Post on 01-Jun-2020
Quaternary Landscape Response to Climate Change
Geochemical and mineralogical evidence for Sahara and Saheldust additions to Quaternary soils on Lanzarote, eastern CanaryIslands, Spain
Daniel R. Muhs,1 James Budahn,1 Gary Skipp,1 Joseph M. Prospero,2 DeAnna Patterson3 andE. Arthur Bettis III41U.S. Geological Survey, MS 980, Box 25046, Federal Center, Denver, CO 80225, USA; 2Rosenstiel School of Marine and Atmospheric
Sciences, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA; 3ATA Services, Inc., 165 South Union Blvd., Suite 350,
Lakewood, CO 80228, USA; 4Department of Geoscience, 121 Trowbridge Hall, University of Iowa, Iowa City, IA 52242, USA
Introduction
Africa hosts the most importantsources of dust in the world today inthe Sahara and Sahel regions (Pros-pero et al., 2002; Goudie and Middle-ton, 2006; Mahowald et al., 2006;Kohfeld and Tegen, 2007). Becauseof the proximity of the Canary Islandsto Africa, dust storms are commonthere (Torres-Padron et al., 2002; Cri-ado and Dorta, 2003; Alastuey et al.,2005). Previous workers have recog-nized that eastern Canary Islands�soils contain quartz and mica, miner-als that do not occur in the localbasaltic rocks. Early investigatorsattributed quartz (Tejedor Salgueroet al., 1985) and mica (Jahn et al.,1987) to pedogenic processes. Morerecent investigators explain quartzand mica in the soils by African dust
ABSTRACT
Africa is the most important source of dust in the world today,and dust storms are frequent on the nearby Canary Islands.Previous workers have inferred that the Sahara is the mostimportant source of dust to Canary Islands soils, with littlecontribution from the Sahel region. Soils overlying a lateQuaternary basalt flow on Lanzarote, Canary Islands, contain, inaddition to volcanic minerals, quartz and mica, exotic to theisland�s bedrock. Kaolinite in the soils also likely has an exotic
origin. Trace-element geochemistry shows that the soils arederived from varying proportions of locally derived basalt andAfrican dust. Major-element geochemistry, clay mineralogy andinterpretation of satellite imagery suggest that dust additionsto the Canary Islands come not only from the Sahara Desert, butalso from the Sahel region.
Terra Nova, 22, 399–410, 2010
Canary Islands
Cape VerdeIslands
30°
40°
20°
10°
Atlantic
Ocean
EUROPE
AFRICA
S A H A R A
S A H E L
0 1000
Kilometres
Lanzarote
0°30° 15°
Algeria
Morocco
Libya
Mauritania
Mali
Niger
Nigeria
Wes
tern
Sahar
a
Senegal
IvoryCoast
BurkinaFaso
Guinea
Cameroon
Ghana
Tuni
sia
Cha
dSAHARANAIR LAYER(summer)
TRADEWINDS
(year-round)
HARMATTAN(winter)
TRADE WINDS(winter only)
Fig. 1 Map showing north-western Africa, the Canary Islands study area, localitiesreferred to in the text and the main dust-transporting winds and their seasons oftransport. Dust-bearing wind paths generalized from Dubief (1979), Kalu (1979),Sarnthein et al. (1981), McTainsh and Walker (1982), Stein and Sarnthein (1984),Tetzlaff and Peters (1986), Pye (1987), Stuut et al. (2005), and Schwanghart andSchutt (2008). Also shown (grey stippled areas) are major active sand seas,generalized from �Global Soil Regions� map, from US Department of Agriculture,Natural Resources Conservation Service (http://www.soils.usda.gov/use/worldsoils/mapindex/order.html), in turn derived from the FAO-UNESCO Soil Map of theWorld (Food and Agriculture Organization of the United Nations, UNESCO, 1974).
Correspondence: Dr Daniel R. Muhs, U.S.
Geological Survey, MS 980, Box 25046,
Federal Center, Denver, CO 80225, USA.
Tel.: +1 303 236 7919; fax: +1 303 236
5349; e-mail: dmuhs@usgs.gov
This article forms part of a thematic set of
articles guest-edited by Professor Vincenzo
Pascucci on the topic of Quaternary land-
scape response to climate change and
presented at the 2009 IAS Alghero confer-
ence.
� Published 2010. This article is a US Government work and is in the public domain in the USA 399
doi: 10.1111/j.1365-3121.2010.00949.x
inputs (Mizota and Matsuhisa, 1995;Zoller et al., 2003, 2004; Meco et al.,2006; Von Suchodoletz et al., 2008,2009a,b; Stuut et al., 2009).There is less of a consensus on the
source of African dust and the trajec-tories by which it arrives to theCanary Islands. One important dustpathway is the north-easterly trade-wind belt (Fig. 1), which occurs at lowaltitudes year-round (Sarnthein et al.,1981; Stein and Sarnthein, 1984; Pye,1987; Stuut et al., 2005). A number ofworkers have emphasized the impor-tance of this dust pathway for theorigin of soils and sediments on theCanary Islands (Coude-Gaussenet al., 1987; Grousset et al., 1992,1998; Rognon et al., 1996).In contrast, Bergametti et al.
(1989) point out that more southerlysources, such as the Sahel, also play arole in delivering dust to the CanaryIslands. Stuut et al. (2009) even pro-pose that Canary Islands� sediments
and soils are derived largely from theSahel region. Dust from the Saheland southern Sahara is transportedto the Atlantic Ocean via the SaharanAir Layer, or SAL (Fig. 1), whichoccurs predominantly in summer(Prospero et al., 1970; Carlson andProspero, 1972; Prospero and Carl-son, 1972; Prospero and Lamb,2003). Near Africa, the SAL reachesaltitudes as high as 5–7 km, abovethe trade-wind zone. Sarnthein et al.(1981), Stein and Sarnthein (1984),Tetzlaff and Peters (1986) and Pye(1987) point out that, although themain direction of dust transport inthe SAL is to the west at latitudesbetween �15� and �21�N, south ofthe Canary Islands, a south-to-northcomponent of flow can occur in thelee of an easterly wave. Thus, a�hook-like� trajectory of dust move-ment from the Sahel to the CanaryIslands via the SAL is observed(Figs 1 and 2). Evidence presented
by both Sarnthein et al. (1981) andGrousset et al. (1998) indicates thatboth the trade winds and the SALwere situated approximately wherethey are now during the last glacialmaximum, c. 20 000 yr BP, but dustfluxes may have been greater.We test hypotheses of Sahara vs.
Sahel dust origins on the CanaryIslands by studying late Quaternarysoils on a well-dated basalt flow onLanzarote (Fig. 3). Geochemistry andmineralogy are used to evaluatewhether young soils are derived fromlocal basalt, Saharan dust, Sahel dustor some combination of these materi-als.
Study area
An extensive basalt flow from theCorona Volcano is found on the north-ern part of Lanzarote (Fig. 3) and isdated to 21 000 ± 6500 yr BP by the40Ar ⁄ 39Ar method (Carracedo et al.,
25 July 2004(a) (b) 9 May 2007
Fig. 2 Examples of summer dust storms over the Canary Islands that have sources in broad areas in western Africa and are derivedfrom the SAL (Saharan Air Layer); note northward �hook-like� form of dust masses west of the African coast, with trajectoriestowards the Canary Islands: (a) 25 July 2004, MODIS image from the Aqua satellite (courtesy of Jesse Allen, NASA EarthObservatory, using data from MODIS Land Rapid Response System); (b) 9 May 2007, MODIS image from the Terra satellite(courtesy of Jeff Schmaltz, MODIS Rapid Response Team, NASA Goddard Space Flight Center).
