Tertiary and Cretaceous paleoenvironments in the southwest Atlantic Ocean: Preliminary results of Deep Sea Drilling Project Leg 71

Ludwig, W. J.; Krasheninnikov, V.A.; Basov, Ivan A; Bayer, U.; Bloemendal, Jan; Bornhold, Brian D.; Ciesielski, Paul F; Goldstein, Elaine H.; Robert, Christian; Salloway, J.C.; Usher, J L; Dick, H. von der; Weaver, Fred M.; Wise, Sherwood W.

doi:10.1130/0016-7606(1980)91<655:tacpit>2.0.co;2

Cited by 23 publications

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“…The Cenozoic sequence begins with a pile of pelagic noncalcareous clays (Site 511) or zeolitic clays (Site 327) of Paleocene age, lacking planktonic foraminifers and overlying, with a distinct unconformity, Maestrichtian calcareous oozes. The nature of the hiatus at the Mesozoic/Cenozoic boundary has been discussed by Sliter (1977), Ludwig, Krasheninnikov, et al (1980), and Basov and Krasheninnikov (this volume). Apparently, strong bottom currents existing at that time scoured the Mesozoic sediments.…”

Section: Geological Historymentioning

confidence: 99%

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Cenozoic Planktonic Foraminifers of the Falkland Plateau and Argentine Basin, Deep Sea Drilling Project Leg 71

Krasheninnikov¹,

Basov²

1983

Initial Reports of the Deep Sea Drilling Project

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Sites 511 and 512 (Falkland Plateau) and 513 (Argentine Basin) penetrated calcareous-siliceous oozes of the middle and upper Eocene and lower Oligocene with rather numerous planktonic foraminifers. Upper Oligocene, Miocene, Pliocene, and Quaternary sections are composed mostly of siliceous sediments (Sites 511-514) where planktonic foraminifers are rare or absent. High-latitude planktonic foraminifers of the Austral Province are characterized by impoverished assemblages-only representatives of Globigerina, Globigerinita, Globorotaloides, and Globorotalia with a rounded peripheral margin are found. In the Paleogene, these species are supplemented, in lesser amounts, by representatives of Globigerapsis, Acarinina, Pseudogloboquadrina, Pseudohastigerina, and Chiloguembelina. Assemblages of planktonic foraminifers have low stratigraphic resolution, especially in the upper Oligocene-Quaternary. This reflects the generally deteriorating Cenozoic climate, which evinced a sharp change in the upper Oligocene that is connected with initiation of the circum-Antarctic current near the Paleogene/Neogene boundary. Comparison of Paleogene and Neogene planktonic foraminifers of the South Atlantic (Falkland Plateau, Argentine Basin, 46-51 °S) and the North Atlantic (Rockall Plateau, 55-56°N) indicates that the South Atlantic climate was much colder than that of the same latitudes of the North Atlantic.Paleogene oozes of the Falkland Plateau rest unconf ormably on Maestrichtian sediments and in their turn are overlain unconformably by Neogene-Quaternary oozes. Cenozoic sections are stratigraphically discontinuous: periods of intensive biogenic sedimentation resulting in a thick succession of sediments alternated with periods of nondeposition and strong erosion that resulted in hiatuses and unconformities. In the Argentine Basin, Oligocene calcareous-siliceous oozes rest on basalts of the oceanic basement; they are replaced upward in the section by Neogene-Quaternary siliceous oozes with some hiatuses. Planktonic foraminifers here clearly demonstrate the processes of oceanic subsidence and CCD fluctuations as well as Polar Front migrations during Cenozoic time. Fifty species of planktonic foraminifers are discussed and illustrated.

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Section: Geological Historymentioning

confidence: 99%

“…Certainly the most precise picture of Polar Front migration and temperature fluctuations is given by the character of siliceous microfossils (Ludwig, Krasheninnikov, et al, 1980). Poor assemblages of planktonic foraminifers do not possess such accurate ecologic resolution.…”

Section: Quaternarymentioning

confidence: 99%

Cenozoic Planktonic Foraminifers of the Falkland Plateau and Argentine Basin, Deep Sea Drilling Project Leg 71

Krasheninnikov¹,

Basov²

1983

Initial Reports of the Deep Sea Drilling Project

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“…); Hiatus in Sedimentation This extensive hiatus is associated with the initial break-up of the Gondwanaland supercontinent and the embryonic stage in the formation of the South Atlantic (Barker, Dalziel et al, 1977;Ludwig, Krasheninnikov, et al, 1980).…”

Section: Discussion: Geochemical History Of Late Mesozoic Sedimentationmentioning

confidence: 99%

“…The clay matter is represented mostly by mixed-layer Na-montmorillonite with a small amount of micaceous packets, hydromica, and an admixture of chlorite and kaolinite. Sediments accumulated in a basin characterized by pronounced stagnation and an oxygen-free regime in bottom waters (Barker, Dalziel, et al, 1977;Ludwig, Krasheninnikov, et al, 1980;Thompson, 1977). A characteristic geochemical feature of the sediments is the accumulation of dispersed organic matter (average C org 3.26%), closely related to Zn, Cu, Cr, Rb, and Be (Assemblage IA[ + ]; see Tables 2, 3, and Fig.…”

