Evolución de la procedencia y redes de drenaje de la cuenca terciaria continental de As Pontes (Galicia), a partir del análisis de las modas detríticas y de minerales pesados

Abstract

The tertiary infill of the As Pontes strike-slip basin overlies a Precambrian-Paleozoic substratum, that also constituted its surrounding source areas. The basin infill resulted from a set of closely related small alluvial fans and lacustrine-palustrine depositional systems. Both, basin and source area evolution, were mainly controlled by tectonism. In an earlier stage, the basin remained divided, by a structural threshold, in two subbasins, which later were connected, acting and developing together. Detrital modes and heavy mineral analysis of the As Pontes sedimentary infill have been obtained from two bore-holes, both of them located in each subbasin. These studies suggest that differences in sediment composition is related to the nature of the source areas. Climatic and depositional factors have a minor influence. The source area of the western subbasin alluvial fans mainly developed over the Olio de Sapo domain and the Cabo Ortegal Complex, whereas the catchment area supplying detrital sediment to the alluvial systems in the eastern subbasin widely covered the Mondohedo nappe domain.