Evolution oligo-miocène de lAltiplano occidental arc et avant arc du nord du Chili, Arica : tectonique , volcanisme, sédimentation, géomorphologie et bilan érosion-sédimentation.Reportar como inadecuado




Evolution oligo-miocène de lAltiplano occidental arc et avant arc du nord du Chili, Arica : tectonique , volcanisme, sédimentation, géomorphologie et bilan érosion-sédimentation. - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

1 LGCA - Laboratoire de Géodynamique des Chaines Alpines

Abstract : The oligo-neogene geodynamic evolution of Altiplano, at the latitude od -Codo de Arica-, is characterised by an important compressive defonnation and volcanism. In the eastern part of the chain Bolivia, the shortening is weIl documented 190-280 km, and it explain a very thick crust 65 km. However, in the western part, the geological history is not weIl known and in part controversial. The study of the Arica region, on three regional transects to scale 1:50.000, permit to propose a representative model for the geodynamic evolution of the western Altiplano. The Oligocene -35-26 Ma is characterised by fluvial sedimentation, recorded in the deeper part of the Central Depression. The deposits, up to 500 m thickness, cover a topographically smooth regional unconformity. They are polymictic and provene from the East, from the erosion of a proto-Cordillera Occidental. They are cut by subvertical west-vergent faults. The Late Oligocene-Early Miocene 26-19 Ma is a period of intense effusive and explosive volcanism. To the East Cordillera Occidental, the volcanic arc is represented by a maximum of 2.500 m of andesites, dacites and rhyolitic ignimbrites, with alluvial and Iacustrine intercalations. This arc, very actif, was asociated to formation of collapse calderas. To the West Precordillera and Central Depression, the fore-arc deposits are represented by up to 1.000m of rhyolitic ignimbrites extra-caldera, with fluvial and lacustrine intercalations. In the Coastal Cordillera, oligo-miocene alluvial sedimentation is recorded in restricted bassins



Autor: Marcelo Garcia -

Fuente: https://hal.archives-ouvertes.fr/



DESCARGAR PDF




Documentos relacionados