most other samples fall in the authigenic field (Fig. 17),indicating low accumulation rates, as with similar units from Site 800.Samples from the basal sedimentary unit plot in both fields, support-ing possible alternations in depositional rate, as suggested by Ogg etal. (this volume).
At Site 802, all of the samples except one from the calcareous unitfall in the authigenic field (Fig. 17).
RARE EARTH ELEMENT PATTERNS
REE patterns provide another means of testing for source compo-nents of marine sediments. Characteristic REE abundances and pat-terns have been determined for terrigenous clay deposits (Fig. 18) andfor pelagic clay deposits, umbers (spreading ridge sediments), ferro-manganese nodules, and seawater (Fig. 19). REE patterns and abun-dances for various types of basalt cored at Sites 800,801, and 802 areavailable for comparison in Floyd and Castillo (this volume).
Comparison of REE patterns of Leg 129 samples studied (Fig. 20)with those of terrigenous shale and pelagic clay (Figs. 18 and 19)shows a distinct difference, based on both REE abundances and onthe presence or absence of a Ce anomaly. Patterns and abundancesindicate the source of REE in Leg 129 samples is seawater. The highbiogenic source component in Leg 129 samples supports this conclu-sion because REE are adsorbed from seawater onto planktonic tests(Bostrom et al., 1973; Piper, 1974). REE may also be incorporated inprimary and authigenic minerals from pore waters during early andlate diagenesis (German and Elderfield, 1990), and La and Ce abun-dances for Leg 129 samples suggest this is a more important processthan biogenic adsorption. Alternatively, REE adsorbed onto biogenictests could subsequently be incorporated into authigenic mineralsduring diagenetic processes. REE patterns, especially the Ce anomaly,also reflect redox conditions of deposition and diagenesis.
Marine clay deposits are commonly normalized to "average shale"using one of the sources in Figure 18, but for several reasons, "averageshale" is considered inappropriate for Leg 129 samples: (1) the lack ofeolian quartz grains, the scarcity of illite, and chemical element abun-dances and ratios argue against a terrigenous source, (2) a negativecerium anomaly suggests a dominant seawater source for REE for mostLeg 129 samples studied, and (3) REE patterns for some units suggestthe source is mixed. Normalization to seawater would not allow readycomparison to other sediments or sources since this approach has notbeen taken by other workers. Normalization to chondrite is a com-
monly used standard of comparison, and has the additional advantageof comparability to basalt REE patterns from Leg 129, since volcanicmaterial derived from basement or local volcanic activity has beentargeted as an important sedimentary source.
REE patterns for the different units from Leg 129 are generally lightrare earth element (LREE) enriched with negative cerium and europiumanomalies. Seawater is not LREE enriched (Fig. 19). The basalt samplesfrom Leg 129 include several units with different chemical charac-teristics. Site 801 basement has an upper sequence of LREE-enrichedalkali basalt and a lower sequence of LREE-depleted tholeiitic basalt(Floyd and Castillo, this volume). Site 802 basalt is homogenous,undepleted tholeiite (Floyd et al., this volume). The basalt has nocerium anomaly, and only the lower tholeiite at Hole 801C has asmall negative europium anomaly. The only basalt that has an REEpattern similar to the sedimentary rocks studied is the LREE-enrichedupper alkali basalt at Site 801. Volcanic sources of the turbidites mayor may not have been LREE enriched. Terrigenous shales are LREEenriched (Fig. 18), but factors previously discussed argue against thissource. LREE enrichment can be a result of diagenetic low-oxygenconditions in biogenic sediments (German and Elderfield, 1990), butevidence cited above indicates these red sedimentary rocks weredeposited under oxidizing conditions and only show subtle signs ofreduction in some places.
At Site 800, chert and siliceous limestone of Units II and III areLREE enriched with pronounced negative Ce and Eu anomalies(Fig. 20A, B). The Ce anomaly is probably due to adsorption of REEfrom seawater by plankton and authigenic minerals. A negative Euanomaly in deep-water marine sediments may be derived from seawa-ter (Fig. 19). Negative Eu anomalies are also found in eolian materialor hydrothermal precipitates (Elderfield, 1988), neither of which iscommon in these Leg 129 deposits. However the negative Eu anoma-lies in most Leg 129 siliceous deposits may reflect an authigenicsource derived from some combination of these three potentialsources. Steinberg et al. (1983) suggested that positive Eu anomaliesin marine sediments probably reflect feldspar content. The lack of aCe anomaly for almost all of the samples from the volcaniclastic unit(Fig. 20C), and the Ce/Al ratio for this unit (Fig. 12), also suggestmixed sources. Samples from the radiolarite of Unit V for REE(Fig. 20D) have a slight negative Ce anomaly, much smaller than theCe anomalies of biogenic Units II and III. This may reflect somevolcaniclastic input for Unit V. The lowest sample from Site 800, frombetween the dolerite sills, has very low REE contents, and negativeCe and Eu anomalies (Fig. 20E). This sample is recrystallized chert,and its protolith may have been similar to the radiolarite of Unit V.The low REE contents may reflect a more dominant biogenic sourcefor this sample than for the radiolarite of Unit V.
At Site 801 the brown chert of Unit II has an identical REE patternto the chert of Unit II at Site 800 (Fig. 20A, F). The pelagic clay fromUnit III turbidites (Fig. 20G) has a very similar pattern to the turbiditesat Site 800 (Fig. 20C), virtually lacking a Ce anomaly. Unit IVradiolarite at Site 801 has low REE contents, and most samples havea negative Ce anomaly (Fig. 20H). This unit has common Fe-Mnmicronodules, which may have imparted additional Ce to the sampleswith no negative Ce anomaly, as described by Piper (1974). Thepronounced negative Eu anomaly may reflect seawater or authigenicsources. The radiolarite and claystone of Unit V at Site 801 havesimilar REE patterns and abundances (Fig. 20) to pelagic Units II ofSites 800 (Fig. 20A) and 801 (Fig. 20F), which may have accumulatedunder similar conditions near the equator. The interpülow chert at thebase of the Site 801 section has very low REE abundances (Fig. 20J),with a pattern similar to seawater (Fig. 19). The hydrothermal quartzhas even lower REE contents, also with a pattern that resemblesseawater (Fig. 20J).
Chert and limestone of Unit III at Site 802 have a strong negativeCe anomaly, a small negative Eu anomaly, and relatively low REEcontents (Fig. 20K). Unit IV brown claystone (Fig. 20L) is similar tothe brown chert of Units II at Sites 800 and 801. Unit V pelagic
56
LEG 129 SILICEOUS DEPOSITS
claystone from between turbidite beds (Fig. 20M) has a similarsignature (with very small negative Ce anomaly and small negativeEu anomaly) to the pelagic claystone from the correlative Cretaceousturbidite units at Sites 800 and 801. Radiolarian claystone of UnitsVI, VII, and VIII have similar light REE-enriched patterns with subtleCe and Eu anomalies (Fig. 20N, O, P) that may reflect dilution byvolcaniclastic material.
