FAJA DE CIZALLA LAS LAJAS: PETROGRAFÍA, ESTRUCTURA INTERNA E IMPLICANCIAS TECTÓNICAS, EXTREMO SUR DE LA SIERRA DE COMECHINGONES, PROVINCIAS DE CÓRDOBA Y SAN LUIS

This paper presents a synthesis of the complex geology of the Las Lajas Shear Zone (LLSZ) through a detailed petrological - structural approach, in order to establish its importance in the evolution of the Sierra de Comechingones basement. The LLSZ is a very important geological discontinuity, that was mainly active during the Paleozoic times although is still active and related to the regional tectonic framework. This shear zone is 35 km long and 1.5 km wide, and their limits and geological characteristic suggest it was active through ductile to fragile domains, been actually related to the Las Lajas- Sampacho-Las Lagunas fault system. Detailed analysis of the lithology and its internal structures suggest, based on the intensity of reworking of the protoliths and the proportions of mylonitic rocks ( s.l .), that the deformation intensity in the shear zone increases from north to south. Detail study of the deformation fabrics and their related structures has demonstrated that LLSZ is a ductile-brittle deformation zone that functions under reverse cinematic conditions with W-verging thrusting.