Paleosurfaces and relief evolution in cratonic areas of the Western Pampean Ranges (Province of San Juan, Argentina)

Abstract

The present investigation was developed in the area of Sierra de Pie de Palo, located at approximately 31º 30’ S and 68°00’ W, in the central eastern portion of San Juan province, Argentina. The main objective is to analyze the ancient flat surfaces located in the mountain block of Precambrian-lower Paleozoic metamorphic rocks of the Western Pampean Ranges System. In the Sierra de Pie de Palo, situated in central western Argentina, five ancient surfaces were determined at altitudes of 3000, 2500-2400, 1900, 1500-1400, and 12001000 m a.s.l., respectively, the oldest one being the highest. These nearly flat five surfaces are arranged in a steplike pattern and are approximately concentric with respect to the central part of the range. Relict and exhumated reliefs coexist in this area. The megafault systems of Valle Fértil (NNW), Tulum (NNE) and Salinas Grandes (ENE) have played an important role in the relief evolution of this area.

Cinco niveles de paleosuperficies fueron determinados, ubicados a los 3000, 2500-2400, 1900, 1500-1400 y entre los 1200 a 1000 m.s.n.m., dispuestos en forma escalonada y aproximadamente concéntrica a la porción central de la Sierra de Pie de Palo. Estas superficies disminuyen en edad a medida que descienden en altura, coexistiendo los relieves relictuales y exhumados. Los megasistemas de fracturación de Valle Fértil (NNO), de Tulum (NNE) y de Salinas Grandes (ENE) juegan un rol importante en la evolución de este relieve pampeano.