SUMMARY AND CONCLUSIONS
The siliceous rocks studied from Leg 129 have complicated geo-chemical signatures reflecting multiple sedimentary sources. Abun-dant radiolarians, high silica concentrations, and major and minorelement partitioning equations and plots indicate a dominant biogenicsource for most of the samples studied. XRD and microprobe analysesof mineral contents, Fe and Al concentrations, and element partition-ing equations identified a significant volcaniclastic source for sam-ples from pelagic intervals in turbidite units, and for samples fromunits directly overlying volcanic rocks. Abundant siliceous microfos-sils and high Si and Ba signify high biogenic productivity as back-ground sedimentation during volcaniclastic turbidite deposition. HighFe concentrations in interpülow sediments and sediments overlyingspreading ridge basement at Site 801 signify hydrothermal input,which is only evident for these basal sediments. Mn distributionsindicate mobilization by diagenetic processes. Cu/Ba ratios indicateelement concentrations were also influenced by authigenic processesin lithol-ogies with low accumulation rates. The very low abundanceof B in these deep marine deposits reinforces its usefulness as ashallow-water indicator. The relative abundance and distribution ofREE, as well as REE patterns for samples studies, suggest seawater,through authigenic or biogenic processes, is the primary source ofREE in deep marine sediments, but a subordinate detrital source isindicated for some units. Volcanic episodes contributed detrital ma-terial to the sedimentary sequences at Leg 129 sites at slightlydifferent times during the Mesozoic and Tertiary, and reworking ofbottom sediments and redistribution of clay minerals beyond the mostdistal turbidite deposits by bottom currents may also have been animportant process.
Paleomagnetic evidence (Steiner and Wallick, this volume; Ogg et al.,this volume) indicates that all three sites were near the equator for mostof the time the samples studied represent. Accumulation rates andsediment compositions for Leg 129 deposits suggest that sedimenta-tion was not symmetrical about the equator, nor consistent withinrespective equatorial depositional zones through time. Accumulationrates in the late Mesozoic were much higher in the southern part ofthe equatorial divergence zone than in the northern part. The southernpart of the equatorial zone was also apparently broader than the partnorth of the equator. During the Jurassic, only siliceous depositsaccumulated in the equatorial zone, but during the Cretaceous siliceouslimestone accumulated. During the Tertiary accumulation rates werelower and considerably less biogenic material is preserved. Paleocean-ographic models (Berger, 1976; Kennett, 1982) suggest that theequatorial province was a zone of high productivity during this time,and that these sites were isolated from terrigenous influence. Leg 129stratigraphic data supports these models. The geochemistry of Leg 129siliceous rocks also supports these models, and provides additionalinformation regarding the oxic depositional conditions and variationsin biogenic, authigenic, and volcanogenic input near the equator duringthe late Mesozoic.
ACKNOWLEDGMENTS
We would like to express our gratitude to Floyd Brown of the U.S.Geological Survey for expediting chemical analyses; to analyticalchemists Zoe Ann Brown, Elizabeth Bailey, Dave Siems, Joe Taggert,and Paul Lamothe; to Jonathan Whitesides for sample preparation;and to Scott Bie for organizing and plotting data. We would like to
thank reviewers David Z. Piper, James R. Hein, and Peter Hempel.We also thank our fellow Leg 129 scientists, the drilling crew, and theship crew on the JOIDES Resolution for their help.
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Heath, G. R., Moore, T. C, and Roberts, G. S., 1974. Mineralogy of surfacesediments from the Panama Basin, eastern equatorial Pacific. J. Geol.,82:145-160.
Hein, J. R., Sancetta, C , and Morgenson, L. A., 1982. Petrology and geochem-istry of silicified upper Miocene chalk, Costa Rica rift, Deep Sea DrillingProject Leg 69. In Cann, J. R., Langseth, M. G., et al., Init. Repts. DSDP,69: Washington (U.S. Govt. Printing Office), 69:395-422.
Hein, J. R., Vallier, T. L., and Allan, M. A., 1981. Chert petrology andgeochemistry mid-Pacific Mountains and Hess Rise, Deep Sea DrillingProject Leg 62. In Thiede, J., Vallier, T. L., et al., Init. Repts. DSDP, 62:Washington (U.S. Govt. Printing Office), 711-748.
Henderson, P. (Ed.), 1984. Rare Earth Element Geochemistry: New York(Elsevier), Dev. in Geochem. Ser., 1—32.
57
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Jenkyns, H. C , 1978. Pelagic environments. In Reading, H.G. (Ed.), Sedimen-tary Environments and Facies: Oxford (Blackwell Sci. Publ.), 314-371.
Karl, S. M., 1982. Geochemical and depositional environments of UpperMesozoic radiolarian cherts from the northwestern Pacific rim and fromPacific DSDP cores [Ph.D dissert.]. Stanford Univ., Stanford, CA.
Karpoff, A. M., 1989. Les facies pelagiques condenses Cenozoiques des oceansPacifique and Atlantique: temoins des grandes crises geodynamiques [TheseDoc. Sci.]. Univ. Louis Pasteur, Strasbourg, France.
Karpoff, A. M., Walter, A. V., and Pflumio, C, 1988. Metalliferous sedimentswithin lava sequences of the Sumail ophiolite (Oman): mineralogicaland geochemical characterization, origin, and evolution, Tectonophysics,151:223-245.
Keene, J. B., 1976. The distribution, mineralogy and petrography of biogenicand authigenic silica from the Pacific basin [Ph.D. dissert.]. Univ. ofCalifornia, San Diego.
Kelts, K., and Arthur, M. A., 1981. Turbidites after ten years of deep-seadrilling-wringing out the mop? Spec. Publ.—Soc. Econ. Paleontol. Min-eral., 32:91-127.
Kennett, J. P., 1982. Marine Geology: Englewood Cliffs, NJ (Prentice Hall).Lancelot, Y., Larson, R. L., et al., 1990. Proc. ODP, Init. Repts., 129: College
Station, TX: Ocean Drilling Program.Larson, R. L., and Pittman, W. C, III, 1973. Worldwide correlation of Meso-
zoic magnetic anomalies and its implications. Geol. Soc. Am. Bull.,83:3645-3662.
Leinen, M, 1981. Metal-rich basal sediments from northeastern Pacific DeepSea Drilling sites. In Yeats, R. S., Haq, B. U., et al., Init. Repts. DSDP, 63:Washington (U.S. Govt. Printing Office), 63:667-676.
Leinen, M., and Pisias, N., 1982. An objective technique for determiningend-member compositions and for partitioning sediments according totheir sources. Geochim. Cosmochim. Acta, 48:47-62.
Leinen, M., and Stakes, D., 1979. Metal accumulation rates in the centralequatorial Pacific during the Cenozoic. Geol. Soc. Am. Bull., 90:357-375.
Lonsdale, P. F, Bishoff, J. L., Burns, V. M., Kastner, M., and Sweeney, R. E.,1980. A high-temperature hydrothermal deposit on the seabed at a Gulf ofCalifornia spreading center. Earth Planet. Sci. Lett., 49:8-20.
Murray, R. W., Buchholtz ten Brink, M. R., Jones, D. L., Gerlach, D. C , andRuss, GP., Ill, 1990. Rare earth elements as indicators of different marinedepositional environments in chert and shale. Geology, 18:268-271.
Olivarez, A. M., Owen, R. M, and Rea, D. K., 1991. Geochemistry of eoliandust in Pacific pelagic sediments: implications for paleoclimactic interpre-tations. Geochim. Cosmochim. Acta, 55:2147-2158.
Piper, D. Z., 1974. Rare earth elements in the sedimentary cycle: a summary.Chem. Geol., 14:285-304.
Price, N. B., 1976. Chemical diagenesis in sediments. In Riley, J. P., andChester, R. (Eds.), Chemical Oceanography, San Francisco (AcademicPress), 6:1-59.
Rea, D. K., Pisias, N. G., and Newberry, T, 1991. Late Pleistocene paleocli-matology of the central equatorial Pacific: flux patterns of biogenic sedi-ments. Paleoceanography, 6:227-244.
Research on Cretaceous Cycles Group (RCCG), 1986. Rhythmic bedding inUpper Cretaceous pelagic carbonate sequences: varying sedimentary re-sponse to climate forcing. Geology, 14:153-156.
