49. MAGNETOBIOSTRATIGRAPHY OF DEEP SEA DRILLING PROJECT LEG 72, SITES 515-518,RIO GRANDE RISE (SOUTH ATLANTIC)

W. A. Berggren2, N. Hamilton3, D. A. Johnson2, C. Pujol4, W. Weiss5, P. Cepek5, and A. M. Gombos, Jr.6

INTRODUCTION

This paper contains magnetobiostratigraphic correla-tion charts for each of the four sites occupied duringDSDP Leg 72. Microfossil zonal boundaries and mag-netic polarity determinations for Sites 515 through 518are summarized in Figures 1 through 4, respectively.Our discussion focuses on the correlations derived forthe Paleogene and late Cretaceous (Coniacian-Mae-strichtian) of Site 516, because of the value of this site asa stratigraphic reference section for the South Atlantic.The Neogene magnetobiostratigraphy of Site 516 istreated in detail elsewhere (Berggren, Aubry, and Ham-ilton, this volume), and will not be discussed further inthis synthesis chapter.

Unless otherwise specified, all core and section num-bers in this paper refer to cores and sections of Hole516F.

PALEOGENE MAGNETOBIOSTRATIGRAPHYA virtually complete Paleogene section (Sections 5-1

to 89-5; 208 to 965 m sub-bottom) is present in Hole516F (Fig. 2). Good quality magnetic polarity strati-graphic data (Hamilton, this volume), the integration ofbiostratigraphic data of Pujol (this volume), and evolu-tion of their correlation by reference to similar studieson the Contessa sections, Gubbio (Lowrie et al., 1982)and South Atlantic DSDP Sites 523 and 524 (Poore etal., in press) allow the assignment of the polarity rever-sal stratigraphy to the standard numbered anomaly se-quence. Some numeric assignments are difficult becauseof the incomplete nature of the magnetic stratigraphicrecord; for instance, the series of normal "events" as-sociated with middle-late Eocene biostratigraphy overthe interval of Cores 45 to 77. Numeric assignment isbased primarily on three correlations:

1) Lower Oligocene and uppermost Eocene calcare-ous nannoplankton and planktonic foraminiferal as-semblages in Cores 35 to 36 and 39 are associated withAnomalies 13 and 15, respectively (cf. Lowrie et al.,1982; Poore et al., in press).

2) The base of Zone NP15 (based on first appearancedatum Nannotetrina fulgens) between 76,CC and 77,CC

1 Barker, P. F., Carlson, R. L., Johnson, D. A., et al., Init. Repts. DSDP, 72: Washing-ton (U.S. Govt. Printing Office).

2 Woods Hole Oceanographic Institution, Woods Hole, Massachusetts.Dept. of Geology, University of Southampton, Southampton, United Kingdom.

* Université de Bordeaux, 33405 Talence, France.Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover 51, West Germany.Exxon Production Research Co., P.O. Box 2189, Houston, Texas.

suggests that the normal polarity event of Cores 75 to 77is Anomaly 21 (cf. Lowrie et al., 1982; Poore et al., inpress).

3) The presence of the last appearance datum (LAD)of Morozovella spinulosa in Core 49 suggests that thesequence of normal events of Cores 45 to 52 representAnomalies 17 and 18. The LAD of M. spinulosa occursessentially simultaneously with the first appearance da-tum (FAD) of Porticulasphaera beckmanni, the nomi-nate taxon of Zone P13, which essentially brackets thetop of Anomaly 18 and base of Anomaly 17 (Lowrie etal., 1982).

Polarity assignments are made on the basis of thisand other magnetobiostratigraphic correlations fromthe studies of Lowrie and others (1982) and Poore andothers (in press), as shown in Figure 2.

The OligoceneThe Oligocene/Miocene boundary is drawn here at

the FAD of Globorotalia kugleri and LAD of Reticulo-fenestra bisecta, both of which occur in Section 5-1 (208m) in Anomaly 6C (see Berggren, Aubry, and Hamilton,this volume). Further discussion of the reasoning for thechoice of these criteria is given in Berggren, Kent, andVan Couvering (in press). The Eocene/Oligocene bound-ary lies within the interval of Cores 38 to 39 and is dis-cussed in greater detail below.

