关键词: 弧形带, 推覆体, 活动构造带, 地震活动性, 帕米尔

Abstract: The external zone of the Pamir is the boundary between the Pamirs and the Tianshan which are two major Cenozoic mountain belts of Central Asia and a part of the most active portion of the India-Eurasia collisional plate boundary. Its eastern section consists of the large Aikaerte and Kazkeaerte arcuate fold-and-thrust belts, whose style ranges from tight folds and northward-verging thrusts in the Aikaerte arc gradually to open folding in the Kazkeaerte arc to the north. Every arcuate belt is composed of a series of varying scales of sub arcs that is a separate fold and thrust sheet with independent characteristics of geometry, kinematics and mechanics and is a self-similar system as well. The kinematics of arc changes from thrusting at the top of the arc(where thrusts have gently dipping planes and the largest slips) to oblique thrusting and wrenching at the sections (steeper faults with sinistral wrenching at the left section and dextral wrenching at the right section), and finally thrusting to the end of the arc. The arcuate thrust tectonics is composed of frontal, lateral and oblique ramps at depth, which merged downward into a series of decollements at different depths. The external zone of the Pamir is most active with shallow-focus seismicity. Each earthquake deformation belt is probably related to the independent arc. Strong earthquakes correspond to the large scale arcs, and middle to small earthquakes to smaller ones.

Key words: Arcuate zone, Nappe, Active tectoic zone, Seismic activity, Pamir