African dust to the Canary Islands • D. R. Muhs et al. Terra Nova, Vol 22, No. 6, 399–410
.............................................................................................................................................................
400 � Published 2010. This article is a US Government work and is in the public domain in the USA
2003). Soils on the flow are relativelythin (�5 to �15 cm thick) silt-loamswith yellowish-brown colours (10YR4 ⁄4, 5 ⁄4, 5 ⁄6, 6 ⁄6, dry). In places, silthas penetrated (to �50 cm or more)into joints and fractures in the basalt(Fig. 4a). Elsewhere, soils cover theflow more evenly, and a sparse stonepavement has formed (Fig. 4b). Soilparticles also fill voids and vesicles onthe undersides of basalt fragments(Fig. 4c). Elsewhere on Lanzarote,thicker soils, but with similar coloursand textures, can be observed overlyingPleistocene aeolian sands (Fig. 4d).
Analytical methods
Geochemical analyses (Tables 1–3)were conducted on splits of bulk soil,the soil fraction<20 lm (clay and finesilt), basalt samples and African dustsamples collected on Barbados (withsome data previously reported byMuhs et al., 2007a). African dust col-lected on Barbados includes both Sah-aran and Sahel sources (Prosperoet al., 1970; Prospero and Nees, 1977,
1986; Glaccum and Prospero, 1980).Major- and trace-element geochemis-try was conducted by instrumentalneutron activation analysis (INAA) inlaboratories of the US Geological Sur-vey, Denver (Budahn and Wandless,2002). INAA is a preferredmethod as ityields very precise concentrations ofimmobile trace elements that are usefulfor provenance studies (Muhs et al.,2007a,b, 2008a). Mineralogy wasdetermined by X-ray diffractometry(XRD). Whole-soil mineralogy wasconducted on bulk, pulverized samplesX-rayed as random mounts. Clay(<2 lm) separates were X-rayed asoriented mounts on glass slides threetimes: air-dry, glycolated and heattreated (550 �C). Clay mineralogy ofthe African dust samples is reported byGlaccum and Prospero (1980). Parti-cle-size analyses were conducted in theDepartment of Geoscience, Universityof Iowa, using wet sieving (sand) andpipette (silt and clay) after pretreat-ments including destruction of organicmatter with hydrogen peroxide,destruction of carbonates with hydro-
chloric acid, and dispersion withsodium hexametaphosphate.
Mineralogy
The Canary Islands, including theCorona Volcano, are composed lar-gely of basalt. The Corona flow con-tains plagioclase, pyroxene, olivineand magnetite. Major-element con-centrations (from Table 1, convertedhere to oxides) support the mineralidentifications: CaO is 9.9–11.4%;Na2O is 2.5–3.2%; K2O is 0.7–1.2%;and total Fe as Fe2O3 is 12.2–13.0%,in agreement with Carracedo et al.(2003).Soils on the flow have abundant
(44–59%) silt-sized particles (53–2lm) with the exception of soils(SP-494, SP-495, SP-502) downwindof small dune fields or modern bea-ches (Fig. 5). Lanzarote soils, unlikeNorth American loess, have more finesilt than coarse silt. Soils on Lanzarote(other than the three sand-dominatedsamples) also have significant (17–30%) amounts of clay (<2 lm).
SP-500
SP-504 SP-499
SP-502
SP-503
SP-494
SP-495
SP-496
SP-497
SP-498
SP-490
SP-492
SP-501
SP-491
SP-493
13°30’ 13°27’ 13°24’
29°09’
29°12’
La Quemada
LA GRACIOSA
Los Helechos
Corona
Atlantic
Ocean
Atlantic
Ocean
LANZAROTE
0 2
Kilometres
Atlantic
Ocean
Soil sample
Basalt sample
Basalt, ~21 ka
Basalt, ~90 ka
Basalt, olderPleistocene
Volcano
Lava flowpaths
Explanation
SP-496
Basalt, Tertiary
Smalldunefields
Fig. 3 Geological map of northernmost Lanzarote island, showing late Quaternary volcanic flows (Carracedo and Day, 2002;Carracedo et al., 2003) and basalt and soil-sample localities from the present study.
Terra Nova, Vol 22, No. 6, 399–410 D. R. Muhs et al. • African dust to the Canary Islands
.............................................................................................................................................................
� Published 2010. This article is a US Government work and is in the public domain in the USA 401
Soils have a bulk mineralogy thatdiffers from the underlying bedrock,although the sand-sized particles areall composed of basalt. Thus,although soils contain the volcanicminerals pyroxene, plagioclase andolivine, the silt and clay fractions ofthe soils also contain quartz, mica,kaolinite and hematite. No calcite wasdetected in any bulk-soil sample. Foursoils spanning the geographical extentof the Corona lava flow were selectedfor clay mineralogy and differ littlefrom one another; all contain mica,kaolinite and quartz (Fig. 6).
Trace-element geochemistry
We use relatively immobile trace ele-ments as �fingerprints� for sourcematerials, following an approach used
elsewhere (Muhs et al., 2007a,b,2008a; Muhs and Budahn, 2009).Suites of certain trace elements showdistinct compositional fields for oce-anic crust and upper continental crust(Taylor and McLennan, 1985). BulkLanzarote soils have a Sc–Th–Tacomposition that spans the rangedefined by the two end-member parentmaterials, basalt and African dust. Incontrast, the <20 lm fractions ofLanzarote soils, although outside therange of African dust, fall closer to it.On both Co–Hf–Th and Cr–Hf–Thplots, bulk-soil samples also fall be-tween the two parent materials(Fig. 7). As with Sc–Th–Ta, the<20 lm fractions of Lanzarote soilsfall much closer to the range ofAfrican dust for both Co–Hf–Th andCr–Hf–Th.
Rare earth elements (REE) are alsoemployed as provenance indicators,particularly when reduced to key ele-ment ratios (chondrite-normalized)that define the nature of the wholeREE suite. LaN ⁄YbN vs. Eu ⁄Eu* andGdN ⁄YbN vs. Eu ⁄Eu* show gooddiscrimination between basalt andAfrican dust (Fig. 8). Both bulk soilsand the soil <20 lm fractions fallbetween the fields defined by the twoparent materials, similar to the Sc–Th–Ta, Co–Hf–Th and Cr–Hf–Thplots. Note that all of the <20 lmfractions of the soils have Eu ⁄Eu*within the range of African dust.
Major-element geochemistry
Chiapello et al. (1997) show thatFe ⁄Ca and K ⁄Ca are distinctive for
(a) (b)
(c) (d)
Fig. 4 Soils on northern Lanzarote island: (a) road cut exposure of silt-rich soil material penetrating c. 21 ka basalt flow nearSP-493 (Fig. 3), with metre stick for scale; (b) basaltic stone pavement (clasts are �2 to �10 cm) with underlying silt-rich soil nearSP-500 and SP-501; (c) underside of hand specimen of c. 21 ka basalt cobble, showing soil-impregnated voids and vesicles;(d) barranco exposure of thick, silt-rich soil overlying aeolian sand, in turn overlying mid-Pleistocene basalt flow near Famara;cliffs in background are composed of Miocene–Pliocene basalt. Locality coordinates: N29�04.548¢; W13�34.495¢.
African dust to the Canary Islands • D. R. Muhs et al. Terra Nova, Vol 22, No. 6, 399–410
.............................................................................................................................................................
402 � Published 2010. This article is a US Government work and is in the public domain in the USA
Tab
le1
Majorandtrace
elem
entconcentrationsofLanzarote
soils,basaltsfrom
CoronavolcanoandAfricandust
collected14June1967.
