Caracterización estratigráfica del Complejo Volcánico Marifil (Jurásico Inferior) al sudeste de Valcheta, provincia de Río Negro

Abstract

The aim of this study is to contribuite to the cartography and stratigraphic analysis of the outcrops of the Marifil Volcanic Complex. The study area is located in the North Patagonian Massif, 20 km SE of the Rio Negro town of Valcheta, between coordinates 40°47' and 40°44' south latitude and meridians 66°1' and 65°56' of west longitude, in the surroundings of the Don Raúl Establishment. The Marifil Volcanic Complex, in the study area, is composed of volcaniclastic and volcanic rocks. Stratigraphic profiles were made, and from these, an integrated stratigraphic column that represents the succession of rocks in the study area. The volcaniclastic rocks in the study area are made up of sandstones, conglomerates and lapillitic tuffs. At the base of the rock succession, sandstones and conglomerates were identified in small outcrops. These rocks are mainly composed of clasts of volcanic origin of predominant rhyolitic. Above the previous units, conglomeratic sandstones were found with a higher percentage of volcanic clasts and, culminating the volcaniclastic succession, extensive banks of lapillitic tuffs were identified. Finally, the stratigraphic succession of the study area ends with coherent volcanic rocks assigned to rhyolitic lavas. The sandstones and conglomerates of the study area were compared with other rocks from the surrounding area, assigned to the Puesto Piris Formation and associated with the rocks presented, finding compositional differences between them.