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Petrogenesis of Late Triassic granitoids and their enclaves with implications for post-collisional lithospheric thinning of the Liaodong Peninsula, North China Craton
被引:221
|作者:
Yang, Jin-Hui
Wu, Fu-Yuan
Wilde, Simon A.
Liu, Xiao-Ming
机构:
[1] Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
[2] Curtin Univ Technol, Dept Appl Geol, Perth, WA 6845, Australia
[3] NW Univ Xian, State Key Continental Dynam, Xian 750069, Peoples R China
基金:
中国国家自然科学基金;
关键词:
Mafic microgranular enclaves;
granite;
Late Triassic;
lithospheric thinning;
North China Craton;
D O I:
10.1016/j.chemgeo.2007.03.007
中图分类号:
P3 [地球物理学];
P59 [地球化学];
学科分类号:
0708 ;
070902 ;
摘要:
Major and trace element, Sr-, Nd- and Hf-isotope, zircon U-Pb and Hf-isotope data are reported for mafic microgranular enclaves and host granitoids from the Xiuyan pluton in the Liaodong Peninsula of the eastern North China Craton, in order to investigate their sources, petrogenesis and tectonic implications. The zircon U-Pb age of the enclaves (211 I Ma) is identical to that of the host granite (210 +/- 1 Ma), establishing that the mafic and felsic magmas were coeval. The enclaves have high MgO concentrations at low silica contents and positive epsilon(Ht)(t) values. They are enriched in large ion lithophile and light rare earth elements and depleted in high field strength elements, which can be explained as melts derived from a depleted (asthenosphelic) mantle, with some crustal contamination. The host granitoids have high SiO2 contents, variable initial Sr-87/(86) Sr ratios and highly negative epsilon(Nd)(t) and epsilon(Hf) t) values, suggesting they were mainly derived from an ancient crustal source, heated by the input of asthenospheric mantle-derived magmas. Field observations, geochronology, geochemistry, Sr and Nd isotopic and zircon Hf isotopic compositions point to a complex petrogenesis, where asthenospheric mantle- and crust-derived magma mixing was coupled with crystal fractionation, thus explaining the genetic link between enclaves and host rocks. Identification of an asthenospheric mantle component in the Xiuyan granitoids suggests asthenospheric mantle upwelling and decompressional melting of the mantle, indicating that post-collisional lithospheric thinning in the Liaodong Peninsula was initiated in the Late Triassic. (C) 2007 Elsevier B.V. All rights reserved.
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页码:155 / 175
页数:21
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