Plio-Quaternary extension in the Venezuelan Andes: Mapping from SAR JERS imagery |
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Authors: | Damien Dhont Guillaume Back Yves Hervouët |
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Institution: | CNRS-FRE 2639, Imagerie Géophysique, CURS-IPRA, BP 1155, Université de Pau et des Pays de l'Adour 64013 PAU, France |
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Abstract: | The geometry of extensional structures is described for the first time in the active setting of the Venezuelan Andes using remote sensing imagery. We favored the use of a mosaic of Synthetic Aperture Radar (SAR) scenes of the Japanese Earth Resources Satellite-1 (JERS-1) assisted by complementary remote sensing devices (Landsat TM, digital elevation models) and field observations to make a structural analysis at regional scale. Radar images are particularly efficient in the Venezuelan Andes where dense vegetation and frequent cloud covering earlier lent difficulties to remote sensing studies. We focused our analysis in the Valera–Rio Momboy and Bocono faults corner and in the Mucujun area. We show that, in an area where ongoing compression and strike–slip deformations occur, brittle extension can be detected independently from previous knowledge. Extensional structures correspond to elongated tilted blocks with dimension less than 10 km in width. Blocks are bounded by curved faults in plan view, the concavity being turned towards the axial part of the belt. The geometry and kinematics of such structures suggest that syn-orogenic extension started together with initiation of right-lateral strike–slip motion along the Bocono Fault in the Plio-Quaternary. |
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Keywords: | Mé rida Andes Venezuela Bocono Fault Radar imagery Extension |
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