Robertson, A.H.F., and Fleet, A. J., 1976. The origins of rare earths inmetalliferous sediments of the Troodos Masif, Cyprus. Earth Planet. Sci.Lett, 28:385-394.
Rona, P. A., Bostrom, K., and Epstein, S., 1980. Hydrothermal quartz vug fromthe mid-Atlantic Ridge. Geology, 8:569-572.
Shimizu, H., and Masuda, A., 1977. Cerium in chert as an indication of marineenvironment of its formation. Nature, 266: 346-348.
Steinberg, M., Bonnot-Courtois, C, and Tlig, S., 1983. Geochemical contri-bution to the understanding of bedded chert. In Iijima, A., Hein, J. R., andSiever, R. (Eds.), Siliceous Deposits in the Pacific Region: Amsterdam(Elsevier), Dev. in Sedimentol. Ser., 36:193-210.
Toyoda, K., Nakamura, Y, and Masuda, A., 1990. Rare earth elements of Pacificpelagic sediments. Geochim. Cosmochim. Acta, 54:1093-1103.
Truscott, M. G., and Shaw, D. M., 1983. Boron in cherts. Progr. Abstracts,Geol. Assoc. Can., A70.
Date of initial receipt: 19 June 1991Date of acceptance: 24 March 1992Ms 129B-111
58
[BLANK PAGE]
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Site 800 Explanation
1 Biogenic ooze2 Red clay
3 Metalliferous sediment4 Oceanic basalt5 Authigenic crust6 Manganese nodules7 Hydrothermal deposits
S Unit IIUnit III
O Unit IV+ Unit VH Unit VI
Site 801 Explanation
1 Biogenic ooze2 Red clay3 Metalliferous sediment4 Oceanic basalt5 Authigenic crust6 Manganese nodules7 Hydrothermal deposits
m Unit IIA Unit IIIO Unit IV+ Unit VE3 Unit VI
Mn
Figure 15. Plot of Al-Fe-Mn for samples from Leg 129. Fields from Karpoff (1989).
60
LEG 129 SILICEOUS DEPOSITS
Site 802 Explanation
1 Biogenic ooze2 Red clay3 Metalliferous sediment4 Oceanic basalt5 Authigenic crust6 Manganese nodules7 Hydrothermal deposits
9 Unit IIIUnit IV
O Unit V+• Unit VIEH Unit VIID Unit VIII
Figure 15 (continued).
61
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Site 800
Fe
Site 801
Explanation
1 Equatorial mid-ocean ridge (Oman)2 North Pacific red clay3 Central Pacific clay4 North Pacific clay5 South Pacific red clay6 Bauer Deep sediment7 East Pacific Rise sediment8 Bauer Deep nodules
ffi Unit IIA Unit IIIO Unit IV* Unit V03 Unit VI
Mn
Explanation
1 Equatorial mid-ocean ridge (Oman)2 North Pacific red clay3 Central Pacific clay4 North Pacific clay5 South Pacific red clay6 Bauer Deep sediment7 East Pacific Rise sediment8 Bauer Deep nodules
B Unit IIA Unit IIIO Unit IV+ Unit VEl Unit VI
Mn
Figure 16. Plot of Si-Fe-Mn for samples from Leg 129. Fields from Karpoff et al. (1988).
LEG 129 SILICEOUS DEPOSITS
Site 802 Explanation
1 Equatorial mid-ocean ridge (Oman)
2 North Pacific red clay
3 Central Pacific clay
4 North Pacific clay
5 South Pacific red clay
6 Bauer Deep sediment
7 East Pacific Rise sediment
8 Bauer Deep nodules
B Unit III
A Unit IV
O Unit V
+ Unit VI
ED Unit VII
DUnit VIII
Mn
Figure 16 (continued).
63
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
ODP SITE 800 (Cu ppm VERSUS Ba ppm)
250
225 -
200 -
175 -
150 -
500 1000 1500 2000 2500
Ba ppm
ODP SITE 801 (Cu ppm VERSUS Ba ppm)
250
ü
225 -
200 -
175 -
150 -
125
100 -
75
50
25
a Unit IIA Unit IIIo Unit IV* Unit V• Unit VI
500 1000 1500 2000 2500
Ba ppm
Figure 17. Plot of copper vs. barium for samples from Leg 129. Fields from Karl (1982). A= authigenic, B = biogenic, R = biogenic dissolution residue.
64
LEG 129 SILICEOUS DEPOSITS
ODP SITE 802 (Cu ppm VERSUS Ba ppm)
250
o
225 -
200 -
175 -
150 -
125 -
100 -
75 -
50 -±
..... 1
1
1 1
1
_ A
i• /
-Δ /-j> /
/ a Unit III/ * Unit IV
/ o Unit V/ + Unit VI
/ • Unit VII/ a Unit VII!
/
B
S ^ ^ ^ ^ ^
R
I
500 1000 1500
Ba ppm
2000 2500
Figure 17 (continued).
100
LU
cra
Oü
LLJ
<
CO
50
20
10
SHALES
A Russian Platform avg. Balashov et. al.,1964 '
• European composite Haskin and Haskin, 1966
• North American composite Gromet et. al.,1984
o Post-Archean Average AustraliaNance and Taylor, 1976
Ce Nd Sm Eu Gd Dy Er
RARE EARTH ELEMENTS
Yb
Figure 18. Distributions of REE for average shales, normalized to chondrite,from Gromet et al. (1984), sources of data in Gromet et al. (1984).
langanese nodules
-East Pacific Rise Crestmetalliferous sediment
"... ..••"^Seawater x 10*
La Ce Pr Nd Sm EuGd Dy Ho Er Tm Yb Lu
RARE EARTH ELEMENTS
Figure 19. Chondrite-normalized distributions of REE in seawater and oceanicsediments. Sources of data: EPR sediment from Bender et al. (1971); lowerMn nodule pattern from Bernat in Bonatti et al. (1976); higher Mn nodulepattern from Ehrlich in Robertson and Fleet (1976); clay and seawater patternsfrom Haskin et al. in Robertson and Fleet (1976); Cyprus umbers pattern fromRobertson and Fleet (1976).
65
Figure 20. Chondrite-normalized (chondrite values of Anders and Ebihara, 1982) rare earth element plots for Leg 129 samples. A. Site 800, Unit II. B. Site 800,Unit III. C. Site 800, Unit IV. D. Site 800, Unit V. E. Site 800, Unit VI. F. Site 801, Unit II. G. Site 801, Unit III. H. Site 801, Unit IV. I. Site 801, Unit V.J. Site 801, Unit VI. K. Site 802, Unit III. L. Site 802, Unit IV. M. Site 802, Unit V. N. Site 802, Unit VI. O. Site 802, Unit VII. P. Site 802, Unit VIII.
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
^ LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU Q LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU
ODP SITE 800 ODP SITE 800100 - 100 -
UNIT II ' * UNIT III :"^ 50 ^\ ', •— 50 Jk\\
I 2° ^ ^ ~ ^ ^ ^ ^ - * - £ 2° ^ ^
| 2 | 2
<σ TOCO ' • : CO 1 :
Q LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU D LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU
ODP SITE 800 ODP SITE 800inn - -
ioo-*v UNIT IV " V UNIT V ;
I ' ^ ^ ― ! ! ^ •& 2
<Λ ' ^ T
E LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU p LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU
ODP SITE 800 ODP SITE 80110°" UNIT VI "; 1 0 0 ' UNIT II "
CL 2 > r ^ ^ ^ ^ ^ - - ^ ^ ^ • "ö. 2
co ] " \ ^ ^ co 1 ;
LEG 129 SILICEOUS DEPOSITS
LA CE PR N P P M S M E U G D T B D Y H O E R T M Y B L U
ODP SITE 801UNIT III
C
oo
ECD
CO
1 0 0
5 0
2 0
10
5
2
LA CE
-
%
PR ND PM SM EU GD TB
- - - - J \ ^
^ ^ ^ " ^
" • • - - . . . . ^ ^ ^ ^
* ^
DY HO ER
ODPUNIT
TM
SITEIV
-–—-.^ = = ^— • —
YB LU
801
\
LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU
ODP SITE 801UNIT V
• ^ 50
ODP SITE 801UNIT VI
V
LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU
ODP SITE 802UNIT III
Figure 20 (continued).
