关于东昆仑地区前寒武纪地质的几点认识  

Some ideas of Precambrian geology in the East Kunlun, China

作　　者：王国灿[1] 魏启荣[1] 贾春兴[2] 张克信[1] 李德威[1] 朱云海[1] 向树元[1] 

机构地区：[1]中国地质大学(武汉)地球科学学院,湖北武汉430074 [2]青海省地质调查院,青海西宁810012

出　　处：《地质通报》2007年第8期929-937,共9页Geological Bulletin of China

基　　金：中国地质调查局项目<青海1:25万库赛湖幅(I46C001002);不冻泉幅(I46C001003)区域地质调查>(编号:200313000005);<青海1:25万阿拉克湖幅(I46C001001)区域地质调查>(编号:19991300004021);<青海1:25万冬给错纳湖幅(I46C001002)区域地质调查>;<青藏高原新生代地质作用过程与第四纪环境演变综合研究>(编号:1212010610103)部分成果。

摘　　要：以1∶25万区域地质调查资料为基础,对东昆仑造山带前寒武纪地质演化的几个关键问题进行了探讨。东昆仑地区3206Ma±14Ma的锆石207Pb/206Pb年龄信息表明,该区存在古太古代基底。代表东昆仑地区基底的"金水口岩群"可以解体为太古宙—古元古代的白沙河岩群和中元古代的小庙岩群,两者是2个不同构造旋回的产物。东昆仑地区万宝沟群的时代应限定在中元古代,而不能延续到新元古代。东昆仑地区的年代构造格架显示,前寒武纪存在3次强烈的区域性构造热事件,分别发生在2400～2500Ma、1800～1900Ma和大约1000Ma。1000Ma左右的聚合事件导致中元古代分隔的不同小陆块的有限裂解小洋盆闭合,陆块聚合形成"西域板块",并可能是整个Rodinia超大陆的组成部分。This paper discusses some important issues concerning the Precambrian geological evolution in the East Kunlun orogenic belt based on a series of 1：250000 regional survey data. The ^207Pb/^206Pb age of 3206±14 Ma for detrital zircons from the Mesoproterozoic Xiaomiao Group in the East Kunlun implies the existence of the Paleoarchean basement. The ＂Jinshuikou Group-complex＂, which is the main part of the basement of the East Kunlun, may be disintegrated into the Archean-Paleo- proterozoic Baishahe Group-complex and Mesoproterozoic Xiaomiao Group-complex, both of which are the product of two different tectonic cycles. The age of the Wanbaogou Group should be restricted in the Mesoproterozoic, rather than persisted to the Neoproterozoic. The chrono-tectonic framework of the East Kunlun shows that there existed three strong regional tectonothermal events in the Precambrian, which took place at 2.4-2.5, 1.8-1.9 and -1.0 Ga respectively. The convergence event at -1.0 Ga resulted in the dosing of a small oceanic basin that broke up limitedly and separated different microblocks in the Mesoproterozoic, thus forming the so-called ＂Western China plate＂, which was probably a component part of the Supercontinent Rodinia.

关 键 词：东昆仑 前寒武纪 基底演化 年代构造格架 

分 类 号：P534.1[天文地球—古生物学与地层学]