Deformación y migración de fluidos en el frente orogénico de Malargüe

MESCUA, JOSÉ; SOTO, JORGE LUIS; GIAMBIAGI, LAURA; DE LA CAL, HERNÁN; BARRIONUEVO, MATÍAS; SURIANO, JULIETA; LOSSADA, ANA

Online

Simposio; Ciclo de Charlas sobre Magmatismo y Sistemas Petroleros; 2020

IAPG (Instituto Argentino del Petróleo y del Gas)

In the southern part ofMendoza province, Neuquén Basin, igneous intrusives hosted in the Mezosoicsedimentary succession produce oil in some regions of the basin as in the Valledel Río Grande area. In order to evaluate the relationship between thestructural evolution and the igneous bodies intrusion, a structural study ofthe Agua Botada field (north of Valle del Río Grande area) near the deformationfront of the Malargüe fold-and-thrust belt, is presented here.A 3D structural model wasdeveloped using surface and subsurface information (oil-well logs and seismicdata) to understand the kinematic evolution of the structures. Previous NNWrift faults show inversion under andean compression while NW to WNW rift faultsare probably not inverted but reactivated as strike-slip fault.In addition the igneousbodies were surveyed and when possible, slip data was obtained. The inversionof these data provided the stress field responsible of faulting which isinferred to be coeval and related to the intrusion. Dykes and sills wererecognized: dykes striking NW to WNW show strike-slip faulting withhydrothermal alteration and hydrocarbon traces, while E-W striking dykes arenot sheared and show weak hydrothermal alteration and no traces of hydrocarbons;some sills are faulted as well with the same kinematic as faulted dykes andsome are intruded using reverse fault planes, showing hydrothermal alterationand oil traces. The swarms of igneous bodies irradiate from two main feedersand show a general WNW trending which coincides with previous normal faults. The interpretation ofthe obtained structural data allowed to develop a geological evolution modelwith three main stages: in the first stage from 17-10 Ma Agua Botada field wasin the foredeep of the foreland basin and the compression took place to thewest of it. In the second stage (10-7 Ma) the deformation migrated to the eastand the western part of Agua Botada was under compression with igneousemplacement as sills in reverse faults. In the eastern zone a strike-slip tocompressional stress field reactived the previous rift faults which weresuitable as magmatic flow paths. Finally in the third stage (7-1 Ma) thedeformation front migrated toward the east with the inversion of Malargüe normalfault that tilted the mesozoic sediments.