67
Figure 20 (continued).
M LA CE PR ND PM SM EU GO TB DY HO EB TM YB LU N LA CE PR ND PM SM EU GD TB DY HO ER TM YB LU
ODP SITE 802 . ODP SITE 802
o
1 0 °•\ UNIT VII ~ o 1 0 ° \ _ U N ' T V "
•σ *^~* "σ ^ _c 10 - c 10 - ^ -O : O :0 5 ü 5
1 2 E 2TO <O
CO 1 : CO ' :
O LA CE PR ND PM SM EU GD TB DY HO ER TM YB LJU p LA CE PR ND PM SM BJ GD TB DY HO ER T M YB UJ
ODP SITE 802 \ ODP SITE 8021 0 0 > UNIT VIII " 1 O O r \ _ _ ^ UNIT VI I
c i o - * - c i o - -O : : O :o 5 o B
I , a ,CO 1 ; CO 1 ;
[BLANK PAGE]
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
APPENDIX A
Table Al. Major element oxide data (in percent) for samples from Site 800, Leg 129.
Sample (cm)
129-800A-
6R-1, 67-697R-1, 2-58R-1,48-509R-1, 30-33
10R-1, 13-1711R-1,7-1O12R-1,30-3213R-1, 12-1414R-1,110-11517R-1,68-7118R-1, 127-13023R-1,69-7024R-1,68-7124R-1,92-9526R-1,22-2626R-1, 135-13927R-1, 61-6427R-1,110-11428R-3, 106-11030R-1, 125-12930R-2, 114-11831R-1, 12-1432R-CC, 10-1333R-7, 14-1834R-2, 139-14235R-3, 84-8836R-1, 110-11436R-4, 28-3241R-1,87-9342R-1,41^344R-1,92-9451R-1, 106-10852R-1, 16-2053R-1,32-3455R-1,76-8155R-2, 25-3056R-1,8-1358R-1, 37-42
Depth(mbsf)
40.249.259.468.878.387.997.6
106.9117.3144.9155.0201.2210.6210.8228.8230.0238.6239.1251.3267.2268.5272.1280.8296.6299.9310.2317.0320.7363.4369.0384.6450.7459.0465.2479.9480.9488.6507.2
SiO2
87.3089.3087.6086.6089.6082.8085.6089.8078.2085.2088.9083.9079.4090.4046.2055.0055.0072.8048.6075.6085.7074.0070.0042.6042.3067.1040.6042.3043.3057.0044.5080.2073.3081.0083.1079.8087.0095.70
A12O3
2.341.802.052.191.602.162.761.694.402.771.882.804.611.572.906.777.973.58
10.605.432.765.936.889.937.956.979.59
10.208.528.899.285.277.254.223.655.333.080.57
FeTO3
1.020.841.541.861.441.341.591.343.271.691.192.433.241.182.515.937.023.379.314.692.534.095.539.877.576.868.979.629.878.53
11.503.334.833.542.713.261.930.35
MgO
0.580.520.640.780.410.680.800.641.440.830.590.981.330.491.863.557.611.65
10.101.770.921.802.077.31
12.503.346.99
10.609.786.93
10.801.551.871.371.041.360.750.14
CaO
0.410.350.290.240.113.480.230.110.490.250.170.501.080.27
22.508.912.544.504.710.910.460.941.337.557.331.239.695.096.551.412.850.580.660.590.930.540.370.05
Na2O
0.460.380.440.440.340.380.480.320.750.580.400.711.010.410.701.842.530.842.691.250.671.541.561.461.661.531.411.891.821.371.780.710.910.770.610.800.640.15
K2O
0.480.370.480.560.460.670.860.581.320.750.550.740.970.330.702.550.790.840.790.790.451.270.933.782.361.172.832.351.382.671.411.391.941.130.971.550.910.20
TiO2
0.090.070.110.130.100.130.170.100.350.220.130.250.450.160.311.031.570.391.510.640.290.510.801.540.900.861.481.701.490.951.770.340.440.270.210.280.150.02
P 2 O 5
0.260.230.180.150.070.060.100.070.210.090.060.160.120.080.130.190.220.090.230.120.070.140.170.180.300.140.250.250.320.330.410.150.150.160.100.150.100.05
MnO
0.160.140.290.490.020.020.020.020.020.020.020.020.060.020.310.150.150.110.150.060.030.050.080.170.150.140.250.230.240.100.200.090.970.470.270.340.180.04
LOI925C
5.775.045.465.634.587.445.634.098.496.594.886.506.873.96
22.0013.8014.4011.4010.908.134.959.049.86
15.6016.8010.1018.0015.7016.9011.7015.505.557.105.405.775.613.981.32
Oxidetotal
98.8799.0499.0899.0798.7399.1698.2498.7698.9498.9998.7798.9999.1498.87
100.1299.7299.8099.5799.5999.3998.8399.3199.2199.9999.8299.44
100.0699.93
100.1799.88
100.0099.1699.4298.9299.3699.0299.0998.59
Note: Analyses obtained by X-ray fluorescence, U.S. Geological Survey laboratories.
70
LEG 129 SILICEOUS DEPOSITS
Table A2. Major element oxide data for (in percent) samples from Site 801, Leg 129.