We recognize approximately 5 to 6 planktonic fora-miniferal datum events in the Oligocene (see Fig. 2). TheFADs of Globigerinoides primordius as rare (255 m)and common (215 m) components in the assemblagesare stratigraphically below the FAD of Globorotalia ku-gleri (208 m, Anomaly 6C). This record is consistentwith findings of this taxon elsewhere in pre-Aquitanian(= pre-Miocene) stratigraphic levels. The FAD of Glo-bigerina angulisuturalis is in Core 24, upper Anomaly11, and the LAD of Chiloguembelina is in Core 20, mid-dle of Anomaly 9, consistent with the records of this da-tum level in DSDP Site 522 (Poore et al., in press). TheLAD of Chiloguembelina (correlative with the NP23/24boundary) has recently been suggested as a more reliablecriterion for the recognition of the Chattian/Rupelianboundary (see discussion in Berggren, Kent, and Flynn,in press) and is essentially coincidental with the NP23/24 boundary (between between 18,CC and 19,CC) inHole 516F as well. The LAD of Pseudohastigerina (Core31; in the reversed interval just below Anomaly 12) isidentical to that seen in DSDP Site 522 (Poore et al., inpress).

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W. A. BERGGREN ET AL.

100-

200

250-

600

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500-

NormalpolarityReversedpolarityNo paleo

iiiiiiJ magnetic data

Figure 1. Magnetostratigraphy and biostratigraphy of Site 515, showing key diatom and radiolarian datum levels.

940

MAGNETOBIOSTRATIGRAPHY

The Eocene

Biostratigraphic determination of the Eocene/Oligo-cene boundary presents somewhat of a problem in Hole516F. The upper part of the range of the Globorotaliacerroazulensis cocoaensis group and Globigerinathekasemiinvoluta exhibits sporadic, rare occurrences. TheEocene/Oligocene boundary is drawn by Pujol (this vol-ume) and Cepek (personal communication, 1982) in Core39 (incomplete Anomaly 15) on the basis of the sup-posed disappearance of these groups and the rosette-shaped discoasters. Elsewhere, the Eocene/Oligoceneboundary lies at a level approximately midway betweenAnomalies 13 and 15 (Lowrie et al., 1982; Poore et al.,in press), and one wonders whether a hiatus may bepresent in Hole 516F.

A more likely explanation appears to be the intensedissolution that characterized the later part of the Eo-cene at this site and that may have selectively removedless-resistant taxa from the stratigraphic record. A"trace" occurrence of the solution-resistant taxon semi-involuta is noted by Pujol (this volume) as high as Sec-tion 38-1. If this is indeed a true, in situ occurrence andif the Eocene/Oligocene boundary is drawn at this level,it would lie approximately midway between (the pre-served parts of) Anomalies 13 and 15, in conformitywith the studies of Gubbio and the South Atlantic citedabove.

The "LAD"s of Globorotalia cocoaensis and Glo-bigerinatheka semiinvoluta are perhaps not true datumevents. Rather they are plotted in Figure 2 merely be-cause of their general importance in upper Eocene bio-stratigraphy.

The lack of diagnostic taxa renders biostratigraphicsubdivision within the Eocene difficult. The LAD ofMorozovella spinulosa (Core 49) is a distinct event thatserves to identify the Anomaly 17 to 18 interval becauseof its close association elsewhere with the FAD of Porti-culasphaera beckmanni and the association of the lattertaxon with the upper part of Anomaly 18 (Lowrie et al.,1982). This magnetobiostratigraphic correlation (in Hole516F) is consistent with the NP17/18 boundary (46,CCto 47,CC) at a level identified as upper Anomaly 17, be-cause the LAD of Chiasmolithus grandis and the FADof Chiasmolithus oamaruensis (taxa used to determinethe NP17/18 zonal boundary) have been recorded fromthe upper part of Anomaly 17 at DSDP Site 522 (Pooreet al., in press).

