DOI: http://dx.doi.org/10.5027/andgeo%25x

Geophysical survey in Lago Yehuin, Isla Grande de Tierra del Fuego, Argentina: origin and evolution

Jorge Gabriel Lozano, Alejandro Alberto Tassone, Emanuele Lodolo, Marco Menichetti, María Elena Cerredo, Donaldo Mauricio Bran, Federico Damián Esteban, Juan Pablo Ormazabal, Luca Baradello, Juan Francisco Vilas

Abstract


Lago Yehuin, a WNW-ESE elongated basin located in the outer fold-and-thrust belt of the Fuegian Andes, occupies a compartmented structural depression originated along a segment of the left-lateral, strike slip Lago Deseado fault system. This paper describes the first geophysical survey performed within the lake. New acquired high-resolution single-channel seismic data, integrated with geological information in the surroundings of the Lago Yehuin, allowed to derive a complete bathymetric map, reconstruct the basement surface of the lake, and the geometry, distribution, and thickness of the sedimentary infill. Two sub-basins were recognized within Lago Yehuin: A western sub-basin, of 7.5 km long with a maximum depth of 118 m; an eastern sub-basin, of 7.2 km length and a maximum depth of 80 m. Both sub-basins are limited by a set of normal faults which overprint NE-verging thrusts. Three seismo-stratigraphic units have been identified in the seismic records: (1) a lower unit with wedged geometry interpreted as mass flow deposits; (2) a thickest (up to  120 m) intermediate unit of glacio-lacustrine nature and irregularly distributed in the Yehuin basin; (3) a thin (generally < 10m) upper lacustrine unit which drapes the entire basin. Lago Yehuin is considered a Neogene basin generated by strike-slip motion that was later affected by glacial and glacio-lacustrine deposition. Interpreted submerged ridge moraines within Lago Yehuin are correlated with onland moraine arcs built by the complete recessional paths of Fuego and Ewan ice lobes. A significant structural control is proposed not only for the formation of Lago Yehuin, but also for the general paths of the northern arms of the Fagnano palaeo-glacier.

Keywords


Lago Yehuin; Fuegian Andes; single-channel seismic profiles; strike-slip tectonics

How to cite this article Lozano, J., Tassone, A., Lodolo, E., Menichetti, M., Cerredo, M., Bran, D., Esteban, F., Ormazabal, J., Baradello, L., and Vilas, J., 2018, Geophysical survey in Lago Yehuin, Isla Grande de Tierra del Fuego, Argentina: origin and evolution: Andean Geology, v. 45, no. 3, p. 318-343., doi:http://dx.doi.org/10.5027/andgeo%x