Microfacies of Some Sediments from the Western North Atlantic: Paleoceanographic Implications (Leg 44 DSDP)

Abstract

We charactenzed the microfacies of sediments encountered dunng Leg 44 on the basis of coarse fraction mineralogy (&> 125 pm), silt mineralogy (63>1#~>20 pm), clay mineralogy (&<2 pm), silt and clay particle size distributions. and calcium carbonate contents. Secondly we attempted to tentatively correlate microfacies changes with major oceanographic events which have affected the sedimentary processes along the continental margin of North America. Because part of the stratigraphic column was not recovered (no Pliocene and Oligocene, and reduced Pleistocene and Barremian sections), and because of the fairly large sampling intervals our results are far from complete and exhaustive. Some important results, however. concerning the evolution of the oceans since Barremian time were obtained. -.

Clay Mineralogical and Inorganic Geochemical Stratigraphy of Blake-Bahama Basin since the Callovian, Site 534, Deep Sea Drilling Project Leg 76

“…Determinations were made of the detailed lithology and composition of sedimentary components. Interpretation of the Quaternary was based on previous data from Site 391 (Pastouret et al, 1978). Our results and interpretations based on clay mineralogy and inorganic geochemistry are discussed.…”

“…Hole 534A-lithology, sampling, clay mineralogy (with reference to Site 391 for the Quaternary; cf., Pastouret et al, 1978).…”

Contourite facies of the Faro Drift, Gulf of Cadiz

“…We are not yet, therefore, sufficiently confident to unambiguously identify contourites in ancient rock sequences, nor to use facies variability as an accurate indicator of the development and fluctuation of palaeo-bottom currents, although several interesting attempts have been made in these fields (e.g. Pastouret et al 1978;Auffret et al 1981;Lovell & Stow 1981).…”

Clay Mineralogy of Cretaceous and Cenozoic Sediments off the Moroccan Margin, Deep Sea Drilling Project Sites 415 and 416

“…Such changes do not exist. For example, the abundance of primary minerals does not increase off the Iberian peninsula, in the uppermost Jurassic to lowermost Cretaceous sediments of Site 398, or at most DSDP sites drilled at (Cretaceous) latitudes comparable to that of Site 416 on the western North Atlantic (i.e., those drilled during Legs 11 and 44; Zemmels et al, 1972;Chamley, unpublished;Pastouret et al, 1978). Thus the event which caused the marked mineralogical peculiarities of Site 416 must have been relatively restricted.…”

“…The same mineral is dominant in the clay fraction of the middle to Upper Cretaceous sediments drilled on outcrops on the northeast Atlantic margin (i.e., Aubry and Pomerol, 1975;Estéoule-Choux and Louail, 1976) and on the northwest Atlantic margin (i.e., Zemmels, et al, 1972;Pastouret et al, 1978). Smectite also prevails in Paleogene sediments which were poorly sampled during Leg 50, but are well represented in cores from other DSDP sites on the African margin (i.e., Berger and von Rad, 1972;Mélières, 1978).…”