Sample (cm)
129-801A-
8R-1, 1-39R-
10R-12R-80-1C13R-14R-15R-
,0-3,0-5,22-250M,21-26, 26-28, 24-26
16R-1, 135-13817R-1, 28-3018R-2, 14-1719R-CC, 12-1620R-1, 8-12
129-801B-
8R-2, 60-631 OR-1,70-7311R-1, 31-3612R-1, 64-7014R-1, 52-5715R-1, 19-2016R-1,40-4317R-1,34-3618R-1,37^019R-1,24-2620R-1,23-2621R-1, 12-1324R-1,69-7325R-1,49-5327R-1, 104-10729R-1, 17-1931R-1, 18-2033R-1, 10-1433R-1, 126-12935R-1,51-5535R-1, 123-12737R-1, 7-1039R-1,4-7
129-801C-
4R-1, 11-165R-4,11-166R-1, 31-34
Depth(mbsf)
60.670.279.599.0
100.0108.7118.5128.1139.0147.5158.6176.3176.5
254.8272.7282.0292.0310.8319.9329.6338.9348.2357.5366.7375.8393.3397.7407.7416.4425.8434.9436.1444.8445.5453.6462.7
521.8535.8540.8
SiO2
96.783.989.876.382.884.186.079.675.478.976.982.988.6
89.558.077.177.485.282.993.192.491.095.591.892.890.784.793.792.792.868.783.764.674.591.894.8
81.111.45.3
A12O3
0.43.41.65.43.53.42.73.94.74.14.62.61.7
1.88.15.33.73.24.21.21.41.80.51.61.42.03.71.01.41.46.34.08.45.20.60.7
0.10.50.9
FeTO3
0.31.50.93.81.92.01.94.04.23.64.02.61.6
1.49.24.46.32.22.30.70.90.90.21.22.01.42.20.91.11.0
10.33.79.98.33.31.7
15.73.97.5
MgO
0.100.800.431.300.900.970.921.291.821.712.181.220.74
0.615.421.092.300.840.990.240.250.320.100.270.270.430.850.160.260.271.450.962.061.380.270.15
0.106.325.88
CaO
0.050.370.220.460.420.360.470.600.940.500.541.230.36
0.271.340.580.490.290.270.100.120.230.050.110.110.100.200.070.150.150.370.180.360.260.050.12
0.0239.3039.90
Na2O
0.150.630.351.230.730.610.490.961.190.880.950.640.48
0.482.011.170.660.720.730.230.230.320.150.270.170.310.710.190.230.240.890.641.070.780.150.15
0.150.150.15
K2O
0.130.770.331.170.760.760.750.971.581.471.810.870.60
0.492.411.172.530.791.070.280.340.420.110.410.340.490.980.280.370.392.151.252.771.640.290.22
0.020.230.03
TiO2
0.020.150.100.620.240.250.180.670.890.450.530.400.27
0.201.690.560.390.180.230.050.070.070.020.060.050.090.180.040.060.070.390.260.600.360.030.04
0.020.020.02
P2O5
0.050.230.140.130.240.120.100.130.190.110.110.090.09
0.080.260.100.170.080.090.050.080.080.050.060.050.050.050.050.080.080.200.050.090.120.050.10
0.060.050.08
MnO
0.040.180.080.330.180.090.030.050.040.040.040.020.02
0.020.130.120.080.320.460.100.180.190.050.150.220.3 10.400.210.280.120.060.020.110.070.050.15
0.020.390.63
LOI 925C
0.846.744.798.457.006.435.566.958.476.777.216.214.38
3.9911.107.455.385.056.102.593.023.331.792.732.703.164.652.142.942.827.044.819.126.861.950.96
2.6638.4040.30
Oxidetotal
98.7498.7198.7199.2798.7299.0599.0399.0999.4098.5698.7998.8598.88
98.8099.7199.0899.4298.8899.3498.6499.0398.6698.6098.62
100.0498.9998.6298.7399.5499.3297.8099.5699.1599.4298.5199.13
99.95100.60100.62
Note: Analyses obtained by X-ray fluorescence, U.S. Geological Survey laboratories.
Table A3. Major element oxide data (in percent) for samples from Site 802, Leg 129.
Sample (cm)
129-802 A-
33R-1,116-12034R-1, 128-13235R-CC, 0-437R-1,11-1538R-CC, 12-1539R-1, 10-1543R-1, 75-7852R-2, 125-13055R-1, 138-14156R-1,43-4756R-2, 88-92
Depth(mbsf)
294.0303.6320.5330.0348.6348.8382.9462.6489.3497.5499.5
SiO2
45.595.894.888.965.470.077.873.276.370.778.8
A12O3
1.030.190.470.806.454.554.727.085.897.933.71
FeTO3
0.480.070.200.395.184.133.223.833.954.845.46
MgO
0.670.100.100.181.721.071.711.801.691.661.45
CaO
27.300.250.102.933.774.820.921.040.911.230.78
Na2O
0.330.150.150.241.451.100.801.221.011.580.69
K2O
0.140.040.110.151.100.751.451.611.471.751.42
TiO2
0.050.020.020.071.160.960.310.450.440.760.24
P 2 O 5
0.150.070.060.100.290.180.360.360.270.220.24
MnO
0.140.020.020.020.090.060.040.190.230.240.05
LOI925C
24.301.902.235.25
13.0011.908.118.907.268.296.48
Oxidetotal
100.0998.6198.2699.0399.6199.5299.4499.6899.4299.2099.32
Note: Analyses obtained by X-ray fluorescence, U.S. Geological Survey laboratories.
71
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
APPENDIX B
Table Bl. Minor element analyses (in parts per million) for samples from Site 800, Leg 129.
Sample (cm)
129-800A-
6R-1,67-69
7R-1,2-5
8R-1,48-50
9R-1,30-33
10R-1, 13-17
11R-1,7-1O
12R-1,30-32
13R-1, 12-14
14R-1, 110-115
17R-1,68-71
18R-1, 127-130
23R-1,69-70
24R-1,68-71
24R-1,92-95
26R-1,22-26
26R-1, 135-139
27R-1, 61-64
27R-1, 110-114
28R-3, 106-110
30R-1, 125-129
3OR-2,114-118
31R-1, 12-14
32R-CC, 10-13
33R-7, 14-1834R-2, 139-142
35R-3, 84-88
36R-1, 110-114
36R-4, 28-32
41R-1, 87-93
42R-1, 41-4344R-
51R-
52R-
53R-
55R-
55R-:
56R-
58R-
, 92-94
, 106-108
, 16-20
, 32-34
,76-81I, 25-30
,8-13,37-42
Depth
(mbsf)
40.2
49.2
59.4
68.8
78.3
87.9
97.6
106.9
117.3
144.9
155.0
201.2
210.6
210.8
228.8
230.0
238.6
239.1
251.3
267.2
268.5
272.1
280.8
296.6
299.9
310.2
317.0
320.7
363.4
369.0
384.6
450.7
459.0
465.2
479.9
480.9
488.6
507.2
Ba
61
51
93
500
331
162
292
54
277
72
58
45
250
35
396
103
4544
226
75
47
7794
69
42
70
29
31
22
85
20
91
615
493
516
754
429
164
Cr
20
20
20
20
20
20
20
2042
20
20
20
20
20
20
170
196
26
65841
20
3035
355
296
70
367
610
573
266
539
20
20
20
20
20
20
20
Cu
70
52
60
73
67
26
24
16
110
31
10
21
43
31
21
84
145
20
93
44
18
29
40
134
277
31
112122
56
49
21
113105
69
63
80
48
10
Ni
32
22
48
37
28
23
19
19
40
36
3923
3317
22
56
79
35326
5020
2654
150
322
65
174
241
242
144
260
44
79
45
3941
20
12
Rb
1711
15
18
13
22
30
17
43
25
13
19
31
10
20
48
22
22
18
22
10
3721
45
28
38
30
18
21
73
18
50
72
44
38
60
37
10
Sr
35
29
33
37
19
76
31
18
58
43
24
80
170
37
228
616
571
119
390
221
95
365
245
121
130
217
122
124
136
131
136
70
122
94
68
74
53
10
Zn
47
38
42
44
43
27
38
3042
40
25
22
58
26
25
49
73
32
84
69
32
37
82
81
67
73
81
87
77
94
93
76
12682
64
71
42
22
Zr
35
33
38
3932
37
43
33
7154
34
54
81
35
49
96
137
61
136
92
44
82
122
146
97
112
133
139
112
110
135
73
108
64
56
70
46
16
Y
35
29
24
22
9
13
20
14
31
18
9
20
20
15
16
11
15
15
18
14
9
17
15
1922
21
19
19
19
33
21
21
28
19
14
20
13
5
La
28
24
20
16
10
16
13
12
35
18
10
22
24
15
15
27
31
19
24
18
11
27
26
29
29
25
29
26
26
39
3117
25
18
11
17
14
10
Ce
20
16
15
19
15
16
11
1034
21
10
23
28
20
20
42
48
27
39
23
19
42
42
49
43
36
46
47
39
60
48
41
44
29
21
31
21
10
B
54
41
49
52
33
45
45
39
63
53
34
39
56
34
63
21
19
35
16
48
30
36
67
47
34
45
44
34
31
51
32
41
48
33
32
43
28
22
Note: Analyses obtained by X-ray spectroscopy, and by mass spectrometer for B, U.S. Geological Survey laboratories.
72
LEG 129 SILICEOUS DEPOSITS
Table B2. Minor element analyses (in parts per million) for samples from Site 801, Leg 129.
