塔里木南缘布雅花岗岩和暗色包体的锆石U-Pb年代学及地球化学特征  

Zircon U-Pb Dating,Petrology,Geochemistry of the Buya Pluton and Its MMEs in the Southern Margin of Tarim,Xinjiang

作　　者：胡雪原 郭瑞清 努尔喀纳提.马达依普 郭羽 邹明煜 吕彪 魏震 

机构地区：[1]新疆大学地质与矿业工程学院,新疆乌鲁木齐830047

出　　处：《岩矿测试》2017年第5期538-550,共13页Rock and Mineral Analysis

基　　金：中国地质调查局地质调查项目"中国主要陆块晚前寒武纪以来裂解重组过程的再造及其对成矿作用的制约"(1212011121064)专题"新疆塔里木南缘南华纪至三叠纪聚散过程研究"(212-61717)

摘　　要：塔里木西南缘铁克里克地区广泛发育早古生代中酸性侵入岩,本文对其中布雅岩体及其暗色包体进行系统的岩石学、年代学及岩石地球化学研究,确定了岩石成因及其构造属性。LA-MC-ICP-MS锆石U-Pb年代学研究表明,寄主石英二长闪长岩结晶年龄为432.6±2.5 Ma(MSWD=1.5),暗色包体结晶年龄为432.4±6.4 Ma(MSWD=0.031),二者形成时代相同,均为志留纪早期岩浆活动的产物。地球化学特征表明,布雅暗色包体应来源于地幔的部分熔融,而寄主岩石岩浆具有壳源岩浆的性质并经历了幔源岩浆不均匀的混合。野外及岩相学特征均显示暗色包体为铁镁质岩浆注入长英质岩浆快速冷凝形成的,是幔源岩浆底侵下地壳形成的岩浆混合作用的产物。它们是塔里木南缘早古生代碰撞造山作用晚期的岩浆记录。Paleozoic acidic intrusive rocks are widespread in the Tiekelike tectonic belt of the southern margin of Tarim.Petrography,whole-rock major and trace elements,and zircon U-Pb dating are reported for the Buya granodiorite and its mafic microgranular enclaves (MMEs),which are used to constrain their petrogenesis and tectonic setting.High-precision LA-MC-ICP-MS zircon U-Pb dating has revealed that the quartz monzobiorite was formed at 432.6 ± 2.5 Ma (MSWD = 1.5),and its microgranular enclaves were formed at 432.4 ± 6.4 Ma(MSWD = 0.031) indicating that both of them are the products of early Silurian magma activity.Chemical composition suggests that the enclaves were derived from partial melting of the mantle,while the magma of the host rocks is mainly crustal and is mixed with minor mantle-derived magma.Both the field and petrographic characteristics show that the dark enclaves were formed by the rapid condensation of the mafic magma into the felsic magma,which is the product of the magmatic mixing by the mantle underplating of the lower crust.They are magmatic records of the late stage of early Paleozoic collision orogeny in the southern margin of Tarim.

关 键 词：铁克里克 布雅岩体 LA-MC-ICP-MS锆石U-Pb年代学 岩浆混合 

分 类 号：P575.5[天文地球—矿物学]