Geometry and kinematics of recent deformation in the Mondy–Tunka area (south-westernmost Baikal rift zone, Mongolia–Siberia) |
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| Authors: | A Arjannikova C Larroque J -F Ritz J Déverchère J F Stéphan S Arjannikov V San'kov |
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| Institution: | Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences, Lermontova street 128, 66 Irkutsk, Russia;;Laboratoire Géosciences Azur, UMR 6526 –Universitéde Nice Sophia Antipolis, CNRS-bat. 4, 250 Av. A. Einstein, 06560 Valbonne, France;;Laboratoire Dynamique de la Lithosphère, UMR 5573 –Universitéde Montpellier-2, 34095 Montpellier cedex 5, France;;Institut Universitaire Européen de la Mer, UMR 6538 –Universitéde Bretagne Occidentale, Place N. Copernic, 29280 Plouzané, France |
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| Abstract: | We used satellite imagery and field data to investigate the south‐westernmost Baikal rift zone. We focus our study in the Mondy and Ikhe Ukhgun valleys, site of an Mw = 6.9 seismic event in 1950. Surface deformations are observed along the E–W‐trending Mondy strike‐slip fault and along the Ikhe Ukhgun thrust. The Mondy fault system is 80 km long and is composed of four segments 10–15 km long. These segments are characterized by subvertical planes with left‐lateral movements. The Ikhe Ukhgun thrust is 20 km long, dips 40° to the south and shows reverse movement with a left‐lateral component. These observations are consistent with the present‐day regional NNE–SSW compression and with the focal mechanism of the 1950 Mondy earthquake that was recently re‐evaluated. These features, like those observed in the Tunka basin, demonstrate a recent change of regional strain regime from transtension to transpression that we place before the Late Pleistocene. |
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