13. cenozoic terrigenous sediments in the western … · this basin receives sediment from a...

13. CENOZOIC TERRIGENOUS SEDIMENTS IN THE WESTERN SOUTH ATLANTIC

E.M. Emelyanov and E.S. Trimonis,P.P. Shirshov Institute of Oceanology, U.S.S.R. Academy of Sciences, Kaliningrad, U.S.S.R.

Terrigenous sediments (those with less than 30%CaCθ3 and amorphous S1O2) presently occur over28.9% of the whole Atlantic Ocean area. Taking intoaccount ice-rafted deposits (1.3%) and red clays (7.9%),the area covered is 38.1% of the total, or almost 36million square kilometers (Emelyanov et al., 1975).Terrigenous sediments are especially widespread in thewestern Atlantic, which receives the discharge of theprincipal arteries that drain about 87% of SouthAmerica—such as the Amazon, Parana, Orinoco, andSào Francisco rivers. We have every reason to supposethat products of South American denudation played animportant role in earlier Cenozoic sedimentation aswell.

To explore this hypothesis in detail, we analyzedseveral hundred samples from all sites of Leg 39 (Figure1), concentrating on minerals and elements whichmight indicate a South American source.

Grain-size analyses of uncemented sediments wereperformed on 72 samples, using the settling method(Petelin, 1961, 1967) and sediment balance (Pro-koptsev, 1964); six size fractions were distinguished:>O.l, 0.1-0.5, 0.05-0.01, 0.01-0.005, 0.005-0.001, and<O.OOl mm (Table 1). The coarse aleurite fraction (0.1-0.05 mm) was separated in bromoform into heavy (sp.gr. >2.9) and light subfractions (Tables 2 and 3), andthe immersed particles studied under the polarizingmicroscope. In counting particles (300 to 400 persample), we accounted for all minerals present in thesubfractions (opaque, biogenic, and chemogenic); theminerals counted in each subfraction totalled 100%.

We determined compositions of the sample sedi-ments by wet chemical analysis, atomic absorptionspectrometry, and quantitative spectral analysis, all ofwhich are described by E.M.E. in a separate report inthis volume. We also performed X-ray diffractionanalysis on part of the samples ground for chemicalstudy, using two methods. The first (Gorbunova, 1969)permits determination of the content, in weight percent,of quartz, plagioclases, and orthoclases in the bulksediment sample (Table 4). The second method yieldscontent of quartz, feldspars, clay minerals, carbonates,and others; this technique is similar to that of Rex andMurray (1970) for studying deepwater drilling cores.The bulk samples were analyzed, and mineral contentdetermined from the sum of crystalline phases (Table5).

GUIANA BASIN AND VEMA FRACTURE ZONEAt present, sediments from the Amazon are

deposited chiefly in the Guiana Basin and the VemaFracture Zone (Bader et al., 1970; Emelyanov and

Kharin, 1974), and those of the Orinoco come to restprimarily in the Caribbean Sea (Demerara CoastalInvestigations Report, 1962). The Amazon Cone ofgray, unconsolidated terrigenous pelitic and pelitic-aleuritic muds extends from the brow of the shelf offthe Amazon estuary up to the North American Basin(Figure IB).

The following minerals prevail in the Amazonsediment and pro-estuarial muds: quartz, feldspars, andchamositic aggregates in the light subfraction, andilmenite-magnetite, limonite-hematite, epidote-zoisite,hornblende, clinopyroxenes, zircon, monacite, apatite,and others, in the heavy subfraction. A highillite/kaolinite ratio of 2.3 (Gibbs, 1967; Milliman etal., 1975) occurs in the Amazon effluence of the coastalAtlantic. In contrast, kaolinite occurs more often thanillite in discharges of other, smaller rivers of northernBrazil. Chlorite constitutes less than 5% of thesesediments.

Approximately the same complex of clastic mineralspredominates in deepwater sediments of the GuianaBasin. The Amazon discharge influences the wholedeepwater part of this basin, which may be defined as aseparate Guianean terrigenous mineralogic province(Figure 2).

Data from Sites 26 (Bader et al., 1970) and 353(Table 2) show that quartz, feldspars, and green andyellow mica prevail among light minerals in Quaternarysediments of the Vema Fracture Zone. As the X-raydiffraction data indicate (Table 4), quartz content ofsediments from Site 353 is very high (up to 58%), butfeldspar content is less than 6%. The high ratio ofquartz to feldspar (>5-10) characterizes detritus fromland in an equatorial humid zone, where feldspars aredecomposed almost completely (Emelyanov et al.,1975).

The heavy-mineral suite of the Guiana Basin istypical of an Amazon source; it contains commonilmenite-magnetite, hornblende, epidote-zoisite, biotite,and pyroxenes. Heavy-mineral content of the fraction0.1-0.05 mm in samples from Hole 353 ranges from 2.2to 14.2% (Table 3). The Pleistocene section (thickness264 m) is largely derived from the Amazon. Accumula-tion rate of these sediments was extraordinarilyhigh—90 to 120 cm/1000 years (see Site 353 chapter); aconsiderable part of the Pleistocene section wasdeposited by turbidity currents.

The Amazon discharge played a lesser role inCenozoic sedimentation in the central (Sites 354 and142) and southeastern (northwest of Sites 23-25) partsof the Guiana Basin. Biogenic material sharply dilutedthe terrigenous contribution, and marly nannofossil

453

E.M. EMELYANOV, E.S. TRIMONIS

40°

Figure la. Bottom sediments in the western South Atlantic in different stages of the Cenozoic,based on the data of deep-sea drilling: disposition of sites.

and nannofossil-foraminifer muds and chalk andpartially siliceous muds accumulated in these areas.Marly and highly calcareous deposits, containing 30%to 60% and 10% to 30% terrigenous material, respec-tively, prevail in the Paleocene-Neogene of the CearáRise. Significant deposition of terrigenous sedimentsbegan there in the Pleistocene, as the lower carbonatecontent and higher sedimentation rate (10 cm/1000years) indicate (Figure 3). The terrigenous depositionprocess is more apparent at the Ceará Abyssal Plain(Site 142). Here, turbidity currents laid down layers ofsand, occasionally during the Miocene and frequentlyduring the Pleistocene, when the sedimentation rate inthis area reached 15 cm/1000 years.

Mineral compositions of suspended material and ofRecent sediments (Emelyanov and Kharin, 1974)indicate that the Amazon sediments are penetrating thewesternmost and southeastern parts of the GuianaBasin, and are governing terrigenous sedimentation

there. This same process has operated since theMiocene, when the Amazon began emptying into theAtlantic (Oliveira, 1956). The prevalence in thesedeposits of such heavy minerals, typical of the Amazondischarge, as magnetite-ilmenite, hornblende, epidote-zoisite, garnet, zircon, and micas, confirms thisconclusion; mineral composition data for sediments atSite 142 (von Rad and Rösch, 1972) reaffirm it.

BRAZIL BASINSediments at Site 355 consist of two components:

terrigenous and chemogenic-diagenetic (Fe-Mnnodules, carbonates, and zeolites, among others).Quartz, green and yellow micas, and muscovite arepredominant among light terrigenous minerals (Table2), and magnetite, ilmenite, hornblende, and biotiteprevail among heavy terrigenous minerals (Table 3).Some minerals characteristic of the Amazon suite—epi-

454

CENOZOIC TERRIGENOUS SEDIMENTS

Recent

0°

40 20*

16

19 ç÷*s 2* [-rη20

28

Figure lb. Bottom sediments in the western South Atlantic in different stages of the Cenozoic,based on the data of deep-sea drilling: recent sediments. Legend: 1 -pelagic clay; 2—diatommud; 3-siliceous mud; 4-coccolith mud; 5-coccolith chalk; 6-foraminifer mud; 7-coccolithforaminifer mud; 8-foraminifer coccolith chalk; 9-calcareous mud; 10-limistone; 11-shellsediments; 12—clays; 13—terrigenous mud; 14—sands; 15—large aleurites; 16—marly deposits;17-admixture of zeolites; 18-barite; 19-sulphides; 20-boundary of guiding influence ofterrigenous material; 21-main directions of terrigenous material supply; 22-secondary di-rections of terrigenous material migrations; 23-volcaniclastic material supply; 24-directionsof turbidity currents; 25-migration of sedimentary material supplied by bottom currents; 26-supply of Antarctic iceberg material; 27-axial line of the Mid-Atlantic Ridge; 28-positions ofsites.

