Geological and geophysical outline of the southern sector of the province of San Luis

Abstract

Geophysical determinations together with geological interpretations in the southern area of San Luis province indicate the existence of a strip of rocks with Pampean ages between Arizona and Justo Daract. The high-gravity anomalies are related to a belt of mafic rocks also recognized at Valle Daza (La Pampa). Low-gravimetric anomalies are consequence of basement rocks, such as those found at the Green quarry and at sedimentary basins. Volcanic rocks equivalent to the Choiyoi Group produce the positives between the basins and are also part of the basin basement. The basins are represented by an elongated, continuum, low-gravimetric anomaly defined here as the New Galia Basin and by a sub-circular feature, considered as an extension of the Alvear sub-basin. According to the correlation with closely areas these basins developed mainly during Permo-Triassic times. These basins extend northward, westward, and southward, connecting with the Mercedes, Alvear and Quehué basins. This last one developed in the La Pampa province.