The Paleocene

The Paleocene/Eocene boundary is placed here be-tween Cores 81 and 82, at approximately 895 m sub-bot-tom (based on the LAD of Morozovella velascoensis).This level is situated within Zone NP10-11 (undiffer-entiated) and within an interval of uncertain magneticpolarity between what is clearly Anomaly 25 (Cores 82to 84) below and probably Anomaly 24 (Cores 80 and81) above. This magnetobiostratigraphic correlation isconsistent with that suggested for Gubbio (Lowrie et al.,1982) and for the South Atlantic, DSDP Leg 74 (Shack-leton and Boersma, personal communication, 1982).

Paleocene magnetobiostratigraphic correlations inHole 516F are shown in Figure 2. They agree well withthose for Gubbio (Alvarez et al., 1977; Lowrie et al.,1982), and for DSDP Legs 73 (Poore et al., in press) and74 (Shackleton and Boersma, personal communication,1982) in the South Atlantic. A more detailed discussionof the relationships of various Paleocene datum levels tomagnetostratigraphy and to Paleocene chronostratig-raphy is presented in Berggren, Kent, and Flynn (inpress).

The Cretaceous/Tertiary Boundary

The Cretaceous/Tertiary boundary is drawn in Sec-tion 89-5 (approximately 965 m sub-bottom) on thebasis of the extinction of Late Cretaceous globotrun-canids and the top of the Micula mura Zone. This levelis situated a short distance down in the reversed intervalbelow Anomaly 29 and agrees well with the boundary'smagnetobiostratigraphic determination at Gubbio (Al-varez et al., 1977), the South Atlantic (Poore et al., inpress; Shackleton and Boersma, personal communica-tion, 1982), and in the boundary stratotype section atStevns Klint, Denmark (Mörner, 1982).

MESOZOIC MAGNETOBIOSTRATIGRAPHY

Analysis of the correlation between the biostrati-graphic and magnetobiostratigraphic record in the laterpart of the Mesozoic (Late Cretaceous) is as yet, at anearly stage. Direct correlation was treated initially in apreliminary manner by Alvarez and others (1977) forthe Cenomanian to Maestrichtian interval at Gubbio,Italy. Van Hinte (1976) and Thierstein (1976) suggestedpossible magnetobiostratigraphic correlations based onan integration of radiometric, biostratigraphic, and geo-magnetic data. The improvement in coring technique(and recovery) of the Glomar Challenger is now makingpossible the integration of more reliable magnetobio-stratigraphic data from the deep sea and the develop-ment of a more reliable magnetochronologic scale forthe Mesozoic.

Estimates of the magnetobiochronology of the stan-dard Late Cretaceous chronostratigraphic units dependsupon an accurate biostratigraphic framework. The bio-stratigraphic framework of Late Cretaceous stages hasbeen discussed by Berggren (1964) and more recently byThierstein (1976), van Hinte (1976), and Sissingh (1977,1978).

The Campanian/Maestrichtian boundary is interpret-ed here in the sense of Berggren (1964), van Hinte(1976), Thierstein (1976), and Sissingh (1977, 1978),namely, in the inclusion of the Craie de Gulpen (Cr4) asits lower unit. The Campanian/Maestrichtian bound-ary, in this sense, corresponds to the base of the Acan-thoscaphites tridens (Tethyan) Zone and the Belemnellalanceolata ("Boreal") Zone, the top of Globotruncanacalcarata (van Hinte, 1976) and lies within the lowerpart of the Tetralithus trifidus Zone (Bukry, 1973). Sis-ingh (1977, 1978) has subsequently equated this zonewith a series of zones: Tetralithus trifidus (22), Tranoli-thus phacelosus (23), Rheinhardtites levis (24), and thelower part of the Arkhangelskiella cymbiformis (25)

941

W. A. BERGGREN ET AL.

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Foraminiferal boundaries onlyprovisionally determinedbecause of poor recovery,dissolution, or lack ofdefinitive taxa

Figure 2. Magnetostratigraphy and biostratigraphy of the Paleogene and Cretaceous of Site 516, showing important calcareous microfossil datumlevels. The Neogene of Site 516 is treated in a separate chapter by Berggren, Aubry, and Hamilton (this volume). Alternate placements of theCampanian/Maestrichtian boundary (1055 or 1085 m sub-bottom depth) and of the Santonian/Campanian boundary are indicated.

