Metamorfismo de soterramiento en la cuenca neuquina e implicancias en la maduración térmica de los hidrocarburos

Abstract

This degree work focuses on the petrographic study of the very low-grade diastathermal metamorphic rocks of the syn-rift in Neuquén Basin. The anomalous heat flow which produces metamorphism and its relationship with the evolution of the basin and the influence on the termal maduration of hydrocarbons is analyzed. The study areas are Precordillera Neuquina Sur and Norte, at Rahue-Chachil and cordillera del Viento troughs, respectively. Extensional tectonic that characterized the syn-rift of the Neuquén Basin was accompanied by an anomalous heat flow caused by lithospheric thinning and the rise of the asthenosphere, and to a lesser extent, by the heat transfer of the precuyano magmatism. This thermal anomaly and the burial effects produced the very low-grade metamorphism that affected the basal succession of the basin. Secundary structures produced by compaction of the pile are micro-stylolites, micro-veinlets and micro-boudins. Mineral associations and paragenesis indicate that the metamorphic grade reached the zeolite to prehnite–pumpellyite facies in the Precuyano Cycle rocks whereas zeolite facies-or diagénesis- was archived in the base of the Cuyo Group. Textural analyses mineral associations also indicate that near peak P-T conditions was reached close to first event of positive tectonic inversion of the hemi-grabens. Loading/heating and subsequent decompression/cooling of the rocks are related to a counterclockwise P-T path.