西藏南部地区现今构造变形分析  

Analysis of present-day tectonic deformation in south Tibet

作　　者：周伟[1,2] 张静华[2] 张中伏[2] 

机构地区：[1]中国科学技术大学地球物理与空间学院,安徽合肥230026 [2]中国地震局第一监测中心,天津300180

出　　处：《华北地震科学》2008年第4期1-6,共6页North China Earthquake Sciences

摘　　要：近十多年来藏南地区GPS网的多期观测结果为研究其构造变形提供了精确数据。本文将该区划分为冈底斯、西喜马拉雅、中喜马拉雅、拉萨4个块体,建立了各块体的弹性运动模型。以藏北高原的旋转框架为参考基准,得到藏南地区的水平形变场和应变场,分析形变场和应变场的空间变化,发现藏南地区存在强烈的S-N向挤压缩短变形,同时也有明显的E-W向伸展变形。南北边界之间的平均缩短速率16.9±2.5mm/a,大约吸收了印度与欧亚汇聚速率的42.4%。在雅鲁藏布江缝合线与班公错—嘉黎断裂之间,从80°E到90°E,地壳E—W向的伸展速率16.3±2.4mm/a。因此,藏南地区现今构造变形是以挤压缩短为主,S-N向挤压缩短与E—W伸展共存的复合变形模式。印度板块向欧亚板块的俯冲推挤是该区域变形的主要驱动力,重力作用对其变形也有重要贡献。The terms of surveying results from GPS networks in South Tibet in the past decade provide accurate data for us to study the tectonic deformation of it.We divide the area into 4 blocks of Western Himalaya,Central Himalaya,Kailash and Lhasa bock,establish their elastic motion models.Making Northern Tibet block as referenced frame,we get the horizontal deformation field and strain field of that area.Our result indicates that South Tibet shows very strong S-N shortening and striking E-W extension;The S-N shortening between the south and north border of Southern Tibet is 16.9±2.5mm/a and about 42.4% of convergence between India and Eurasian plates is absorbed.The E-W extensive between Yarlung Zangbu suture and Bangong Co-Jiali fault.is about 16.3±2.4mm/a.Strong push force from the India plate is the main driving force of current tectonic deformation in South Tibet,and the gravity is another important factor.

关 键 词：GPS观测 块体划分 形变场 应变场 动力学分析 

分 类 号：P315.2[天文地球—地震学]