Sam
ple
Fe (%)
Ca
(%)
Na
(%)
K (%)
Rb
(p.p
.m.)
Sr (p.p
.m.)
Cs
(p.p
.m.)
Ba
(p.p
.m.)
Th (p.p
.m.)
U (p.p
.m.)
Zr (p.p
.m.)
Hf
(p.p
.m.)
Ta (p.p
.m.)
W (p.p
.m.)
Sc (p.p
.m.)
Cr
(p.p
.m.)
Co
(p.p
.m.)
Ni
(p.p
.m.)
Zn (p.p
.m.)
As
(p.p
.m.)
Sb (p.p
.m.)
Who
leso
ilsSP
-490
7.12
2.91
0.87
1.74
8130
23.
1354
310
.62.
9132
48.
083.
581.
3120
.138
440
.315
798
6.79
0.54
SP-4
917.
762.
641.
231.
6769
303
2.60
432
9.62
2.69
281
7.23
3.64
0.64
20.6
397
43.9
215
975.
990.
52SP
-492
7.00
4.16
1.03
1.25
6241
62.
4841
48.
912.
3926
96.
623.
261.
2219
.236
239
.418
290
5.58
0.57
SP-4
937.
615.
631.
291.
4059
611
2.33
484
8.65
1.80
285
6.75
3.49
0.85
20.9
378
41.7
174
974.
350.
37SP
-494
7.98
5.39
1.67
1.24
4856
61.
7646
66.
951.
8425
16.
263.
620.
9121
.637
744
.921
110
13.
420.
32SP
-495
8.45
3.66
1.18
1.14
6842
72.
9554
710
.13.
2732
28.
073.
931.
7623
.141
947
.923
313
05.
310.
69SP
-496
6.07
1.02
1.00
2.04
102
262
3.87
487
11.2
2.94
308
7.78
3.00
0.48
17.1
254
29.5
115
828.
090.
66SP
-497
6.41
2.39
1.02
1.87
8435
23.
1451
510
.12.
5734
18.
043.
321.
5217
.630
731
.712
491
6.42
0.60
SP-4
986.
952.
011.
021.
5382
294
3.32
465
10.2
3.11
325
7.88
3.17
0.68
18.7
333
38.0
179
907.
050.
62SP
-499
6.78
2.71
1.10
1.91
9632
83.
9749
910
.63.
1633
27.
783.
151.
4118
.325
529
.211
110
07.
350.
52SP
-500
6.64
3.60
1.29
1.79
8543
73.
4456
210
.12.
8031
57.
853.
532.
1917
.628
431
.212
912
45.
550.
58SP
-501
6.49
2.35
1.07
2.40
104
353
4.44
540
10.9
3.16
324
8.36
3.20
1.79
16.7
250
26.7
9111
97.
470.
70SP
-502
7.81
6.25
1.57
1.66
4960
61.
6944
37.
141.
4227
15.
783.
320.
4821
.438
143
.318
310
72.
840.
25SP
-503
6.72
4.43
1.07
1.56
6846
12.
6849
68.
741.
8326
06.
533.
140.
6418
.730
036
.113
110
34.
540.
45SP
-504
7.04
2.27
1.00
1.57
8530
03.
5447
710
.53.
1734
48.
803.
330.
8617
.734
834
.113
599
7.12
0.66
Soils
,<
20l
mSP
-490
6.73
0.89
1.93
2.23
100
209
4.03
482
11.4
2.45
255
5.82
3.40
0.25
19.5
173
32.2
6812
87.
400.
74SP
-491
7.29
0.95
1.98
1.98
8619
23.
5940
411
.02.
4123
75.
853.
710.
3319
.814
030
.176
105
6.91
0.62
SP-4
926.
113.
142.
212.
2188
248
4.00
367
11.0
2.76
246
5.70
3.04
1.43
17.6
135
26.2
5699
9.08
0.85
SP-4
935.
762.
221.
922.
1698
301
4.25
344
11.3
1.84
207
5.00
3.42
1.51
14.1
110
26.0
6791
6.38
0.62
SP-4
945.
682.
513.
091.
6691
274
4.09
347
9.69
2.13
213
5.28
2.65
1.21
15.1
127
25.8
7413
47.
560.
73SP
-495
6.39
1.39
3.19
2.13
9022
24.
4544
711
.23.
5223
36.
082.
930.
3218
.811
523
.167
114
7.47
0.81
SP-4
966.
291.
541.
882.
5512
422
55.
0144
012
.02.
9921
65.
532.
851.
9017
.613
226
.663
819.
980.
76SP
-497
6.35
1.98
1.75
2.44
118
309
4.67
503
11.9
2.49
213
5.82
3.15
2.14
17.6
148
24.7
4310
09.
090.
78SP
-498
6.12
1.19
2.12
2.06
106
151
4.37
438
11.1
2.89
218
5.98
2.77
1.41
17.7
148
26.0
6210
18.
890.
72SP
-499
5.74
1.22
2.17
2.06
115
175
5.04
425
10.9
2.82
235
5.20
2.24
1.66
16.4
121
19.5
6799
9.26
0.82
SP-5
005.
871.
382.
182.
4011
121
94.
9850
410
.72.
6421
35.
352.
671.
7815
.711
920
.746
148
7.75
0.80
SP-5
016.
041.
561.
752.
4112
524
05.
4746
111
.12.
7021
15.
582.
711.
4815
.313
620
.641
118
9.52
0.79
SP-5
025.
243.
543.
192.
1391
239
3.83
323
8.91
1.60
213
4.87
2.56
1.04
13.3
100
25.0
9091
5.55
0.65
SP-5
035.
773.
302.
062.
2010
528
64.
4341
310
.91.
7619
95.
282.
971.
4014
.811
027
.977
178
6.40
0.66
SP-5
046.
761.
522.
161.
9310
720
04.
5541
611
.03.
2523
26.
452.
951.
7016
.714
726
.584
105
9.30
0.83
Bas
alts
SP-4
90A
9.22
7.50
2.05
0.66
1975
30.
3353
34.
450.
9221
54.
783.
110.
6524
.948
060
.029
213
10.
710.
12SP
-492
A9.
118.
052.
050.
6416
790
0.24
490
4.84
1.36
227
4.90
3.51
1.04
24.4
485
58.4
309
140
0.74
0.14
SP-4
93A
8.94
7.63
2.21
0.82
2290
90.
4166
95.
991.
6023
65.
544.
060.
9723
.847
757
.030
812
50.
770.
13SP
-494
A8.
947.
812.
410.
6123
661
0.38
382
4.43
1.08
214
5.11
3.46
0.73
23.8
427
55.7
261
119
0.91
0.12
SP-4
96A
9.11
7.08
2.12
0.58
2075
10.
2548
94.
591.
1323
35.
133.
540.
6624
.745
458
.228
411
40.
580.
09SP
-497
A9.
128.
121.
870.
9218
744
0.26
491
4.85
1.09
230
5.03
3.44
0.68
24.4
453
59.2
287
122
0.44
0.10
SP-4
98A
8.84
7.05
2.19
0.79
1660
10.
2055
33.
230.
8420
54.
212.
450.
5022
.939
354
.924
512
40.
600.
07SP
-502
A8.
667.
972.
260.
9720
825
0.28
453
5.91
1.34
229
4.83
3.26
0.88
23.3
445
54.9
280
120
0.58
0.14
Afr
ican
dust
14Ju
ne19
67<
2l
m5.
961.
500.
151.
7511
522
36.
0161
115
.73.
3817
13.
891.
911.
8820
.412
026
.979
195
9.06
1.07
2–5
lm4.
402.
120.
412.
0411
122
65.
1475
213
.03.