Section: Discussion: Geochemical History Of Late Mesozoic Sedimentationmentioning

confidence: 99%

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Trace Element Geochemical History of Late Mesozoic Sedimentation in the Southwest Atlantic, Falkland Plateau, Site 511

Варенцов¹

1983

Initial Reports of the Deep Sea Drilling Project

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The distribution of paragenetic assemblages of trace and rare elements, as revealed by factor analysis (R-mode, Q-mode), the ratios of elements to Zr and the interpretation of these data in the context of the known mineralogy, lithology, and geology of the region, provide the bases for the outline of the geochemical history of sedimentation in the study area that forms the subject of this chapter. Two stages may be discerned.1. . The sediments that accumulated in relatively shallow water (shelf) were predominantly clay, with dispersed sapropelic organic matter, plant fragments, pyrite, admixtures of acid-medium volcanic glass, and epigenetic crystals of gypsum. The bottom water layers of the basin are notably stagnant. The sediments are characterized by higher amounts of V, Zn, Cu, Cr, Rb, and Be associated with organic matter. Lower Cretaceous sediments, separated from those of the Upper Jurassic by a hiatus, accumulated in a deepened and enlarging basin. These Lower Cretaceous deposits are chemically similar to those of the Upper Jurassic, but contain diagenetic concentrations of Zn, Ni, and La. (1067-66.6Ma). The prevailing regime was that of an open ocean basin that tended to expand and deepen. Early-middle Albian (Unit 5)-middle MaestrichtianDuring the second half of the early-middle Albian, the biogenic components Ba, Sr, and CaCO 3 accumulated. By the end of this interval, Ti/Zr values had increased. In conjunction data on mineral composition, they testify to an outburst of basaltoid volcanism related to tectonic activity before an erosional hiatus (late Albian-Cenomanian).At the end of the Cenomanian-Turonian, residual deposits of predominantly clay sediments with relatively high amounts of Ti and Zr and associated rare alkalis (Li, Rb) accumulated.Clay sediments deposited during the Coniacian-Santonian were characterized by higher concentrations of Ti, Zr, Li, and Rb, by diagenetic carbonate phases of Ni, Zn, and La, and by sulphides and Fe-oxides with an admixture of Ni and Co. The latter half of the interval saw the deposition of fine basaltoid volcanoclastic material, diagenetically altered by zeolitization and carbonatization and enriched with Se, Pb, Ti, Sr, Ba, Y, and Yb. Sediments with a similar chemistry accumulated in the Campanian-middle Maestrichtian.Strong current activity preceding a global hiatus at the Mesozoic/Cenozoic boundary is reflected in both lower sedimentation rates and the presence of higher residual concentrations of Ti, Zr, Ba, Sr, and other elements studied in this chapter.

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Plate tectonics and the problem of anthropoid origins

Cachel

1981

Am. J. Phys. Anthropol.

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Using plate tectonic theory, geologic and geophysical determinants of South Atlantic opening are assessed during the Cretaceous through the Oligocene (approximately 135-25 m.y.B.P.1. This is done to evalute the feasibility of statements on paleontologic and neontologic distributional data that relate to African and South American separation as the South Atlantic was created. In particular, the question of anthropoid origins is examined in light of plate tectonic theory, and the idea that monophyly of the anthropoid grade is supported by continental drift is refuted. When geological and geophysical evidence is examined in detail, the occurrence of Tertiary transfer of primates between Africa and South America is improbable. Thus one must look to either North America or Middle America for the ancestors of the platyrrhines, and to Eurasia for the ancestors of the catarrhines. The problem of whether those ancestors were prosimians or anthropoids is not dealt with, because the question of whether the Platyrrhini and the Catarrhini are independently evolved from prosimian ancestors (anthropoid diphyly) or are evolved from ancestors that were already of an anthropoid level of structural organization (anthropoid monophyly) can only be resolved on biological grounds and at a level of analysis that allows one to distinguish between analogies developed in parallel, homologies caused by symplesiomorphy, and homologies caused by synapomorphy.

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Tertiary and Cretaceous paleoenvironments in the southwest Atlantic Ocean: Preliminary results of Deep Sea Drilling Project Leg 71

Cited by 23 publications

References 0 publications

Cenozoic Planktonic Foraminifers of the Falkland Plateau and Argentine Basin, Deep Sea Drilling Project Leg 71

Cenozoic Planktonic Foraminifers of the Falkland Plateau and Argentine Basin, Deep Sea Drilling Project Leg 71

Trace Element Geochemical History of Late Mesozoic Sedimentation in the Southwest Atlantic, Falkland Plateau, Site 511

Plate tectonics and the problem of anthropoid origins

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