Geological and geophysical evidences of the polyphase structural evolution of the Southern Precordillera (31º42?S-69º24?W) in the central-western Argentina

ARIZA, J.P.; CONTRERA, J.P.; PÉREZ LUJÁN, S.; BOEDO, F.L.; LUDUEÑA, M.A.; MARTÍNEZ, M.P.; SANCHEZ, M.A.; CEBALLOS, J.P.; VUJOVICH, G.I.

Santiago de Chile

Simposio; Primer Simposio de Tectónica Sudamericana; 2016

Asociación Tectónica Sudamericana

The study area is located in the west-central Argentina (31º42´S - 69º24´W). At this latitude the basement of Central Andes is composed by a collage of cratonic blocks that were amalgamated to the proto-pacific margin of South America between the Neoproterozoic and mid Paleozoic. The subhorizontal subduction of the Nazca plate beneath the South American plate during the late Cenozoic has controlled the eastward migration of the Andean orogenic front and the generation of several thrust sheets that uplift different terranes which are linked to each other along suture zones. These suture zones shows typical geological features (represented by belts of mafic-ultramafic rocks, ancient magmatic arcs, metamorphic and sedimentary rocks related to the existence of orogenic belts) and are coincident with areas of anomalous geophysical properties. This study is focused on the structural evolution of the north part of Southern Precordillera where the existing evidences point to a polyphase tectonic evolution in which three main orogenies are recognized: Chanica (late Devonian), San Rafael (Early Permian) and Andina (Neogene - today). However, some important issues needs to review: How are the structures corresponding to each tectonic phase and how to separate them; the stratigraphy arrangement of Early-Mid Paleozoic units; How was the role and the control of pre-Andean structures on the Andean deformation and active seismicity of this region.In this paper an evolution scheme of the geological structures is proposed on the basis of interference fold pattern and by constrain with aeromagnetic and remote sensing data. Moreover, we present a focal mechanism determinates from a crustal seismic event that allow as to evaluate the influence of pre-Andean structures on the active seismicity.