松潘-甘孜带:是弧前增生还是弧后消减?  

SONGPAN-GANZE BELT:FOREARC ACCRETION OR BACKARC COLLAPSING?

作　　者：徐强[1] 潘桂棠[2] 江新胜[2] 

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]成都地质矿产研究所,四川成都610082

出　　处：《矿物岩石》2003年第2期27-31,共5页Mineralogy and Petrology

基　　金：国土资源部 2 0 0 0重点科技项目 ( 2 0 0 0 2 0 1);中国海洋石油博士后基金资助

摘　　要：根据多年在该区工作实践 ,认为松潘 -甘孜造山带前身的巴颜喀拉盆地是羌塘 -他念他翁晚古生代前缘弧之后的一系列多岛弧 -盆系的一个大型弧后盆地。三叠纪时 ,围限此“三角形”盆地三条边缘的构造动力学作用方式具有不同的特征。其东侧为扬子西缘被动大陆边缘 (D- T2 ) ,中三叠晚期 (拉丁期 )转化为与华北和羌塘陆块有关的前陆盆地(T2 - T3) ,由于扬子陆块向西双向斜向俯冲作用 ,在其北侧和南侧边缘形成南昆仑和可可西里 -甘孜 -理塘俯冲消减杂岩。重建的地层层序和沉积地质特征显示巴颜喀拉盆地主体三叠系复理石沉积是周缘前陆盆地。The Bayan Har Basin which was thought to be the former of Songpan-Garze belt,is a back-arc basin among a series of Polyarc-basin systems behind Qiangtang-Taniantawong front arc in the Late Paleozoic. The three margins surrounding this'triangular'basin have their own tectonic dynamic properties. The eastern margin started as the western passive continental margin of Yangtze block (D-T 2), then changed into a foreland basin related to North China block and Qiangtang block during the middle to late Triassic (Ladinian). Because of the westward oblique subduction of Yangtze block, two subduction mélanges, the South Kunlun mélange in the north and Hoh Xil-Garze-Litang mélange in the south, were formed on both north and south sides of this basin at almost the same period. The stratigraphic sequences and sedimentological characteristics indicate that the main body of Bayan Har Basin is composed of Triassic flysch sediments deposited in a foreland basin during Triassic.

关 键 词：松潘-甘孜造山带 弧前增生 地层层序 沉积地质特征 巴颜喀拉盆地 三叠系 弧后消减 

分 类 号：P542.2[天文地球—构造地质学]