Opening of an early Paleozoic limited oceanic basin in the northern Altyn area: Constraints from plagiogranites in the Hongliugou-Lapeiquan ophiolitic mélange  

作　　者：GAO XiaoFeng XIAO PeiXi GUO Lei DONG ZengChan XI RenGang 

机构地区：[1]Xi＇an Institute of Geology and Mineral Resources, Xi＇an 710054, China

出　　处：《Science China Earth Sciences》2011年第12期1871-1879,共9页中国科学（地球科学英文版）

基　　金：financially supported by the China Geological Survey (Grant No. 1212010911025);National Natural Science Foundation of China (Grant No. 41002020)

摘　　要：This paper reports petrological and geochemical features and zircon U-Pb age of plagiogranite from the Hongliugou-Lapeiquan ophiolitic melange belt in the northern Altyn Tagh. The zircon U-Pb dating results yield a mean ^238U/^206pb age of 512.1 ± 1.5 Ma, representing an emplacement time of the plagiogranites in the Middle Cambrian. The plagiogranites are interpreted to have derived from anatexis of hydrated amphibolites by ductile shearing during transports of the oceanic crust. Thus it is believed that the formation age of such type of plagiogranite was coeval to or slightly younger than the spreading of the Hongliugou-Lapeiquan limited oceanic basin. The new results from the plagiogranites suggest that an oceanic basin existed in the northern Altyn area during the Middle Cambrian.This paper reports petrological and geochemical features and zircon U-Pb age of plagiogranite from the Hongliugou-Lapeiquan ophiolitic mélange belt in the northern Altyn Tagh. The zircon U-Pb dating results yield a mean 238U/206Pb age of 512.1 - 1.5 Ma, representing an emplacement time of the plagiogranites in the Middle Cambrian. The plagiogranites are interpreted to have derived from anatexis of hydrated amphibolites by ductile shearing during transports of the oceanic crust. Thus it is believed that the formation age of such type of plagiogranite was coeval to or slightly younger than the spreading of the Hongliugou-Lapeiquan limited oceanic basin. The new results from the plagiogranites suggest that an oceanic basin existed in the northern Altyn area during the Middle Cambrian.

关 键 词：PLAGIOGRANITE limited oceanic basin early Paleozoic northern Altyn area 

分 类 号：P588.1[天文地球—岩石学] P544.4[天文地球—地质学]