The Alojamiento Formation (Cambrian) in its type locality. Sedimentary paleoenvironment of the Eopaleozoic continental margin, Precordillera Mendocina

Abstract

Due to the tectonic activity in the western Precordillera area, the Eopaleozoic outcrops are tectonically truncated and the overprint effect many times is misinterpreted as synsedimentary deformation processes. These outcrops constitute tectonic bodies with lateral and vertical extension limited by reverse faults and they have isolated distribution from north to south along to the Cuyo Precordillera. A detailed and complete analysis of the Cambrian limestones outcropping in the Alojamientos locality, is presented from stratigraphical, geological, lithological, paleontological and paleoenvironmental point of view, with the object to update the geological knowledge in this sector of the Precordillera, based on recently discovered paleontological and new geological evidence. The sedimentary characteristics and lithofacial associations from the study sequence, reveal the sedimentary paleoenvironment in the upper Middle Cambrian - Upper Cambrian interval, of the Precordillera basin and identified a paleogeographic place wich is interpreted as the edge of a platform. The internal lithofacial framework is indicating progressive shallowing upward conditions that are attributed to eustatic regressions and they are correlated with those identified in limestone sequences of the same age in the eastern Precordillera area.