942

MAGNETOBIOSTRATIGRAPHY

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Figure 2. (Continued).

943

W. A. BERGGREN ET AL.

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MAGNETOBIOSTRATIGRAPHY

trinidadensis) above an unzoned interval (Sections 104-4to 101-4) in which Globotruncanella havanensis andGlobotruncana scutilla make their first appearance. Un-fortunately, typical lower Maestrichtian elements as G.tricarinata or Rugotruncana subcircumnodifera and up-

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Figure 4. Magnetostratigraphy and biostratigraphy of Site 518. SeeFigure 1 for key.

Table 1. Relationship between definitive datum levels and magneticpolarity stratigraphy in Hole 516F.

1.

2.

3.

4.

Datum level(FAD)

Abathomphalusmayaroensis

GlobotruncanafalsostuartiGlobotruncanellahavanensis

Globotruncanaarea

Sub-bottomdepth(m)

1016

1055

1065

1155

Magneticpolarity stratigraphy

Reversed intervaljust below (com-bined) Anomaly30-31

Early part ofAnomaly 32

Reversed intervalbetween Anom-lies 32 and 33

Approximately mid-way betweenAnomalies 33and 34

Remarks

Within the Arkhangelskiella cymbiformisZone

Approximately in the middle part of theTetralithus trifldus Zone

Just below the middle part of the T.trifidus Zone

Within the Eiffellithus eximius Zone

Note: FAD = first appearance datum.

per Campanian forms as Globotruncana calcarata aremissing at this site.

The Campanian/Maestrichtian boundary in Hole516F is within the middle part of the Tetralithus trifidusZone which, by correlation, is within the lower part ofthe Tranolithusphacelosus (23) Zone of Sissingh (1977);this location agrees with Sissingh's biostratigraphic place-ment of the Campanian/Maestrichtian boundary interms of stratotype stratigraphy. This level lies in thelower part of Anomaly 32 and is approximately equiva-lent to the level of this boundary as estimated (pre-dicted) by van Hinte (1976), although we disagree withhis chronology for reasons presented below. Alvarezand others (1977, fig. 2) show the G. calcarata/G. tri-carinata zonal boundary (= Campanian/Maestrichtianboundary) in the upper part of the Gubbio Normal ZoneB+ (= Anomaly 33), as do Channell and Medizza(1981) in the Carcoselle section, Belluno Basin, Venet-ian Alps. The top of the late Campanian calcarata Zoneis within the middle part of the trifidus (calcareous nan-noplankton) Zone (van Hinte, 1976; Sissingh, 1977,1978) and is situated about one-third of the way downfrom the top of Gubbio Polarity Zone B + (= Anomaly33) in the Carcoselle section (Channell and Medizza,1981). In the Carcoselle section, Tetralithus trifidus(= Quadrum trifidum) Total-Range Zone spans the in-terval from the top of Gubbio Polarity Zone D+ ( =Anomaly 32) to the lower part of Gubbio Polarity Zone6+ (= Anomaly 33) (Channell and Medizza, 1981),whereas in Hole 516 this zone spans the interval fromjust above Anomaly 32 to the upper part of Anomaly33. We are as yet at an early stage in correlating bio-stratigraphic data to magnetobiostratigraphy. We wouldsuggest that the differences noted here may be due todifferences in taxonomic determination and biostrati-graphic interpretation.

On the basis of the data received here we have twochoices in determining the Campanian/Maestrichtianboundary in Hole 516F:

1) At a level within the trifidus zone approximatelyone-third of the way down from the top of Anomaly 33,in order to agree with the determination at Gubbio (Al-varez et al., 1977) and the Belluno Basin (Channell andMedizza, 1981). This level would be at approximately1085 m sub-bottom (in Core 105) in Hole 516F.

