IDEAN   23403
INSTITUTO DE ESTUDIOS ANDINOS "DON PABLO GROEBER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Geology and structure of the area around Paso de las Nubes, North-Patagonian Andes, Argentina
Autor/es:
BECHIS, F.; ORIOLO, S.; OLAIZOLA, E.; BRAN, D.; YAGUPSKY, D.L.
Lugar:
Montgenevre
Reunión:
Congreso; Young Researchers in Structural Geology and Tectonics Conference; 2018
Institución organizadora:
University of Leeds
Resumen:
The present study constitutes a lithological and structural analysis located in the central sector of the North-Patagonian Andes, between 41°06?00?? and 41°11?00??S, and 71°50?00??and 71°33?40??W, east of the Tronador Mount. Currently there are two non-exclusive theories that explain the mechanism through which the North-Patagonian Andes at these latitudes were formed from Neogene times: the first of them proposes a compressive regime, while the second one considers a transpressive structural style.The objectives of this study consisted in the mapping and analysis of the outcropping lithological units, the kinematic and chronological characterization of the observed structures, and the understanding of the deformation evolution and the structural style of the region. The lithological characterization of the exposed units consisted in a petrographical analysis of all the units, a stratigraphic section and an Ar-Ar dating of the Tronador I unit. In order to develop the structural analysis, the methodology employed was constituted by: the identification of lineaments along with statistical and spatial analysis of the obtained data; the classification of the interpreted lineaments according to the unit they affected and their longitude; the measurement of fault slip data in 34 mesoscopic faults; the determination of the slip direction and the sense of fault-slip in each fault measuring the orientation of striae in fault planes and of associated secondary Riedel fractures. The outcropping units mapped are: the Colohuincul Complex (Devonian-Permian), a Jurassic Volcano-Sedimentary Complex, the Miocene Coluco Formation and the volcanic Tronador Complex (Pleistocene), represented by the Tronador I and Tronador III units. An obtained age of 1.178 ± 0.057 My constitutes a high resolution dating for the Tronador I unit and helped refining the stratigraphy of the homonym complex, whose eruptive activity is limited between 1.2 ? 0.3 My. The kinematic results from the structural analysis allowed to determine two fault systems: a transtensive population and a right-lateral strike-slip one. Taking into account the obtained data and the regional tectonic context, the following inferences were made: i) the reactivation of former structures of the basement would have played a fundamental role in the Mesozoic-Cenozoic tectonic evolution of the region; ii) as the measurements reveal the presence of a strike-slip deformation component in the region, the mechanism of construction of the Andean orogeny at this latitude is more consistent with the transpressive regime, than to the purely compressive one; iii) a coupled structural evolution is proposed between the studied region and the Liquiñe-Ofqui Fault Zone in Chile.