Publication Date:
2011-09-01
Description:
By combining terrace riser offsets with terrace ages dated by 14C, optically stimulated luminescence (OSL), and 10Be techniques, we determine average slip rates of 1.1 {+/-} 0.3 mm/yr and 1.2 {+/-} 0.4 mm/yr for the Elashan and Riyueshan faults, two north-northwest-trending, right-lateral, strike-slip faults west and east of the lake Qinghai in the northeastern margin of the Tibetan Plateau. These faults are conjugate to the major easterly trending, left-lateral Altyn Tagh, Haiyuan-Qilianshan, and Kunlun faults, and they contribute to the subdivision of the region between the Haiyuan-Qilianshan and Kunlun faults into small blocks tens to [~]100 km in dimension. The relatively low slip rates in this region reflect distributed deformation. The total right-lateral offsets of geological contacts are [~]9-12 km along the Elashan fault and [~]11-12 km for the northern segment of the Riyueshan fault. If long-term slip rates were constant during late Cenozoic time, dates of initiation of dextral movement would be 9 or 10 {+/-} 3 Ma for the two strike-slip faults, concurrent with onsets or acceleration of tectonic deformation in Cenozoic basins nearby. Our study highlights a stage of tectonic deformation in the northeastern margin of the Tibetan Plateau beginning since ca. 8-12 Ma, tens of millions of years after the collision between India and Eurasia began.
Print ISSN:
0016-7606
Electronic ISSN:
1943-2674
Topics:
Geosciences
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