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LA-ICP-MS zircon U-Pb chronology and Lu-Hf isotopic features of the Mihunzhen pluton in the South Qinling tectonic belt

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2014

Year

Min Yan

Unknown Venue

Abstract

Mihunzhen pluton,located in Jiangjiagou-Mogouxia-Xiaoling area of Shaanxi Province,emplaced into an older block within the eastern segment of South Qinling tectonic zone. This pluton consists chiefly of diorites,quartz diorites and granodiorites. Field geological relationships and LA-ICP-MS zircon U-Pb isotopic dating results indicate two magmatic emplacement stages of the pluton,namely,diorites at early stage with an age of 885 ± 4Ma,and quartz diorites-granodiorites at late stage with an age of ~ 737 ± 4Ma. In situ Lu-Hf isotopic analyses for the dated zircon reveal that the early dioritic magma was mainly derived from partial melting of the depleted mantle,and the late quartz dioritic-granodioritic magmas were from crystallization fractionation of the early dioritic magma, which suffered either contaminations of crustal materials or mixing with a crust-sourced magma.