Detrital zircon provenance constraints on the final closure of the middle segment of the Paleo-Asian Ocean

Liu, Q., Zhao, G., Han, Y., Zhu, Y., Wang, B., Eizenhoefer, P. R. and Zhang, X. (2019) Detrital zircon provenance constraints on the final closure of the middle segment of the Paleo-Asian Ocean. Gondwana Research, 69, pp. 73-88. (doi: 10.1016/j.gr.2019.01.001)

Abstract

The main site and timing of the final closure of the middle segment of the Paleo-Asian Ocean (PAO) has been an issue of hot debate, which hampers us from better understanding the late-stage tectonic evolution of the Central Asian Orogenic Belt (CAOB). Synthesizing the available geological records for the ophiolitic mélanges in the Beishan Orogenic Belt (BOB), we regard the Liuyuan ophiolitic mélange as the main site of the final closure of the middle segment of the PAO. To determine the final closure time of the middle segment of the PAO, this study mainly applied field-based, systematic zircon U-Pb-Hf isotopic analyses for the Carboniferous and Permian sedimentary successions on the northern and southern sides of the Liuyuan ophiolitic mélange. Our results indicate that the late Carboniferous sedimentary successions north of the Liuyuan mélange consisting mainly of interbedded sandstone and siltstone with minor conglomerate show primarily affinity with a local, single source, i.e. the constituent units of the BOB north of the Liuyuan mélange. They were closely associated with the northward subduction of the middle segment of the PAO. By contrast, the unconformably overlying Permian clastic deposition on both sides of the Liuyuan ophiolitic mélange shows comparable lithology that fines from a thick sequence of conglomerate at the base to thin-bedded turbidite sequences up section. These Permian units were probably deposited in a progressively deepening basin within an extensional post-collision regime after the disappearance of the middle segment of the PAO. All the <274–261 Ma sandstones on both sides of the Liuyuan ophiolitic mélange were derived from commingling source regions on both sides of the Liuyuan mélange, as supported by comparable, diagnostic ages and εHf(t) values between the studied detrital zircons and coeval magmatic zircons from the BOB and north Tarim. Such a marked transition from a single, local provenance in the late Carboniferous to commingling provenances at ca. 274–261 Ma indicates the final closure of the middle segment of the PAO prior to the end of the early Permian. In conjunction with available data for the eastern and western segments of the PAO, we establish the eastward-younging, scissor-like closure for the whole PAO during mid Carboniferous to Early Triassic time.

• Item Type: Articles
• Additional Information: This study was financially supported by the National Natural Science Foundation of China (NSFC) Project (41190075) entitled, “Final Closure of the Paleo-Asian ocean and Reconstruction of East Asian Blocks in Pangea,” which is the fifth research project in the NSFC Major Program (41190070), “Reconstruction of East Asian Blocks in Pangea,” Hong Kong Research Grants Council (RGC) General Research Fund (GRF) (grants HKU7063/13P and 17301915), NSFC General Projects (41230207 and 41390441), and the University of Hong Kong (HKU) Seed Funding Programmes for Basic Research (grant 201311159126 and 201611159210).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Eizenhoefer, Dr Paul
• Authors: Liu, Q., Zhao, G., Han, Y., Zhu, Y., Wang, B., Eizenhoefer, P. R., and Zhang, X.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Gondwana Research
• Publisher: Elsevier
• ISSN: 1342-937X
• ISSN (Online): 1878-0571
• Published Online: 16 January 2019