Early Carboniferous extension regime in South Tianshan: Constraints from alluvial fan of Bashisuogong Formation in Sepabayi area in Xinjiang, China

The Bashisuogong Formation, exposed along the southern margin of the Chinese South Tianshan and north‐western edge of the Tarim Block, is divided into the lower member conglomerates and sandstones and upper member limestones. In the present contribution, four lithofacies types are recognized and fur...

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Published inGeological journal (Chichester, England) Vol. 55; no. 4; pp. 2902 - 2914
Main Authors Yu, Hao‐Cheng, Qiu, Kun‐Feng, Pang, Yao, Zhao, Zhi‐Gang, Sun, Zhi‐Jia, Wen, Yi‐Tong, Chen, Z.
Format Journal Article
LanguageEnglish
Published Liverpool Wiley Subscription Services, Inc 01.04.2020
Subjects
Alluvial deposits
alluvial fan
Alluvial fans
Bashisuogong Formation
Carboniferous
Conglomerates
Debris flow
Early Carboniferous
Graben
Lithofacies
Permian
Sandstone
Sedimentary facies
Sedimentary rocks
Sedimentation
Sepabayi
South Tianshan
Tarim
Tectonics
Volcanic activity
Volcanism
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Summary:The Bashisuogong Formation, exposed along the southern margin of the Chinese South Tianshan and north‐western edge of the Tarim Block, is divided into the lower member conglomerates and sandstones and upper member limestones. In the present contribution, four lithofacies types are recognized and further grouped into two distinct lithofacies sub‐associations based on sedimentary features of the alluvial fan of the Bashisuogong Formation in Sepabayi area. The debris flow products, with lenticular clast‐supported conglomerate, dominate the proximal fan. Couplets composed of conglomerate and sandstone represent the middle fan. The sedimentary features and palaeocurrent data indicate that clasts are sourced from the north‐east adjacent area. We propose that the Bashisuogong Formation, with an upward‐fining facies sequence pattern in this study, reveals an extensional regime during the Early Carboniferous. This fits within the context of synchronous volcanism and Bashisuogong Formation in north‐west Tarim. This tectonic setting resulted in the onset of the Carboniferous to Permian sedimentary cycle. The sedimentation centres were confined to Tuogemaiti‐Wushi band, where the alluvial fan was deposited. The Carboniferous transgressive succession controlled by the former graben shoulders thins progressively south‐eastward in north‐west Tarim.
ISSN:0072-1050
1099-1034
DOI:10.1002/gj.3558