新疆北天山拜辛德-吉吾恰依一带蛇绿岩地球化学特征研究  

Geochemical Characteristics of Ophiolite in the Baixinde-Jiwuqiayi Area in the Northern Tianshan,Xinjiang,China and Their Geological Significances

作　　者：高轩[1] 弓小平[1] 谢巍然 朱守忠[1] 薛晓峰 

机构地区：[1]新疆大学地质与矿业工程学院,乌鲁木齐830049 [2]新疆维吾尔自治区地质调查院,乌鲁木齐830000

出　　处：《矿物岩石地球化学通报》2017年第4期611-619,共9页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41462004);中国地质调查局项目(12120114000101)

摘　　要：为探讨北天山拜辛德-吉吾恰依一带蛇绿岩的形成环境,对该带内辉长岩进行了LA-ICP-MS锆石U-Pb定年。结果表明,辉长岩的形成年龄为336.2±2.3 Ma,说明辉长岩形成于早石炭世。岩石地球化学研究表明,辉长岩具有球粒陨石10倍左右的REE含量,具有平坦型分布的球粒陨石标准化配分曲线,与MORB型较为相似;玄武岩分别具有MORB型和OIB型岩石地球化学性质,表明该地区早石炭世基底单元火山岩系形成于大陆裂谷环境,源区为与OIB源区类似的地幔软流圈源。综上可认为该地区蛇绿岩可能形成于强烈大陆拉伸作用导致的大陆裂谷向大洋裂谷转变的动力学环境中,进而初步判断该区蛇绿岩为"红海型"。In order to discuss the formation environment of the ophiolite in the Baixinde-Jiwuqiayi area in the Northern Tianshan,the LA-ICP-MS U-Pb dating method has been applied for zircons form the gabbro in the area. Results show that the formation age of gabbro is 336. 2 ± 2. 3 Ma,indicating that the gabbro was formed in early Carboniferous. Petrogeochemical study indicates that the gabbro contains about 10 times of REE contents of the chondrite,with flat chondrite-normalized REE distribution patterns,relatively similar to those of the MORB. The basalt has petrogeochemical characteristics of the MORB and OIB,showing that the early Carboniferous volcanic rocks in the area were formed in the continental rift environment,with the material sourced from the asthenosphere,similar to the OIB. Therefore,we believe that the ophiolite in the area could be formed in a dynamic environment of the transition from the continental rift,resulted from strong continental extension,to the ocean rift,and then preliminary judg that the ophiolite belongs to the Red Sea type.

关 键 词：北天山 锆石U-PB年龄 大陆裂谷 红海型 

分 类 号：P584[天文地球—岩石学]