455


Pliocene

40*

Figure lc. Bottom sediments in the western South Atlantic in different stages of the Cenozoic,based on the data of deep-sea drilling: Pliocene. See Figure lb for legend.

dote-zoisite, zircon, apatite, pyroxenes, and others—are scarce or lacking in the Brazil Basin.

Mineral composition of the Plio-Pleistocenesediments is very close to the average composition ofRecent sediments in the Brazil Basin (Shurko, 1968).This basin receives sediment from a separate Brazilianterrigenous mineralogic province (Figure 3), theBrazilian Precambrian Shield, consisting of acid erup-tive rocks and metamorphic rocks.

In Plio-Pleistocene sediments from Site 355, theheavy subfractions are strikingly large, owing to con-centration not of clastic minerals, as at Site 353, but ofauthigenic constituents (Fe-Mn nodules and ironhydroxides). High concentration of these constituents istypical of Recent oxidized pelagic muds (Emelyanov etal., 1975). Heavy minerals are scarce in the greenishgray zeolitic pelagic muds of the Eocene, and thosepresent are generally sulphides.

X-ray diffraction analysis of samples from Site 355(Table 5) shows quartz contents ranging from 4% to

about 18%: 17.7% in the Plio-Pleistocene samples,Miocene 4 to 16%, and Eocene 5 to 12%. Plagioclasesoccur in all the Tertiary sediments, potassic feldsparsonly in some sequences. Quartz-to-feldspar ratio isoften greater than 1, sometimes greater than 2; suchvalues characterize denudation products of theequatorial humid zone, where chemical weathering isactive. Quartz content in samples from Sites 23 and 24ranges from 7.4% to 78.3% of the crystalline fraction, or40% on the average (Rex and Murray, 1970)—muchmore than in sediments at Site 355. This is because Sites23 and 24 are closer to the continent than Site 355. Highcontents of potassic feldspars and plagioclases alsooccur in sediments at Sites 23 and 24, but the quartz-to-feldspar ratio is usually greater than 2-3.

Turbidites and high sedimentation rates ( 5cm/1000 years) characterize deposits at Site 355 (Figure3). In the upper part of the core (Miocene), turbiditesare generally of bioclastic origin. They may therefore beassociated with slumping on the continental slope and

456


Late Miocene

Figure Id. Bottom sediments in the western South Atlantic in different stages of the Cenozoic,based on the data of deep-sea drilling: late Miocene. See Figure lb for legend.

underwater rises, areas where biogenic calcareoussediments were presumably accumulating in the Mio-cene. In lower and upper Eocene sediments, turbiditesare terrigenous, evidently derived from the continentalshelves. The mineral compositions of turbidites was notstudied.

SAO PAULO PLATEAUAlthough Site 356 is near the continent, the content

of terrigenous material in its sediments seldom exceeds50%. Both terrigenous and biogenic (calcareous andsiliceous) materials accumulated there at a high rate(Figure 3).

In Cenozoic sediments at this site, quartz makes up 2to 12%, plagioclases 0 to 3%, potassic feldspars 0 to 4%(Table 4). Quartz-to-feldspar ratio is usually high (>2-3). Quartz is also common in the coarse aleuritefraction, along with clastic minerals. Clastic minerals ofthe heavy subfraction include magnetite-ilmenite,

hornblende, garnet, zircon, chlorite, and muscovite andother minerals (Table 3). The same minerals occur inRecent sands and in sediments of the continentalslope—that is, within the so-called mineralogicprovinces of Brazil and the Patagonian pampas andenvirons (Etchichury and Remiro, 1963). From this, weconclude that the clastic part of the Site 356 sedimentsformed from detritus from adjacent parts of SouthAmerica (Precambrian shield of eastern Brazil andTertiary traps).

Material from slumped Cretaceous deposits occurs inPliocene sediments of Hole 356 (Cores 19, 24, and 25).They were presumably derived from the Sào PauloRidge (Site 356 report, this volume).

RIO GRANDE RISESediments at Site 357 are generally calcareous

biogenic material. The content of terrigenous materialis minimal (Figure 3).

457

E. M. EMELYANOV, E. S. TRIMONIS

Early Miocene

40°

Figure le. Bottom sediments in the western South Atlantic in different stages of the Cenozoic,based on the data of deep-sea drilling: early Miocene. See Figure lb for legend.

The quartz content (on a carbonate-free basis) inCenozoic sediments varies from 0 to 38.5%, plagio-clases 0 to 52.7%, potassic feldspars 0 to 19.1%. Thehighest feldspar contents occur in sediments of thePaleocene and early Eocene. Total feldspar content isoften higher than the quartz content, resulting in aquartz-to-feldspar ratio either less than 1 or about 1.This is not usual for terrigenous sediments. Volcanicrocks buried under Tertiary sediments of the SouthAmerican continental margin seem to have been thechief sources of terrigenous material in the Paleocene-early Eocene. In the middle Eocene, terrigenous con-tribution to sediment formation was insignificant.

The source of terrigenous material was different inthe Oligocene, Miocene, and Pleistocene, as is evidentin the high quartz contents of sediments of this period,their almost complete lack of potassic feldspars, andtheir increased illite contents (Table 5). The ratio of

quartz to feldspar is usually greater than 1. Largequantities of montmorillonite persist, however.

Heavy minerals in the fraction 0.1 to 0.05 mm areusually scant. Most frequent (Table 3) are magnetite-ilmenite, garnet, hornblende, zircon, clinopyroxenes,epidote-zoisite, and muscovite—ie., the same mineralsthat occur in sediments of the Brazilian coast(Etchichury and Remiro, 1963). This again, indicatesthat the clastic part of the Cenozoic section was derivedfrom erosion of the South American land mass.

Differences in mineral compositions of the Cenozoicsediments indicate that a volcanic island or ridge, whichconnected the Rio Grande Rise with South Americaand served as a principal source of clastic and claymaterials, existed before the Eocene (Site 357 report,this volume).

In the Maestrichtian or early Eocene, this source dis-appeared, and biogenic and chemogenic sedimentation

458


Oligocene

40c

60

Figure If. Bottom sediments in the western South Atlantic in different stages of the Cenozoic,based on the data of deep-sea drilling: Oligocene. See Figure lb for legend.

(limestone, chalk, dolomite) gained ascendancy; thesediment accumulation rate dropped to 0.3 cm/1000years.

Sediments rich in siliceous biogenic matter occur inthe Eocene. Deposition of calcareous biogenic material,without abundant siliceous material, prevailed in theOligocene-Pleistocene. The source of clastic and muddymaterials was South America.

ARGENTINE BASINTerrigenous material dominates in the sediments at

Site 358. Clay minerals, plagioclases, orthoclases, andquartz occur in varying proportions.

The quartz-to-feldspar ratio is usually greater than1.5 in the lower Paleocene sediments. Illite andmontmorillonite are the chief clay minerals (Table 5).Apatite, zircon, garnet, ilmenite, hornblende, and otherterrigenous minerals occur in the heavy subfraction 0.1-

0.05 mm (Table 3), and flocculent clay dominates thelight subfraction (Table 2).

The composition of the terrigenous part of theEocene sediment is very different: feldspars are oftenabsent, illite dwindles, montmorillonite prevails.

In deposits from the Oligocene to the Pleistocene, themineral content changes again. Plagioclases andpotassic feldspars are abundant; the ratio of quartz tofeldspar decreases (usually <l); illite is more abundantthan montmorillonite; kaolinite and cristobalite occur.Ilmenite, hornblende, garnet, epidote-zoisite, zircon,sphene, and other minerals occur frequently in thealeurite fraction (0.1-0.05 mm) of clastic material.

It is evident, then, that the source of clastic materialsand clay minerals changed twice since the earlyPaleocene. From the Oligocene to the present, thesource has remained essentially unchanged. This sourceappears to be the complex of volcanogenic rocks of the

459

E. M. EMELYANOV, E. S. TRIMONIS

Eocene

Figure lg. Bottom sediments in the western South Atlantic in different stages of the Cenozoic,based on the data of deep-sea drilling: Eocene. See Figure lb for legend.

Parana river basin, where the largest trappean field onearth—about 2000 by 1000 kilometers—is situated. TheParana River now drains this field; perhaps in theTertiary, some pre-Paraná river existed which emptiedinto the Atlantic.

