【摘 要】
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The timing of the emplacement of the Weiya pluton remains controversial due to the absence of systematic and precise dating.This paper reports zircon SHRIMP U-P
【基金项目】
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This work was supported by the National Major Basic Research Program of China
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The timing of the emplacement of the Weiya pluton remains controversial due to the absence of systematic and precise dating.This paper reports zircon SHRIMP U-Pb dating of different lithologic phases in the Weiya pluton,and discusses the genesis and tectonic environment.The ages of gabbro,quartz syenite,diorite porphyrite and fine-grained granite are 236±6 Ma,246±6 Ma,233±8 Ma and 237±8 Ma,respectively.All these phases were formed in early-middle Indosinian (Triassic) in a post-orogenic environment.In addition to underplating,intraplating of mantle-derived magmas is also a substantial mechanism for magma generation and vertical accretion of the continental crust.Granitoid rocks are important products of vertical continental accretion as underplating evolves gradually to intraplating.The existence of post-orogenic Indosinian granites shows that the middle Tianshan orogenic belt underwent an important tectonic conversion from the Paleo-Asian ocean subduction-collision system to the Paleo-Tethys ocean regime.
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