Miocene deformation in the orogenic front of the Malargüe fold-and-thrust belt (35°30′–36° S): Controls on the migration of magmatic and hydrocarbon fluids

BARRIONUEVO, M.; GIAMBIAGI, L.; MESCUA, J.; SURIANO, J.; DE LA CAL, H.; SOTO, J.L.; LOSSADA, A.C.

TECTONOPHYSICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019

0040-1951

The integration of surface observations and sub-surface data (wellbore and seismic) fromthe orogenic front of the Malargüe fold-and-thrust belt allows us to study its structuralkinematics, and to interpret the local stress field and its control over fluid (magmatic andhydrocarbon) migration. Reverse faults correspond to inverted NNW-striking Mesozoicnormal faults and N-S striking Cenozoic low-angle thrusts parallel to the orogen. Obliquestructures with strike-slip movement are also present. The magmatic activity in the studyarea was strongly controlled by this structural framework and the in-situ stress field. Miocenedykes and sills were emplaced in relation to strike-slip and reverse faults, respectively. Wepropose an evolution of the study region from a foredeep sector, in the early-middleMiocene, to a peak in deformation in the late Miocene, and finally a waning of deformation from the Pliocene to the present. Our structural model suggests that during the evolution ofthe thrust front, the in-situ stress field changed from a compressional to strikeslip/compressional stress field, favouring the synchronous emplacement of sills and dykes.This alternation of stress regimes favours hydrocarbon migration through both thrusts andsubvertical strike-slip faults. This exchange between both stress regimes is likely related tothe similar values of the minimum (σ3) and intermediate (σ2) principal stress with an E-Woriented maximum principal stress (σ1) according to the plate convergence vector.