Geochemical and Nd isotopic variations in sediments of the South China Sea; a response to Cenozoic tectonism in SE Asia

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doi: 10.1016/S0012-821X(03)00229-2
Author(s): Li Xianhua; Wei Gangjian; Shao Lei; Liu Ying; Liang Xirong; Jian Zhimin; Sun Min; Wang Pinxian
Author Affiliation(s): Primary:
Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, Guangzhou, China
Tongji University, China
University of Hong Kong, China
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 211(3-4), p.207-220. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 56 refs.; illus., incl. 2 tables, sketch maps
Summary: Secular variations in geochemistry and Nd isotopic data have been documented in sediment samples at ODP Site 1148 in the South China Sea. Major and trace elements show significant changes at ca. 29.5 Ma and 26-23 Ma, whereas εNd values show a single change at ca. 26-23 Ma. Increases in Al/Ti, Al/K, Rb/Sr, and La/Lu ratios and a decrease in the Th/La ratio of the sediments beginning at 29.5 Ma are consistent with more intense chemical weathering in the source region. The abrupt change in Nd isotopes and geochemistry at ca. 26-23 Ma coincides with a major discontinuity in the sedimentology and physical properties of the sediments, implying a drastic change in sedimentary provenance and environment at the drill site. Comparison of the Nd isotopes of sediments from major rivers flowing into the South China Sea suggests that pre-27 Ma sediments were dominantly derived from a southwestern provenance (Indochina-Sunda Shelf and possibly northwestern Borneo), whereas post-23 Ma sediments were derived from a northern provenance (South China). This change in provenance from southwest to north was largely caused by ridge jumping during seafloor spreading of the South China Sea, associated with a southwestward expansion of the ocean basin crust and a global rise in sea level. Thus, the geochemical and Nd isotopic changes in the sediments at ODP Site 1148 are interpreted as a response to a major plate reorganization in SE Asia at ca. 25 Ma. Abstract Copyright (2003) Elsevier, B.V.
Year of Publication: 2003
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Asia; Biostratigraphy; Cenozoic; Chemical ratios; Ferromanganese crusts; Foraminifera; Geochemistry; Invertebrata; Isotope ratios; Isotopes; Leg 184; Major elements; Marine sediments; Metals; Microfossils; Nd-144/Nd-143; Neodymium; North Pacific; Northwest Pacific; ODP Site 1148; Ocean Drilling Program; Pacific Ocean; Physical properties; Planktonic taxa; Plate tectonics; Protista; Provenance; Rare earths; Secular variations; Sedimentation rates; Sediments; South China Sea; Southeast Asia; Stable isotopes; Tectonics; Trace elements; Weathering; West Pacific
Coordinates: N185010 N185010 E1163356 E1163356
Record ID: 2003053534
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands