东昆仑造山带龙什更公玛混杂岩岩石地球化学特征及其古环境重塑  

Petro-geochemistry Characteristics of Longshigenggongma Mélanges of Eastern Kunlun Orogenic Belt and Paleoenvironment Reconstruction

作　　者：骆满生[1] 张克信[2] 殷鸿福[2] 王国灿[2] 王永标[2] 陈能松[2] 侯光久[2] 

机构地区：[1]中国地质大学研究生院 [2]中国地质大学地球科学学院,武汉430074

出　　处：《地质科技情报》2006年第2期19-24,共6页Geological Science and Technology Information

基　　金：高等学校全国优秀博士学位论文作者专项资金资助项目"造山带混杂岩区非史密斯地层研究--以青海东昆仑和拉脊山混杂岩带为例"(200228);中国地质调查局项目"东昆仑地区1:25万冬给措纳湖幅区域地质调查"(19961300010121)

摘　　要：东昆仑造山带清水泉南部的龙什更公玛混杂岩(新元古界万保沟岩群—下古生界纳赤台岩群)按岩性可分为3类岩片:复理石岩片、碳酸盐岩岩片、玄武岩岩片,其中复理石岩片根据其形成年代不同分为新元古界复理石岩片和下古生界复理石岩片。对复理石岩片、玄武岩岩片的沉积学特征和岩石地球化学特征的研究结果表明,龙什更公玛混杂岩中的新元古界复理石岩片为洋盆斜坡浊积扇环境的产物,新元古界玄武岩岩片为火山岛弧环境的产物,下古生界复理石岩片为有限小洋盆浊积扇远端相或远洋环境的产物。研究区龙什更公玛新元古界—下古生界混杂岩建造代表东昆仑造山带晋宁—加里东阶段陆壳裂解—闭合的洋陆转化过程,新元古代-加里东早期为洋盆裂解期,加里东中晚期洋盆由扩张状态转变为汇聚收缩状态,加里东晚期的中志留世末为小洋盆碰撞闭合期。According to rock characteristics,the Longshigenggongma mélanges （Neoproterozoic Wanbaogou Group-Early Paleozoic Nachitai Group）,southern Qingshuiquan,Eastern Kunlun orogenic belt can be divided into 3 types： flysch rock slice,carbonate rock slice and basalt rock slice. Among them, the flysch rock slice can be divided into Neoproterozoic and Early Paleozoic flysch rock slice based on their different forming ages. The results of the detailed research of the sedimentary and petro-geochemistry characteristics of flysch and basalt rock slices show that the Neoproterozoic flysch rock slice of Longshigengongma mélanges is the alluvial fan material of the ocean basin slope; Neoproterozoic basalt slice, the material of volcanic land-arc environment; Early Paleozoic flysch rock slice, the material of far end facies of limited ocean basin turbidite fan or far ocean environment. The Longshigenggongma Neoproterozoic-Early Paleozoic mélanges reconstruction in the study area represents the ocean-continent transition of split-close of continent crust at Jinningian-Caledonian. Neoproterozoic-Caledonian is the early time of the split of ocean basin. The middle and late Caledonian is the time that the ocean basin changed from expansion state to convergent state, and late Caledonian, late Middle Silurian is the collision and closing time of the small ocean basin.

关 键 词：龙什更公玛混杂岩 岩石地球化学 古环境 新元古代-早古生代 东昆仑造山带 

分 类 号：P588.36[天文地球—岩石学]