1623
54.
872.
211.
3915
.294
18.8
6611
16.
801.
065–
10l
m3.
981.
020.
672.
1099
165
4.37
766
12.8
3.54
328
8.52
2.59
1.89
13.4
8914
.444
906.
230.
8910
–20
lm
3.80
1.62
0.82
1.94
8521
63.
6073
214
.64.
5861
514
.80
3.30
2.17
12.9
9713
.046
746
6.00
1.11
Typi
cal
coef
ficie
ntof
varia
tion
(as
perc
ent
ofre
port
edva
lue)
one-
sigm
a
13–
121–
44–
202–
72–
92–
101–
51–
23–
113–
71–
21–
211
–20
11–
21
2–10
2–3
3–17
4–13
Terra Nova, Vol 22, No. 6, 399–410 D. R. Muhs et al. • African dust to the Canary Islands
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� Published 2010. This article is a US Government work and is in the public domain in the USA 403
three African dust-source areas(northern and western Sahara, south-ern and central Sahara, and Sahel) onthe basis of back-trajectory analysesof dust events. We recognize that,unlike the mostly immobile trace ele-ments discussed above, Fe, Ca and Kare potentially mobile in near-surface
soil zones. However, given that Lan-zarote has a mean annual precipita-tion of only 100–200 mm a)1 (GarcıaHerrera et al., 2001) and that thesubstrate is only c. 21 ka old, thesesoils have probably experienced min-imal chemical weathering. The reten-tion of easily weatherable minerals
in the soils, such as olivine and py-roxenes, supports this assumption.Thus, we use these elements cautiouslyin making interpretations of prove-nance.Both southern ⁄central Saharan dust
and northern ⁄western Saharan dusthave relatively low Fe ⁄Ca and K ⁄Ca,
Table 2 Rare earth element concentrations of Lanzarote soils, basalts from Corona volcano and African dust collected 14 June
1967.
Sample
La
(p.p.m.)
Ce
(p.p.m.)
Nd
(p.p.m.)
Sm
(p.p.m.)
Eu
(p.p.m.)
Gd
(p.p.m.)
Tb
(p.p.m.)
Ho
(p.p.m.)
Tm
(p.p.m.)
Yb
(p.p.m.)
Lu
(p.p.m.)
Whole soils
SP-490 51.4 111 50.7 9.80 2.27 7.93 1.16 1.33 0.47 2.91 0.433
SP-491 52.7 113 49.9 9.73 2.36 8.07 1.14 1.30 0.39 2.42 0.365
SP-492 46.9 102 46.5 9.05 2.23 8.11 1.06 1.24 0.41 2.34 0.342
SP-493 49.2 106 46.9 9.11 2.31 7.81 1.07 1.23 0.38 2.24 0.336
SP-494 43.6 93.8 44.9 8.90 2.39 7.48 1.09 1.17 0.40 2.13 0.300
SP-495 57.9 123 60.0 11.8 2.84 10.5 1.38 1.43 0.50 2.98 0.439
SP-496 46.4 98.4 42.8 8.86 1.85 6.99 1.05 1.31 0.47 2.93 0.446
SP-497 44.9 96.8 44.3 8.50 1.98 7.34 1.05 1.19 0.45 2.72 0.416
SP-498 48.0 102 49.5 9.34 2.10 7.97 1.11 1.29 0.47 2.76 0.422
SP-499 48.0 99.5 47.3 9.44 2.10 7.78 1.12 1.35 0.47 2.90 0.446
SP-500 48.0 101 47.3 9.29 2.13 7.68 1.03 1.32 0.44 2.68 0.405
SP-501 43.2 90.2 41.2 8.09 1.73 6.65 0.97 1.22 0.47 2.91 0.435
SP-502 46.3 96.8 44.8 9.12 2.42 7.57 1.02 1.02 0.34 2.05 0.300
SP-503 45.0 97.9 43.4 8.54 2.06 7.45 0.97 1.16 0.41 2.35 0.350
SP-504 44.1 95.8 42.4 8.44 1.87 6.90 1.02 1.18 0.44 2.83 0.417
Soils, <20 lm
SP-490 50.2 114 51.3 8.67 2.12 8.79 1.07 1.22 0.44 2.54 0.364
SP-491 54.3 127 50.6 9.93 2.39 8.72 1.10 1.06 0.39 2.30 0.314
SP-492 53.6 116 44.2 8.74 2.14 7.84 1.01 1.19 0.43 2.49 0.346
SP-493 46.8 112 40.3 6.93 1.60 6.94 0.84 0.95 0.36 2.07 0.292
SP-494 41.1 95.3 33.5 7.08 1.71 6.65 0.85 1.04 0.38 2.22 0.300
SP-495 56.8 118 66.6 10.4 2.52 9.12 1.25 1.36 0.52 2.96 0.422
SP-496 49.3 106 46.4 8.21 1.81 6.86 1.00 1.14 0.42 2.72 0.391
SP-497 48.3 103 39.6 8.07 1.79 6.93 0.99 1.12 0.43 2.64 0.370
SP-498 49.5 105 49.2 8.52 1.97 8.65 1.04 1.33 0.46 2.73 0.385
SP-499 44.1 90.0 38.8 7.44 1.64 6.48 0.93 1.07 0.43 2.51 0.370
SP-500 44.2 91.6 42.0 7.23 1.67 6.55 0.88 1.02 0.42 2.48 0.367
SP-501 39.6 82.1 37.5 6.35 1.34 5.32 0.79 1.02 0.40 2.54 0.360
SP-502 37.9 80.9 29.2 6.13 1.48 5.43 0.74 0.81 0.31 1.86 0.268
SP-503 44.9 99.2 42.3 7.10 1.65 6.72 0.90 1.14 0.40 2.22 0.328
SP-504 43.9 93.8 42.5 7.47 1.64 7.07 0.90 1.09 0.41 2.60 0.386
Basalts
SP-490A 40.4 80.2 39.2 7.92 2.58 7.57 1.05 0.99 0.32 1.78 0.243
SP-492A 50.3 95.7 45.9 8.82 2.85 8.61 1.11 1.09 0.33 1.81 0.252
SP-493A 58.4 107 50.0 9.33 2.94 8.34 1.17 1.13 0.33 1.87 0.254
SP-494A 40.2 78.3 38.5 7.73 2.52 7.96 1.01 1.06 0.31 1.73 0.244
SP-496A 43.5 83.7 40.1 8.11 2.67 7.95 1.06 1.01 0.30 1.74 0.238
SP-497A 46.9 88.5 43.7 8.38 2.73 7.39 1.07 0.97 0.30 1.75 0.242
SP-498A 28.9 58.7 29.5 6.40 2.25 6.27 0.92 0.97 0.29 1.65 0.219
SP-502A 57.6 107 49.9 9.18 2.95 8.75 1.15 1.18 0.33 1.92 0.261
African dust
<2 lm 61.0 133 57.1 11.5 2.31 11.4 1.35 1.62 3.69 0.543
2–5 lm 48.4 104 49.7 9.64 2.00 10.2 1.16 1.41 3.45 0.517
5–10 lm 44.2 90.2 42.9 8.43 1.64 9.19 1.19 1.58 4.33 0.617
10–20 lm 46.6 94.9 45.7 8.96 1.77 9.48 1.34 1.95 5.81 0.846
Typical coefficient of
variation (as percent
of reported value)
one-sigma
1 1 2–8 1 1–2 4–10 2–4 10–15 8–20 2–3 2–3
African dust to the Canary Islands • D. R. Muhs et al. Terra Nova, Vol 22, No. 6, 399–410
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404 � Published 2010. This article is a US Government work and is in the public domain in the USA
due to high carbonate contents in thesource areas (Chiapello et al., 1997).The geochemical fields for these twoSaharan regions do not form a rea-sonable mixing-line plot with basaltfor either whole Lanzarote soils or the<20 lm fraction of the soils (Fig. 9).In contrast, the Fe ⁄Ca–K ⁄Ca field forSahel dust (Fig. 9c) forms a goodmixing-line plot with basalt for Lan-zarote whole soils (Fig. 9c). A reason-able mixing-line plot is also seen forbasalt and fine-grained (<2 lm) Afri-can dust collected on Barbados, whichrepresents a mix of Saharan and Sahelsources (Fig. 9d).