2) At the FAD of Globotruncana falsostuarti and afaunal association typical of the Maestrichtian above anunzoned interval (Sections 104-4 to 101-4) in which Glo-botruncanella havanensis and Globotruncana scutillamade their first appearances. This level, chosen byWeiss (this volume), is at about 1055 m (Section 101-3)and lies in the lower part of Anomaly 32.

The fact that the FAD of Globotruncana gansseri (=middle Maestrichtian) is shown to occur within Anom-aly 32 and within the uppermost part of the Q. trifidumZone in the Belluno Basin (Channell and Medizza, 1981)suggests that the true position of the Campanian/Maestrichtian boundary in Hole 516F may be closer tothe first option suggested above, i.e., within the upperpart of Anomaly 33. Both positions are shown, how-ever, on Figure 2.

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W. A. BERGGREN ET AL.

AGE OF THE CAMPANIAN/MAESTRICHTIANBOUNDARY

The chronology of this boundary, while somewhatbeyond the scope of this report, will be treated brieflybecause of the controversy that has surrounded it.Based on K-Ar dates of bentonites associated with vari-ous baculitid and ammonite zones, Obradovich andCobban (1975) suggest ages of 69 Ma (about 71 Ma),7 70to 71 Ma (about 72 to 73 Ma), and 72 to 73 Ma (about74 to 75 Ma) for the Campanian/Maestrichtian bound-ary. The age estimate of 69 Ma (about 71 Ma) is basedon dates in the western interior of Canada on strati-graphic levels equivalent in the United States to the Bac-ulites grandis Zone. The Campanian/Maestrichtianboundary in the western interior of Canada was provi-sionally drawn by Jeletzky (1968) at a level equivalent inthe United States to the boundary between the Baculiteseliasi and B. baculus zones, the next two zones belowthe B. grandis Zone (see Obradovich and Cobban, 1975,p. 47). However, this boundary is incorrectly correlatedto the stratotype Maestrichtian and is clearly too high.Jeletzky (1951) has shown that the base of the Mae-strichtian Stage coincides with the bases of the Belem-nella lanceolata and Acanthoscaphites tridens zones,which are correlative, in turn, with the top of the calcar-ata Zone (van Hinte, 1976). The base of the Maestrich-tian is correlative also with the initial appearance ofRugotruncana subcircumnodifera (Berggren, 1962). Us-ing the same criterion, Pessagno (1967,1969) recognizedthis boundary in the Gulf Coast. But the boundary de-termined in this way corresponds approximately to theboundary between the Didymoceras nebrascense and D.stevensoni zones in the United States, some 8 zones be-low the boundary as correlated made by Jeletzky (1968)(Obradovich and Cobban, 1975, p. 48). Thus the corre-lation made by Jeletzky (1968) from the western interiorto the stratotype Maestrichtian is clearly too young.That made by Pessagno (1967, 1969) is more nearly cor-rect, and the age estimate of 72 to 73 Ma (approximately74 to 75 Ma) is based on radiometric dates made on theD. nebrascense Zone and (two zones above) the Exitelo-ceros jenneyi Zone. Olsson (1964) determined the Cam-panian/Maestrichtian boundary in New Jersey at a levelcorrelated with the Baculites scotti Zone, a zone belowthe D. nebrascense Zone. The radiometric dates onthese biostratigraphic levels can serve as the basis forgeochronologic estimates of the age of the Campa-nian/Maestrichtian boundary, not those made at thelevel of the Baculites grandis Zone.

A recently proposed Late Cretaceous-Cenozoic timescale (Berggren, Kent, and Flynn, in press) uses cali-bration points of 84 Ma (top of Anomaly 34) and 56.2Ma (base of Anomaly 24) to determine the magneto-chronology of the lower of 3 distinct segments of thescale. In terms of this scale, our magnetochronologicage estimate of the Campanian/Maestrichtian boundarywould be: (1) later part of Anomaly 33 (-1085 m, - 74

Ages in parentheses refer to reevaluations based on newer decay constants.

