北大别黄土岭长英质麻粒岩的原岩、变质作用及源区热事件年龄的锆石LA-ICPMS U-Pb测年约束  

LA-ICPMS U-Pb Zircon Dating for Felsic Granulite, Huangtuling Area, North Dabieshan: Constraints on Timing of Its Protolith and Granulite-Facies Metamorphism, and Thermal Events in Its Provenance

作　　者：陈能松[1] 刘嵘[1] 孙敏[2] 李惠民[3] 何蕾[1] 王勤燕[1] 张宏飞[4] 

机构地区：[1]中国地质大学地球科学学院,湖北武汉430074 [2]香港大学地球科学系 [3]天津地质矿产研究所,天津300170 [4]中国地质大学地质过程与矿产资源国家重点实验室,湖北武汉430074

出　　处：《地球科学（中国地质大学学报）》2006年第3期294-300,共7页Earth Science-Journal of China University of Geosciences

基　　金：高校博士点基金项目(No.98049114);国家自然科学基金项目(Nos.49972023;40202008);中国地质大学地质过程与矿产资源国家重点实验室自由基金项目(MGMR200229);香港大学杰出科研奖项目.

摘　　要：本研究应用激光剥蚀技术测定了北大别黄土岭高温-高压长英质麻粒岩锆石3个结构域的UPb年龄.变质锆石成因的碎屑锆石域的207Pb/206Pb年龄范围为(2493±54)Ma～(2500±180)Ma,岩浆成因的碎屑锆石域的207Pb/206Pb年龄范围为2628～2690Ma,其最大的206Pb/238U年龄为(2790±150)Ma,变质增生或变质重结晶锆石域的不一致线上交点年龄为(2044.7±29.3)Ma.长英质麻粒岩的矿物组合成分、主量元素地球化学,尤其是锆石副矿物内部结构特征显示其原岩为沉积岩.这表明,麻粒岩原岩物质来自具有复杂热历史的蚀源区,该蚀源区曾发生过～2.8Ga的岩浆作用和～2.5Ga变质作用,因此其原岩的沉积年龄不应早于2.5Ga.高温-高压麻粒岩相变质作用的精确年龄为(2.04±0.03)Ga,表明黄土岭麻粒岩是一个晚古元古代超高温变质岩之残块.LA-ICPMS U-Pb dating was conducted on three textural domains in zircon from a high-temperature high-pressure felsic granulite in the Huangtuling area, North Dabieshan, Central China. The metamorphic growth-derived detrital zircon domain yielded a ^207Pb/^206Pb Pb age in the range of （2 493±54）-（2 500±180）Ma. The magmatic genesis-derived detrital zircon domain gave a ^207Pb/^206Pb age ranging from 2 628 Ma to 2 690 Ma, with an oldest ^206Pb/^238U age of （2 790±150）Ma. The metamorphic overgrowth or metamorphic recrystallization zircon domain yielded a discordia with an upper intercept age of （2 044. 7±29. 3）Ma. Compositions of the mineral assemblage, major element geochemistry, and an especially complex interior texture of zircon suggest that the protolith of the felsie granulite is of sedimentary origin. The protolith material of the granulite came from a provenance with a complex thermal history, i.e. -2. 8 Ga magmatism and -2.5 Ga metamorphism,and deposited in a basin not earlier than 2. 5 Ga. The high-temperature and high-pressure granulite-facies metamorphic age was precisely constrained at （2. 04±0. 03）Ga, which indicates the granulite in Huangtuling area should be a relict of the Paleoproterozoic UHT metamorphosed slab.

关 键 词：激光锆石U-Pb年 原岩和麻粒岩相变质年龄 蚀源区 长英质麻粒岩 北大别. 

分 类 号：P597[天文地球—地球化学]