Basic and acid plagioclases, clay flocci, and volcanicmaterial prevail in the alluvium of the modern La Plataand in clastic material of the Patagonia shelf sediments(Etchichury and Remiro, 1960, 1963; Emelyanov et al.,1975). The heavy subfraction consits of augite,magnetite, epidote, hypersthene, green and brownhornblende, and garnet. Recent (Shurko, 1968, 1971)and Oligocene-Pleistocene sediments of the ArgentineBasin have roughly similar compositions.

In the Quaternary Period, sedimentary materialentered the Argentine Basin from three sources: LaPlata River discharge; the southern part of Argentina:and the Antarctic, as glacial debris (Biscaye, 1965;

Groot et al., 1967; Biscaye and Dash, 1971; Krinsley etal., 1973). In the Oligocene-Miocene, the principalsources were southern Argentina and the La PlataRiver.

CONCLUSIONFrom the beginning of the Cenozoic Era to the

present (60-70 m.y.), accumulation of terrigenousmaterial has contributed significantly to the overallsedimentation process in the western South Atlantic,although it has varied in space and time, as shown byLeg 39 data (Figure 3).

In the Paleocene (Figure 1H), terrigenous depositsformed at the continental slope off Brazil (Site 24) andin the Brazil Basin, where material was supplied notonly from erosion of the continent, but also frombottom erosion; brecciated layers of Upper Cretaceouscalcareous rock in the sequence at Site 355 testify to

460


Paleocene

40°

Figure lh. Bottom sediments in the western South Atlantic in idfferent stages of the Cenozoic,based on the data of deep-sea drilling: Paleocene. See Figure lb for legend.

this. The amount of terrigenous material in the BrazilBasin declined toward the end of the Paleocene.

In the Argentine Basin, heavy accumulation ofcalcareous biogenic material accompanied depositionof terrigenous material. Minimal accumulation ofterrigenous material in the Paleocene occurred at theRio Grande Rise, the Sào Paulo Plateau, and theGuiana Basin (Ceará Rise, Site 354). Paleocenesediments at the Ceará Rise are highly calcareous, andthose at the Rio Grande Rise (Site 357) are calcareouswith a pronounced admixture of siliceous biogenicmaterial. Except at the Sào Paulo Plateau, sedimentaccumulation rates were low, 0.03 to 0.3 cm/1000years.

In the Eocene (Figure 1G), terrigenous sedimenta-tion increased in the western South Atlantic. Pelagicclays consisting primarily of terrigenous components,with a notable admixture of zeolites and sometimes ofsiliceous material, accumulated in the Brazil Basin at

relatively high rates (5 cm/1000 years). The content ofterrigenous components, inversely proportional to thecontent of calcareous material, also increased insediments of the Argentine Basin. CaCOa content hereis 30% to 60% in lower Eocene deposits, and less than10% in the upper Eocene. The terrigenous material isprincipally clay minerals. Almost the same sedimenta-tion pattern existed at the Sào Paulo Plateau.Quantities of terrigenous sediment greater than those ofthe Paleocene entered the Guiana Basin, and, added tobiogenic material, resulted in higher sedimentaccumulation rates.

In the Oligocene (Figure IF), terrigenous materialcontinued to play an important but diminished role inthe Brazil and Argentine basins. Accumulation of theOligocene pelagic clays was very slow in the BrazilBasin (0.2 cm/1000 years); terrigenous materialpresumably was derived from the same sources as in theEocene, but entered the basin in considerably reduced

461


TABLE 1Grain-size Composition of Bottom Sediments from Leg 39 (in %)

Sample(Interval in cm)

Hole 353

2-1, 120-1223-2, 4-53-2, 70-723-2, 130-1323-2, 145-147

Hole 353A

1-1,62-641-2,120-122

Site 354

1-2,552,CC3-2,1204-3,1004-6,1105-1,71-736-3, 1047-4,137

Site 355

1-4, 73-751-5, 60-621-6, 80-829-2, 97-99

Hole 356

2-1,111-1133-2,15-174-3,15-175-4,50-536-4,100-1037.4> 40-438-2, 50-539-2,108-110

10-4,104-10611-2,13-1717-4, 40-4326-2,9-1129-2,100-10229-6, 22-2431-5, 87-8933-2,98-100

Hole 356A

1-4,68-702-5, 40-42

Site 357

1-2,123-1266-5, 64-678-4, 50-539-3,70-73

13-5, 84-8740-4, 45-4641-2, 79-8051-6,125-126

>O.l

5.3351.3480.7089.8213.85

0.250.07

6.888.91

14.870.955.070.88

12.1620.16

trtr

0.100.11

29.291.050.27

18.580.621.700.731.43

31.551.86

tr1.660.181.212.050.51

0.483.52

43.9112.584.934.615.64

tr0.185.32

0.1-0.05

2.3335.0313.176.808.20

0.170.07

1.632.454.470.892.861.104.50

10.99

trtr

0.100.32

12.724.291.52

20.003.800.852.093.385.571.867.052.203.083.693.632.32

0.733.52

19.0712.156.015.92

14.070.741.270.69

Diameter of Particles

0.05-0.01

55.8710.544.091.69

11.54

4.9015.21

16.3017.0411.7819.6212.289.80

14.6446.42

2.732.374.695.19

12.4738.1731.5124.8311.2910.31

8.9910.7612.49

7.649.25

12.4915.3114.93

8.3713.51

36.0325.70

12.4221.9424.1918.6016.231.852.90

16.90

0.01-0.005

9.99__

10.59

13.9415.36

6.8813.3442.3730.4154.8625.2237.00

-

26.5622.0636.2520.53

9.1224.7123.3716.5917.5616.7414.1113.0111.996.39

13.953.652.818.528.56

11.97

31.3225.18

6.1521.3726.5819.0614.7622.5523.9628.94

(mm)

0.005-0.001

16.49—__

29.22

38.9438.50

47.8351.6223.8843.1122.4247.8826.46

-

30.9331.4627.0849.31

21.2621.1823.37

3.4145.6950.2445.8745.4923.9850.6232.6045.4733.7044.2642.9838.22

15.7225.18

6.1521.3029.4343.6639.4222.3715.9728.94

<O.OOl

9.99—__

26.59

41.8130.79

20.476.652.635.022.51

15.135.24-

39.7844.1131.7724.55

15.1510.5919.9616.5921.0520.1528.2125.9214.4231.6237.1534.5344.9327.3934.4233.46

15.7216.90

12.3010.65

8.868.159.89

52.4955.7219.21

462


TABLE 1 - Continued


Site 358

1-3, 79-803-2, 75-773-5, 75-774-1,108-1105-2, 75-776-2,124-1267-1,63-658-1,121-1239-2, 62-64

10-3, 72-7411-3,7-911-4,91-9312-3,73-7512-4,63-6513-1,107-10914-2,136-13815-1,67-6916-2,99-101

Hole 359

1-3, 52-542-6,100-1023-1,94-963-3,119-1213-4, 43-453-4, 68-703-5, 79-81

Hole 359A

1-4,29-312-5,111-113

>O.l

tr0.070.28tr

0.120.140.42tr

0.160.090.240.130.310.140.160.110.080.19

26.3541.1915.2457.8816.2758.8010.53

30.0828.78

0.1-0.05

0.130.130.351.500.870.731.270.290.160.170.420.810.210.560.240.220.080.38

24.6817.3219.2710.7410.57

8.9717.68

22.5625.87

Diameter of (mm) particles

0.05-0.01

20.1814.1413.8140.4239.0031.5434.4621.7217.0922.578.72

42.4374.6616.5019.5512.4220.3645.95

15.7716.1432.1013.0629.9617.5936.37

14.8015.60

0.01-0.005

12.6122.0915.649.58

18.7619.3318.2215.6026.6824.6712.6928.249.95

30.4922.0518.5519.1816.64

13.229.49

16.694.529.583.63

11.81

11.6011.93

0.005-0.001

25.2235.9633.669.88

15.0314.5322.7431.1929.3124.6752.679.464.92

30.4930.3742.7230.1520.28

13.226.368.314.649.583,63

11.81

9.287.90

<O.OOl

41.8727.6136.2638.6226.2133.7222.8831.2026.6027.8225.2718.929.95

21.8227.6225.9730.1516.57

6.669.498.399.16

24.037.38

11.81

11.689.92

quantity. In the Argentine Basin, by contrast, increasedcontributions of siliceous material, together with theterrigenous contribution, resulted in higher overallaccumulation rates in the Oligocene. In neither theOligocene nor the late Eocene did calcareous materialdeposit in the Argentine Basin. Sedimentation seems tohave been generally controlled by the influence of coldcurrents from the Antarctic (Site 358 report, thisvolume). The other important source of terrigenousmaterial for this area was the continental drainageregion of a pre-Paraná river.

