Facies Structure and Quantitative Parameters of Pleistocene Sedimentation on the Deep-Sea Floor of the Southern Pacific
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es Structure and Quantitative Parameters of Pleistocene Sedimentation on the Deep-Sea Floor of the Southern Pacific Ocean and in the Scotia Sea M. A. Levitana, *, T. N. Gelvia, and L. G. Domaratskayaa a
Vernadsky Institute of Geochemistry and Analytical Chemistry RAS, Moscow, 119991 Russia *e-mail: [email protected] Received January 15, 2020; revised January 28, 2020; accepted February 26, 2020
Abstract—Based on the data from long sediment cores retrieved by R/V Eltanin (United States) during the 1950s–1960s, Neo- and Eopleistocene lithofacies maps of the southern Pacific Ocean (scale 1 : 20000000) and Scotia Sea (scale 1 : 10000000) were compiled for the first time. For the Scotia Sea, schemes of isopachites are shown on the respective lithofacies maps. All maps are processed with the volumetric method proposed by A.B. Ronov. The results revealed that accumulation rates of the terrigenous and siliceous sediments increased during the Pleistocene in both sedimentation basins due to neotectonic activity in the Antarctic Peninsula, which enhanced fluxes of not only terrigenous matter but also nutrients delivered by melted waters to the photosynthesis zone via vertical circulation. Keywords: Pacific Ocean, Scotia Sea, bottom sediments, Neopleistocene, Eopleistocene DOI: 10.1134/S0024490220040045
INTRODUCTION The present paper continues the series of works dedicated to Pleistocene deposits in the World Ocean based on the volumetric method proposed by A.B. Ronov (1949) and the compilation of general lithofacies maps on scales 1 : 35000000, 1 : 20000000, or 1 : 10000000 (Levitan and Gel’vi, 2016; Levitan et al., 2013, 2014, 2018a; and others). Compilation of these maps is based on the deep-sea drilling data and, partly, long sediment cores retrieved during R/V cruises of different countries. As is known, DSDP sites are located irregularly over the World Ocean. In particular, drilling sites are scarce in several large regions of the Arctic Ocean, South Pacific, and SW Indian Ocean. Moreover, such sites are lacking at all in some seas, e.g., Okhotsk and Scotia. The present paper is based completely on materials pertaining to lithology and magnetic stratigraphy of long (up to 18 m) sediment cores retrieved by R/V Eltanin (United States) during several cruises in the South Ocean in the 1950s–1960s (Goodell and Watkins, 1968). The aim of our work was to study the facies structures and quantitative parameters of Pleistocene sedimentation on the deep-sea floor of the southern Pacific and in the Scotia Sea.
MATERIALS AND METHODS Location of long sediment cores retrieved in the southern Pacific and Scotia Sea during cruises of R/V Eltanin is shown in Figs. 1 and 2, correspondingly. Data on lithology of the recovered sections and their stratigraphic subdivision based on magnetostratigraphy are given in (Goodell and Watkins, 1968). We accepted the Pleistocene subdivision based on the old scale (Gradstein et al., 2004): Neopleistocene corresponds, in general, to the Brunhes magnetic chron (except Holocene), i.e., middle and late Pl
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