内蒙古索伦山地区蛇绿岩岩石单元地质特征、就位机制及时限

发布时间：2018-03-09 08:01

本文选题：蛇绿岩　切入点：就位机制　出处：《现代地质》2017年03期 　论文类型：期刊论文

【摘要】：内蒙古索伦山地区出露蛇绿岩,其研究对探讨古亚洲洋演化具有重要意义。对内蒙古索伦山地区蛇绿岩进行了系统的调查和研究,探讨了其就位机制与时限。结合索伦山蛇绿岩地质特征和区域地质背景综合分析,认为研究区蛇绿岩组合包括地幔与洋壳组分。索伦山地区蛇绿岩存在较为完整的蛇绿岩组合模式,出露地幔岩石组合为蛇纹石化纯橄榄岩、蛇纹石化二辉-方辉橄榄岩、橄榄辉石岩和硅化碳酸盐化蚀变超基性岩(风化壳)等。蛇绿岩组合中洋壳组分为辉长岩、辉绿岩、玄武岩和硅质岩。蛇绿岩就位机制划分为4种,即碰撞仰冲型、增生底垫型、俯冲剥离型和角流型。其中,俯冲剥离型就位机制表现为岩石组合齐全完整的特征,产出形态为岩块、岩片,其中岩块、岩片与基质为构造断层接触;在俯冲带近大陆一侧常形成岛弧岩浆岩等特征。索伦山蛇绿岩地质特征与俯冲剥离型就位机制特征完全相符,故索伦山蛇绿岩就位机制大致为洋中脊俯冲剥离型。根据大洋岩石圈形成之后在10 Ma之内就位这一原则,结合索伦山地区辉长岩SHRIMP锆石U-Pb年龄为(280.7±5.3)Ma,认为索伦山蛇绿岩就位时限在270 Ma左右。
[Abstract]:The study of exposed ophiolite in the Suolun Mountain area of Inner Mongolia is of great significance to the study of the evolution of the Paleo-Asian Ocean, and a systematic investigation and study of ophiolite in the Suolun Mountain area of Inner Mongolia has been carried out. The mechanism and time limit of its location are discussed, combined with the comprehensive analysis of the geological characteristics and regional geological background of the ophiolite in the Solenshan Mountains. It is considered that the ophiolite assemblage in the study area includes mantle and oceanic crust components. There is a relatively complete ophiolite assemblage model in the ophiolite in the Solenshan area. Olivine pyroxenite and silicated carbonate altered ultrabasic rocks (weathering crust). The oceanic crust components in ophiolite assemblage are divided into gabbro, diabase, basalt and siliceous rocks. The placement mechanism of subduction and peeling type is that the rock assemblage is complete and complete, and the occurrence form is rock block, rock slice, among which rock block, rock slice and matrix are tectonic fault contact. The island arc magmatic rocks are often formed on the near continental side of the subduction zone. The geological characteristics of the Solenshan ophiolite are completely consistent with the subduction and stripping mechanism. Therefore, the mechanism of ophiolite emplacement in Soolun Mountain is approximately subducted and stripped from the mid-oceanic ridge. According to the principle that the oceanic lithosphere is in place within 10 Ma after the formation of the oceanic lithosphere, According to the U-Pb zircon U-Pb age of gabbro in Suolenshan area, which is 280.7 卤5.3 Ma, it is considered that the time limit of ophiolite emplacement is about 270Ma.
【作者单位】：中国地质大学(北京)地球科学与资源学院;武警黄金第二支队;
【基金】：中国地质调查局区域地质矿产调查项目(12120113071800)
【分类号】：P588

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