Northward subduction of the South Qilian ocean: Insights from early Paleozoic magmatism in the South-Central Qilian belts

Yilong Li; Wenjiao Xiao; Jianping Zheng; F.M. Brouwer

doi:10.1016/j.geogeo.2021.100013

Northward subduction of the South Qilian ocean: Insights from early Paleozoic magmatism in the South-Central Qilian belts

Yilong Li, Wenjiao Xiao, Jianping Zheng, F.M. Brouwer

Geology and Geochemistry

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

The Qilian orogen consists of the North Qilian belt, the Central Qilian block and the South Qilian belt and is regarded as part of the northern margin of the Proto-Tethys Ocean. The tectonic mechanism re- sponsible for the early Paleozoic magma generation in the Qilian orogen is crucial to understanding the ocean-continent configurations and the closure of the Proto-Tethys Ocean. This paper compiles the early Paleozoic mafic and granitic intrusions in the South Qilian belt and the Central Qilian block, to constrain the subduction and accretion of the South Qilian ocean. The early Paleozoic mafic intrusions in the Cen- tral Qilian block indicate that the influence of slab-derived fluids dominates their petrogenesis, while the mafic intrusions in the South Qilian belt were mostly affected by involvement of significant sediment- derived melts in their formation. They are supportive of a mélange model, in which melting of mélange diapirs originating at the slab-mantle interface generates fluid-metasomatised magma source in the deep mantle under the Central Qilian block and sediment-derived melts-metasomatised magma source un- der the Hualong block in the South Qilian belt, consistent with northward subduction of the South Qilian ocean. It is proposed that northward intra-oceanic subduction of the South Qilian Ocean occurred at 530–470 Ma in front of the Hualong block and continued at 470–446 Ma but was then accompanied by the development of a mature volcanic arc. Continuous subduction resulted in accretion of the Hualong block northwards onto the Central Qilian block, and this collision started at ca. 446 Ma and lasted to ca. 420 Ma. The final closure of the South Qilian ocean was marked by the onset of continental collision between the Qaidam-Quanji block and the amalgamated Hualong-Central Qilian block at ca. 440 Ma, and also the cause of the A-type granitoids after final collision occurred at ca. 420 Ma.

Original language	English
Article number	100013
Pages (from-to)	1-10
Number of pages	10
Journal	Geosystems and Geoenvironment
Volume	1
Issue number	1
Early online date	6 Nov 2021
DOIs	https://doi.org/10.1016/j.geogeo.2021.100013
Publication status	Published - Feb 2022

Funding

The authors are indebted to graduate students Guikai Cui and Fei Wu of the School of Earth Sciences, China University of Geosciences (Wuhan) for help during field work and sample preparation. This study was funded by grants from the National Natural Science Foundation of China (41872063, 41930215, 41520104003, 41802092, and 41888101), and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (CAS) (XDB18020203). This is a contribution to IGCP 662. We are grateful for careful reviews by Dr. Shengyao Yu and an anonymous reviewer, as well as supportive editorial handling by Prof. Sanzhong Li, which greatly helped us improve the paper. The authors are indebted to graduate students Guikai Cui and Fei Wu of the School of Earth Sciences, China University of Geosciences (Wuhan) for help during field work and sample preparation. This study was funded by grants from the National Natural Science Foundation of China ( 41872063, 41930215, 41520104003, 41802092, and 41888101 ), and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (CAS) ( XDB18020203 ). This is a contribution to IGCP 662. We are grateful for careful reviews by Dr. Shengyao Yu and an anonymous reviewer, as well as supportive editorial handling by Prof. Sanzhong Li, which greatly helped us improve the paper.

