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Recognition of a Permian to Triassic foreland basin in the central Beishan Orogen, NW China: Provenance variations and their constraints on latest Palaeozoic orogeny.

Authors :
Wang, Shengdong
Zhang, Kexin
Chen, Fenning
Wang, Jiaxuan
Song, Bowen
Li, Jianxing
Wang, Wen
Dai, Peng
Source :
Palaeogeography, Palaeoclimatology, Palaeoecology. Mar2021, Vol. 565, pN.PAG-N.PAG. 1p.
Publication Year :
2021

Abstract

The Beishan Orogen, located in the southernmost Central Asian Orogenic Belt, is a key area for research on accretionary orogens. The formation of the Beishan Orogen is closely related to the evolution of the Paleo-Asian Ocean, but the closure time of a significant branch of the Paleo-Asian Ocean in the Beishan area, i.e., the Hongliuhe–Niujuanzi–Xichangjing (HNX) Ocean, remains controversial. This study investigates the sedimentary sequences of Baihu Basin adjacent to the HNX suture zone and presents new detrital zircon U Pb geochronology and whole-rock geochemistry data to reveal depositional ages, provenance variations, paleogeography changes and attributes of Baihu Basin. Detrital zircon ages indicate that deposition began in the Permian and lasted until the Triassic. Two coarse sandstones in Member 1 and one siltstone in Member 2 contain abundant detrital zircons older than 700 Ma, in addition to the typical age peak that characterises the Gongpoquan Arc at ca. 450 Ma, while two sandstones in Member 3 contain rare detrital zircons older than 700 Ma. The whole-rock geochemistry shows that the lower part of the Hongyanjing Formation possesses numerous old components and higher chemical index of alteration values. The sediment in the lower part of the Hongyanjing Formation was derived from both the Gongpoquan Arc, mainly comprising Palaeozoic arc-related magmatic rocks, and the Shuangyingshan Arc, including large quantities of Precambrian meta-sedimentary rocks. The upper part originated solely from the juvenile Gongpoquan Arc. During the collision, the Shuangyingshan Arc played a role similar to a craton. Craton-derived source rocks and fining-upward sequences in the lower part indicate uplift of the Shuangyingshan Arc, which may represent the development of a forebulge and foredeep. In the upper part, the source rocks were derived from the Gongpoquan Arc and accretionary wedges, with coarsening-upward sequences reflecting the springback of the Shuangyingshan Arc and disappearance of the forebulge. Based on the sedimentary sequences, provenance variations, and paleogeographic changes, we suggest that Baihu Basin is a foreland basin associated with the collision between the Gongpoquan Arc and Shuangyingshan Arc, marking the final closure of the HNX Ocean from the Late Permian to Early Triassic. We investigate the closure of the HNX Ocean and reconstruct the evolution of the central Beishan Orogen in the youngest Palaeozoic. • Baihu Basin adjacent to the Niujuanzi suture zone is proved to be a foreland basin. • Baihu foreland basin began to form in the Permian and lasted until the Triassic. • In the early stage, sediments derived from two arcs and accretionary wedge. • In the late stage, the source areas were mainly the Gongpoquan Arc and wedge. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00310182
Volume :
565
Database :
Academic Search Index
Journal :
Palaeogeography, Palaeoclimatology, Palaeoecology
Publication Type :
Academic Journal
Accession number :
148566843
Full Text :
https://doi.org/10.1016/j.palaeo.2020.110168