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	Petrogenesis and tectonic implications of Permian post-collisional granitoids in the Chinese southwestern Tianshan, NW China
	Xia, Bin ; Zhang, Lifei ; Zhang, Lu
	2016
关键词	Porphyritic granite Leucogranite Early-middle Permian Post-collision The Chinese SW Tianshan ASIAN OROGENIC BELT TI-IN-ZIRCON PLASMA-MASS SPECTROMETRY U-PB AGE WESTERN TIANSHAN SLAB BREAKOFF CONTINENTAL GROWTH METAMORPHIC BELT MUZHAERTE RIVER CALC-ALKALINE
英文摘要	Permian porphyritic granite and leucogranite from the Kekesu and Muzhaerte Valleys in the southwestern (SW) Tianshan orogenic belt, NW China have been studied to decipher their petrogenesis and tectonic implications. For porphyritic granite in the Kekesu Valley, in situ LA-ICPMS zircon U-Pb dating yields crystallization ages of 295-291 Ma. The granite is a high potassic calc-alkaline, slightly peraluminous type, enriched in large ion lithosphere elements (LILE) and light rare earth elements (LREE), but depleted in high field strength elements (HFSE). Zircon Hf isotopic analysis (zircon epsilon(Hf)(t) of -5.8 to -0.2, two-stage Hf model ages of 1323-1680 Ma) and Ti-in-zircon thermometry, which yields crystallization temperatures of 744-749 degrees C, indicate the parent magma was likely formed by partial melting of a Mesoproterozoic crustal source. By contrast, leucogranite in the Kekesu valley yields crystallization ages of 274-267 Ma. It contains muscovite and garnet, has high silicon and potassium, and is strongly peraluminous. Multiple inherited zircon cores and low zircon crystallization temperatures (687-701 degrees C), combined with negative zircon epsilon(Hf)(t) values (-7.0 to -4.0), indicate its parent magma was sourced from supracrustal metasedimentary rocks by muscovite-breakdown partial melting. In the Muzhaerte Valley, porphyritic granite has similar major and trace elements characteristics to the Kekesu porphyritic granite. However, its higher zircon epsilon(Hf)(t) values (-0.9 to +3.8) and corresponding lower two-stage Hf model ages (1070-1367 Ma) indicate that the parent magma likely included an input from a more juvenile mantle source. Ti-in-zircon thermometry gives lower crystallization temperature of similar to 705 degrees C. The intrusive relationships between the Permian granitoids and Paleozoic arc plutons, and the LP-HT and (U)HP metamorphic belts, combined with geochronological studies, suggest that these Permian granitoids were generated in a post-collisional environment. It is suggested that the formation of the porphyritic granites in the Kekesu and Muzhaerte Valleys could be related to slab breakoff, while the leucogranite could be formed by hydrate-breakdown melting in an extensional tectonic regime in response to intra-continental adjustments after collision. (C) 2016 Elsevier Ltd. All rights reserved.; CPCI-S(ISTP); ,SI; 60-74; 130
语种	英语
出处	Annual Convention of the International-Association-for-Gondwana-Research (IAGR) / 12th International Conference on Gondwana to Asia
DOI标识	10.1016/j.jseaes.2016.08.007
内容类型	其他
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/459421]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Xia, Bin,Zhang, Lifei,Zhang, Lu. Petrogenesis and tectonic implications of Permian post-collisional granitoids in the Chinese southwestern Tianshan, NW China. 2016-01-01.

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