Estudio y aplicación de criterios de discriminación de granitos con datos ASTER, LANDSAT 8 y SENTINEL 2A, precordillera patagónica

Abstract

In the present work, geological mapping and identification criteria were defined, through the processing and digital analysis of multispectral optical satellite images, of outcrops of granitoid and metamorphic rocks. The study was carried out in the Gastre and Pilcaniyeu areas, northern sector of the Patagonian Precordillera, Chubut and Río Negro provinces. In this region, the Gastre and Lipetrén plutonic suites of the Batholith of Central Patagonia outcrop. The results were analyzed together with the bibliography, the microscopic observation of thin sections and the field control. The digital processing of the compositions ASTER RGB 321, RGB 431, RGB 461, RGB 468, LANDSAT 8 RGB 752 and SENTINEL 2 RGB 12 4 2, allowed to identify a set of granitoid rocks composed of monzogranites, granodiorites and syenogranites. For their part, the Pilcaniyeu metamorphic rocks responded better to the ASTER RGB 431 composition, which allowed them to be distinguished from the surrounding volcanic rocks. In Gastre, the application of the ASTER RGB QRI FRI MRI, RGB 7 4 14 compositions and the SI quotient made it possible to verify the acid nature of the Lipetrén Suite, compared to the Gastre Suite, which is more mafic. While in the Pilcaniyeu Plutonites of the homonymous region, these same band combinations allowed us to distinguish the biotite granites with cataclasis from the more mafic granodiorites and tonalites, with hornblende and biotite. The geological criteria for the identification of granitoids proposed in this thesis show the importance of applying ASTER, LANDSAT 8 and SENTINEL 2 image composition techniques. In this sense, this sensor should be a commonly used tool to assist mapping and discrimination works of granitic facies.