Nuevas evidencias sobre la importancia del fallamiento en la estructura de las Sierras Australes de la Provincia de Buenos Aires.

TOMEZZOLI R.N.; CRISTALLINI, E.O.

REVISTA DE LA ASOCIACIÓN GEOLÓGICA ARGENTINA

Asociación Geológica Argentina

Año: 1998 vol. 53 p. 117 - 129

Abstract: New evidences of the importance of faulting in the structure of the Sierras Australes de la Provincia de Buenos Aires. The Sierras Australes de la Provincia de Buenos Aires or Sierra de la Ventana are in the south part of Buenos Aires province, Argentine, between 37°-39° S and 61°-63° W and constitute a curved fold and thrust belt with a general northwest strike. They are formed by Precambrian to Permian rocks. The oldest and more intensely deformed rocks outcrop in the western ranges, while the younger and less deformed are placed through the east. Traditionally, these ranges were considered as one example of pure folding without faults participation. In this paper mesoscale structural sections that prove the importance of faulting in the ranges development are presented. In a regional scale, tectonic contact between Lolén Formation (upper Devonian) and Providencia Formation (lower Devonian), and between the last and Napostá Formation (lower Devonian) are proposed in Parque Tornquist, Estancia Las Vertientes and Cerro Tres Picos localities. According to field evidences, the Pillahuincó Ranges are structured over Ventana Ranges through an underthrust northeast dipping composing a triangle zone between these two ranges.