新疆西准噶尔库尔尕克希岩体年代学、地球化学特征及岩石成因

发布时间：2018-02-12 23:18

本文关键词： 年代学地球化学 Ⅰ型花岗岩岛弧库尔尕克希西准噶尔　出处：《岩石矿物学杂志》2017年03期 　论文类型：期刊论文

【摘要】：新疆西准噶尔构造带发育大量晚古生代中酸性侵入体,其岩石成因和侵位期次对于认识该构造带的岩浆演化具有十分重要的意义。本文对库尔尕克希岩体进行了详细的野外地质调查、LA-ICP-MS锆石U-Pb同位素测年及岩石地球化学分析,旨在查明其成岩时代和成因类型。结果表明,该岩体出露面积仅约0.55 km~2,岩性主要为花岗闪长岩,锆石U-Pb年龄为312.9±2.9 Ma(n=20,MSWD=0.072),形成于晚石炭世早期。地球化学特征显示其为钙碱性弱过铝质I型花岗岩。岩体具有较高硅、中等铝,富碱、贫镁,富集Rb、Ba、K等大离子亲石元素,强烈亏损Nb、Ta、Ti、P等高场强元素和重稀土元素,负Eu异常较微弱,A/CNK=0.99~1.20,与区内别鲁阿嘎希、包古图等小岩体在成岩时代、地球化学特征等方面有着显著的相似性,形成于晚石炭世早期与俯冲作用相关的岛弧环境,其源岩更可能是受俯冲流体交代的亏损地幔衍生出来的年轻地壳物质。
[Abstract]:A large number of late Paleozoic intermediate-acid intrusions developed in the West Junggar tectonic belt of Xinjiang. The petrogenesis and emplacement stage are of great significance for understanding the magmatic evolution of the tectonic zone. In this paper, detailed field geological survey of the Kulgarkexi rock body has been carried out, and zircon U-Pb isotopic dating and petrogeochemical analysis of the Kulgarkexi rock body have been carried out in detail. In order to find out the diagenetic age and genetic type, the result shows that the exposed area of this rock is only about 0.55 km2, and the lithology is mainly granodiorite. The U-Pb zircon U-Pb age is 312.9 卤2.9 Maanzao 20 MSWDU 0.072, which was formed in the early late Carboniferous. Geochemical characteristics show that it is a calc-alkaline weakly peraluminous I-type granite. The rock mass is characterized by high silicon, moderate aluminum, alkali rich, poor magnesium, and rich in large ion lithophile elements, such as RbBU, Bak, etc. Strong depletion of high field strength elements and heavy rare earth elements, negative EU anomaly is weak A / CNK = 0.991.20, which is similar to that of small rock bodies such as Beeruagahi and Baogutu in diagenetic age and geochemical characteristics, etc. Formed in the island arc environment associated with subduction in the early late Carboniferous, the source rocks are more likely to be young crustal materials derived from depleted mantle derived from subduction fluid metasomatism.
【作者单位】：长安大学地球科学与资源学院;国土资源部岩浆作用成矿与找矿重点实验室;新疆维吾尔族自治区地质矿产勘查开发局第一地质大队;中国科学院大学地球科学学院;
【基金】：国家自然科学基金项目(41402044,41273033,41303027)~~
【分类号】：P587;P597.3

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