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Tectonique néogène et bassins transpressifs en bordure méridionale de l'Altiplano-Puna (2~S), Nord-Ouest argentin.

Abstract : The Andes are one of the highest and largest mountain ranges on Earth. They are the product of the oblique subduction of the oceanic Nazca plate beneath the continental South American plate. The plate convergence has been accommodated by subduction and the déformation of a zone, up to 700 km wide. In the central Andes there are remarkable variations in shape, trend amount of continental deformation and structural style. In general terms, segments can be defined with particular morphologies and patterns of deformation, which coincide with variations in the obliquity of the relative convergence vector with respect to the continental boundaries. This study of the southern boundary of the AltiplanoPuna (27°S), in the Central Andes, is based on field observations, fault population analysis, paleomagnetic results and a restoration in map view of the area. There the Tucuman Transfer Zone (TTZ) extending at the southern edge of the Puna is a major dextral transpressional zone. Across this 100 km wide zone, bloc rotations are shown by the paleomagnetic study. Regional kinematics reflect the superimposition of two main deformation fields: ENE-WSW to E-W subhorizontal shortening related to bulk convergence between Nazca and South America plates, and NW-SE subhorizontal shortening consistent with dextral wrenching along the TTZ and with southeastward expansion of the high plateau. The area consists of alternating Neogene compressional basins (ramp basins) and uplifted ranges of PreMesozoic crystalline basement. Both, the amount of bulk strain and the overall depths of depocentres decrease from North to South. Basin maturity and amount of thickening seem thus strongly linked. Basement uplifts between basins are recorded by upward coarsening sedimentary sequences since Miocene times. Neogene thick-skin tectonics and basin development show an overall southeastward younging of deformation, and probably account for most of the crustal thickening at the edge of the Puna.
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Submitted on : Friday, March 2, 2012 - 11:29:07 AM
Last modification on : Thursday, January 14, 2021 - 11:38:49 AM
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  • HAL Id : tel-00675903, version 1

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Marc de Urreiztieta. Tectonique néogène et bassins transpressifs en bordure méridionale de l'Altiplano-Puna (2~S), Nord-Ouest argentin.. Tectonique. Université Rennes 1, 1995. Français. ⟨tel-00675903⟩

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