Identification of Quaternary thrusts, folds and faults in a low seismicity area: examples in the Southern Alps (France) |
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| Authors: | J-C Hippolyte & T Dumont |
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| Institution: | Laboratoire de Geodynamique des Chaines Alpines, UPRES-A 5025 CNRS, Universitéde Savoie–Campus Scientifique Technolac, 73376 Le Bourget du LAC Cedex, France |
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| Abstract: | In low seismicity areas, folds, faults and striated pebbles in recent alluvial deposits can demonstrate the Quaternary activity of tectonic structures and can reveal their kinematics. In the Digne nappe (Southern Alps), an out-of-sequence thrust occurred in the late Quaternary in response to WSW-trending compression. The presence of late Quaternary compressional deformation in the Valavoire thrust could have resulted from the activity of the underlying Durance flexure with a maximum Pliocene–Quaternary uplift rate of about 0.1 mm yr?1. The Quaternary top surface of the Valensole basin, that truncates SW-vergent thrust propagation folds, is folded above the Lambruissier anticline. Exceptional conditions resulted in the local preservation of this Quaternary fold morphology created with a minimum uplift-rate of 0.05 mm yr?1 under a NE-trending compression. At the front of the Digne nappe the deformation is characterized by WSW to WNW trends of compression and low strain rates during the Quaternary period. |
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