Deposition of calcareous material continued at theRio Grande Rise. Terrigenous contributions came fromthe same sources, but in reduced amounts.

At the Ceará Rise, accumulation of biogenic materialproceeded at a high rate in the Oligocene, andaccumulation of terrigenous material was reduced.CaCO3 typically makes up 50% to 60% of Oligocenesediments at this site, and the admixture of zeolites issignificant. Clay minerals account for 5 to 20% of thesediment, and quartz occurs in the aleurite fraction.

In the Miocene (Figures ID, IE), non-calcareousterrigenous sediments were deposited in the BrazilBasin and on the continental slope off Brazil (Site 24).Calcareous biogenic deposits prevail in other" areas.Non-calcareous muds in the Argentine Basin containlarge quantities of siliceous material; the main com-ponent is clay, 50% to 60% on the average, and the

siliceous biogenic content varies from 25 to 50%.Miocene accumulation rates were high.

Accumulation rates in the Brazil Basin increasedfrom a minimum in the early Miocene to higher valuesin the late Miocene. Layers of bioclastic turbidites, withsignificantly changed CaCθ3 content, occur in Miocenesediments. The clay content is variable (5 to 70%); otherterrigenous minerals, of which quartz in principal (0 to10%), are scarce.

In the Miocene, accumulation of biogenic materialcombined with the deposition of terrigenous material inthe Guiana Basin, with fluctuations in the early and lateMiocene (Figures ID, IE).

In the Pliocene, deposition of terrigenous materialwas rapid in the Brazil Basin, less intensive in theArgentine Basin. Although accumulation rates in thetwo basins were the same ( 2 cm/1000 years), muchmore siliceous biogenic material was deposited in theArgentine Basin. Pliocene sediments in the Brazil Basinare terrigenous, and contain not more than 5% biogenicdetritus.

Accumulation of terrigenous material was scant atthe Sào Paulo Plateau and the Rio Grande Rise. Lowsedimentation rates and high CaCθ3 contents char-acterize the Pliocene deposits at Sites 356, 21, and 22.

Heavy accumulation of biogenic material continuedin the Guiana Basin during the Pliocene. Terrigenousmaterial with a mineral composition indicating an

463


TABLE 2Mineralogic Composition of Bottom Sediments From Leg 39 (light-mineral content, in %)

Terrigenous

I i| I .» Ie ii i ^ i § u > -* θ

Sample | ~ | 2 á 2 -S | |Depth (m) (Interval in cm) O <_ 2. S i_ >, £ u a s p Total Total Total TotalHole 353

119.7 2-1,120-122 4.8 4.4 - 6.9 8.2 - - 24.3 - 75.4262.5 3-2,4-5 43.3 43.6 12.0 0.4 - - 99.3 - 0.4 0.4263.2 3-2,70-72 50.4 42.9 6.4 - - - - 99.7 -263.8 3-2,130-132 41.4 47.0 10.8 0.7 - - 99.9 - 0.3264.0 3-2,145-147 56.9 30.4 6.2 - 1.8 - - 95.3 - 4.0

Hole 35 3A

1-1.62-64 53.4 28.0 9.8 - 0.7 0.5 0.7 93.1 1.0 5.81-2,120-122 26.2 8.6 53.4 - - - 88.2 11.8

Site 354

5.5 1-2.55 0.3 - - - - - 0.3 99.754.5 2. CC - 8.4 - - 0.4 9.2 - 91.3

101.2 3-2.120 - - - - - 100.0144.0 4-3.100 - - - - - - 99.7 0.3148.6 4-6.110 - 0.2 - - 0.2 99.7194.2 5-1.71-73 0.3 - - 0.3 - 99.7243.5 6-3.104 - _ _ _ _ _ _ _ 100.0288.4 7-4.137 _ _ _ _ _ 100.0

Site 355

58.2 1-4.73-75 5.7 54.4 3.9 0.4 3.5 - - 70.9 0.9 29.5 1.759.6 1-5.60-62 54.0 19.1 7.5 0.6 - 81.2 18.2 0.661.3 1-6.80-82 19.1 10.6 37.6 1.7 5.0 0.6 - 74.6 0.6 24.7

321.5 9-2.97-99 0.3 89.5 - 0.3 - - 90.1 - 6.6 1.3

Hole 356

10.6 2-1. 111-113 0.7 - _ _ _ _ _ _ 0.7 - 99.339.7 3-2.15-17 0.3 0.3 ' – - - 0.3 0.9 - 99.160.2 4-3.15-17 0.3 - - - - - 0.3 99.090.5 5-4.50-53 0.7 6.6 0.7 0.3 - - 8.6 91.3

119.5 6-4.100-103 0.3 8.6 0.3 0.3 - - - 9.5 - 89.5137.5 74 .4043 0.3 0.6 0.6 - - - 1.5 - 98.4169.5 8-2.50-53 0.3 19.9 0 7 - - - 20.9 - 78.9198.6 9-2,108-110 20.(1 - - - 20.0 - 80.0227.1 104.104-106 1.6 5.5 - _ _ _ _ _ 7.1 _ 90.9 0.3243.7 11-2.13-17 - 4.6 - - - 4.6 95.1299.4 17-4.4043 0.9 95.0 - _ _ _ _ 95.9 - 2.4 0.3381.6 26-2.9-11 0.6 0.3 1.0 - - 1.9 97.7411.0 29-2,100-102 0.3 2.0 - - - - 2.3 97.7416.2 29-6,22-24 1.0 0.3 1.3 1.0 - - - 3.6 94.7443.9 31-5.87-89 0.3 0.3 0.5 0.3 - - 1.4 98.3487.0 33-2,98-100 1.6 0.6 0.3 2.5 93.8 2.3

Hole 356A

24.2 14,68-70 2.2 0.3 - 0.6 0.6 - - 3.1 96.134.9 2-5,4042 0.9 - - - - 0.9 99.1

Site 357

2.7 1-2,123-126 0.3 - - - - - 0.3 99.753.2 6-5,64-67 - - - _ _ _ _ _ _ 100.070.5 84,50-53 - - _ _ _ _ _ _ _ 100.078.7 9-3,70-73 - - - _ _ _ _ _ _ 100.0

138.9 13-5,84-87 - 0.3 - - - - 0.3 - 99.7697.5 404,4546 - 88.1 - - - - 88.1 - 12.0705.3 41-2,79-80 - 97.6 0.3 - - - - 97.9 2.0796.2 51-6,125-126 [ 0.7 83.2 - 0.3 - - - 84.2 | 13.9 2.0

464


Depth (m)

Site 358

51.3201.7206.3282.6359.8425.2491.1552.2595.6640.2706.1708.4754.2756.6780.2791.4804.7825.5

Hole 359

7.0

36.559.062.262.963.264.8

Hole 359A

13.826.1


1-3,79-803-2, 75-773-5, 75-774-1, 108-1105-2, 75-776-2, 124-1267-1,63-658-1, 121-1239-2. 62-64

10-3, 72-7411-3.7-911-4.91-9312-3.73-7512-4.63-6513-1. 107-10914-2. 136-13815-1.67-6916-2,99-101

1-3.52-542-6. 100-1023-1,94-963-3. 119-1213-4. 43-453-4. 68-703-5.79-81

1-4. 29-312-5. 1 1 1-113

N

a

δ>

3.10.71.00.6_

0.40.40.91.00.80.30.30.4

0.70.4—

6.52.0

_

1.72.31.02.40.31.7

0.3

-

>>α>>.

