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Biostratigraphic and Chemostratigraphic Correlation for the Base of the Middle Ordovician between Yichang and Western Zhejiang Areas, South China
Author(s) -
ZHANG Yuandong,
MUNNECKE Axel,
CHEN Xu,
CHENG Junfeng,
LIU Xiao
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.1755-6724.2011.00401.x
Subject(s) - conodont , global boundary stratotype section and point , biostratigraphy , chemostratigraphy , paleontology , geology , ordovician , stratotype , facies , section (typography) , stage (stratigraphy) , isotopes of carbon , advertising , business , isotope , physics , quantum mechanics , structural basin
The base of the Middle Ordovician (i.e. Dapingian Stage) has been defined at the first appearance datum (FAD) of conodont Baltoniodus ? triangularis at Huanghuachang, Yichang, China, but the precise correlation of the boundary to regions of other facies remain to be resolved. Herein we review the biostratigraphy and chemostratigraphy of the Huanghuachang Global Standard Stratotype‐Section and Point (GSSP) section, and present our latest stratigraphic work on the nearby Chenjiahe section in Yichang, and the Hengtang Quarry section, Jiangshan, Zhejiang, which is regarded as representative of slope facies. The conodont and graptolite biostratigraphy as well as chemostratigraphy of the Chenjiahe section indicate that the base of the Middle Ordovician also falls within the graptolite Azygograptus suecicus Zone, and coincides with a high or maximum δ 13 C value within a minor positive carbon isotope excursion, suggesting that the base boundary can be readily recognized across the entire Yangtze Gorges area. The integrated graptolite and conodont biostratigraphy and chemostratigraphy of the Hengtang section, Jiangshan, indicates that the basal boundary probably falls within the graptolite Isograptus caduceus imitatus Zone that overlies the Azygograptus suecicus Zone, and coincides with a remarkable drop of δ 13 C. This difference indicates that a multi‐disciplinary approach is critical to identify the base boundary in those regions where the Baltoniodus ? triangularis is absent