Sample (cm)
129-801A-
8R-1, 1-39R-1,0-310R-l,0-512R-1,22-2580-100M13R-1,21-2614R-1, 26-2815R-1, 24-2616R-1, 135-13817R-1, 28-3018R-2, 14-1719R-CC, 12-1620R-1, 8-12
129-801B-
8R-2, 60-631 OR-1,70-7311R-1, 31-3612R-1, 64-7014R-1,52-5715R-1, 19-2016R-1,40-4317R-1, 34-3618R-1,37^019R-1,24-2620R-1,23-2621R-1, 12-1324R-1,69-7325R-1, 49-5326R-CC, 0 ^27R-1, 104-10729R-1, 17-1931R-1, 18-2033R-1, 10-1433R-1, 126-12935R-1,051-05535R-1, 123-12737R-1, 7-1039R-1,4-7
129-801C-
4R-1, 11-165R-4, 11-166R-1,31-34
Depth(mbsf)
60.670.279.599.0100.0108.7118.5128.1139.0147.5158.6176.3176.5
254.8272.7282.0292.0310.8319.9329.6338.9348.2357.5366.7375.8393.3397.7407.0407.7416.4425.8434.9436.1444.8445.5453.6462.7
521.8535.8540.8
Ba
13178381881091241479747717248417394
3685127411915341513252057850367260310201690251395369
40001010400097824279
182121
Cr
20202020202020416929472520
2030425232020202020202020202020202020403751302020
202020
Cu
10683246614930404444401817
2110654274038131727103453508012055584015455106872417
101010
Ni
10381438302737364035342415
1417537223334101515101114142218101010622569592014
203745
Rb
10331128293630355544662612
11413048284410I010101410214745101012734193591010
101010
Sr
1043241104754401332381101167438
42259170485813517222610272829595810161515937137481010
10120124
Zn
19493064584646513937382620
25123813458512632342129282737472327269845114853219
171233
Zr
1449351235763449612978835945
391568157496122252914312936535219262912460125942618
131615
Y
5352015292421221816161712
141816261313791258891310575235121156
5511
La
I0301121262720272320131713
162412141010101010101010101010101010101010131010
101010
Ce
10321043242912303027232316
164429222223101010101310161520101210131424201010
101010
B
8.4653169465237495650463626
20345536424223262129231224283716181758366163206.3
3511
Note: Analyses obtained by X-ray spectroscopy, and by mass spectrometer for B, U.S. Geological Survey laboratories.
Table B3. Minor element analyses (in parts per million) for samples from Site 802, Leg 129.
Sample (cm)
129-802A-
33R-1, 116-12034R-1, 128-13235R-CC, 0-437R-1, 11-1538R-CC, 12-1539R-1, 10-1543R-1,75-7852R-2, 125-13055R-1, 138-14156R-1,43-4756R-2, 88-92
Depth(mbsf)
294.0303.6320.5330.0348.6348.8382.9462.6489.3497.5499.5
Ba
1020193226111607911511613256
Cr
2020202561453030212420
Cu
37101118445326591047718
Ni
2214161688503254818246
Rb
1010101021174249434436
Si-
SOS1010562402458015310225439
Zn
25272825907237869810748
Zr
2810112013110261969212149
Y
16551431284449453340
La
1010101028233949322626
Ce
1010101032285557453334
B
2049357564555978364780
Note: Analyses obtained by X-ray spectroscopy, and by mass spectrometer for B, U.S. Geological Survey laboratories.
73
APPENDIX C
Table Cl. Rare earth element and minor element analyses (in parts per million) for samples from Site 800, Leg 129.
DepthSample (cm)
Rare earth element data
129-800 A-
6R-1,67-697R-1,2-58R-1,48-509R-1, 30-33
10R-1, 13-1711R-1,7-1O12R-1,30-3213R-1, 12-1414R-1,110-11517R-1,68-7118R-1, 127-13023 R-1,69-7024R-1,68-7124R-1,92-9526R-1,22-2626R-1, 135-13927R-1, 61-6427R-1,110-11428R-3, 106-11030R-1, 125-12930R-2,114-11831R-1, 12-1432R-CC, 10-1333R-7, 14-1834R-2, 139-14235R-3, 84-8836R-1,110-11436R-4, 28-3241R-1,87-9342R-1,41^344R-1,92-9451R-1, 106-10852R-1, 16-2053R-1,32-3455R-1,76-8155R-2, 25-3056R-1, 8-1358R-1,37-42
(mbsf)
40.249.259.468.878.387.997.6
106.9117.3144.9155.0201.2210.6210.8228.8230.0238.6239.1251.3267.2268.5272.1280.8296.6299.9310.2317.0320.7363.4369.0384.6450.7459.0465.2479.9480.9488.6507.2
La
21.7016.3017.0016.406.72
10.0014.008.55
27.4013.806.80
17.4019.1011.0016.720.424.313.919.615.79.3
21.320.720.621.318.021.122.218.732.025.516.127.919.713.118.511.42.0
Ce
20.0015.2015.6018.209.40
11.7016.008.70
29.4017.009.50
22.0026.0012.0021.138.744.021.338.024.015.332.038.039.639.034.041.644.036.457.544.835.644.627.819.830.116.73.2
Nd
21.0015.0015.0015.006.208.30
12.007.10
22.0013.006.80
15.0015.009.20
14.016.019.013.017.012.07.4
16.016.018.016.014.019.020.016.029.021.014.024.017.012.017.011.02.0
Sm
4.683.643.393.201.452.133.001.835.172.781.333.323.912.062.913.484.512.934.292.771.623.583.444.464.243.584.574.904.116.505.083.035.083.982.633.592.560.52
Eu
1.070.840.770.740.330.460.650.401.200.630.300.780.920.490.7521.0101.2000.6801.2600.6600.3900.8600.9281.2301.2000.9331.3401.4301.2301.6601.5100.6531.0700.8340.5380.7030.5120.120
Th
0.69 :0.560.510.49
Yb
.15
.80
.60
.500.25 0.710.30 0.770.43 .100.29 0.700.76 .700.41 0.930.21 0.540.490.52
.10
.400.31 0.820.4300.4500.5600.4100.6100.3800.240 (0.4800.4600.6000.5600.5000.6100.6500.5600.9230.6800.4410.7180.5400.3740.4700.3570.077
.30
.10
.40
.30
.60
.10).66.30.40.70.70.50.60.60.40
i.50.70.60
2.10.60.10.50
191).31
Lu
0.290.250.220.200.100.100.130.080.220.110.080.150.180.100.180.140.170.160.200.150.100.160.190.230.220.200.220.190.170.340.230.220.290.200.150.200.120.03
Ba Cr Cs
Minor element data
665989
49034214028049
26068694317
240393975842
2307050579987476324703285
11098
590470477725396140
7.05.19.4
11.020.012.016.011.036.016.014.020.09.0
24.028.8
167.0140.035.3
575.041.616.931.037.0
343.0200.064.0
335.0549.0604.0214.0565.0
20.424.913.011.016.18.92.5
1.100.831.000.971.100.951.200.741.901.100.900.960.591.400.930.450.221.000.230.890.551.000.880.780.521.200.600.460.282.200.402.093.332.222.013.251.940.36
Hf
0.560.480.600.640.510.560.690.441.200.860.560.820.531.400.851.872.641.002.681.570.741.402.393.001.902.102.802.942.402.252.921.332.011.210.991.390.830.17
Rb
19.012.017.020.018.023.030.019.044.023.018.020.011.028.023.043.011.023.015.019.013.028.023.043.026.030.032.024.022.067.026.045.063.040.035.454.233.0
8.5
Sb
0.290.250.450.581.090.190.260.370.330.240.330.210.210.210.150.140.190.160.570.120.150.150.180.160.090.160.210.190.120.220.240.220.550.300.270.350.260.12
Th
1.981.441.591.781.411.702.301.403.402.301.742.001.203.061.482.473.401.982.302.901.672.903.482.821.902.902.352.391.803.882.103.625.593.292.764.382.610.56
U
1.7001.1001.3000.4602.3400.2000.4000.2800.4801.2000.3100.4300.4000.5800.4500.4400.6200.3900.3700.4100.3900.5900.5201.2000.8000.4700.7800.6100.5300.5400.3500.7700.9800.9001.1001.2001.3001.300
Zn
35.027.034.036.032.021.026.022.036.027.021.016.016.047.022.345.064.025.075.058.024.030.069.078.056.056.069.076.064.080.276.059.997.762.649.255.833.013.0
Zr
423059609040
11050
120505060867280
160170160110946862
15015011096
130120140150230
52965961694424
Sc
4.634.204.474.223.143.614.402.937.194.752.904.312.446.304.64
16.0018.005.99
19.607.303.627.508.53
22.4014.0011.9019.5023.3023.1015.1023.20
6.938.905.754.926.684.090.84
Ni
292044322730182353703624183217626430
27041182952
14025047
15021020014021040613630322220
Sr
27402728308071404076907728
14024059050012038018010030024012015023012019014014017089
1408558775650
Note: Analyses obtained by induced neutron activation analysis (INAA), U.S. Geological Survey laboratories.
