TY - JOUR
T1 - Carbon isotopic excursions and detailed ammonoid and conodont biostratigraphies around Smithian-Spathian boundary in the Bac Thuy Formation, Vietnam
AU - Komatsu, Toshifumi
AU - Takashima, Reishi
AU - Shigeta, Yasunari
AU - Maekawa, Takumi
AU - Tran, Huyen Dang
AU - Cong, Tien Dinh
AU - Sakata, Susumu
AU - Dinh, Hung Doan
AU - Takahashi, Osamu
N1 - Funding Information:
We thank Nguyen Duc Phong and Dinh Cong Tien (Vietnam Institute of Geosciences and Mineral Resources) for their cooperation in the field and laboratory. This study was financially supported by the JSPS-VAST Joint Research Program and Grant-in-Aids from the Japan Society for Promotion of Science ( 25400500 and 16K05593 to Komatsu).
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/7/15
Y1 - 2016/7/15
N2 - The Smithian-Spathian boundary is indicated by the first occurrence of the ammonoid Tirolites cf. cassianus in the Olenekian Bac Thuy Formation, northeastern Vietnam. The boundary is intercalated within organic-rich dark gray mudstone that accumulated under anoxic to dysoxic conditions in the An Chau and Nanpanjiang Basins on the South China Block. In Lang Son area, three conodont zones, Novispathodus ex gr. waageni, Novispathodus ex gr. pingdingshanensis, and Icriospathodus collinsoni, are recognized in the formation. The Smithian-Spathian boundary is intercalated within N. ex gr. pingdingshanensis conodont Zone. The positive excursion inδ13C with values increasing from around -2.3‰ to +5.7‰ was recorded in the uppermost Smithian Xenoceltites variocostatus ammonoid beds and N. ex gr. pingdingshanensis conodont Zone. The δ13C values decrease across the Smithian-Spathian boundary. These δ13C isotopic patterns are correlated with well-known positive excursions around the Smithian-Spathian boundary globally.
AB - The Smithian-Spathian boundary is indicated by the first occurrence of the ammonoid Tirolites cf. cassianus in the Olenekian Bac Thuy Formation, northeastern Vietnam. The boundary is intercalated within organic-rich dark gray mudstone that accumulated under anoxic to dysoxic conditions in the An Chau and Nanpanjiang Basins on the South China Block. In Lang Son area, three conodont zones, Novispathodus ex gr. waageni, Novispathodus ex gr. pingdingshanensis, and Icriospathodus collinsoni, are recognized in the formation. The Smithian-Spathian boundary is intercalated within N. ex gr. pingdingshanensis conodont Zone. The positive excursion inδ13C with values increasing from around -2.3‰ to +5.7‰ was recorded in the uppermost Smithian Xenoceltites variocostatus ammonoid beds and N. ex gr. pingdingshanensis conodont Zone. The δ13C values decrease across the Smithian-Spathian boundary. These δ13C isotopic patterns are correlated with well-known positive excursions around the Smithian-Spathian boundary globally.
KW - Ammonoid
KW - Anoxic to dysoxic facies
KW - Biostratigraphy
KW - Carbon isotopic excursion
KW - Conodont
KW - Lower Triassic
KW - Smithian-Spathian boundary
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U2 - 10.1016/j.palaeo.2016.04.017
DO - 10.1016/j.palaeo.2016.04.017
M3 - Article
AN - SCOPUS:84963957311
SN - 0031-0182
VL - 454
SP - 65
EP - 74
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
ER -