内蒙古锡林浩特博仁敖包—巴彦门德过铝质岩的锆石U-Pb年代学、地球化学及其构造意义-Zircon U-Pb geochronology, geochemistry and tectonic significance of the Peraluminous intrusive rocks in the Borenaobao-Bayanmende area, Xilinhot, Inner Mongolia

文章摘要

陈方宇,王波,李海泉,常风.内蒙古锡林浩特博仁敖包—巴彦门德过铝质岩的锆石U-Pb年代学、地球化学及其构造意义[J].矿产勘查,2019,(4):768-780

内蒙古锡林浩特博仁敖包—巴彦门德过铝质岩的锆石U-Pb年代学、地球化学及其构造意义

Zircon U-Pb geochronology, geochemistry and tectonic significance of the Peraluminous intrusive rocks in the Borenaobao-Bayanmende area, Xilinhot, Inner Mongolia

投稿时间：2019-01-22

DOI：

中文关键词: 内蒙古锡林浩特早二叠纪晚古生代锆石年代学地球化学

英文关键词: Inner Mongolia Xilinhot Permian Late Paleozoic zircon chronology geochemistry

基金项目:中国地质调查局内蒙古1:5万杭嘎拉土乌拉等4幅区域地质调查项目(1212011120702)；国家自然科学基金项目(41703024). 中国地质调查局项目(项目编号:DD20160001)资助。

作者	单位
陈方宇	曲阜师范大学日照校区地理与旅游学院,山东日照 273165
王波	中国地质大学武汉地质调查研究院,湖北武汉 430074
李海泉	中国地质大学武汉地质调查研究院,湖北武汉 430074
常风	中国地质大学武汉地质调查研究院,湖北武汉 430074

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中文摘要:

锡林浩特博仁敖包花岗闪长岩主要由花岗闪长岩、闪长岩等侵入岩组成。通过对该岩体开展系统的锆石LA-ICP-MSU-Pb年代学、岩石地球化学等综合研究,锆石U-Pb测年结果表明该地区过铝质侵入岩主要由形成于早二叠世花岗闪长岩(278±2Ma),晚二叠世花岗闪长岩(252±2Ma)组成。二者的岩石地球化学特征显示,均以钙碱性系列为主,具过铝质的特点。岩体富含大离子亲石元素Rb、K、Ce和高场强元素Zr、Hf、Th等,而Sr、Ba、P、Ti等元素较低,Nb呈现了亏损的正常弧造山花岗岩的特征。Sr、Ba的亏损反映花岗岩分离结晶作用的存在。早二叠世的花岗闪长岩从其总体的化学组成与典型的I型花岗岩相似,为碰撞前的花岗岩组合,与大陆弧花岗岩类组合的构造环境相同。晚二叠世的组合特征代表了碰撞后的抬升阶段的花岗岩组合。微量元素Ta-Yb、Nb-Y构造判别图解显示从早叠世的花岗闪长岩到晚二叠世的花岗闪长岩代表了锡林浩特地区从碰撞前的大陆弧环境到其间的小洋盆闭合隆升的过程。从晚二叠世开始该地区进入了造山活动的活跃期,暗示滨太平洋构造体系对内蒙古东南缘的影响可能从二叠世已经开始显现。

英文摘要:

The Peraluminous intrusive rocks in the Borentunbao area of ?偆h?偆hXilinhot are mainly composed of invasive rocks such as the Early Permian granodiorite, diorite and Late Permian granodiorite. Through the systematic study of zircon LA-ICP-MS U-Pb geochronology and rock geochemistry of the rock mass, the zircon U-Pb dating results indicate that the Early Permian granodiorite was formed in (278 ±2 Ma), Late Permian granodiorite (252±2 Ma). The geochemical characteristics of the rocks show that they are mainly calcium-alkaline series and have the characteristics of peraluminous. The rock mass is rich in large ion lithophile elements Rb, K, Ce and high field strength elements Zr, Hf, Th, etc., while Sr, Ba, P, Ti and other elements are lower, and Nb presents the characteristics of loss-making normal arc orogenic granite. . The loss of Sr and Ba reflects the existence of separation and crystallization of granite. The Early Permian granodiorite is similar in its overall chemical composition to the typical I-type granite, and is the granite combination before the collision, which is the same as the continental arc granite combination. The combined features of the Late Permian represent granite combinations during the ascending phase of the collision. The tracing diagrams of trace elements Ta-Yb and Nb-Y show that the granodiorite from the Early Permian granodiorite to the Late Permian represents the small ocean basin in the Xilinhot area from the continental arc environment before the collision. The process of closing the uplift. Since the Late Permian, the area has entered an active period of orogenic activities, suggesting that the influence of the Pacific Ocean tectonic system on the southeastern margin of Inner Mongolia may have begun to appear from the Permian.

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