Table C2. Rare earth element and minor element analyses (in parts per million) for samples from Site 801, Leg 129.
Sample (cm)Depth(mbsf) La Ce Nd Sm Tb Yb Lu Ba Cr Cs Hf Rb Sb Th Zn Zr Ni
Note: Analyses obtained by induced neutron activation analysis (INAA), U.S. Geological Survey laboratories.
Sr
Rare earth element data
129-801A-
8R-1, 1-39R-1,0-3
1 OR-1,0-512R-1,22-2580-100M13R-1, 21-2614R-1,26-2815R-1,24-2616R-1, 135-13817R-1,28-3018R-2, 14-1719R-CC, 12-1620R-1,8-12
129-801B-
8R-2, 60-631 OR-1,70-7311R-1, 31-3612R-1,64-7014R-1,52-5715R-1, 19-2016R-1,40-4317R-1,34-3618R-1, 37-4019R-1,24-2620R-1,23-2621R-1, 12-1324R-1,69-7325R-1,49-5326R-CC, 0-427R-1, 104-10729R-1, 17-1931R-1, 18-2033R-1, 10-1433R-1, 126-12935R-1, 51-5535R-1, 123-12737R-1.7-1039R-1,4-7
129-801C-
4R-1,11-165R-4,11-166R-1,31-34
60.670.279.599.0
100.0108.7118.5128.1139.0147.5158.6176.3176.5
254.8272.7282.0292.0310.8319.9329.6338.9348.2357.5366.7375.8393.3397.7407.0407.7416.4425.8434.9436.1444.8445.5453.6462.7
521.8535.8540.8
2.722.210.516.718.116.914.218.718.314.414.112.09.8
12.017.712.0010.2010.5011.704.807.108.761.804.706.206.40
10.9010.503.607.345.00
19.608.09
25.6011.601.804.90
0.771.901.60
2.926.011.932.319.825.514.728.330.924.124.020.515.0
16.535.726.4020.2018.1025.30
6.558.319.943.308.737.19
11.5016.7015.906.019.606.68
28.0010.0029.9014.502.303.90
0.221.602.20
3.220.09.7
13.016.016.014.016.017.013.012.011.08.2
8.118.011.010.08.8
10.04.37.88.11.94.85.66.5
10.09.83.56.44.1
27.06.8
22.010.0
1.45.0
0.61.82.4
0.704.892.432.833.943.663.183.593.682.982.722.641.84
1.944.222.7602.8201.9802.1001.1401.8701.8000.4201.1501.3901.4502.1702.1500.7931.4801.0405.9401.4203.8302.3000.4401.110
0.1300.4600.868
0.1401.0600.5570.7040.8540.8010.6950.8760.9090.7270.6490.6500.449
0.4531.2100.6610.7560.3890.4080.2200.4030.3870.0960.2500.3000.2950.4360.4380.1700.3080.2101.3700.3000.7730.5160.1100.270
0.0470.1200.260
0.0980.7200.3600.3410.5530.5050.4740.5200.4730.4000.3700.3580.280
0.3010.5530.4120.5100.2800.2900.1400.2700.2880.0700.1700.2100.2100.3040.3070.1300.2100.1500.9150.2000.4600.3600.0650.200
0.0510.0830.230
0.402.151.100.901.681.301.301.200.920.960.980.810.66
0.791.301.202.020.871.100.410.660.790.290.570.830.711.061.000.370.770.502.240.661.301.200.230.65
0.280.281.10
0.020.290.160.120.220.170.180.170.120.120.130.110.08
0.100.170.1500.2860.1300.1400.0570.0870.0970.0210.0680.0900.1000.1510.1500.0460.0960.0740.3230.0950.2000.1700.0350.080
0.0220.0400.150
Minor element data
1805739
18097
11013081
43016044316089
2173
12035
200532130330200
67510684580958
1500240360330
6190917
400089420
250
179.9
12
2.009.885.70
15.4011.4012.2014.5037.1052.9029.4038.4028.3023.00
16.30213.00
29.633.311.512.73.93.95.92.55.24.46.0
11.911.13.54.04.5
27.228.939.322.9
2.95.3
3.63.4
21.6
0.21.60.720.971.231.171.110.971.11.31.530.840.49
0.580.672.121.101.772.160.730.870.930.281.200.861.642.582.570.771.101.074.813.055.303.380.560.31
0.090.160.07
0.170.770.452.050.890.930.661.451.951.211.320.920.69
0.592.981.5001.0600.8691.0700.3300.4200.4700.2000.4800.4300.6000.9520.9400.3200.4500.4903.0501.4003.2002.1700.6500.380
0.0960.1100.140
4.326.011.025.025.025.025.023.033.032.041.220.014.0
12.035.031.0048.2030.0033.0012.0014.0015.004.00
17.0014.0024.0043.0042.0012.0016.0018.0078.0046.8094.7059.0013.007.60
3.109.302.00
0.140.330.240.240.290.160.270.240.180.170.190.190.10
0.160.170.240.200.180.290.090.240.200.120.250.230.220.530.560.350.270.201.300.480.991.400.210.10
0.310.050.04
0.392.601.082.892.372.672.162.683.042.573.101.741.26
1.111.972.501.562.633.251.051.231.490.471.371.251.702.952.820.921.191.184.602.555.382.980.380.58
0.080.160.11
0.601.802.000.440.460.390.350.310.390.340.290.250.20
0.391.500.800.250.760.742.501.201.702.901.700.540.540.520.941.500.830.681.101.000.980.900.460.23
0.210.300.44
18.036.021.050.439.535.033.336.027.029.029.018.014.0
15.0103.064.026.043.337.015.017.022.011.017.019.020.029.432.08.8
15.015.077.934.492.163.517.07.5
13.07.3
34.0
40392880504350798149446057
501207043589050574040394837395542
425
10060
1101302927
401730
0.6085.2302.8406.3104.5704.4903.9205.4206.4505.3505.5603.4802.400
2.40015.1008.395.804.415.481.802.152.370.912.572.363.254.825.161.772.362.32
15.406.56
14.7010.502.762.11
0.500.987.32
11321127212531323324292011
1215033.016.029.034.011.022.012.012.018.016.08.9
15.015.08.0
12.08.3
65.024.061.052.017.022.0
22.015.032.0
4033199026363497
14095764039
34220150.044.051.0
100.022.028.030.030.032.028.025.055.060.023.030.022.0
180.039.0
150.040.00.0052
24.0
40.0130.0140.0
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
Table C3. Rare earth element and minor element analyses (in parts per million) for samplesfrom Site 802, Leg 129.
