Evolution of the Neogene Andean foreland basins of the Southern Pampas and Northern Patagonia (34

FOLGUERA, A.; ZARATE, M.; TEDESCO, A.; DÁVILA, F.M.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 64 p. 452 - 466

0895-9811

The Pampas plain (30e41S) has historically been considered as a sector that evolved independentlyfrom the adjacent Andean ranges. Nevertheless, the study of the Pampas showed that it is reasonable toexpect an important influence from the Andes into the extraandean area. The Pampas plain can bedivided into two sectors: the northern portion, adjacent to the Pampean Ranges, has been studied byDavila (2005, 2007, 2010). The southern sector (34e41S) is the objective of the present work. The studyof this area allowed to characterize two separate foreland basins: the Southern Pampa basin and theNorthern Patagonian basin. The infill is composed of Late Miocene and Pliocene units, interpreted asdistal synorogenic sequences associated with the late Cenozoic Andean uplift at this latitudinal range.These foreland basins have been defined based on facies changes, distinct depositional styles, along withthe analysis of sedimentary and isopach maps. The basins geometries are proposed following De Cellesand Gilles (1996) taking into account the infill geometry, distribution and grain size. In both cases, thesedepocenters are located remarkably far away from the Andean tectonics loads. Therefore they cannot beexplained with short-wave subsidence patterns. Elastic models explain the tectonic subsidence in theproximal depocenters but fail to replicate the complete distal basins. These characteristics show thatdynamic subsidence is controlling the subsidence in the Southern Pampas and Northern Patagonianbasins.