Discussion
The particle-size distribution of Lan-zarote soils permits an inferenceof multiple parent materials. Localbasalt is the source of the sand frac-tion. Excluding the three soils withvery high sand contents, we interpretthe abundant (44–59%) quantities ofsilt to reflect aeolian inputs fromAfrica, in agreement with previousworkers. Silt-sized particles with diam-eters of �20–30 lm are expected forshort-to-intermediate range aeoliantransport from Africa. Long-range-transported particles from Africa aremore likely to be <20 lm, with most
Table 3 Major element concentrations in African dust collected on Barbados.
Date collected
Particle
size (lm)
Na
(%)
K
(%)
Ca
(%)
Fe
(%)
27 May 1967 0–2 0.32 2.35 1.90 5.32
2–5 0.50 2.4 2.16 4.19
5–10 0.64 2.05 2.47 4.01
10–20 0.62 2.1 1.17 3.20
7 June 1967 0–2 0.24 2.22 1.21 5.41
2–5 0.49 2.35 2.43 4.49
5–10 0.66 2.54 2.58 3.57
10–20 0.71 2.07 1.63 3.71
14 June 1967 0–2 0.154 1.75 1.50 5.96
2–5 0.411 2.04 2.12 4.40
5–10 0.673 2.1 1.02 3.98
10–20 0.821 1.94 1.62 3.80
3 July 1967 0–2 0.29 1.65 1.23 5.68
2–5 0.48 1.8 2.66 4.72
5–10 0.67 1.19 2.92 3.98
10–20 0.84 1.07 2.14 3.99
24 August 1967 0–2 0.24 2.53 1.24 5.33
2–5 0.53 2.23 3.09 4.40
5–10 0.80 2.63 3.38 4.01
10–20 0.92 2.05 2.65 3.85
27 September 1967 0–2 0.35 2.66 1.31 5.21
2–5 0.68 3.32 2.20 4.64
5–10 0.76 2.7 1.25 4.15
1 October 1968 0–2 0.28 1.67 2.20 5.45
2–5 0.52 1.69 3.65 4.45
5–10 0.74 3.26 3.35 4.15
3 July 1969 0–2 0.199 1.86 1.22 6.10
2–5 0.403 1.97 2.34 4.89
5–10 0.633 2.07 2.17 4.20
10–20 0.784 1.82 1.30 3.59
>20 0.770 1.34 1.66 3.53
6 July 1969 0–2 0.19 2.32 0.95 5.96
2–5 0.37 3.55 2.04 4.79
5–10 0.62 2.41 2.42 4.05
10–20 0.81 1.62 1.88 3.84
1
0.8
0.6
0.4
0.2
0 1 0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0 1 0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0
Coarse silt
Silt Fine silt
Cla
y
Sand
Cla
y
Iowaloess
Illinoisloess
Coloradoloess Iowa
loess
Illinoisloess
Coloradoloess
Lanzarotesoils
Lanzarotesoils
Fig. 5 Ternary diagrams showing amounts of sand (>53 lm), silt (53–2 lm) and clay(<2 lm) (left) and amounts of coarse silt (53–20 lm), fine silt (20–2 lm) and clay ona sand-free basis (right). Also shown for comparison are values for these particle-sizeclasses from North American loess sections of last-glacial age at Fort Morgan,Colorado, Sioux City, Iowa, and Greenbay Hollow, Illinois (North American loessdata from Muhs et al., 2008b).
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
SP-492
SP-496
SP-499
SP-504
Sm
ectit
e
Mic
a Kao
linite
Qua
rtz
Qua
rtz
+m
ica
Mic
a
Kao
linite
Degrees 2-theta
Fig. 6 X-ray diffractograms for glyco-lated clay separates from four soils onLanzarote (see Fig. 3 for locations).
Terra Nova, Vol 22, No. 6, 399–410 D. R. Muhs et al. • African dust to the Canary Islands
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being <10 lm. A number of the dustsamples collected immediately offshoreAfrica by Stuut et al. (2005) haveprimary modes in the 20–30 lm sizerange, although many others havemodes that are <10 lm. The highamounts of fine (20–2 lm) silt and clay(<2 lm) in Lanzarote soils suggest thepossibility of long-range transportfrom distal African sources.The soil mineralogy, with quartz
and mica both in bulk samples and inthe clay fraction, indicates inputs fromsources external to the island. Thedominance of mica and quartz is con-
sistent with the most abundant miner-als found in modern dust collectedelsewhere on the Canary Islands (Alas-tuey et al., 2005). Kaolinite is moredifficult to explain in Lanzarote soils.Kaolinite could be an alteration prod-uct of plagioclase, which is well docu-mented (Birkeland, 1999) but is not aprocess expected on relatively younglava in an arid climate. Lanzarotecurrently receives only 100–200 mmof precipitation annually (Garcıa Her-rera et al., 2001) andwas probably aridduring the late glacial period as well(Hooghiemstra et al., 1992). Thus, we
interpret kaolinite in Lanzarote soils tohave an external, aeolian origin.Kaolinite is not abundant in the
Entisols and Aridisols that dominatethe soil geography of the SaharaDesert of northern and western Africa(Fig. 10). Paquet et al. (1984) studieda north–south soil ⁄ sediment transectacross Algeria, from �35� to �19�N.They report that mica and chlorite aredominant at higher latitudes, withgreater amounts of kaolinite at lowerlatitudes. On the basis of this study,we would not expect the largeamounts of kaolinite we observe in
0.8
0.6
0.4
0.2
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
1
0.8
0.6
0.4
0.2
0 1 0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0
Th
Ta
x 10
Sc
1
0.8
0.6
0.4
0.2
0 1 0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0
Th
Ta
x 10 Sc
Hf
Th
Cr/10
1
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0
Hf
Th C
o
Africandust Corona
basalt
Africandust
Corona basalt
Africandust
Coronabasalt
Africandust
Corona basalt
Lanzarote soils:
Whole soil
< 20 µm fraction
< 20 µm
Whole soil
< 20 µm
Whole soil
< 20 µm
Whole soil < 20 µm
Whole soil
Fig. 7 Sc–Th–Ta x10 (full plot, plus blow-up of partial plot), Cr ⁄10–Hf–Th and Co–Hf–Th ternary plots of Lanzarote soils(circles) compared with c. 21 ka basalt samples and African dust collected on Barbados. Soil and basalt data are from the presentstudy; African dust data are from the present study and data in Muhs et al. (2007a).
African dust to the Canary Islands • D. R. Muhs et al. Terra Nova, Vol 22, No. 6, 399–410
.............................................................................................................................................................
