朝鲜狼林地块东南缘太古宙岩石及其对古元古代构造热事件的响应  

Archean rocks at the southeastern margin of the Rangnim massif,northern Korean Peninsula,and their response to Paleoproterozoic tectonothermal event

作　　者：赵磊[1] 张艳斌[1] 杨正赫 韩龙渊 金正男[2] 

机构地区：[1]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029 [2]朝鲜国家科学院地质研究所,平壤381210

出　　处：《岩石学报》2016年第10期2948-2964,共17页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41530208、41502182);重大国际合作项目(41210003)联合资助

摘　　要：朝鲜狼林地体是中朝克拉通的重要组成部分,其早前寒武纪基底岩系的岩石组成、形成和变质作用时代,直接影响到人们对古元古代辽吉活动带乃至整个华北克拉通地质演化历史的理解和认识。本文选取位于狼林地块东南缘,狼林群变质杂岩中的3个花岗片麻岩样品进行锆石U-Pb定年分析。锆石的LA-ICPMS和SIMS定年结果显示,3个片麻岩原岩的岩浆结晶时代为2521～2567Ma,并且它们都经历了古元古代1.87～1.89Ga的构造热事件改造,表现为原始岩浆锆石不同程度的铅丢失以及变质锆石的形成。基于这一认识,并结合其他学者的最新研究结果可知,太古宙片麻岩存在于狼林地块平南盆地的南缘和东缘地区,由此推测狼林地块太古宙基底岩系的规模可能远大于目前所识别的这几个地区。这些太古宙片麻岩普遍遭受了古元古代强烈变质作用（深熔作用）改造,并且变质作用的时代可以与华北克拉通三条古元古代活动带的变质-深熔作用时代相对比,表明狼林地块可能至少在古元古代之前,就已经与华北克拉通组成了统一的大陆。Rangnim Massif in North Korea is an important constituent part of the Sino-Korea Craton and the study of its rock assemblages, geochronology and metamorphic and deformation features will greatly influence the thorough interpretation and understanding of the geological evolution of the North China Craton and the whole northeastern Asia continent.In this study,we present the U-Pb dating and trace element analysis results of zircons from three granitoid gneisses from the Rangnim Complex, at the southeastern margin of the Rangnim Massif.Three gneissic samples give protolith magmatic ages of 2521 ~ 2567 Ma and they also record the Paleoproterozoic（ 1.87 ~ 1.89 Ga） tectonothermal event as certified by the different extend of recrystallization of zircons and the accompanied Pb-loss,and also the formation of new metamorphic zircons.Based on the results of this study and a synthesis of other studies,we proposed that the scale of the Archean basement rocks of the Rangnim Massif might be much larger than the several locations identified from the south and the east margin of the Pyongnam Basin.All the identified Archean gneisses in the Rangnim massif experienced strong Paleoproterozoic metamorphic overprinting and anatexis with ages similar to those reported from the whole North China Craton.This similarity likely suggests that the Rangnim massif might have amalgamated with the NCC to form a coherent continent before this Paleoproterozoic episode of tectonothermal event.

关 键 词：朝鲜 狼林杂岩 太古宙基底 构造热事件叠加 巨型构造带 

分 类 号：P588.345[天文地球—岩石学] P597.3[天文地球—地质学]