T 3 CΛ<u α>N •Q

α> c3

50.091.432.825.460.964.635.089.979.584.5

1.7__

43.982.631.871.383.2

_

11.417.055.4

3.013.99.0

-

TABLE

a'>9

s

_0.30.3___0.30.30.4_

_

__1.0

-

___-

-

2 - Continued

Terrigenous

α>

« _oM α>-5 >>

1.01.7

_

0.3__

0.80.7

_____

0.4

_

0.71.5

0.7__

0.30.31.0

-

α>

s §

£ ö

_

_ _

_ _

_ __ __ __ __ __ __ __ _

0.3_ __ _-

0.3_ __ __ __ _-

-

+3 <SC "oα> •—p t_,SP (2

kJU J

o c

__——_____

1.0____

0.77.50.3

_0.8

___-

-

Total

54.193.834.126.650.964.836.291.880.885.7

3.00.30.4

45.083.332.587.087.0

14.120.156.4

5.714.511.7

0.3-

α>00OC

s"o

Total

7.61.50.7

55.217.3

0.71.41.20.3

_0.30.30.4

_-_

0.4-

_

0.316.626.025.366.5

6.0

_

u'§fi)o03

Total

37.83.8

60.218.031.433.962.6

5.816.513.695.999.398.622.715.467.7

8.93.0

100.084.060.0

8.461.3

1.065.6

99.7100.0

Ioε6

Total

_

0.3---0.4--1.60.4-0.3-

32.01.0-2.79.0

_

0.70.4-0.71.70.3

_

-

Amazon source did not extend into the central andsoutheastern parts of the basin.

In the Pleistocene, abundant terrigenous materialentered the Guiana Basin and particularly the VemaFracture Zone (Sites 353, 26), where a thick Pleistoceneturbi<fite sequence was deposited. A similar pictureappears in the southeastern Guiana Basin, whereAmazon sediment was being deposited.

Accumulation of terrigenous material dominatedduring the Pleistocene in the Brazil and Argentinebasins, and has continued to do so up to the present(Figure IB).

We have seen that the supply of terrigenous materialto the western South Atlantic was continuous duringthe Cenozoic, and that this supply frequently providedthe principal component of the total sediment budget,especially in the Brazil and Argentine basins. Thepattern of accumulation of terrigenous sedimentschanged repeatedly through the Cenozoic. The changeswere dependent primarily upon local factors.

ACKNOWLEDGMENTS

The authors thank Peter R. Supko, the head of the Leg 39,and Yuri P. Neprochnov for giving us the opportunity to takepart in the study of samples from all sites of Leg 39. Analysts

were as follows: Granulometry, G.V. Zhuravlev and A.I.Panikhina; Microscopy, N.G. Lozovaya; X-ray Diffraction,K.P. Zangalis and A.S. Kozhevnikov.

REFERENCES

Bader, R.G. et al., 1970. Site 23. In Bader, R.G., Gerard,R.D., et al., Initial Reports of the Deep Sea DrillingProject, Volume 4: Washington (U.S. Government Print-ing Office), p 17-35.

Biscaye, P., 1965. Mineralogy and sedimentation of recentdeep-sea clay in the Atlantic Ocean and adjacent seas andoceans: Geol. Soc. Am. Bull., v. 76, p. 803-831.

Biscaye, P.E. and Dash, E.J., 1971. The rubidium, strontium,strontium-isotope system in deep-sea sediments. Argentinebasin: J. Geophys. Res., v. 76, p. 5087-5096.

Demerara Coastal Investigation, 1962. Report on siltation ofDemerara Barr Channel and coastal erosion in BritishGuiana: The Netherlands.

Emelyanov, E.M., Lisitzin, A.P., and Ilyin, A.V., 1975. Tipydonnykh osadkov Atlanticheskogo okeana (Types ofbottom sediments of the Atlantic Ocean): Results ofResearches of the International Geophysical Projects,Kaliningrad, p. 1-570.

Emelyanov, E.M. and Kharin, G.S., 1974. Osad-koobrazovaniye v Gvianskoy i Severo-Amerikanskoy kot-lovinakh v svyasi s tvyordymi vynosami Amazonki iOrinoko (Sedimentation in the Guiana and North

465

TABLE 3Mineralogic Composition of Bottom Sediments from Leg 39 (Heavy Minerals of

0.1-0.05 mm Fraction; sp. gr.> 2.9)

Depth(m)

Hole 353

119.7262.5263.2263.8264.0


2,1, 120-1223-2, 4-53-2, 70-723-2, 130-1323-2, 145-147

Hole 353A

Site 354

5.554.5

101.2144.0148.6194.2288.4

Site 35558.259.661.3

321.5

Hole 356

10.639.760.290.5

119.5137.9169.5198.6227.1243.7299.4381.6411.0416.2443.9487.0

1-1, 62-641-2, 120-122

1-2, 552,CC3-2, 1204-3, 1004-6, 1105-1,71-737-4, 137

1-4, 73-751-5, 60-621-6, 80-829-2, 97-99

2-1, 111-1133-2, 15-174-3, 15-175-4, 50-536-4, 100-1037-4, 40-438-2, 50-539-2, 108-11010-4, 104-10611-2, 13-1717-4, 40-4326-2,9-1129-2, 100-10229-6, 22-2431-5, 87-8933-2, 98-100

Magne-tite

4.63.65.7

12.07.3

++

_7.2-----

1.6--

0.8

2.50.7-0.50.7-5.25.3-1.80.3--1.50.30.3

Ilmen-ite

26.110.712.232.420.8

++

_-2.4----

3.5--1.9

46.2---0.70.4_-0.50.90.3--0.3_0.3

Hydro-goe-thite,

limon-ite

3.510.3

6.88.79.7

+-

+.89.1

1.2++++

54.42.1--

1.71.1-2.80.72.5

5.68.41.0

11.70.62.2-0.90.30.3

Leuc-oxen

1.46.43.25.41.7

++

_---

-+

_---

0.9---------

0.3--0.3_-

Horn-blende

11.313.014.4

3.711.5

++

_-

0.6--++

3.60.71.0-

2.6_--0.7-_--__--__-

Actino-lite-tre-molite

_

1.10.60.7

+-

_---__-

_0.3--

__-

0.5-----__--__-

Terrigenous

EpiAlkalic Basaltic dote,Horn- Horn- zoi-

blende blende site

0.4 - 16.621.025.9

0.7 - 9.316.5

++

_ _ __

0.6_

_+

- - -

- - -0.3

__

4.3_ _ _______ _ ___

__

__

_ _ _- - -

Gar-net

0.70.71.82.71.7

_

-

_-0.6__--

__--

6.8_-----_-__--

0.3_-

Zir-con

1.51.81.43.73.1

+-

__

0.6___-

__--

27.4_---

0.4---__--__-

SphenApa- (titan-tite ite)

0.40.4

1.10.31.0

_ _-

_ _------

_ _0.3

--

0.9_-------_---__-

Bio-Rutile tite

15.62.50.41.71.4

_ _+

_ _0.4

_---

+

1.80.3

-

1.70.4

-0.50.7

---_-

4.332.6

9.44.65.63.1

Chlor-rite

0.7-

0.70.30.7

_+

+1.10.6----

_---

_0.70.35.2

58.215.015.717.748.5

3.681.149.479.273.964.868.3

Musco-vite

2.51.1--

0.3

_

-

_0.4

-----

_--

0.6

_---

9.13.21.01.3

14.10.9

11.61.12.19.2

18.921.1

Hole 356A

24.234.9

Site 357

2.753.270.578.7138.9697.5705.3796.2

Site 358

51.3201.7206.3282.6359.8425.2491.1552.2595.6640.2706.1708.4754.2755.6780.2791.4804.7825.5

Hole 359

7.036.559.062.262.963.264.8

1-4, 68-702-5, 40-42

1-2, 123-1266-5, 64-678-4, 50-539-3, 70-7313-5, 84-8740-4, 45-4641-2, 79-8051-6, 125-126

1-3, 79-803-2, 75-773-5, 75-774-1, 108-1105-2, 75-776-2, 124-1267-1, 63-658-1, 121-1239-2, 62-6410-3, 72-7411-3,7-911-4,91-9312-2, 73-7512-4,63-6513-1, 107-10914-2, 136-13815-1, 67-6916-2, 99-101

