最新GPS数据揭示的东构造结周边主要断裂带的运动特征

最新GPS观测资料研究表明喜马拉雅东构造结周边主要断裂带在不同构造部位其运动特征不同.雅鲁藏布江断裂总体表现为右旋挤压运动,东构造结以西走滑速率为2~4 mm/a、挤压速率为1~4 mm/a,东构造结附近走滑速率为6~7 mm/a、挤压速率为1~4 mm/a;嘉黎断裂带从东构造结以西的右旋走滑运动,到东构造结附近的弱右旋走滑运动,转变为东构造结东南部的左旋走滑运动,走滑速率分别为4~6 mm/a、1~2 mm/a和3~5 mm/a.怒江断裂带在构造结以西主要为挤压运动,运动速率1~2 mm/a;在东构造结及其东南部则表现为右旋挤压运动,走滑速率为2~3 mm/a、挤压速率1~2.5 mm/a.以上结果表明,尽管东构造结形成于中生代,但现今对周边主要断裂带的运动仍有一定的影响;嘉黎断裂带东南段可能不是青藏高原右旋剪切带的南部边界.

The movement characters of main faults around Eastern Himalayan Syntaxis revealed by the latest GPS data

We have studied the present movement characteristics of three main faults around the Eastern Himalayan Syntaxis(EHS) by recent observational data of GPS. The research data show that there are different movement characteristics in different tectonic area. The Yarlung Zangbo Jiang fault shows the same movement features in the west and near EHS, that is, right-lateral strike-slip and extrusion movement. On the west of EHS the strike-slip rate is 2~4 mm/a and compression rate is 1~4 mm/a, near EHS the strike-slip rate is 6~7 mm/a and compression rate is 1~4 mm/a. To the west of EHS, the Jiali fault in the section from Lhasa to Nagqu shows right-lateral strike-slip with a rate of 4~6 mm/a; while near EHS it exhibits a weak right-lateral strike-slip movement, the rate is only 1~2 mm/a; but to the southeast of EHS, the Jiali fault zone in the section from Shijie to Zayü changes into left-lateral strike-slip movement, the strike-slip rate is 3~5 mm/a. On the west of EHS the Nujiang fault zone shows compressional movement, the rate is 1~2 mm/a; while near EHS and to the southeast of EHS of the fault shows right-lateral transpression movement, the strike-slip rate is 2~3 mm/a, the compression rate is 1~2.5 mm/a. The above results show that, although EHS is formed in the Mesozoic, the recent movement of main faults around EHS is still controlled by it. The southeast part of the Jiali fault zone may not be the southern border of dextral shear zone of Tibetan Plateau.