Sedimentary geochemistry of chert from the Middle-Upper Ordovician in Shihuigou area, North Qilian orogenic belt and its tectonic implication |
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Authors: | Du Yuansheng Zhu Jie and Gu Songzhu |
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Institution: | (1) Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, China |
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Abstract: | The North Qilian orogenic belt is an elongate tectonic unit that lies between the North China plate to the north and the Middle
Qilian microplate to the south, and is formed by a collision of the two plates in the Caledonian. The Shihuigou Section from
Yongdeng County, Gansu Province, is in the eastern sector of the North Qilian Mountains, spanning the Ordovician island-arc
zones. The Zhongpu Group is distributed in the Shihuigou area and composed of medium-basic volcanic rocks and volcanic clastic
rocks interspersed with cherts, limestones, slates, and metamorphic sandstones. The geochemistry of chert from the Zhongpu
Group reveals that all cherts coexisting with island-arc volcanic rocks formed in a continental margin basin environment.
Research results of the rare earth elements reveal that these cherts formed in a relatively deep-water basin with no significant
terrestrial interference. Therefore, it is inferred that the North Qilian orogenic belt was previously an archipelagic ocean
in the Ordovician.
Translated from Geological Review, 2006, 52(2): 184–189 译自: 地质论评] |
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Keywords: | North Qilian orogenic belt Ordovician chert sedimentary geochemistry tectonics |
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