Metamorphism and structure of the basement of Las Aguadas (Conlara Metamorphic Complex), San Luis province

Abstract

The petrological and structural characteristics of the rocks belonging to the basement of Las Aguadas were studied. The lithology of the region is comprised of biotite – plagioclase - quartz schists (sometime banded or garnet - bearing), biotite - quartz schists with andalusite porphyroblasts, biotite – quartz - plagioclase schist, hornblende – biotite – quartz - plagioclase schist and hornblende – epidote - quartz granofels. The metamorphic conditions of the basement were determined using mineral paragenesis analysis and multi-reactional, indicating temperatures of 620 ±  28 ºC and pressures of 0.59 ± 0.1 Gpa for the metamorphic climax, marking a thermal gradient of 28.8 ºC / km and with a probably clockwise evolution under stable andalusite and later sillimanite conditions. The structure of the analyzed rocks shows the development of four ductile deformation phases, the third coinciding with the metamorphic climax and associated with a compressive stage. The lithologies studied extend for more than 1000 km², within the Conlara Metamorphic Complex and it is proposed to group them under the name of Las Aguadas Group. The metamorphic conditions of the Las Aguadas Group, as well as the ages of detrital zircons obtained previously, show similarities with other sectors of the Sierras Pampeanas such as the Tuclame Formation in the province of Córdoba and the Ancasti Metamorphic Complex in Catamarca.