Tracing magma mixing in granite genesis:in situ U-Pb dating and Hf-isotope analysis of zircons
作者单位：Department of Applied Geology Curtin University of TechnologyP.O.Box U1987PerthWA 6845Australia
会议名称：《中国科学院地质与地球物理研究所2007学术年会》
会议日期：2008年
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
摘 要：In situ zircon U-Pb and Hf-isotopic data have been determined for mafic microgranular enclaves and host granitoids from the Early Cretaceous Gudaoling batholith in the Liaodong Peninsula,NE China,in order to constrain the sources and petrogenesis of *** zircon U-Pb age of the enclaves(120±1 Ma) is identical to that of the host monzogranite (120±1 Ma),establishing that the mafic and felsic magmas were *** Hf isotopic composition of the enclaves[ε(t) = +4.5 to -6.2]is distinct from the host monzogranite[ε(t)=-15.1 to -25.4],indicating that both depleted mantle and crustal sources contributed to their *** depleted mantle component was not previously revealed by geochemical and Nd and Sr isotopic studies,showing that zircon Hf isotopic data can be a powerful geochemical tracer with the potential to provide unique petrogenetic *** wallrock contamination is indicated by inherited zircons with considerably older U-Pb ages and low initial Hf isotopic *** isotopic variations in Early Cretaceous zircons rule-out simple crystal-liquid fractionation or restite unmixing as the major genetic link between enclaves and host ***,mixing of mantle-derived mafic magmas with crustal-derived felsic magmas,coupled with assimilation of wall rocks,is compatible with the data.