Evolution of a thick-skinned thrust system and associated basins, Northern Tien Shan, Kzakhstan

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The Tien Shan mountains of Central Asia are a distal part of the Earth´s most active continental collision zone. They are an ideal site to study long-lived, yet rapidly evolving and presently seismogenic fault networks on various time scales. Strong seismicity, high topography and fast motions derived from satellite geodesy demonstrate that intraplate orogeny in the Tien Shan is fully active. Exposed faults and geomorphic indicators reveal active thrusting, folding and strike-slip motion. The earlier uplift history is documented by the infill of Cenozoic syntectonic basins, both within the Tien Shan and in the large Ili Basin north of it. The Ili basin exhibits steep-sided, fault-controlled depressions atypical of flexural foreland basins. Its southern margin is presently being segmented and exhumed by the active thrust front, whereas its distal parts preserve a long record of the Tien Shan´s uplift. We will integrate structural geology, morphotectonics and basin analysis with remote sensing and GIS, to derive for a selected transect a quantitative reconstruction of fault system propagation as recorded by deformation, uplift and basin evolution. The timing will be constrained from apatite fission track, (U-Th)/He, luminescence and cosmogenic surface dating. Existing biostratigraphic data are included. Estimated rates of denudation, uplift and deformation will be combined with 3D structural modelling to derive a time-space model of fault system evolution.