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Slip rate at the north-eastern front of the Qilian Shan, China

Authors


Jean-Daniel Champagnac, Geological Institute - Earth Surface Dynamics, Sonneggstrasse 5, NO E 45, CH-8092 Zürich, Switzerland. e-mail: champagnac@gmail.com

Abstract

Terra Nova, 22, 180–187, 2010

Abstract

We constrain the slip rate for the frontal thrust of the Qilian Shan (north-eastern Tibet) by combining structural investigations, satellite imagery, topographic profiling, and 10Be exposure dating. We surveyed two terrace levels, and from each, we took 6–7 samples in profiles dug to depths of 2 m. These constrain inheritance and determine the precise ages of abandonment of the terraces: 29.9 ± 7.8 ka for the upper terrace and 16.3 ± 4.4 ka for the lower one. Topographic profiles with a determination of burial of the footwall by sediment yield offsets of the surfaces of 96.4 ± 4.4 and 40.1 ± 2.8 m. The average vertical rate is 2.8 ± 1.3 mm a−1 with a horizontal slip rate of ∼2.5 mm a−1. This rate is higher than those determined farther north on similar structures, but is consistent with the GPS velocity field, and accounts for roughly half of the geodetic shortening across the Qilian Shan.

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