TY - JOUR
T1 - Devonian-Carboniferous transition containing a Hangenberg Black Shale equivalent in the Pho Han Formation on Cat Ba Island, northeastern Vietnam
AU - Komatsu, Toshifumi
AU - Kato, Satoru
AU - Hirata, Kento
AU - Takashima, Reishi
AU - Ogata, Yukari
AU - Oba, Masahiro
AU - Naruse, Hajime
AU - Ta, Phuong H.
AU - Nguyen, Phong D.
AU - Dang, Huyen T.
AU - Doan, Truong N.
AU - Nguyen, Hung H.
AU - Sakata, Susumu
AU - Kaiho, Kunio
AU - Königshof, Peter
N1 - Funding Information:
We thank the staff of both the Vietnam Institute of Geosciences and Mineral Resources (VIGMR) and the Vietnam National Museum of Nature (VNMN) for their cooperation both in the field and in the laboratory. We gratefully thank Hisayoshi Igo (Institute of Natural History) for the useful comments about conodont taxonomy. Our special thanks go to anonymous referees. This study was supported by the JSPS-VAST Joint Research Program , Grants-in-Aid for Encouragement of Young Scientists (No. 20740300 ) from the Japanese Ministry of Education, Culture, Sports, Science, and Technology, and Grants-in-Aid for Scientific Research (No. 25400500 ) from the Japan Society for Promotion of Science. This paper is a contribution to IGCP 596 (Climate change and biodiversity patterns in the mid-Paleozoic).
PY - 2014/6/15
Y1 - 2014/6/15
N2 - On Cat Ba Island in northeastern Vietnam, the Devonian to Carboniferous (D-C) transition consists mainly of ramp carbonates intercalated with black shale beds (Beds 1 to 176) in the Pho Han Formation and is one of the few records of the D-C transition of the eastern Paleotethys. The three main facies of the sequence are Facies 1 (alternations of whitish gray to gray limestone and marl), Facies 2 (calcirudite, Bed 115b), and Facies 3 (alternations of dark gray limestone and organic-carbon-rich black shale, Beds 115c-120 and 126-129). The latest Famennian (Siphonodella praesulcata Subzone) conodont assemblage of S. praesulcata, Palmatolepis gracilis, Palmatolepis sigmoidalis, and Rhodalepis polylophodontiformis was recognized in Beds 113-115c. Beds 105-112 commonly contain Palmatolepis expansa, P. gracilis, and P. sigmoidalis. Bed 119 yielded a basal Carboniferous index conodont Siphonodella sulcata. In Beds 116-118, solenoporids such as Pseudochaetetes elliotti and Parachaetetes sp. were characteristic species in organic-carbon-rich dark gray limestone. Facies 1 is characterized by bioclastic, peloidal, and intraclastic grainstone and packstone containing massive normal grading and cross-laminations, and is interpreted to represent deep ramp carbonates above storm wave base. Facies 2 is represented by typical lag deposits overlying a transgressive surface. Facies 3 comprises organic-carbon-rich black shale and minor scour-filling bioclastic, peloidal, and intraclastic packstone, and may represent a marginal basin plain environment surrounding a carbonate ramp. The alternations of organic-carbon-rich black shale and dark gray packstone (Facies 3) show no evidence of bioturbation and have high TOC contents (0.18-5.73. wt.%). A minor succession within the transgressive lag deposits (from Bed 115b of Facies 2 to Beds 115c-120 in the lower part of Facies 3) is equivalent to the Hangenberg Black Shale (s. l.) in the middle part of the Siphonodella praesulcata to Siphonodella sulcata zones, because Beds 115b-120 characterized by no evidence of bioturbation and high TOC contents are interpreted to be accumulated in anoxic to dysoxic conditions. We report Devonian-Carboniferous transitions in the Pho Han Fm., Vietnam.P. expansa, S. praesulcata, S. sulcata and S. duplicata zones are recognized. The D-C transition is composed of deep ramp and marginal basin plain deposits. The D-C transition is characterized by a typical transgressive succession. The section intercalates anoxic to dysoxic facies dominated by organic-rich deposits.
AB - On Cat Ba Island in northeastern Vietnam, the Devonian to Carboniferous (D-C) transition consists mainly of ramp carbonates intercalated with black shale beds (Beds 1 to 176) in the Pho Han Formation and is one of the few records of the D-C transition of the eastern Paleotethys. The three main facies of the sequence are Facies 1 (alternations of whitish gray to gray limestone and marl), Facies 2 (calcirudite, Bed 115b), and Facies 3 (alternations of dark gray limestone and organic-carbon-rich black shale, Beds 115c-120 and 126-129). The latest Famennian (Siphonodella praesulcata Subzone) conodont assemblage of S. praesulcata, Palmatolepis gracilis, Palmatolepis sigmoidalis, and Rhodalepis polylophodontiformis was recognized in Beds 113-115c. Beds 105-112 commonly contain Palmatolepis expansa, P. gracilis, and P. sigmoidalis. Bed 119 yielded a basal Carboniferous index conodont Siphonodella sulcata. In Beds 116-118, solenoporids such as Pseudochaetetes elliotti and Parachaetetes sp. were characteristic species in organic-carbon-rich dark gray limestone. Facies 1 is characterized by bioclastic, peloidal, and intraclastic grainstone and packstone containing massive normal grading and cross-laminations, and is interpreted to represent deep ramp carbonates above storm wave base. Facies 2 is represented by typical lag deposits overlying a transgressive surface. Facies 3 comprises organic-carbon-rich black shale and minor scour-filling bioclastic, peloidal, and intraclastic packstone, and may represent a marginal basin plain environment surrounding a carbonate ramp. The alternations of organic-carbon-rich black shale and dark gray packstone (Facies 3) show no evidence of bioturbation and have high TOC contents (0.18-5.73. wt.%). A minor succession within the transgressive lag deposits (from Bed 115b of Facies 2 to Beds 115c-120 in the lower part of Facies 3) is equivalent to the Hangenberg Black Shale (s. l.) in the middle part of the Siphonodella praesulcata to Siphonodella sulcata zones, because Beds 115b-120 characterized by no evidence of bioturbation and high TOC contents are interpreted to be accumulated in anoxic to dysoxic conditions. We report Devonian-Carboniferous transitions in the Pho Han Fm., Vietnam.P. expansa, S. praesulcata, S. sulcata and S. duplicata zones are recognized. The D-C transition is composed of deep ramp and marginal basin plain deposits. The D-C transition is characterized by a typical transgressive succession. The section intercalates anoxic to dysoxic facies dominated by organic-rich deposits.
KW - Anoxic to dysoxic facies
KW - Devonian-Carboniferous boundary
KW - Extinction
KW - Hangenberg Black Shale
KW - Recovery
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U2 - 10.1016/j.palaeo.2014.03.021
DO - 10.1016/j.palaeo.2014.03.021
M3 - Article
AN - SCOPUS:84940280140
VL - 404
SP - 30
EP - 43
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
SN - 0031-0182
ER -