1-3, 52-542-6, 100-1023-1, 94-963-3, 119-1213-4, 43-453-4, 68-703-5, 79-81

Hole 359A

13.826.1

1-4,29-312-5, 111-113

3.00.5

3.30.71.5__+

4.60.3

_

___

---_-0.3_0.4_--_-

3.20.8-0.30.3--

_

2.1

0.5-

11.91.3-_0.6__-

_

+_1.2--_0.40.6_

0.30.4..1.00.8-1.20.9

20.715.9

2.29.97.99.41.8

7.57.1

5.61.4

3.4_2.31.11.9+_

-

_

__

6.10.5_0.7__0.30.3__1.00.81.01.21.8

6.620.0

1.01.11.7_2.9

2.35.0

_

-

11.9___0.6__-

___1.2________-_

0.8__0.9

2.53.4__

0.3_

-

0.61.7

1.00.7

8.5--_

0.6__

-

0.4+_1.2____0.6__

0.41.1_0.8__

-

0.8

__

_

-

2.30.4

_

-

_

______

-

_

__1.2_

0.4____-______

-

_

_____0.4

_

-

_

-

1.7-----_-

_

----------_----_-

_

-0.4

__-

0.7

_

-

_

-

_

----__-

_

__-----_--__---_

-

_

-1.1__-

0.4

_

-

1.0-

1.7------

0.4+_-_-1.1-1.30.3-_0.4_--_

-

5.8--

0.30.6-

0.4

0.6-

0.50.7

6.8-_1.1_-_0.4

0.8___

0.50.41.10.4_0.70.3_0.40.50.8-2.40.9

7.4_-__-

-

0.60.4

_

-

22.0---

---

0.4_

0.43.7

--

0.4_

0.60.70.3

_0.7

_0.4

_--

5.81.7__

0.4-

2.9-

_

-

_

--_-_

1.5-

_

-_

1.2-_--_-

0.3__

0.50.40.3

_0.9

1.6_

0.7__-

-

_

_

_

-----

12.30.4

_

--

1.2-

0.4----------_-

1.6--__--

_

-

_

-

-

-------

0.4+----------------

0.8---_--

-

-

-

-

-------

-

+-7.31.0-----------1.21.8

-

-0.40.3---

_

-

0.51.4

-

-----

1.5-

-

--

1.20.5

-----

-----

1.27.9

2.5--

0.3--

0.4

_

-

-

1.4

3.4------

0.4

-

--

2.40.5

-------------

2.5-

0.4-

0.3--

-

0.4

Note: - = missing; + = trace; ++ = present

nwzoNooH

wfo

O

wocCΛ

CΛ

W

α

TABLE 3 - Continued

Depth(m)

Sample(Intervalin cm)

Terrigenous

TourmalineStaur-olite

Chlor-itoid Kyanite

Others, Andalu-site, Orthite,

(topaz)Rock

FragmentsMonoclinicPyroxene

RhombicPyroxene

Olivine,Idding-

site TotalVolcano-

genie BiogenicChemo-genic

2.80.40.8-

1.0

Heavy Mine-rals in fr.

0.1-0.05 mm(in %)

3.32.25.8

14.22.4

tn00

H

üzHole 353

119.7262.5263.2263.8264.0

2-1, 120-1223-2, 4-53-2, 70-723-2, 130-1323-2, 145-147

Hole 35 3A

1-1, 62-641-2, 120-122

Site 354

5.554.5101.2144.0148.6194.2288.4

Site 355

58.259.661.3321.5

Hole 356

10.639.790.5119.5137.9169.5198.6227.1243.7299.4381.6411.0416.2443.9487.0

1-2, 552, CC3-2, 1204-3, 1004-6, 1105-1,71-737-4, 137

1-4, 73-751-5, 60-621-6, 80-829-2, 97-99

2-1, 111-1133-2, 15-175-4, 50-536-4, 110-1037-4, 40-438-2, 50-539-2, 108-11010-4, 104-10611-2, 13-1717-4, 40-4326-2,9-1129-2, 100-10229-6, 22-2431-5, 87-8933-2, 98-100

1.41.42.20.3

0.4

0.4

0.4

0.3

0.4

0.30.4 0.6

3.815.66.85.78.0

1.51.8

10.17.78.0

0.4

0.30.3

0.3

1.0

92.290.394.695.593.8

4.29.2

4.34.9

3.3

+98.26.6-

+1.1

92.1++

+0.40.6_

0.10.40.20.4

0.3

64.94.31.33.3

95.02.90.3

71.421.527.532.764.183.098.585.391.791.089.993.7

7.00.3

-—

----------

8.3-

0.3_

14.039.5

1.33.8

1.785.1

1.02.73.2

21.631.933.881.1

-13.58.38.59.35.4

10.055.697.492.6

3.412.098.625.975.350.835.4

2.0_

1.21.1-

0.30.30.6

11.060.244.6

0.9

0.24.1

0.541.780.401.270.440.860.480.560.500.430.490.47

24.2 1-4,68-70 _ _ _ _ _ _ _ _ _ 12.1 - 65.8 21.9 0.634.9 2-5,40-42 _ _ _ _ _ _ _ _ _ 6 . i _ 23.0 70.9 0.2

Site 3572.7 1-2, 132-126 _ _ _ _ _ _ 1.7 76.3 - 22.0 1.753.2 6-5, 64-67 - - - 2.0 0.7 63.6 33.870.5 8-4,60-53 _ _ _ _ _ _ _ _ _ 3.3 _ 93.2 3.0 0.378.7 9-3, 70-73 _ _ _ _ _ _ _ _ _ 2 . 2 - 87.0 10.9138.9 13-5,84-87 _ _ _ _ _ _ _ _ _ 3 . 7 _ 94.3 1.9697.5 40-4,45-46 - + _ _ _ _ _ _ _ + _ _ +705.3 41-2, 79-80 _ _ _ _ _ _ _ _ _ 19.9 1.5 - 78.5 0.5796.2 51-6,125-126 - 0.4 - - - 1.9 98.3 3.6

Site 358

51.3 1-3, 79-80 - - - - - - - 2.4 1.2 0.4 95.9 4.8201.7 3-2, 75-77 _ _ _ _ + _ _ _ _ + _ _ _206.3 3-5, 77-77 _ _ _ _ _ _ _ _ _ o . 4 99.2 14.0 85.7 43.3282.6 4-1, 108-110 _ _ _ _ _ _ _ _ _ 26.7 - 28.0 45.2 0.5359.8 5-2, 75-77 - - - 3.0 2.6 10.9 83.3 1.8425.2 6-2, 124-126 - - - - - 1.2 - 0.7 98.2 12.6491.1 7-1,63-65 - - - - - - - 3.3 0.4 2.8 93.7 3.7552.2 8-1, 121-123 - - - - - - - 0.8 - 2.2 97.1 10.1595.6 9-2, 62-64 0.6 - - 3.7 81.4 14.7 10.6

"640.2 10-3, 72-74 _ _ _ _ _ _ _ _ _ 2 . 0 - 92.5 5.6 18.7706.1 11-3,7-9 _ _ _ _ _ _ _ _ _ i . 8 _ 90.0 8.3 2.9708.4 11-4,91-93 _ _ _ _ _ _ _ _ _ 0 . 8 - 26.0 78.3 7.8754.2 12-2, 73-75 _ _ _ _ _ _ _ _ _ 3.0 _ 63.5 33.6 4.3755.6 12-4,63-65 _ _ _ _ _ _ _ _ _ 3 . o - 86.5 10.4 1.8780.2 13-1, 107-109 0.4 - - 5.2 93.6 1.6 2.0791.4 14-2,136-138 - _ _ _ _ _ _ _ - 1.3 . - 94.6 4.0 9.6804.7 15-1,67-69 - - - 9.6 1.2 66.7 22.7 3.6825.5 16-2,99-101 _ _ _ _ _ _ _ _ _ 1 5 . i _ 7 1 9 1 3 2 1.1

Hole 359

7.0 1-3,52-54 - - - - - - - - 61.8 9.9 27.3 - 0.0236.5 2-6,100-102 _ _ _ _ _ _ 0.8 - - 42.6 9.8 43.4 0.4 0.759.0 3-1, 94-96 - 0.4 0.4 5.8 10.9 - 0.4 76.2 19.5 1.1 3.3 1.462.2 3-3, 119-121 - - 0.3 2.1 40.9 - - 54.4 18.6 1.0 25.7 1.262.9 3-4,43-45 - - - - 86.8 - - 96.6 1.5 - 1.8 1.864.8 3-5,79-81 - - 0.7 3.9 11.6 86.3 2.2 - 1.3

Hole 359A

13.8 1-4,29-31 _ _ _ _ _ _ _ _ _ 17.4 9.8 72.8 - 0.0426.1 2-5,111-113 - _ _ _ _ _ _ _ _ 17.1 10.4 72.1 0.4 0.04

Note: - = missing; + = trace; ++ = present


TABLE 4Content of Carbonate Minerals, Quartz, and Feldspars

in Bottom Sediments from Leg 39 (in %)

