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Geochemical Stratigraphy and Microvertebrate Assemblage Sequences across the Silurian/Devonian Transition in South China
Author(s) -
ZHAO Wenjin,
WANG Nianzhong,
ZHU Min,
MANN Ulrich,
HERTEN Ulrich,
LÜCKE Andreas
Publication year - 2011
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2011.00403.x
Subject(s) - devonian , geology , paleontology , conodont , global boundary stratotype section and point , stratotype , stratigraphy , paleozoic , biostratigraphy , fauna , stage (stratigraphy) , ecology , tectonics , biology
Carbon isotope (δ 13 C org ) analyses of non‐marine clastic rocks and neritic carbonates and black shales spanning the Silurian/Devonian transition are compared from two richly fossiliferous sequences in Qujing of East Yunnan and Zoige of Sichuan, South China. The two sections, Xishancun and Putonggou sections in South China, reveal positive δ 13 C org shifts happening in the Upper Pridoli and Lower Devonian and reaching peak values as heavy as –25.2%‰ (Xishancun) and –19.9%‰ (Putonggou) in the lowermost Lochkovian following the first occurrence of the thelodont Parathelodus and the conodont Icriodus woschmidti woschmidti (only in Putonggou Section and together with Protathyris‐Lanceomyonia brachiopod fauna). These results replicate a globally known positive shift in δ 13 C org from the uppermost Silurian to the lowermost Devonian. The δ 13 C org variations across the Silurian/Devonian Boundary (SDB) at the two sections in South China exhibit a shift in carbon isotopic composition similar to the detailed SDB curves from the borehole Klonk‐1 drilled at top of the Klonk Global Standard Stratotype‐Section and Point (GSSP) in the Prague Basin, Czech Republic. In addition, four microvertebrate assemblages, including the Liaojiaoshan, Xishancun, Yanglugou and Xiaputonggou assemblages, are recognized from the Silurian/Devonian transition exposed in the Xishancun and Putonggou sections, respectively. The results from both carbon isotope stratigraphy and microvertebrate assemblage sequences suggest that the SDB in South China is located at the base of the Xishancun Formation (between sample QX‐20 and sample QX‐21) in the Xishancun Section and the lower part of the Xiaputonggou Formation (between sample ZP‐09 and sample ZP‐10) in the Putonggou Section. The isotopic trend for organic carbon together with the changes of microvertebrate remains across the SDB can offer an approach to a potential correlation of the SDB from different sedimentary facies, which help to correlate the marine with non‐marine deposits.