406 � Published 2010. This article is a US Government work and is in the public domain in the USA
young Lanzarote soils to be derivedfrom the northern and central parts ofthe Sahara. A more likely source forkaolinite is the east–west-trending belt
of Alfisols and Inceptisols found in theSahel region (Figs 1 and 10). TheSahel is an important dust sourcewhen droughts occur in this region,
as they did in the 1970s (Prospero andNees, 1977, 1986; Prospero and Lamb,2003). Chester et al. (1972) and Stuutet al. (2005), in shipboard studies of
1.2
0.8
0.6
0.4
1.0
5 10 15 20 25
Eu/
Eu*
Coronabasalt
African dust
Lanzarote soils
(a)
Whole soil< 20 µm fraction
LaN/YbN
1.0
1.2
0.8
0.6
0.41.0 1.5 2.0 2.5 3.0 3.5 4.0
Eu/
Eu*
GdN/YbN
Coronabasalt
African dust
(b)
Lanzarote soils
Whole soil< 20 µm fraction
Fig. 8 (a) Eu ⁄Eu* vs. LaN ⁄YbN and (b) Eu ⁄Eu* vs. GdN ⁄YbN in Lanzarote soils compared with c. 21 ka basalt samples andAfrican dust collected on Barbados. Soil and basalt data are from the present study; African dust data are from the present studyand data in Muhs et al. (2007a).
3.0
2.5
2.0
1.5
1.0
0.5
0.00 1 2 3 4 5 6 7
K/C
a
Fe/Ca0 1 2 3 4 5 6 7
Fe/Ca
3.0
2.5
2.0
1.5
1.0
0.5
0.00 1 2 3 4 5 6 7
K/C
a
Fe/Ca0 1 2 3 4 5 6 7
Fe/Ca8
88
8
Northern and western Saharan
dust
Southern and central Saharan
dust
Sahelregiondust
Corona basalt
Corona basalt Corona basalt
Corona basalt
African dust at
Barbados: 2–20 µm African
dust atBarbados:
<2 µm
Lanzarote soils:
Whole soil
< 20 µm fraction
Lanzarote soils:
Whole soil
< 20 µm fraction
Lanzarote soils:
Whole soil
< 20 µm fraction
Lanzarote soils:
Whole soil
< 20 µm fraction
(a) (b)
(c) (d)
Fig. 9 Fe ⁄Ca vs. K ⁄Ca for Lanzarote soils (circles), Corona basalt on Lanzarote (black ellipse), African dust collected onBarbados (stipple) and Sal Island (Cape Verde Islands) dust identified as being from the Sahel, southern and central Sahara, andnorthern and western Sahara (stippled boxes). Sahel and Saharan dust data are from Chiapello et al. (1997) and boxes define themean ±2 standard deviations. All other data are from the present study.
Terra Nova, Vol 22, No. 6, 399–410 D. R. Muhs et al. • African dust to the Canary Islands
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� Published 2010. This article is a US Government work and is in the public domain in the USA 407
African dust, report a decrease in themica ⁄kaolinite ratio from the CanaryIslands southward. The southwardincrease in the kaolinite content ofdust probably reflects the increasingkaolinite content of adjacent Africansoils, moving from the Sahara to theSahel. Soils on Lanzarote havemica ⁄kaolinite peak-area ratios of0.9–2.0, corresponding to the rangesof mica ⁄kaolinite values in dust re-ported by Chester et al. (1972) forlatitudes of �15� to �5�S (Fig. 10).The arid climate ofLanzarote should
also retain calcite, if delivered fromcalcite-rich sources in Morocco (Khiriet al., 2004), as suggested by previousworkers. Its absence in all the soils weexamined suggests that much of theAfrican dust delivered to these soils isfrom a calcite-poor source, such as theSahel. A Sahel contribution also ex-plains the relatively high Fe ⁄Ca values
that are observed in soils on Lanzarote.Soils in the Sahel region not only haverelatively high kaolinite contents butalso have low Ca contents and high Fecontents (e.g., Ambrost et al., 1986;Faure and Volkoff, 1998; Duclouxet al., 2002).Although the main direction of
dust transport in the SAL is to thewest, at latitudes between �15� and�21�N, the northward hook-like tra-jectory of air-mass movement candeliver dust to the Canary Islands.MODIS imagery from the Terra andAqua satellites shows this componentof dust movement from southerlysources in the summers of 2004 and2007 (Fig. 2).
Conclusions
Soils on a late Quaternary volcanicflow in the Canary Islands contain
abundant fine silt and clay, evidenceof long-range aeolian transport. Thesoils contain quartz and mica, notfound in the local basalt and likelyfrom Africa. Kaolinite may also bederived from western-African soils ofthe Sahel region that are rich in thismineral. Immobile trace-element geo-chemistry shows that the soils arederived from varying proportions oflocally derived basalt and Africandust. Major-element geochemistry,along with the presence of kaolinitesuggest that of the aeolian compo-nent, both Sahel and Saharan dustsources in western Africa play animportant role in soil genesis. Satel-lite imagery shows that dust fromSahel sources is transported north-ward, in a hook-like form, west ofthe African coast and toward theCanary Islands. Our results showthat even young soils in an aridclimate can have a complex origin,with dust inputs from both theSahara and Sahel.
Acknowledgements
This study was supported by the GlobalChange Program of the US GeologicalSurvey and is a contribution to the�Impacts of Climate Change on Coastaland Eolian Landscapes� project (http://esp.cr.usgs.gov/info/eolian/). We appreciatethe efforts of Zachary Muhs Rowland,who ably assisted with field work. Manythanks to Dr Joaquın Meco (Universidadde Las Palmas de Gran Canaria) and hisfamily members, who taught us the localQuaternary geology and were gracioushosts while we visited the islands. A sam-pling permit was kindly provided by DrMaria Aranzazu Gutierrez Avila, Directo-ra General de Cooperacion y PatrimonioCultural, Gobierno de Canarias. Sincerethanks also to Dr Ludwig Zoller and DrHans Von Suchodoletz who introduced usto the geology of Lanzarote. We thankMax Coleman, Vincenzo Pascucci, RandySchaetzl, Yehouda Enzel, Paul Carrara,Jeff Pigati, Gene Ellis and three anony-mous reviewers who read an earlier versionof the paper and made helpful commentsfor its improvement.
References
Alastuey, A., Querol, X., Castillo, S.,Escudero, M., Avila, A., Cuevas, E.,Torres, C., Romero, P.-M., Exposito, F.,Garcıa, O., Diaz, J.P., Van Dingenen, R.and Putaud, J.P., 2005. Characterisationof TSP and PM2.5 at Izana and Sta.Cruz de Tenerife (Canary Islands, Spain)
Lanazarotesoils:
Cape VerdeIslands
0°30°
30°
40°
20°
10°
Atlantic
Ocean
Atlantic
Ocean
AFRICA
EUROPE
Active aeolian sand
Aridisols and Entisols
Alfisols and Inceptisols
Ultisols
Oxisols
Explanation
15°
CanaryIslands
Mica/Kaolinite:2.17
Mica/Kaolinite:2.17
Mica/Kaolinite:1.55
Mica/Kaolinite:0.97
Mica/Kaolinite: 0.20
Mica/Kaolinite:0.9–1.6
AlgeriaMorocco
Libya
Mauritania
Mali
Niger
Nigeria
Wes
tern
Sahar
a
Senegal
IvoryCoast
BurkinaFaso
Guinea
Cameroon
Ghana
Tuni
sia
Cha
d
Fig. 10 Soil geography of western Africa, redrawn and generalized from USDepartment of Agriculture, Natural Resources Conservation Service �Global SoilRegions� map (http://www.soils.usda.gov/use/worldsoils/mapindex/order.html), inturn derived from the FAO–UNESCO Soil Map of the World (Food and AgricultureOrganization of the United Nations, UNESCO, 1974). Also shown are ship tracks(dashed lines) in the dust-collecting expedition of Chester et al. (1972); solid horizontallines mark boundaries of individual dust-collection traverses. Mica ⁄kaolinite ratiosgiven are clay-mineral peak-height ratios (<2 lm fraction) calculated from data foreach dust-collection traverse in Chester et al. (1972) and Lanzarote soils (Fig. 6).
