U-Pb geochronology and kinematic preliminary analyses of Late Triassic-Early Jurassic basins in northern Chile (24.5º-26ºS)

MAURICIO ESPINOZA; VERÓNICA OLIVEROS; PAULINA VÁSQUEZ; FLORENCIA BECHIS

La Serena

Congreso; XIV Congreso Geológico Chileno; 2015

Colegio de Geólogos de Chile y Sociedad Geológica de Chile

In northern Chile (24.5°-26°S) two Late Triassic-Early Jurassic depocenters crop out: the Cifuncho basin in Coastal Cordillera, and Profeta basin in Precordillera. There is scarce systematic studies of these basins resulting in major gaps in the knowledge of its chronostratigraphy and structural framework. In this contribution we present preliminary results (U-Pb geochronological and structural synrift data) of a tectonostratigraphic study of the Cifuncho and Profeta basins. The geochronological data along the Cifuncho and Profeta basins show a main continental sedimentary deposition during the Norian to Raethian. Volcanosedimentary rocks show a main detrital supply of Early Permian age (~297-283 Ma). This input can be associated with the volcanic La Tabla Formation and/or the exhumation of Permian granitoids. A minor supply close to ~478 Ma is related to a source from the Lower Ordovician arc (~480 Ma), suggesting the tectonic exhumation of this source to the east of the Profeta basin during the Late Triassic. On the other hand, the kinematic analyses evidence a variability in the orientation of the maximum strain axes from a main northwest to a subordinate northeast direction of extension, probably reflecting local variation in the strain field across the basins.