辽宁抚顺—清原地区太古宙岩石SHRIMP锆石U-Pb年代学及其地质意义  

Zircon SHRIMP U-Pb Geochronology of Archaean Rocks from the Fushun— Qingyuan Area, Liaoning Province and Its Geological Significance

作　　者：万渝生[1,2] 宋彪[1,2] 杨淳[1] 刘敦一[1,2] 

机构地区：[1]中国地质科学院地质研究所 [2]北京离子探针中心,100037

出　　处：《地质学报》2005年第1期78-87,共10页Acta Geologica Sinica

基　　金：国土资源部重点项目 (编号 DKD2 0 0 10 2 0 -3 ;2 0 0 10 2 0 9和 DKD990 40 11)资助的成果

摘　　要：本文对辽宁抚顺、清原地区太古宙表壳岩系和 TTG花岗质岩石进行了 SHRIMP锆石 U- Pb年龄测定。角闪变粒岩 L Q0 10 7和 L F0 10 7岩浆锆石年龄分别为 2 5 15± 6 Ma和 2 5 10± 7Ma。角闪变粒岩 L Q0 10 4变质锆石年龄为 2 4 79± 5 Ma。深熔片麻状 TTG花岗岩 L F0 10 6内核残余锆石年龄为 2 5 2 8± 2 7Ma,大致代表了熔融母岩TTG花岗岩的形成时代 ,外带新生锆石年龄为 2 4 77± 13Ma,代表了深熔作用时代。片麻状 TTG花岗岩 L Q0 110内核残余锆石年龄 2 5 5 6± 18Ma,很可能为熔融母岩中酸性火山岩的形成时代 ,外带新生锆石年龄 2 4 6 9± 19Ma为深熔作用时代。研究表明 ,辽北地区太古宙基底主要由新太古宙岛弧系统火山物质组成 ,不存在以往认为的大范围分布的中太古代穹窿 ,但不排除存在少量新太古宙以前古老物质的可能。辽北新太古宙弧陆碰撞增生型造山带为华北克拉通太古宙晚期吉 (吉林 )—辽 (辽宁 )—冀 (河北 ) (弧陆碰撞增生型 )造山带的重要组成部分。洋壳俯冲时间为2 .5 1～ 2 .5 6 Ga,弧陆碰撞时间为 2 .4 7～ 2 .4 8Ga,总的演化时间约为 10 0 Ma左右。This paper focused on the zircon SHRIMP U-Pb geochronology of Archaean supracrustal rocks and TTG from the Fushun—Qingyuan area, Liaoning Province. Ages of magmatic zircons from hornblende fine-grained gneiss samples LQ0107 and LF0107 are 2510±7 Ma and 2515±6 Ma, respectively. Metamorphic zircon from hornblende fine-grained gneiss sample LQ0104 shows an age of 2479±5 Ma. Zircon core and rim from anatectic gneissic TTG granite (LF0106) record ages of 2528±27 Ma and 2477±13 Ma, which are explained as indicating the formation and anatectic ages of the TTG rock, respectively. 2556±18 Ma and 2469±19 Ma ages of zircon core and rim from gneissic TTG granite (LQ0110) are considered representing the formation and anatectic times of its protolith-volcanic rock. According to the new geochronological results obtained, some general conclusions are drawn as follows: (1) The Archaean basement of the Fushun—Qingyuan area is mainly made of Neoarchaean volcanic and TTG material, without a huge dome of Mesoarchaean, as previously thought. (2) It constitutes a typical arc-continent collision belt, a part of the huge Neoarchaean Jilin—Liaoning—Hebei orogeic belt in the North China Craton. (3) The tectonic evolution of the belt lasted about 100 Ma, from oceanic crust subduction in 2.51～2.56Ga to arc-continent collision in 2.47～2.48Ga.

关 键 词：锆石 太古宙 SHRIMP 深熔作用 形成时代 地质意义 年代学 熔融 LF 研究 

分 类 号：P597.3[天文地球—地球化学]