African dust to the Canary Islands • D. R. Muhs et al. Terra Nova, Vol 22, No. 6, 399–410
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408 � Published 2010. This article is a US Government work and is in the public domain in the USA
during a Saharan dust episode (July2002). Atmos. Environ., 39, 4715–4728.
Ambrost, J.P., Nahon, D. and Herbillon,A.J., 1986. The epigenetic replacement ofkaolinite by hematite in laterite; petro-graphic evidence and the mechanismsinvolved. Geoderma, 37, 283–294.
Bergametti, G., Gomes, L., Coude-Gaus-sen, C., Rognon, P. and Le Coutumer,M.-N., 1989. African dust observed overCanary Islands: Source-regions identifi-cation and transport pattern for somesummer situations. J. Geophys. Res., 94,14855–14864.
Birkeland, P.W., 1999. Soils and Geomor-phology. Oxford University Press, NewYork.
Budahn, J.R. and Wandless, G.A., 2002.Instrumental neutron activation by longcount. U.S. Geol. Surv. Open-File Rep.OF, 02-0223, Y1–Y9.
Carlson, T.N. and Prospero, J.M., 1972.The large-scale movement of Saharanair outbreaks over the Northern Equa-torial Atlantic. J. Appl. Meteorol., 11,283–297.
Carracedo, J.C. and Day, S., 2002. CanaryIslands. Terra Publishing, Harpenden,UK.
Carracedo, J.C., Singer, B., Jicha, B.,Guillo, H., Rodrıguez Badiola, E.,Meco, J., Perez Torrado, F.J., Gimeno,D., Socorro, S. and Lainez, A., 2003. Laerupcion y el tubo volcanico del volcanCorona (Lanzarote, Isla Canarias). Es-tud. Geol., 59, 277–302.
Chester, R., Elderfield, H., Griffin, J.J.,Johnson, L.R. and Padgham, R.C.,1972. Eolian dust along the easternmargins of the Atlantic Ocean. Mar.Geol., 13, 91–105.
Chiapello, I., Bergametti, G., Chatenet, B.,Bousquet, P., Dulac, F. and Santos So-ares, E.S., 1997. Origins of African dusttransported over the northeastern tropi-cal Atlantic. J. Geophys. Res., 102,13701–13709.
Coude-Gaussen, G., Rognon, P., Berga-metti, G., Gomes, L., Strauss, B., Gros,J.M. and Le Coustumer, M.N., 1987.Saharan dust on Fuerteventura Island(Canaries): chemical and mineralogicalcharacteristics, air mass trajectories, andprobable sources. J. Geophys. Res., 92,9753–9771.
Criado, C. and Dorta, P., 2003. An unu-sual �blood rain� over the Canary Islands(Spain). The storm of January 1999.J. Arid Environ., 55, 765–783.
Dubief, J., 1979. Review of the northAfrican climate with particular emphasison the production of eolian dust in theSahel zone and in the Sahara. In: Saha-ran Dust: Mobilization, Transport,Deposition (C. Morales, ed.), pp. 27–48.John Wiley & Sons, Chicester.
Ducloux, J., Guero, Y., Sardini, P. andDecarreau, A., 2002. Xerolysis: a hypo-
thetical process of clay particles weath-ering under Sahelian climate. Geoderma,105, 93–110.
Faure, P. and Volkoff, B., 1998. Somefactors affecting regional differentiationof the soils in the Republic of Benin(West Africa). Catena, 32, 281–306.
Food and Agriculture Organization of theUnited Nations, UNESCO, 1974. SoilMap of the World, 1: 5,000,000, v. 6,Africa. UNESCO, Paris.
Garcıa Herrera, R., Gallego Puyol, D.,Hernandez Martın, E., Gimeno Presa, L.and Ribera Rodrıguez, P., 2001. Influ-ence of the North Atlantic Oscillationon the Canary Islands precipitation.J. Climate, 14, 3889–3903.
Glaccum, R.A. and Prospero, J.M., 1980.Saharan aerosols over the tropical northAtlantic – Mineralogy. Mar. Geol., 37,295–321.
Goudie, A.S. and Middleton, N.J., 2006.Desert Dust in the Global System.Springer, Heidelberg.
Grousset, F.E., Rognon, P., Coude-Gaus-sen, G. and Pedemay, P., 1992. Originsof peri-Saharan dust deposits traced bytheir Nd and Sr isotopic composition.Palaeogeogr. Palaeoclimatol. Palaeo-ecol., 93, 203–212.
Grousset, F.E., Parra, M., Bory, A.,Martinez, P., Bertrand, P., Shimmield,G. and Ellam, R.M., 1998. Saharan windregimes traced by the Sr-Nd isotopiccomposition of subtropical Atlanticsediments: last glacial maximum vstoday. Quatern. Sci. Rev., 17, 395–409.
Hooghiemstra, H., Stalling, H., Agwu,C.O.C. and Dupont, L.M., 1992.Vegetational and climatic changes atthe northern fringe of the Sahara250,000-5000 years BP: evidence from 4marine pollen records located betweenPortugal and the Canary Islands. Pal-aeogeogr. Palaeoclimatol. Palaeoecol.,74, 1–53.
Jahn, R., Zarei, M. and Stahr, K., 1987.Formation of clay minerals in soilsdeveloped from basic volcanic rocksunder semiarid climatic conditions inLanzarote, Spain. Catena, 14, 359–368.
Kalu, A.E., 1979. The African dust plume:Its characteristics and propagationacross west Africa in winter. In: Saharandust: Mobilization, Transport, Deposition(C. Morales, ed.), pp. 95–118. JohnWiley & Sons, Chicester.
Khiri, F., Ezaidi, A. and Kabbachi, K.,2004. Dust deposits in Souss-Massabasin, South-West of Morocco:granulometrical, mineralogical andgeochemical characterization. J. Afr.Earth Sci., 39, 459–464.
Kohfeld, K.E. and Tegen, I., 2007. Recordof mineral aerosols and their role in theEarth system. In: Treatise on Geochem-istry (H.D. Holland and K.K. Turekian,eds), 26 pp. Elsevier. Available at: http://
www.sciencedirect.com/science/refer-enceworks/9780080437514.
Mahowald, N.M., Muhs, D.R., Levis, S.,Rasch, P.J., Yoshioka, M., Zender, C.S.and Luo, C., 2006. Change in atmo-spheric mineral aerosols in response toclimate: Last glacial period, preindustri-al, modern, and doubled carbon dioxideclimates. J. Geophys. Res., 111, D10202.doi:10.1029/2005JD006653.
McTainsh, G. and Walker, P.H., 1982.Nature and distribution of Harmattandust. Z. Geomorphol., 26, 417–435.
Meco, J., Ballester, J., Betancort, J.F.,Cilleros, A., Scaillet, S., Guillou, H.,Carracedo, J.C., Lomoschitz, A., Petit-Maire, N., Ramos, A.J.G., Perera, N.,Meco, J.M., 2006. Paleoclimatologıa delNeogeno en las Islas Canarias. Geliense,Pleistoceno y Holoceno. Ministerio deMedio Ambiente – Universidad de LasPalmas de Gran Canaria, Servicio dePublicaciones de la ULPGC, LasPalmas, Spain.
Mizota, C. and Matsuhisa, Y., 1995.Isotopic evidence for the eolian originof quartz and mica in soils developedon volcanic materials in the CanaryArchipelago. Geoderma, 66, 313–320.
