Caracterización geológica de domos subvolcánicos riolíticos en el Compejo Los Menucos (Permo-Triásico), Macizo Norpatagónico, Río Negro.

Abstract

Two rhyolitic intrusive domes were identified northwest of Los Menucos in the north-central sector of the North Patagonian Massif, in the province of Rio Negro. The domes cover an area of about 3 km2 and intrude volcanic rocks belonging to the Permo-Triassic Los Menucos Complex. Field observations and petrographic analyses allowed the characterization of different lithofacies, corresponding to both the subvolcanic bodies and the host rocks. The magmatic flow foliation data and textural variations study as well as their distribution within the subvolcanic bodies allowed us to know the dynamics of the magma inside the domes and its relationship with the host rock and the regional structure at the time of the intrusion. We concluded that the rhyolitic domes would have taken advantage of the space generated by the pre-existing regional faults, using the fault zones as a supply conduit. The emplacement of the domes was driven by the magmatic forces that predominated over the tectonic ones and this occurred in at least 3 stages belonging to the same magmatic cycle, possibly associated to the structural evolution of the area during the Early Jurassic-Cretaceous interval.