Metamorphic P-T paths and New Zircon U-Pb age data for garnet-mica   schist from the Wutai Group, North China Craton

doi:10.1016/j.precamres.2013.05.012

CORC > 北京大学 > 地球与空间科学学院

	Metamorphic P-T paths and New Zircon U-Pb age data for garnet-mica schist from the Wutai Group, North China Craton
	Qian, Jiahui ; Wei, Chunjing ; Zhou, Xiwen ; Zhang, Yinghui
刊名	precambrian research
	2013
关键词	Garnet-mica schist P-T path Zircon dating Wutai Group North China Craton PARTIAL MELTING EQUILIBRIA HIGH-PRESSURE GRANULITES LOWER CRUSTAL SECTION TECTONIC EVOLUTION HENGSHAN COMPLEX HUTUO-GROUP PALEOPROTEROZOIC EVOLUTION METASEDIMENTARY ROCKS DEFORMATION HISTORY MIXING PROPERTIES
DOI	10.1016/j.precamres.2013.05.012
英文摘要	The amalgamation of the North China Craton (NCC) is popularly viewed as a result of assembling between the Western and Eastern Blocks at similar to 1.85 Ga, forming the Trans-North China Orogen. Disputations still exist on the age and detailed tectonic processes involved in the assembling. Garnet-mica schist samples were collected from the lower part of Wutai Group in the central Trans-North China Orogen for determination of the metamorphic P-T path and age and for better understanding the tectonic evolution of the NCC. The garnet-mica schist generally contains mega-garnet porphyroblasts together with biotite, muscovite, quartz and ilmenite with or without plagioclase, epidote, ortho-amphibole, staurolite and lcyanite. Garnet is mostly weakly zoned with core-rim increasing pyrope and decreasing grossular, but occasionally exhibits pronounced zoning involving different patterns in the core and mantle, suggesting two-stage growth. Pseudosections were calculated using THERMOCALC for three representative samples. The modeling results, together with the petrographic observations suggest that the garnet-mica schist may have experienced four metamorphic stages. The first-stage (S-I), which is revealed only from the infrequent garnet core zoning, is characterized by a flat P-T vector dominated by heating, closing to the low-pressure facies series. The second-stage (S-II) exhibits a steep P-T vector with increasing pressure and temperature to the pressure peak at >9.0 kbar/615-645 degrees C, being the medium-pressure fades series (kyanite type). The third stage (S-III) is the decompression with heating to the temperature peak at similar to 7.5 kbar/660 degrees C. The fourth stage (S-IV) is the further decompression after the temperature peak, accompanied with considerable cooling. Metamorphic overgrowth rims of zircon and fully metamorphic crystals from two samples dated using SHRIMP and LA-ICP-MS methods yield new metamorphic ages of similar to 1.95 Ga, which were interpreted to represent the pre- or peak stages (i.e. S-II and S-III) of the kyanite type metamorphism for the dated zircon grains contain inclusions similar to the minerals in the host rocks and the REE patterns in zircon show metamorphic characteristics. This suggests that there would be a collision or crust thickening event coupled with the kyanite type metamorphism occurring at similar to 1.95 Ga, which is about 100 Ma older than the popularly viewed collision age (similar to 1.85 Ga). A probable interpretation is that there may be a long-lived orogenic process where the older metamorphic ages of similar to 1.95 Ga represent the main collision stage, and the younger ages of similar to 1.85 Ga indicate uplifting and cooling of high-grade terranes. The first stage (S-I) metamorphism of low-pressure facies series could be an indicator of crust extension before the collision event. (C) 2013 Elsevier B.V. All rights reserved.; http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000322348600017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701 ; Geosciences, Multidisciplinary; SCI(E); 45; ARTICLE; 282-296; 233
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/155607]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Qian, Jiahui,Wei, Chunjing,Zhou, Xiwen,et al. Metamorphic P-T paths and New Zircon U-Pb age data for garnet-mica schist from the Wutai Group, North China Craton[J]. precambrian research,2013.
APA	Qian, Jiahui,Wei, Chunjing,Zhou, Xiwen,&Zhang, Yinghui.(2013).Metamorphic P-T paths and New Zircon U-Pb age data for garnet-mica schist from the Wutai Group, North China Craton.precambrian research.
MLA	Qian, Jiahui,et al."Metamorphic P-T paths and New Zircon U-Pb age data for garnet-mica schist from the Wutai Group, North China Craton".precambrian research (2013).