ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    新疆西昆仑塔什库尔干地区珈玛勒厄格勒中酸性侵入岩体及其大地构造意义

    Gamaleegrad Intermediate Intrusive Rock and Its Geotectonic Significance in the Taxkorgan Region of Western Kunlun Orogenic Belt,Xinjiang

    • 摘要: 新疆西昆仑塔什库尔干地区珈玛勒厄格勒侵入岩体位于塔里木板块西南缘,喀喇昆仑大陆边缘的东北缘,主要由形成于晚寒武世至早奥陶世的钙碱性二长花岗岩系列和碱性花岗岩系列组成。依据珈玛勒厄格勒中酸性侵入岩体的岩石学和地球化学特征,讨论了该侵入岩体的成因、构造环境和与其相关的板块间地球动力学模式,表明该侵入岩体属二长花岗岩-花岗岩(MG-G)组合,且岩体演化过程中存在壳源重熔的高Sr、高Zr、低Rb的偏中性花岗质岩浆混入;该岩体主要为I型花岗岩,形成于板块俯冲碰撞背景下的大陆弧后拉张盆地环境;根据岩浆演化的物理环境和构造环境,推测该侵入岩体的形成与库地洋壳向塔里木古地块俯冲密切相关,表明库地洋已消亡,形成弧后扩张花岗岩,指示塔里木古地块和柴达木古陆块已发生陆-陆碰撞。

       

      Abstract: Gamaleegrad intermediate intrusive rock, located at the southwestern margin of the Tarim Block and the northeast edge of Karakoram continental margin, is composed of calc-alkaline monzogranite series and alkaline granite series, which were formed between late Cambrian and early Ordovician.Based on geochemical analysis, the main elements and trace elements of Gamaleegrad intrusive rock have been studied in detail, as well as the tectonic setting of the intrusive sequence and geodynamic model between plates around the intrusive sequence have been discussed.The results show that the Gamaleegrad intermediate intrusive rock is a combination of monzogranite-granite (MG-G), which is mixed with sub-neutral granitic magma (high Sr, Zr and low Rb) that experienced the crustal remelting in the evolutionary process of intrusive sequence.It mainly belongs to I-type granites, which was formed in continental backarc extensional basin under the condition of subduction collision.Based on physical environment and tectonic setting in the course of magmatic evolution, it is speculated that the formation of these intrusive rock is closely related to subduction collision of Kuda oceanic crust towards Tarim ancient block, indicating the disappearance of Kuda Ocean and the formation of back-arc spreading granite.Meanwhile, it means that the continent-continent collision had taken place between Tarim ancient block and Qaidam ancient block, indicating that both of them were finally converged into Rodinia supercontinent.

       

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