Geochemical changes across the Ordovician-Silurian transition on the Yangtze Platform,South China
The trace element and rare earth element(REE) variations across the Ordovician-Silurian succession are presented from two outcrop sections on the Yangtze Platform:the Nanbazi section,Guizhou Province,deposited in a shallow platform interior setting,and the Wangjiawan section,Hubei Province,deposited...
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Published in | Science China. Earth sciences Vol. 52; no. 1; pp. 38 - 54 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Heidelberg
SP Science in China Press
2009
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
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Summary: | The trace element and rare earth element(REE) variations across the Ordovician-Silurian succession are presented from two outcrop sections on the Yangtze Platform:the Nanbazi section,Guizhou Province,deposited in a shallow platform interior setting,and the Wangjiawan section,Hubei Province,deposited in a deeper basinal environment.Geochemical analysis of closely spaced samples through three intervals,the Wufeng,Guanyinqiao and Longmaxi,revealed vast palaeoceanographic changes.Some geochemical proxies,including Th/U,Ni/Co,V/Cr,and V/(V+Ni) ratios,together with sedimentary facies and biotic data,indicate that an anoxic condition on the most of the Yangtze Platform during the Wufeng and Longmaxi intervals,but an oxic condition during the Guanyinqiao time.The shift of the anoxic to the oxic environment during the Guanyinqiao time coincided with a global sea-level lowstand,in parallel with the global glaciation.The Longmaxian anoxic environment was a result of a global sea-level rise,which may be synchronized with a mainly catastrophic event in the latest Ordovician.Although the two sections generally show similar variation patterns of trace and REE concentrations and some element ratios,a minor difference occurs between the Wangjiawan and Nanbazi sections,likely reflecting a difference in depositional setting during the accumulation.Such an oceanic oxygen-level variation may add a useful constraint to the current arguments on the cause and consequence of the latest Ordovician mass extinction. |
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Bibliography: | 11-5843/P YAN DeTian1,2,CHEN DaiZhao2,WANG QingChen2 & WANG JianGuo2 1 Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education,China University of Geosciences,Wuhan 430074,China;2 State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China |
ISSN: | 1674-7313 1006-9313 1869-1897 1862-2801 |
DOI: | 10.1007/s11430-008-0143-z |