Ma); or (2) early part of Anomaly 32 (~ 1055 m, -73Ma). The appendix at the end of the chapter shows arevised geomagnetic polarity time scale for the Cenozoicand Late Cretaceous.

The Eiffellithus eximius Zone (Cores 114 to 116) hasbeen equated with the Campanian-Santonian (undiffer-entiated) and the Marthasterites furcatus zones in thebasal part of Hole 516F (Cores 116 to 124) to the Santo-nian-Coniacian (undifferentiated) (Cepek, personal com-munication, 1982). Weiss (this volume) assigns the lowerpart of the section of Hole 516F (Cores 114 to 122) tolate to middle Santonian (undifferentiated) and drawsthe Santonian/Campanian boundary at the FAD of Glo-botruncana area (Section 114-4; approximately 1159 m).The associated fauna (G. renzi, G. coronata, G. para-concavata), and similar marginotruncanid elements, aswell as G. fornicata, followed by the disappearance ofthe multiserial heterohelicid Ventilabella eggeri and thedevelopment of a more typical Globotruncana s.s. as-semblage in the overlying Globotruncana ventricosaZone (Sections 112-2 to 104-5) is a characteristic featureof early Campanian assemblages. Van Hinte (1976)shows the Campanian/Santonian boundary to be essen-tially correlative with the base of the Eiffellithus eximiusZone. We have thus drawn the boundary between theseunits in Hole 516F as a diagonal line encompassing thestratigraphic interval (less than 15 m) of these two bio-stratigraphic levels.

AGE OF THE CAMPANIAN/SANTONIANBOUNDARY

Van Hinte (1976) suggests a correlation of the base ofthe Eiffellithus eximius Zone with the reversed intervalbetween Anomalies 33 and 34. It falls at essentially thesame level in Hole 516F. The FAD of G. area is located15 m higher within the middle part of the reversed inter-val between Anomalies 33 and 34. In the Gubbio sec-tion, the Santonian/Campanian boundary (= Globo-truncana carnata/G. elevata boundary) is drawn at alevel near the top of the Gubbio Long Normal Zone(= Anomaly 34) (Alvarez et al., 1977).

The Campanian/Santonian boundary has been dated(K-Ar date on bentonite in the Desmoscaphites bassleriZone from the western interior of the United States) at82.5 Ma (= 84.5 Ma), which led Obradovich and Cob-ban (1975, p. 47) to suggest an age of about 82 Ma forthe Campanian/Santonian boundary. In the magneto-biochronologic scale developed by Berggren and others(in press), the base of the E. eximius Zone falls at a levelabout one-third of the way up between the top ofAnomaly 34 (84.00 Ma) and the base of Anomaly 33(80.17 Ma), or at about 83 Ma. The base of G. area (ap-proximately midway between the two anomalies) is atapproximately 82 Ma.

AGE OF THE CONIACIAN/SANTONIANBOUNDARY

Hole 516F terminated in basaltic basement overlainby sediments assigned to the Marthasterites furcatusZone. The Coniacian/Santonian boundary is shown byvan Hinte (1976) and Sissingh (1977) to lie within the M.

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MAGNETOBIOSTRATIGRAPHY

furcatus Zone. Problems with the virtually barren stra-totype Coniacian preclude accurate biostratigraphic cor-relation (Sissingh, 1978), but there is general agreementthat it is a very short time-stratigraphic unit (1-2 sca-phitid zones at the most; Obradovich and Cobban, 1975).Because the lower part of the stratigraphic sequence inHole 516F cannot be zoned with planktonic foramini-fers, neither the position of the Coniacian/Santonianboundary nor the base of the Coniacian can be deter-mined at Site 516. Van Hinte (1976) suggests correlationof the Coniacian/Santonian boundary with a level with-in the later part of the Long Normal Zone (Anomaly34), about 3 Ma (82 Ma ago) below its top (79 Ma ago).

