Oligocene extension to Miocene contraction in the Aluminé Basin, Neuquén, Argentina

JUAN FRANZESE; LEANDRO D´ELIA; ANDRÉS BILMES; MARTIN MURAVCHIK; MARIANO HERNANDEZ

Mendoza

Congreso; 18th international sedimentological congress; 2010

IAS

  The Aluminé Basin is a volcano-sedimentary depocentre located in the Andean retroarc at 39°S. It is the southern part of a major depositional system: the Bío Bio-Aluminé Basin. Stratigraphical, geochronological, sedimentological and structural analysis allow us to conclude that the basin evolved through two stages: an Oligocene extensional stage filled with basalts and reworked volcaniclastic and pyroclastic de-posits (Rancahue Formation) and a Miocene contractional stage, filled with alluvial and pyroclastic deposits covered by basaltic lavas (Chimehuín and Tipilihuque Formations). The volcanic-rich (basaltic) infill of the extensional stage has a western provenance and was derived from widespread magmatic activity that took place during the Oligocene in the adjacent cordilleran axis. The contractional stage basin is an intramontane depocentre limited by uplifted blocks gene-rated mainly by the inversion of Mesozoic extensional faults. It is strongly asymmetric and shows eastern provenance. Structural and geomorphological evidence indicate the existence of a non-depositional hiatus between the two stages.