Depth(m)

Hole 353

126.5263.7263.9


2-3, 50-523-2, 120-1223-2, 142-144

Hole 35 3A

181.0

Hole 356

10.339.860.691.0

119.0138.0169.6198.5225.0244.8253.1273.8292.0299.5318.4353.7365.0365.9368.2372.8381.7408.8411.1416.3443 7487.0545.0654.3681.3701.4705.0734.1

1-2,91-941,CC

2-1,82-853-2, 28-304-3,55-5754,101-10364 > 50-537-4, 50-538-2, 60-639-2, 98-10010-3,48-5011-2, 129-13112-1,11-1314-1,25-2716-1,100-10217-4,50-5319-4,404223-2, 70-7224-3, 101-10324-4, 35-3724-5, 120-12225-2, 30-3326-2, 23-2529-2, 30-3229-2,110-11229-6, 30-3231-5,68-7033-2, 94-9735-3, 50-5238-3, 82-8439-5,75-7740-6,424441-2,48-5044-2, 110-112

Hole 356A

24.235.1

Hole 359

6.436.958.262.062.891.2

14, 72-742-5,55-57

1-3,91-1412-6,139-1413-1,15-173-3, 96-9834, 26-284-2,19-21

Hole 359A

17.617.621.5

1-6, 108-1101-6, 112-1142-2, 104-106

TotalCarbonates

1.01.02.0

1.0

67.052.042.052.030.024.030.036.029.016.021.031.017.044.016.038.021.070.042.050.046.0

8.024.050.063.045.046.045.0

0.02.00.0

26.0

34.043.0

74.058.047.040.0<l.O

3.0

73.072.072.0

Quartz

12.556.027.0

16.058.0

2.05.07.05.04.05.05.04.04.05.03.03.02.04.06.05.08.04.04.04.04.0

12.09.06.05.06.09.07.0

17.021.017.018.0

8.07.0

0.01.01.01.01.00.0

0.00.00.0

Clastic Minerals

Plagioclase

<4.0<5.0<4.0

<2.0<6.0

0.01.01.01.01.01.01.01.01.01.0

tr.tr.tr.1.02.01.01.01.01.01.01.03.02.0tr.tr.1.01.01.02.02.02.02.0

2.02.0

0.01.02.02.0

15.0tr.

0.00.00.0

K-Feldspar

0.01.00.00.00.00.00.00.00.01.0tr.0.00.00.00.00.01.00.00.00.00.04.02.0tr.tr.1.00.00.00.00.00.00.0

0.00.0

0.00.00.00.00.00.0

0.00.00.0

470


TABLE 5X-ray Diffraction Analysis of Bulk Samples, Leg 39 (in percent from total crystalline components)


Site 3541-1, 751-1, 1402,CC3-1, 1104-1, 60-624-2, 60-624-4,754-6, 104-6, 1025-2, 91-936-3, 846-3. 946-3, 1387-3, 438-2,59-1,11710-2, 12611-2, 7912-5, 4012-5, 9113-6, 12414-4, 35-4015-2, 3515-3, 13816-2, 4716-6, 12417-1, 12718-1, 13018-4, 127

Site 355

1-2, 72-742-3, 50-522-5, 130-1323-2, 90-923-5, 60-624-3,110-1125-1, 38-405-4, 100-1026-2, 66-687-2, 90-927-3, 100-1028-2, 120-1219-2, 58-6011-2,86-8812-5, 86-8813-3, 75-7715-1, 8615-1, 10117-3, 143-14517-4, 20-2217-6, 65-6718-1, 120-12218-3, 41-4319-2, 131-13320-2, 148-150

Site 357

1-3, 100-1033-2, 90-925-3, 100-102

Montmori-llonite

12.210.19.98.98.54.78.68.46.87.08.95.6

13.18.6

18.75.58.79.79.56.88.66.58.6

16.011.221.0

4.34.84.5

25.834.833.518.951.638.126.528.849.435.831.513.814.817.528.635.119.634.1

4.13.86.45.37.25.13.9

3.32.62.2

Clay Minerals

Illite

22.219.019.716.713.814.816.221.311.414.015.2

2.84.2trtr4.25.26.10.03.44.83.7tr4.84.8tr4.85.45.9

24.218.628.79.9

23.319.0

8.612.3

7.48.97.34.29.76.67.1

13.250.630.7

6.27.2tr4.08.1

12.74.4

0.0tr.2.8

Kao-iinite

9.17.69.75.65.36.88.1

12.66.38.8

10.27.0

25.46.5

15.55.46.6

12.1tr3.53.24.90.03.60.00.0

18.424.028.7

12.912.9

7.2trtr

11.16.64.10.06.16.7tr4.60.06.19.2

10.09.50.00.00.00.00.03.40.0

0.00.00.0

Chlor-ite

7.86.37.44.44.24.56.5

11.35.15.35.1trtr0.07.80.03.9

tr0.00.00.03.50.0tr0.00.0

tr0.00.0

6.510.1

3.6trtr

10.17.92.10.05.6

10.1tr5.60.07.77.94.4

10.90.00.00.00.00.0

tr0.0

0.00.00.0

MixedLayer

0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

0.00.00.0

Quartz

15.212.713.1

9.37.14.9

12.410.04.69.9

10.11.95.62.76.72.84.1

12.21.83.92.72.09.4

17.218.511.816.015.820.6

17.716.114.4

4.211.6

9.010.611.6

9.910.1

8.94.87.47.08.26.66.6

11.42.62.91.61.84.54.72.0

1.8tr.3.3

K-feld-spar

2.6trtr1.11.10.0tr1.30.00.00.00.00.00.03.10.00.00.00.00.00.00.00.00.00.00.00.01.82.5

4.8trtr0.00.00.00.04.10.03.43.42.12.80.00.00.05.53.40.00.00.00.01.31.3

0.0

0.00.00.0

Plagio-clase

3.93.82.52.22.11.31.62.5trtrtr

0.00.00.01.60.00.00.00.00.00.00.03.9tr

0.00.00.00.00.0

8.17.57.12.87.76.36.06.20.08.33.91.74.22.53.02.63.3tr

0.00.00.00.01.8tr

0.0

0.00.01.6

Crist o-balite

0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.05.00.00.00.00.00.00.00.0

0.00.00.00.00.00.00.00.00.00.00.06.9

23.115.325.57.00.00.00.00.00.00.00.00.00.0

0.00.00.0

Clinop-tilolite

0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.04.90.00.00.02.30.00.00.00.00.00.00.0

0.00.05.50.05.86.4

33.830.833.321.828.466.527.851.113.818.4

0.00.00.00.00.00.00.00.00.0

0.00.00.0

TotalCar-

bonate OtherMin- Min-erals erals

27.040.537.751.857.963.046.632.665.855.050.582.751.782.246.682.172.555.088.782.480.772.178.158.465.567.256.548.237.8

0.0tr0.0

64.20.00.00.0

tr0.00.00.00.00.00.00.00.00.00.0

87.186.192.088.977.172.889.7

95.2 0.097.4 0.090.5 0.0

471


TABLE 5 - Continued


Site 357 - Conti

6-4, 80-838-2, 70-739-2, 70-7310-1, 80-8210-2, 80-8211-2, 103-10613-4, 62-6515-2, 78-8117-3, 100-10217-5, 100-10220-2, 117-12022-4, 13-1623-2, 61-6424-1, 45-4824-5, 84-8724-6, 101-10424-6, 132-13526-3, 148-15127-3, 108-11128-1,9129-1, 98-10130-1, 31-3431-2, 123-12633-3, 142-14534-4, 32-3536-1, 68-7140-1, 74-7740-4, 44-4540-4, 45-4641-2, 76-7941-2, 79-8041-2, 81-8242-3, 96-9943-3, 140-14344-2, 18-2146-3, 31-3447-3, 56-5948-1, 47-4850-3, 42-4451-3, 34-3651-6, 125-126Site 3581-6, 70-722-4, 94-963-2,71-733-5, 71-734-1, 96-985-2, 62-646-3, 139-1417-2, 99-1018-1,117-1199-2, 63-6510-3, 73-7511-3,7-911-4,86-8812-2, 59-6112-3, 75-7713-2, 130-13214-2, 137-13915-1, 66-6816-2, 103-105

