Holocene seismic stratigraphy of the southern arms of Lago Argentino

Abstract

Lago Argentino hosts various calving glaciers, including the famous Perito Moreno. Although the onland Holocene glacier dynamics is rather well constrained, the paleoenvironments developed in association with a retreating ice front remain largely unknown. A detailed analysis of high-resolution seismic reflection profiles acquired in the southern arms of Lago Argentino has allowed the identification of several unconformities within the lacustrine sedimentary infill. Four seismostratigraphic sequences have been identified in Brazo Rico and three in Brazo Sur. These sequences are separated by three erosive unconformities in Brazo Rico and two in Brazo Sur, and reflect the sedimentation of a pre-Holocene deep basin in a proglacial lake. The older unconformities are associated with instability events within the basin which triggered several mass movements, possibly related to enhanced seismic activity. The younger erosive unconformities were correlated with the “Pearson 1a/Frias 1 advance”, the major glacier advance in the Holocene of the Lago Argentino Basin. This research highlights the importance of studying the glaciolacustrine sediments, representing decisive records of the glacial history and palaeoclimate, which could help unveiling the factors controlling glacier dynamics in the basin and reconstructing the deglacial landscape of the area.