Aportes estratigráficos y paleontológicos al estudio de la Formación Los Espejos en la Quebrada Poblete Norte, Talacasto, Precordillera Central, Provincia de San Juan

PERSIA, ELBA. E.; LEÓN, LAURA I.; PERALTA, SILVIO H.; PÖTHE DEBALDIS, ELBA D.

CIENCIAS

Fundación Universidad Nacional de San Juan

Lugar: San Juan; Año: 2003 vol. 8 p. 30 - 40

0327-4446

ABSTRACT: The Los Espejos Formation at Poblete Norte creek (Talacasto, San Juan) is divided into three members: the lower one with predominance of shales alternating with thin sandstone bed bearing trace fossils of the Cruziana ichnofacies and para-authochtonous bioclastic concentration indicating distal platform of biogenic sedimentological genesis, with short storm episodes. The middle member also show predominance of shales with thin sandstone levels bearing many trace fossils in subhorizontal and vertical predominated disposition, indicating a moderate to high energy environment, above storm wave-base level, during short concentration episodes, preserved as discretes episodes.Towards the top, the upper member is characterized by a strong shallowness with thick psammitic beds of tabular geometry, bearing structures indicating a moderate tohigh energy environment. The bioclastic concentrations included in this member are allochthonous, of sedimentological genesis. Their presence associated to the former characteristics indicate the existence of a mixed platform, with evidence of combined streams and storm waves activity.