利用航磁、重力资料研究川滇地区大陆变形特征  

STUDY ON CONTINENTAL DEFORMATION FEATURES IN SICHUAN-YUNNAN REGION FROM AEROMAGNETIC AND GRAVITY DATA

作　　者：钟锴[1] 徐鸣洁[1] 王良书[1] 丁增勇[1] 徐震[1] 

机构地区：[1]南京大学地球科学系,江苏南京210093

出　　处：《地球科学进展》2005年第10期1089-1094,共6页Advances in Earth Science

基　　金：国家自然科学基金重点项目"滇西特提斯造山带地壳上地幔结构研究"(编号:40034010);中国科学院兰州地质研究所科技创新基金项目"西部塔里木盆地及邻区深部构造研究和地球动力学"(编号:03-12)资助

摘　　要：利用航磁、重力资料对川滇地区大陆变形特征进行了研究。航磁异常揭示了研究区内的基底性质及其横向差异,研究区内的强烈地震主要集中在航磁异常突变带上,基底性质横向差异有利于应力的相对集中,成为地震孕育和发生的有利部位。康定—绵阳一带刚性基底的阻挡造成了青藏高原下地壳物质向东的塑性流动被迫转向南东—南南东方向,进而造成了川滇菱形块体内广泛的地壳增厚,布格重力异常等值线呈向南东伸出的舌状是其地壳增厚作用的直观反映。川滇地区的大陆变形特征既存在广泛的地壳增厚现象,同时在下地壳塑性流动的驱动下,中、上地壳破碎成大小不一的块体,变形特征表现出整体刚性,因而不能简单地套用“地壳增厚”或“大陆逃逸”模式。Based on aeromagnetic and gravity data, continental deformation features in Sichuan-Yunnan Reion（SYR） have been studied. We get the characteristics of basement and its lateral heterogeneity beneath SYR from aeromagnetic data. The eastward viscosity lower crustal flow of Tibet was blocked by the rigid basement near Kangding-Mianyang area, and turn to SE-SSE direction. Most strong earthquakes occurred on the large areomagnetic variation belts. The lateral heterogeneity of basement, which inferred by large areomagnetic variation, vailed stress concentration, earthquakes preparation and occurrence. We also get distribution of crustal thickness and continental deformation features in SYR from gravity data. On the background of collision between India plate and Eurasia plate and uplifting of Tibet, the viscosity lower crustal flow induced crust thicken extensively, and driven upper middle-up crust break into some big and small sub-blocks. The continental deformation features in SYR, including remotion of rigid sub-block through the movement of huge slip faults and extensive crustal thickening, are not fit “Crustal thickening” mode or “Continental extrusion” mode.

关 键 词：航磁 重力 基底 地震 大陆变形 

分 类 号：P54[天文地球—构造地质学]