ACKNOWLEDGMENTS

We would like to acknowledge the kind cooperation of colleagueswho have provided us with (often unpublished) magnetobiostrati-graphic data, in particular R. Z. Poore (U.S. Geological Survey, Res-ton, VA), N. J. Shackleton (Cambridge University, England), AnneBoersma (Lamont-Doherty Geological Observatory, NY), Jan Back-mann (University of Stockholm, Sweden). Discussions with these col-leagues and reviews of a draft of this paper by them and by E. Vincent(Scripps Institution of Oceanography), Dennis Kent (Lamont-DohertyGeological Observatory, NY), and John Obradovich (U.S. GeologicalSurvey, Denver, CO) are gratefully acknowledged.

Preparation of this paper has been made possible by grants fromthe National Science Foundation, OCE-80-19052 (to W.A.B.), andOCE-80-25208 (to D.A.J.). This is Woods Hole Oceanographic Insti-tution Contribution No. 5266.

REFERENCES

Alvarez, W., Arthur, M. A., Fischer, A. G., Lowrie, W., Napoleone,G., Premoli Silva, I., and Roggenthen, W. M., 1977. Upper Cre-taceous-Paleocene magnetic stratigraphy at Gubbio, Italy. V.Type section for the Late Cretaceous-Paleocene geomagnetic re-versal time scale. Geol. Soc. Am. Bull., 88:383-389.

Berggren, W. A., 1962. Some planktonic foraminifers from the Mae-strichtian and type Danian stage of Southern Scandinavia. Stock-holm Contrib. Geol., 9(1): 1-106.

, 1964. The Maestrichtian, Danian and Montian Stages andthe Cretaceous-Tertiary boundary. Stockholm Contrib. Geology,11(5): 103-176.

Berggren, W. A., Kent, D. V., and Flynn, J. J., in press. Paleogenegeochronology and chronostratigraphy, In Snelling, N. J. (Ed.),Geochronology and the Geological Record: London (Geol. Soc.London Spec. Publ.).

Berggren, W. A., Kent, D. V., and Van Couvering, J. A., in press.Neogene geochronology and chronostratigraphy. In Snelling, N.J. (Ed.), Geochronology and the Geological Record: London(Geol. Soc. London Spec. Publ.).

Bukry, D., 1973. Low-latitude coccolith biostratigraphic zonation. InEdgar, N. T., Saunders, J. B., et al., Init. Repts. DSDP, 15: Wash-ington (U.S. Govt. Printing Office), 685-703.

Channell, J. E. T., and Medizza, F., 1981. Upper Cretaceous andPaleogene magnetic stratigraphy and biostratigraphy from the Ve-netian (southern) Alps. Earth Planet. Sci. Lett. 55(1981):419-432.

Jeletzky, J. A., 1951. Die Stratigraphie und Belemnitenfauna des Ober-campan und Maestricht Westfalens, Nordwestdeutschlands undDánemarks, sowie einige allemeine Gliederungs-Probleme derjüngeren borealen Oberkreide Eurasiens. Geol. Jahrb. Beih.,1:1-142.

, 1968. Macrofossil zones of the marine Cretaceous of theWestern Interior of Canada and their correlation with the zonesand stages of Europe and the Western Interior of the UnitedStates. Geol. Surv. Paper Geol. Surv. Can., No. 67-72.

Lowrie, W., Alvarez, W., Napoleone, G., Perch-Nielsen, K. P., Pre-moli Silva, I., and Toumarkine, M., 1982. Paleogene magneticstratigraphy in Umbrian pelagic carbonate rocks: the Contessa sec-tions, Gubbio. Geol. Soc. Am. Bull., 93:414-432.

Mörner, N. A., 1982. The Cretaceous/Tertiary boundary: chrono-stratigraphic position and sequence of events. J. Geol., 90:564-573.

Obradovich, J. D., and Cobban, W. A., 1975. A time-scale for theLate Cretaceous of the Western Interior of North America. Geol.Soc. Can. Spec. Pap., 13:31-54.

Olsson, R. K., 1964. Late Cretaceous planktonic foraminifera fromNew Jersey and Delaware. Micropaleontology, 10(2): 157-188.

