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Durham University

Institute of Medieval and Early Modern Studies (IMEMS)

Members

The list below shows Durham University research staff who are members of IMEMS. Click the member's name to see a more detailed biography and department.

We also welcome anyone from outside the University with an interest in our work to join. Membership is free of charge. You will receive invitations to our programme of events, with a weekly emails digest about what is happening in the Insitute and further afield. To join IMEMS contact: admin.imems@durham.ac.uk

Publication details for Prof Mark Allen

Allen, M.B., Walters, R.J., Song, S.G., Saville, C., De Paola, N., Ford, J., Hu, Z.X. & Sun, W.L. (2017). Partitioning of oblique convergence coupled to the fault locking behavior of fold-and-thrust belts: evidence from the Qilian Shan, northeastern Tibetan Plateau. Tectonics 36(9): 1679-1698.

Author(s) from Durham

Abstract

Oblique plate convergence is common, but it is not clear how the obliquity is achieved by continental fold-and-thrust belts. We address this problem in the Qilian Shan, northeastern Tibetan Plateau, using fieldwork observations, geomorphic analysis and elastic dislocation modeling of published geodetic data. A thrust dips SSW from the northern range front, and underlies steeper thrusts in the interior. Cenozoic thrust-related shortening across the Qilian Shan is ~155-175 km, based on two transects. Elastic dislocation modeling indicates that horizontal strain in the interseismic period is consistent with oblique slip on a single low angle detachment thrust below ~26 km depth, dipping SSW at ~17o. We suggest this detachment is located above North China Block crust, originally underthrust during Paleozoic orogeny. Horizontal shear strain is localized directly above the up-dip limit of creep on the detachment, and is coincident with the left-lateral Haiyuan Fault. This configuration implies oblique slip on the detachment below seismogenic depths is partitioned in the shallow crust onto separate strike-slip and thrust faults. This is consistent with strain partitioning in oceanic subduction zones, but has not previously been found by dislocation models of continental interiors. The marginal, strike-slip, Altyn Tagh Fault influences thrusting within the Qilian Shan for 100-200 km from the fault, but does not control the regional structure, where Paleozoic basement faults have been reactivated. The Qilian Shan resembles the main Tibetan Plateau in nascent form: active thrusts are marginal to an interior that is developing plateau characteristics, involving low relief, and low seismicity.