塔里木北缘库鲁克塔格地区古元古界——祝贺芮行健先生90华诞
Paleoproterozoic in Quruqtagh terrane in Northern Tarim
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摘要: 库鲁克塔格地区出露了塔里木克拉通最完整的前寒武纪基底,其中新太古界—古元古界构成了塔里木早前寒武纪结晶基底。本文详细总结了该区古元古界岩石组成及变质变形特征,并获得其中的变质火山岩锆石U-Pb年龄为(1 965±13) Ma,代表了该区古元古界沉积年龄。结合区域地层格架、变质事件的研究,认为古元古界沉积时代为2.0~1.8 Ga,并在1.8 Ga发生角闪岩相变质。该变质事件是对北塔里木地体哥伦比亚超大陆汇聚的构造响应。依据岩石组合、前寒武纪大陆地壳生长过程及变质事件综合分析,推测北塔里木地体在中元古代之前属于印度—华北克拉通的一部分,哥伦比亚超大陆裂解过程中与印度—华北克拉通分离,形成一个独立的微陆块,并在罗迪尼亚超大陆汇聚过程中,与南塔里木地体拼合形成了统一的塔里木克拉通前南华纪基底。Abstract: Precambrian basement of the Tarim Craton was well preserved in the Quruqtagh terrane at its northern margin. Among them, the crystallized basement was mainly composed by Neoarchean-Paleoproterozoic. In this contribution, we have a comprehensive synthesis on the rock assemblage and metamorphism of the Paleoproterozoic in this area and also measured the zircon U-Pb age of a meta-volcanic rock sample. Zircons from this sample yielded an excellent age of (1 965±13) Ma. Combing new data obtained in this study and previous works on regional stratigraphic framework and metamorphic events, we suggest that the Paleoproterozoic deposited during 2.0~1.8 Ga and the amphibolite-facies metamorphism took place during 1.90~1.80 Ga, which is coupled with the assembly of the Columbia supercontinent and northern Tarim terrane. Rock association, Precambrian continental crustal growth process and metamorphic features of the Northern Tarim terrane reveal that the northern Tarim terrane could be a continental massif drifted from the North China-India Craton during the breakup of the Columbia. During the assembly process of the Rodinia, the Northern Tarim terrane and Southern Tarim terrane amalgamated together, leading to the final formation of the basement of the Tarim.