Pessagno, E. A., Jr., 1967. Upper Cretaceous planktonic Foraminif-era from the western Gulf Coastal Plain. Paleontographica Am-ericana, 5(37):245-445.

r 1969. Upper Cretaceous stratigraphy of the western GulfCoast area of Mexico, Texas, and Arkansas: Boulder, CO (Geol.Soc. Mem.), 111.

Poore, R. Z., Tauxe, L., Percival, S. F., Jr., LaBrecque, J. L.,Wright, R., Petersen, N. P., Smith, C. C , Tucker, P., and Hsü,K. J., in press. Late Cretaceous-Cenozoic magnetostratigraphyand biostratigraphy correlations of the South Atlantic Ocean:DSDP Leg 73. In Hsü, K. J., LaBrecque, J. L., et al., Init. Repts.DSDP, 73: Washington (U.S. Govt. Printing Office).

Premoli Silva, I., and Boersma, A., 1977. Cretaceous planktonic fora-minifers—DSDP Leg 39 (South Atlantic). In Supko, P. R., Perch-Nielsen, K., et al., Init. Repts. DSDP, 39: Washington (U.S. Govt.Printing Office), 615-641.

Sissingh, W., 1977. Biostratigraphy of Cretaceous calcareous nanno-plankton. Geol. Mijnbouw, 56(l):37-65.

, 1978. Microfossil biostratigraphy and stage-stratotypes ofthe Cretaceous. Geol. Mijnbouw, 57(3):433-440.

Thierstein, H. R., 1976. Mesozoic calcareous nannoplankton bio-stratigraphy of marine sediments. Mar. Micropaleontol., 1:325-362.

van Hinte, J. E., 1976. A Cretaceous time scale. Am. Assoc. Pet.Geol. Bull., 60(4):498-516.

Date of Initial Receipt: October 28, 1982

APPENDIXRevised Geomagnetic

Polarity Time-Scale for theCenozoic and Late Cretaceous

Normal polarityinterval (Ma)

0.00-0.730.91-0.981.66-1.882.47-2.922.99-3.083.18-3.403.88-3.974.10-4.244.40-4.474.57-4.775.35-5.535.68-5.896.37-6.506.70-6.786.85-7.287.35-7.417.90-8.218.41-8.508.71-8.808.92-10.42

10.54-10.5911.03-11.0911.55-11.7311.86-12.1212.46-12.4912.58-12.6212.83-13.0113.20-13.4613.69-14.0814.20-14.6614.87-14.9615.13-15.2716.22-16.5216.56-16.7316.80-16.98

Anomaly

1

22A2A2A33333A3A

4444A4A

5

5A5A

5B5B5C5C5C

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W. A. BERGGREN ET AL.

Appendix. (Continued). Appendix. (Continued).

Normal polarityinterval (Ma)

17.57-17.9018.12-18.1418.56-19.0919.35-20.4520.88-21.1621.38-21.7121.90-22.0622.25-22.3522.57-22.9723.27-23.4423.55-23.7924.04-24.2125.50-25.6025.67-25.9726.38-26.5626.86-26.9327.01-27.7428.15-28.7428.80-29.2129.73-30.0330.09-30.3331.23-31.5831.64-32.0632.46-32.9035.29-35.4735.54-35.8737.24-37.4637.48-37.6838.10-38.3438.50-38.79

Anomaly

5D5D5E66A6A

6Bβc6C6C777A8899

1010111112131315151616

Normal polarityinterval (Ma)

38.83-39.2439.53-40.4340.50-40.7040.77-41.1141.29-41.7341.80-42.2342.30-42.7343.60-44.0644.66-46.1748.75-50.3451.95-52.6253.88-54.0354.09-54.7055.14-55.3755.66-56.1458.64-59.2460.21-60.7563.03-63.5464.29-65.1265.50-66.1766.74-68.4268.52-69.4071.37-71.6571.91-73.5573.96-74.0174.30-80.1784.00

Anomaly

161717171818181920212223232424252627282930313232

3334

Note: After Berggren, Kent,and Flynn, in press. Blanksindicate "not assigned."

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