Descripción e interpretación de la columna estratigráfica tipo de la serie vulcano-sedimentaria neógena del Valle del Cajón (Catamarca, Argentina)

Abstract

El Cajón Valley is a tectonic depression elongated in a N-5 direction into the geologic province of Sierras Pampeanas (Argentina). The present dynamic in the study area is controlled by a continetal extremely arid climate, where the rains displays an average of 180 mm/year and the teperatures may supper 40°C in summer.

The sedimentary evolution during the Neogene and the influence on it from a volcanic centre located at the north is the aim of this paper. The sedimentological analysis of the stratigraphic formations was realized in a E-W section named Quebrada del Áspero which is affected by a tectonic shortening sliding on muddy strata. Sedimentation consists in an alternance between conglomeratic channels, conglomeratic sandy bodies and wide lutitic strata. The base is constituted by a lutitic formation with lacustrine or lagoonal character. A conglomeratic sequence is located on it. The middle sector of the serie is mainly sandy and finally the top is composed by muds and sands. This sedimentation is characteristic of a braided system. It is significant the presence of epiclastic elemets in the conglomerates and a andesitic/ dacitic formation is also present in the middle sequence