作　　者： (张帅）; (朱光）; (顾承串）; (刘程）; (李云剑）; (赵田）; (王薇）;

机构地区： 合肥工业大学资源与环境工程学院,合肥230009

出　　处： 《科学通报》 2017年第24期2814-2828,共15页

摘　　要： 华北克拉通内部的辽-吉造山带,代表着东部陆块的汇聚带.然而,这一重要构造带的东南边界位置长期没有准确地限定,存在着认识上的分歧.本文选择丹东地区基底内变沉积岩与变形-变质侵入岩进行了锆石年代学分析.结果表明,在丹东地区多处残留的变沉积岩,其沉积时代为古元古代,可与辽-吉造山带内的辽河群对比.丹东地区在古元古代也经历过广泛而强烈的区域变质作用,变质时间限定为1910~1864 Ma,可与辽-吉造山带碰撞造山中的变质作用对比.锆石年代学结果显示,丹东地区存在着一系列古元古代侵入岩,以1882~1827 Ma间岩浆活动产物居多.岩浆锆石年龄谱指示该区基底演化阶段经历过多期岩浆活动,峰期分别为2665,2500,2200,2095,2030和1865 Ma,也显示与辽-吉造山带的相似性.这一系列事实表明,丹东地区的基底组成与演化均与辽-吉造山带相似,应划归为该造山带的一部分,而非前人认为的狼林地块.对比分析前人的研究成果发现,整个辽东半岛都应属于辽-吉造山带的延伸,其东南边界至少达北东走向的鸭绿江断裂带. The basement of the North China Craton formed through collision of the Eastern and Western blocks along the Trans- orth China Orogen at ca. 1.85 Ga. The Liao-Ji orogenic belt in the Liaodong Peninsula and southern Jilin represents a Paleoproterozoic convergent belt between the Longgang and Nangrim blocks in the Eastern Block, and has been considered as the northern segment of the entire NNE- to NE-trending Jiao-Liao-Ji Orogen across the whole Eastern Block from south to north. The Liao-Ji orogenic belt is characterized by the presence of sedimentary and volcanic successions, metamorphism, deformation and magmatism of the Paleoproterozoic ages whereas the Archean blocks show the dominance of Archean TTG gneisses and the absence of the Paleoproterozoic sedimentation, metamorphism and magmatism. However, the southeastern boundary location of the Liao-Ji orogenic belt remains uncertain and controversial, and the southeastern Liaodong Peninsula was considered as an Archean block by many authors. Two samples of meta-sediments and seven samples of meta-igneous rocks were collected from the Dandong area for zircon U-Pb dating in this study. Detrital zircon dating for the two meta-sediment samples, muscovite schist and meta-sandstone, constrains their depositional ages between 2013 （youngest magmatic zircon age） and 1864 Ma （metamorphic age）, 2064 and 1910 Ma respectively, indicating Paleoproterozoic ages for their deposition. The Paleoproterozoic meta-sediments, also called the Liaohe Group, are scattered in many places of the Dandong area, and show similar lithology and metamorphic grade to those in the Liao-Ji orogenic belt. These show that the Paleoproterozoic meta-sediments in the Dandong area can be correlated with the Liaohe Group in the Liao-Ji orogenic belt. The basement rocks in the Dandong area, including meta-sediments and meta-plutons, exhibit extensive medium-grade metamorphism. Our zircon dating results suggest that the regional metamorphism experienced by the basement rocks in the Dandong area took

关 键 词： 华北克拉通基底 辽 吉造山带 东南边界位置 锆石 定年 古元古代