塔里木盆地沙雅隆起北部三道桥地区前震旦纪基底岩浆岩特征与锆石U-Pb年龄研究

Petrological characteristics and zircon U-Pb age for magmatic rocks from Pre-Sinian basement of the SDQ area of Shaya Rise in Tarim Basin,NW China

对塔里木盆地北部三道桥地区前震旦纪基底的岩浆岩进行岩石学分析及时代限定研究。研究区前震旦纪基底的岩浆岩主要由钾长花岗岩、石英二长岩及角闪二辉岩组成。钾长花岗岩局部受断裂影响,发生碎裂化作用,形成碎裂化钾长花岗岩。通过对Qg2、Qg3、S53及Qg4井4口钻井的4个岩心样品进行LA-ICP-MS锆石U-Pb年代学研究,获得钾长花岗岩、石英二长岩及碎裂钾长花岗岩年龄分别为1846±1Ma、1791±1Ma、1824±2Ma,代表了古元古代岩浆岩的变质年龄;角闪二辉岩年龄为879±4Ma,代表了中新元古代火山侵入年龄。说明塔里木盆地沙雅隆起北部存在前震旦纪古老基底,这些结果也为塔里木克拉通的前寒武纪构造演化提供了新的限定。

Petrological characteristics and zircon U-Pb chronology of Pre-Sinian magmatic rocks from the Sandaoqiao（ SDQ） area in the northern Shaya Rise of the Tarim Basin was reported in this paper. The Pre-Sinian magmatic rocks are composed of K-feldspar granite,adamellite and hornblende-websterite in this area. The cataclastic rock was formed from the local K-feldspar granite as fracture effect. Four core samples of Qg2,Qg3,S53 and Qg4 in 4 wells drilling have been studied on U-Pb zircon geochronology by LA-ICPMS. The zircon U-Pb dating results gave ages of 1846 ± 1Ma,1791 ± 1Ma,1824 ± 2Ma for K-feldspar granite（ sample from Qg2）,adamellite（ sample from S53） and fragmentation K-feldspar granite（ sample from Qg3）, respectively, representing the Paleoproterozoic metamorphic age of magmatic ptotoliths. The age of 879 ± 4Ma from hornblende-websterite（ sample from Qg4） is interpreted as the Neoproterozoic igneous intrusive time. These data suggest the existence of the Pre-Sinian ancient basement in Shaya Rise in the northern Tarim Basin,and these results supply significant constrains on Precambrian tectonic evolution of Tarim Craton.