Montmori-llonite

nued

2.72.22.84.32.82.22.63.22.73.12.63.43.23.07.50.00.00.02.8

19.62.72.92.72.64.43.32.4

82.6100.0

18.751.951.9

4.46.22.63.62.32.01.92.94.4

12.17.77.5

11.78.7

10.111.5

6.56.88.87.6

20.93.8

16.13.53.36.7

12.112.7

Clay

Illite

2.72.90.0trtr0.06.53.85.5-8.62.60.00.00.00.00.00.00.02.80.0tr2.24.1

14.714.315.812.0

0.0tr

15.60.00.0

13.722.111.613.312.86.72.68.08.7

21.423.127.2

5.121.615.631.628.426.631.833.011.9

2.96.40.02.68.6

33.634.5

Minerals

Kao-linite

0.00.00.00.0tr0.01.30.00.02.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.05.60.00.00.00.0

11.28.30.00.00.00.00.00.00.00.00.0

8.07.75.43.95.88.85.35.20.06.45.40.00.00.00.00.00.04.02.3

Chlor-ite

0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

• o.o0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

MixedLayer

0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

0.00.00.00.00.00.00.00.00.0

17.914.00.00.00.00.00.00.00.00.0

Quartz

2.02.21.01.62.11.23.52.42.63.72.00.00.0trtr0.00.0tr0.00.01.00.01.52.76.2

10.93.20.00.04.10.00.07.67.72.81.83.13.02.06.5

14.0

19.617.916.411.811.4

7.614.6

8.816.918.626.026.1

6.613.1

7.34.59.0

22.015.6

K-feld-spar

0.00.00.00.00.00.01.50.00.00.00.00.00.00.0tr0.00.00.00.08.11.10.00.01.51.92.62.70.00.00.00.00.03.93.72.42.12.11.50.01.90.0

12.113.815.412.516.319.913.912.416.94.54.9

10.10.00.00.01.52.8

13.75.8

Plagio-clase

1.58.30.00.02.30.03.0tr

0.01.4tr

0.00.00.00.00.00.0tr

6.46.31.50.0tr1.21.22.13.40.00.04.10.00.04.43.73.01.42.11.60.01.32.8

14.416.214.112.515.517.812.312.415.4

8.19.1

11.50.00.00.01.52.8

10.66.5

Cristo-balite

0.00.00.00.00.00.00.00.00.00 00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.03.03.10.00.00.03.05.9

17.35.6

8.18.77.25.99.87.67.9

26.317.4

0.00.00.00.00.00.00.00.00.00.0

Clinop-tilolite

0.03.3

o;o0.00.00.00.00.00.00.04.98.56.07.50.00.00.00.00.00.05.10.00.00.00.00.00.00.00.06.00.00.00.00.00.00.00.00.00.00.00.0

0.00.06.86.57.29.50.00.00.00.00.0

19.50.00.00.00.00.00.00.0

TotalCar-

bonateMin-erals

91.381.096.294.392.896.681.890.689.280.888.488.191.289.592.4

100.0100.0100.087.957.688.594.891.677.571.959.876.417.4tr51.417.919.562.853.677.577.877.682.287.562.164.5

4.44.50.00.03.63.12.90.00.04.00.00.0

86.764.389.186.670.9

3.922.5

OtherMin-erals

0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.08.30.00.00.00.00.00.00.00.0tr

0.018.920.3

0.00.00.00.00.00.00.00.00.0

0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

472


20

1 II I | 2α b I' li #\d

Figure 2. Mineralogic provinces of large aleurite fraction of upper-layer sediments of the AtlanticOcean (by Emelyanov and Kharin, 1974; A. V. Soldatov et al, unpublished data). Legend:1-Lesser Antilles volcanogenic; 2~Guiana (pyroxene-zircon-epidote-amphibole) with subpro-vinces (a—Amazonian, b-Orinocina, c—Guiana deep-water, d—Tocantincan relict); 3-Brazilian(ilmenite-pyroxene-zircon-epidote); 4-Argentine (ilmenite-pyrozene-amphibole); 5-Mid-Atlan-tic Ridge (olivine-pyroxene-amphibole-serpentine).

American basins in respect with solid evacuations of theAmazon and Orinoco rivers): Litologiya i polezn. iskop.,v. 2, p. 22-35.

Etchichury, M.C. and Remiro, J.R., 1960. Muestras de fondode la platforma continental: Ciencias Geologicas, v. VI,Buenos-Aires, p. 197-263.

Etchichury, M.C. and Remiro, J.R., 1963. La corriente deMalvinas y los sedimentos Pampeano-Patagónicos: Cien-cias Geologicas, v. I, Buenos Aires, p. 1-11.

Gibbs, R.J., 1967. The geochemistry of Amazon river system:part 1. The factors that control the salinity and thecomposition and concentration of the suspended solids:Geol. Soc. Am. Bull., v. 78, p. 1203-1232.

Gorbunova, Z.N., 1969. Rentgen-difraktometricheskiymetod opredeleniya karbonatov i drugikh mineralov

osadka. (X-ray diffractometric analysis of determiningcarbonates, quartz and other minerals of sediments):Litologiya i polezn. iskop., v. 2, p. 125-130.

Groot, J.J., Groot, G.R., Ewing, M., Burckle, L., andConolly, J.R., 1967. Spores, pollen, diatoms and provinceof the Argentine Basin sediments: Progress in Oceanog-raphy, v. 4, Pergamon Press, p. 179-217.

Krinsley, D., Biscaye, P.E., and Turekian, K.K., 1973.Argentine basin sediment sources as indicated by quartzsurface textures: J. Sediment. Petrol., v. 43, p. 251-257.

Milliman, J.D., Summerhayes, CP., and Barrette, H.T.,1975. Oceanography and suspended matter off theAmazon river February-March: J. Sediment. Petrol.,v. 45, p. 189-206.

473

1

1 V 2 I 3 HU 4 5Z

6//

7 8B

9. . . .

10 11 12

Figure 3. Cenozoic deposits at sites of the western South Atlantic. Legend: 1-4 indicate CaCO^ content of sediments (I—less than 10%, 2-10-30%, 3-30-60%,4-more than 60% CaCOj); 5-siliceous material (10-50%); 6-zeolites (over 10%); 7-volcanogenic material (over 10%); 8-brecciated layers, slumping deposits;9-admixture ofbarite; 10-turbidites; 11-red clays; 12-hiatuses; 13-rates of sediment accumulation in cm/1000 years.


Oliveira, A.I., 1956. Brazil. In Jenks, W.F. (Ed.), Handbookof South American Geology: Geol. Soc. Am. Mem., v. 65,p. 2-62.

Petelin, V.P., 1961. Novyiy metod vodnogo mekhaniches-kogo analiza morskikh osadkov (New method of watermechanical analysis of marine sediments): Okeanologiya,v. 1, p. 143-148.

Petelin, V.P., 1967. Granulometricheskiy analiz morskikhdonnykh osadkov (Granulometric analysis of marinebottom sediments), Izd-vo "Nauka", Moscow, p. 1-75.

Prokoptsev, N.G., 1964. K metodike mekhanicheskogoanaliza pelitovykh fraktsiy morskikh osadkov—suspen-zionnye vesy. (On method of mechanical analysis of peliticfractions of marine sediments—suspensional weight):Okeanologiya, v. 4, p. 699-707.

Rex, R.W. and Murray, B., 1970. X-ray mineralogy studies,Leg 4. In Bader, R.G. et al., Initial Reports of the Deep

Sea Drilling Project, Volume 4: Washington (U.S.Government Printing Office), p. 325-370.

Shurko, 1.1., 1968. Mineralogicheskiye zony i provintsii vosadkakh Atlanticheskogo okeana (Mineralogic zones andprovinces in sediments of the Atlantic Ocean): Litologiya ipolezn. iskop., v. 4, p. 112-117.

Shurko, 1.1., 1971. Osobennosti pozdnechetvertichnogoosadkoobrazovaniya v Argentinskoy kotlovine. (Thefeatures of late Quaternary sedimentation in the ArgentineBasin). Doklady AN SSSR, v. 198, p. 696-698.

Von Rad, U. and Rösch, H., 1972. Mineralogy and origin ofclay minerals, silica and authigenic silicates in Leg 14sediments. In Hayes, D.E., Pimm, A.C., et al., InitialReports of the Deep Sea Drilling Project, Volume 14:Washington (U.S. Government Printing Office), p. 727-752.

475

13. cenozoic terrigenous sediments in the western … · this basin receives sediment from a...

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