Glacial-related morphology and sedimentary setting of a high-latitude lacustrine basin: The Lago Chepelmut (Tierra del Fuego, Argentina)

LOZANO, JORGE G.; TASSONE, ALEJANDRO; BRAN, DONALDO M.; LODOLO, EMANUELE; MENICHETTI, MARCO; CERREDO, MARÍA E.; ESTEBAN, FEDERICO; ORMAZABAL, JUAN P.; ÍSOLA, JOSÉ; BARADELLO, LUCA; VILAS, JUAN F.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2018 vol. 86 p. 259 - 270

0895-9811

Lago Chepelmut is a relatively small lake in size, of ellipsoidal shape, located in the outer fold-and-thrust belt ofthe Fuegian Andes (southernmost South America). High-resolution single-channel seismic profiles, integratedwith geological information in the surrounding area, have allowed to reconstruct for the first time a bathymetricmap of the lake and the architecture, distribution and thickness of the sedimentary cover. Two main seismicunits were identified in the seismic records: (i) a Lower Unit of glacial nature, likely associated to the Last GlacialMaximum (LGM), and irregularly distributed through the basin, and (ii) an Upper Unit of lacustrine origin whichdrapes the entire basin. Submerged moraine deposits within the lake were also found from seismic data, andcorrelated with moraine arcs widespread distributed in the surroundings of the basin. These morphologies representthe recessional deposits left by the Ewan glacier lobe, one of the easternmost fronts of the Tierra delFuego glaciers during the LGM. The lacustrine sedimentary record shows that the lake level was not constantthrough the recent history of the lake. Moreover, data analysis has shown that there is also an importantstructural component that has conditioned the evolution of the basin, in addition to that linked to glacial activity.