Sample (cm)
Rare earth element data
129-802A-
33R-1, 116-12034R-1, 128-13235R-CC, 0-437R-1, 11-1538R-CC, 12-1539R-1, 10-1543R-1, 75-7852R-2, 125-13055R-1, 138-14156R-1,43^756R-2, 88-92
Sample (cm)
Minor element data
129-802 A-
33R-1, 116-12034R-1, 128-13235R-CC, 0-437R-1, 11-1538R-CC, 12-1539R-1, 10-1543R-1,75-7852R-2, 125-13055R-1, 138-14156R-1,43-4-156R-2, 88-92
Depth(mbsf)
294.0303.6320.5330.0348.6348.8382.9462.6489.3497.5499.5
Depth(mbsf)
294.0303.6320.5330.0348.6348.8382.9462.6489.3497.5499.5
La
12.204.704.70
11.0029.1024.8034.3043.0032.0027.0020.70
Ba Cr
897 3.513 2.118 1.927 11.7
100 51.454 36.972 21.2
100 24.099 21.8
110 26.645 12.1
Ce
7.922.103.506.91
34.8024.2048.4052.8040.0035.0028.80
Cs
0.230.090.200.300.950.612.022.972.131.921.54
Nd
12.04.54.49.4
28.023.029.036.026.025.022.0
Hf
0.3300.1400.1900.2902.6001.7801.1401.8701.7202.3100.930
Sm
2.5901.0301.0602.1906.8005.6406.9708.7106.1405.8705.900
Rb
4.303.104.205.00
25.0015.0040.2047.8040.0039.0041.00
Eu
0.5980.2550.2300.4891.6701.3001.6501.9801.4301.4001.550
Sb
0.100.160.120.150.340.240.200.220.300.230.19
Tb
0.3850.1820.1700.3400.9770.7641.0701.2800.9830.8400.980
Th
0.560.190.300.763.232.143.144.764.084.012.29
Yb
1.230.540.510.952.592.152.643.513.182.433.12
U
0.190.541.901.600.620.470.830.930.660.820.48
Lu
0.1700.0670.0480.1300.3460.3030.3500.4800.4380.3440.429
Zn
17.07.4
21.013.068.155.330.065.572.386.637.0
Zr
25301840
12060529687
11033
Sc
2.480.671.121.778.737.086.31
10.108.61
11.406.90
Ni
19.012.011.08.0
71.039.026.047.069.074.034.0
Sr
480.040.040.041.0
230.0200.071.0
160.0100.0230.050.0
Note: Analyses obtained by induced neutron activation analysis (INAA), U.S. Geological Survey laboratories.
76
[BLANK PAGE]
S. M. KARL, G. A. WANDLESS, A. M. KARPOFF
APPENDIX D
Table Dl. Major element oxide data (in percent) for additional samples from Leg 129.
Sample (cm)
129-800 A-
6R-1,76R-1,377R-1,668R-1, 18R-1, 22
10R-1, 1312R-1, 3713R-1,4614R-1, 10117R-1.2518R-1, 7018R-1, 12119R-1, 119R-1, 3721R-2, 822R-1, 1924R-l,30
129-801A-
7R-CC, 110R-1,11
129-801B-
14R-1, 2418R-1.2424R-1.5425R-1, 127R-l,3033R-1,4333R-2, 4835R-2, 12035R-2, 14035R-3, 135R-3, 19
Depth(mbsf)
39.740.049.858.959.178.397.7
107.2117.2144.4154.4154.9162.9163.3182.9191.2210.2
60.479.6
310.5348.0393.1397.2407.0435.2436.8447.0447.2447.3447.5
Unit
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
11II
IVIVIVIVIVVVVVVV
SiO2
85.5080.8092.0087.5089.0092.8090.6069.1093.0062.2083.6092.0085.5080.1048.7033.6085.30
90.890.5
82.585.485.385.996.881.483.756.364.866.769.8
A12O3
4.405.301.502.902.501.502.400.701.500.803.901.503.505.500.506.703.30
1.92.1
4.83.73.23.40.34.53.0
11.38.38.47.8
FeTO3
2.002.501.001.501.301.701.300.501.100.502.901.102.504.400.305.202.70
1.11.2
3.42.42.72.80.55.75.4
15.313.311.19.8
MgO
1.041.360.420.900.830.330.750.250.540.361.280.511.241.900.312.271.20
0.530.54
1.420.900.970.880.061.110.772.841.962.141.76
CaO
0.400.700.200.900.200.200.30
14.400.30
18.700.700.300.400.50
26.2025.000.50
0.500.30
0.600.500.400.600.300.500.401.400.800.700.60
Na2O
1.001.140.390.700.700.370.510.220.440.240.920.500.690.970.171.270.73
0.420.55
1.190.800.800.880.190.880.681.431.411.371.13
K2O
1.071.380.440.660.690.480.880.260.570.281.140.501.131.680.110.840.93
0.490.51
1.361.150.940.990.131.631.223.672.783.062.70
TiO2
0.200.230.130.150.140.160.160.100.130.100.370.150.280.460.081.080.31
0.100.16
0.300.210.170.210.050.310.200.850.560.590.54
Mn3O4
0.270.440.200.220.110.010.010.030.010.080.020.010.010.030.090.070.07
0.1350.118
0.5610.3030.5280.4280.1100.0400.0390.4020.1570.1490.070
LOI925C
4.305.542.743.903.502.852.62
13.332.52
16.523.632.333.595.00
23.1024.203.28
2.502.68
4.513.773.213.721.604.013.556.856.175.835.19
Oxidetotal
100.1899.3999.0299.3398.97
100.4099.5398.89
100.1199.7898.4698.9098.84
100.5499.56
100.2398.32
98.47598.658
100.64199.13398.21899.808
100.04100.0898.959
100.342100.237100.03999.39
Note: Analyses obtained by microprobe at the University of Strasbourg, France.
78
LEG 129 SILICEOUS DEPOSITS
Table D2. Minor element data (in parts per million) for additionalsamples from Leg 129.
Sample (cm)
129-800A-
6R-1.76R-1.377R-1.668R-1, 18R-1.2210R-1, 1312R-1.3713R-1.4614R-1, 10117R-1.2518R-l,7018R-1, 12119R-1, 119R-1,3721R-2, 822R-1, 1924R-l,30
129-801A-
7R-CC, 110R-1, 11
129-801B-
14R-1, 2418R-1.2424R-1,5425R-1, 127R-1.3033R-1.4333R-2, 4835R-2, 12035R-2, 14035R-3, 135R-3, 19
Depth(mbsf)
39.740.049.858.959.178.397.7107.2117.2144.4154.4154.9162.9163.3182.9191.2210.2
60.479.6
310.5348.0393.1397.2407.0435.2436.8447.0447.2447.3447.5
Ba
851505962572142918412732449416056871419952282
43100
23610592629154488
18499231227256024492036
Cr
191912161431301152135031254378229
129
11161481
201654394313
Cu
8713832854842201620123721598164229
7742
626473693259941371198762
Ni
38447231526132816356634372211446
3423
4630291812929142827660
Sr
40591757191625195191946622447120454257
2826
8256777211754210811411292
Zn
819838572544230161516542032562010355
1632
7851476646639159124109104
Zr
54602744362937152919692945768
11848
2314
68534649108673148155140112
Note: Analyses obtained by microprobe at the University of Strasbourg, France.
79