Muhs, D.R. and Budahn, J.R., 2009.Geochemical evidence for African dustand volcanic ash inputs to terra rossasoils on carbonate reef terraces, northernJamaica, West Indies. Quatern. Int., 196,13–35.
Muhs, D.R., Budahn, J., Prospero, J.M.and Carey, S.N., 2007a. Geochemicalevidence for African dust inputs to soilsof western Atlantic islands: Barbados,the Bahamas and Florida. J. Geophys.Res., 112, F02009. doi:10.1029/2005JF000445.
Muhs, D.R., Budahn, J., Reheis, M., Be-ann, J., Skipp, G. and Fisher, E., 2007b.Airborne dust transport to the easternPacific Ocean off southern California:evidence from San Clemente Island.J. Geophys. Res., 112, D13203.doi:10.1029/2006JD007577.
Muhs, D.R., Budahn, J., Johnson, D.L.,Reheis, M., Beann, J., Skipp, G., Fisher,E. and Jones, J.A., 2008a. Geochemicalevidence for airborne dust additions tosoils in Channel Islands National Park,California. Geol. Soc. Am. Bull., 120,106–126.
Muhs, D.R., Bettis, E.A., III, Aleinikoff,J., McGeehin, J.P., Beann, J., Skipp, G.,Marshall, B.D., Roberts, H.M., John-son, W.C. and Benton, R., 2008b. Originand paleoclimatic significance of lateQuaternary loess in Nebraska: Evidencefrom stratigraphy, chronology, sedi-mentology, and geochemistry. Geol. Soc.Am. Bull., 120, 1378–1407.
Paquet, H., Coude-Gaussen, G. andRognon, P., 1984. Etude mineralogiquede poussieres sahariennes le long d�un
Terra Nova, Vol 22, No. 6, 399–410 D. R. Muhs et al. • African dust to the Canary Islands
.............................................................................................................................................................
� Published 2010. This article is a US Government work and is in the public domain in the USA 409
itineraire entre 19� et 35� de latitudenord. Rev. Geol. Dynam. Geog. Phys., 25,257–265.
Prospero, J.M. and Carlson, T.N., 1972.Vertical and areal distribution of Saha-ran dust over the western equatorialNorth Atlantic Ocean. J. Geophys. Res.,77, 5255–5265.
Prospero, J.M. and Lamb, P.J., 2003.African droughts and dust transport tothe Caribbean: climate change implica-tions. Science, 302, 1024–1027.
Prospero, J.M. and Nees, R.T., 1977. Dustconcentration in the atmosphere of theequatorial North Atlantic: possible rela-tionship to the Sahelian drought. Sci-ence, 196, 1196–1198.
Prospero, J.M. and Nees, R.T., 1986. Im-pact of the North African drought andEl Nino on mineral dust in the Barbadostrade winds. Nature, 320, 735–738.
Prospero, J.M., Bonatti, E., Schubert, C.and Carlson, T.N., 1970. Dust in theCaribbean atmosphere traced to anAfrican dust storm. Earth Planet. Sci.Lett., 9, 287–293.
Prospero, J.M., Ginoux, P., Torres, O.,Nicholson, S.E. and Gill, T.E., 2002.Environmental characterization of glo-bal sources of atmospheric soil dustidentified with the Nimbus 7 TotalOzone Mapping Spectrometer (TOMS)absorbing aerosol product. Rev. Geo-phys., 40, 1002. doi:10.1029/2000RG000095.
Pye, K., 1987. Aeolian Dust and DustDeposits. Academic Press, London.
Rognon, P., Coude-Gaussen, G., Revel,M., Grousset, F.E. and Pedemay, P.,1996. Holocene Saharan dust depositionon the Cape Verde Islands: sedimento-logical and Nd-Sr isotopic evidence.Sedimentology, 43, 359–366.
Sarnthein, M., Tetzlaff, G., Koopman, B.,Wolter, K. and Pflaumann, U., 1981.Glacial and interglacial wind regimesover the eastern subtropical Atlantic andNorth-West Africa. Nature, 293, 193–196.
Schwanghart, W. and Schutt, B., 2008.Meteorological causes of Harmattandust in West Africa. Geomorphology, 95,412–428.
Stein, R. and Sarnthein, M., 1984. LateNeogene events of atmospheric andoceanic circulation offshore northwestAfrica: High-resolution record fromdeep-sea sediments. Palaeoecol. Afr., 16,9–36.
Stuut, J.-B., Zabel, M., Ratmeyer, V.,Helmke, P., Schefuß, E., Lavik, G. andSchneider, R., 2005. Provenance ofpresent-day eolian dust collected off NWAfrica. J. Geophys. Res., 110, D04202.doi:10.1029/2004JD005161.
Stuut, J.-B., Smalley, I. and O�Hara-Dhand, K., 2009. Aeolian dust in Eur-ope: African sources and Europeandeposits. Quatern. Int., 198, 234–245.
Taylor, S.R. and McLennan, S.M., 1985.The Continental Crust: Its Compositionand Evolution. Blackwell Scientific Pub-lications, Oxford.
Tejedor Salguero, M.L., Jimenez Mendoza,C., Rodriguez, A. and Caldas, E.F.,1985. Polygenesis on deeply weatheredPliocene basalt, Gomera (Canary is-lands): from ferrallitization to saliniza-tion. Catena Suppl., 7, 131–151.
Tetzlaff, G. and Peters, M., 1986. Deep-seasediments in the eastern equatorialAtlantic off the African coast and mete-orological flow patterns over the Sahel.Geol. Rundsch., 75, 71–79.
Torres-Padron, M.E., Gelado-Caballero,M.D., Collado-Sanchez, C., Siruela-
Matos, V.F., Cardona-Castellano, P.J.and Hernandez-Brito, J.J., 2002. Vari-ability of dust inputs to the CANIGOzone. Deep-Sea Res. II, 49, 3455–3464.
Von Suchodoletz, H., Fuchs, M. and Zol-ler, L., 2008. Dating Saharan dustdeposits on Lanzarote (Canary Islands)by luminescence dating techniques andtheir implication for paleoclimate con-struction of NW Africa. Geochem. Geo-phys. Geosyst., 9, Q02Q07. doi:10.1029/2007GC001658.
Von Suchodoletz, H., Faust, D. andZoller, L., 2009a. Geomorphologicalinvestigations of sediment traps onLanzarote (Canary Islands) as a keyfor the interpretation of a paleoclimateoff NW Africa. Quatern. Int., 196, 44–56.
Von Suchodoletz, H., Kuhn, P., Hambach,U., Dietz, M., Zoller, L. and Faust, D.,2009b. Loess-like and palaeosol sedi-ments from Lanzarote (Canary Is-lands ⁄Spain) – indicators ofpalaeoenvironmental change during theLate Quaternary. Palaeogeogr. Palaeo-climatol. Palaeoecol., 278, 71–87.
Zoller, L., H. Von Suchodoletz, H. andKuster, N., 2003. Geoarchaeological andchronometrical evidence of early humanoccupation on Lanzarote (Canary Is-lands).Quatern. Sci. Rev., 22, 1299–1307.
Zoller, L., Von Suchodoletz, H., Blan-chard, H., Faust, D. and Hambach, U.,2004. Reply to the comment by J.C.Carracedo et al. on �Geoarchaaeologicaland chronometrical evidence of earlyhuman occupation on Lanzarote (Can-ary Islands)�. Quatern. Sci. Rev., 23,2049–2055.
Received 2 March 2010; revised versionaccepted 27 April 2010
African dust to the Canary Islands • D. R. Muhs et al. Terra Nova, Vol 22, No. 6, 399–410
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410 � Published 2010. This article is a US Government work and is in the public domain in the USA