Funders	Funder number
School of Earth Sciences, Ohio State University
National Natural Science Foundation of China	41802092, 41520104003, 41888101, 41930215, 41872063
Chinese Academy of Sciences	XDB18020203
China University of Geosciences, Wuhan

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title = "Northward subduction of the South Qilian ocean: Insights from early Paleozoic magmatism in the South-Central Qilian belts",

abstract = "The Qilian orogen consists of the North Qilian belt, the Central Qilian block and the South Qilian belt and is regarded as part of the northern margin of the Proto-Tethys Ocean. The tectonic mechanism re- sponsible for the early Paleozoic magma generation in the Qilian orogen is crucial to understanding the ocean-continent configurations and the closure of the Proto-Tethys Ocean. This paper compiles the early Paleozoic mafic and granitic intrusions in the South Qilian belt and the Central Qilian block, to constrain the subduction and accretion of the South Qilian ocean. The early Paleozoic mafic intrusions in the Cen- tral Qilian block indicate that the influence of slab-derived fluids dominates their petrogenesis, while the mafic intrusions in the South Qilian belt were mostly affected by involvement of significant sediment- derived melts in their formation. They are supportive of a m{\'e}lange model, in which melting of m{\'e}lange diapirs originating at the slab-mantle interface generates fluid-metasomatised magma source in the deep mantle under the Central Qilian block and sediment-derived melts-metasomatised magma source un- der the Hualong block in the South Qilian belt, consistent with northward subduction of the South Qilian ocean. It is proposed that northward intra-oceanic subduction of the South Qilian Ocean occurred at 530–470 Ma in front of the Hualong block and continued at 470–446 Ma but was then accompanied by the development of a mature volcanic arc. Continuous subduction resulted in accretion of the Hualong block northwards onto the Central Qilian block, and this collision started at ca. 446 Ma and lasted to ca. 420 Ma. The final closure of the South Qilian ocean was marked by the onset of continental collision between the Qaidam-Quanji block and the amalgamated Hualong-Central Qilian block at ca. 440 Ma, and also the cause of the A-type granitoids after final collision occurred at ca. 420 Ma.",

author = "Yilong Li and Wenjiao Xiao and Jianping Zheng and F.M. Brouwer",

year = "2022",

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doi = "10.1016/j.geogeo.2021.100013",

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AU - Brouwer, F.M.

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AB - The Qilian orogen consists of the North Qilian belt, the Central Qilian block and the South Qilian belt and is regarded as part of the northern margin of the Proto-Tethys Ocean. The tectonic mechanism re- sponsible for the early Paleozoic magma generation in the Qilian orogen is crucial to understanding the ocean-continent configurations and the closure of the Proto-Tethys Ocean. This paper compiles the early Paleozoic mafic and granitic intrusions in the South Qilian belt and the Central Qilian block, to constrain the subduction and accretion of the South Qilian ocean. The early Paleozoic mafic intrusions in the Cen- tral Qilian block indicate that the influence of slab-derived fluids dominates their petrogenesis, while the mafic intrusions in the South Qilian belt were mostly affected by involvement of significant sediment- derived melts in their formation. They are supportive of a mélange model, in which melting of mélange diapirs originating at the slab-mantle interface generates fluid-metasomatised magma source in the deep mantle under the Central Qilian block and sediment-derived melts-metasomatised magma source un- der the Hualong block in the South Qilian belt, consistent with northward subduction of the South Qilian ocean. It is proposed that northward intra-oceanic subduction of the South Qilian Ocean occurred at 530–470 Ma in front of the Hualong block and continued at 470–446 Ma but was then accompanied by the development of a mature volcanic arc. Continuous subduction resulted in accretion of the Hualong block northwards onto the Central Qilian block, and this collision started at ca. 446 Ma and lasted to ca. 420 Ma. The final closure of the South Qilian ocean was marked by the onset of continental collision between the Qaidam-Quanji block and the amalgamated Hualong-Central Qilian block at ca. 440 Ma, and also the cause of the A-type granitoids after final collision occurred at ca. 420 Ma.

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DO - 10.1016/j.geogeo.2021.100013

M3 - Article

SN - 2772-8838

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JO - Geosystems and Geoenvironment

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ER -

Northward subduction of the South Qilian ocean: Insights from early Paleozoic magmatism in the South-Central Qilian belts

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