Fig. 3
From: Subaqueous evidence of the last glacial maximum and its termination in southern Patagonia
(a) Uninterpreted and (b) interpreted composite W-E multi-channel seismic reflection profile LINE1, showing seismic facies (M-F), reflection truncations (blue arrows), seismo-stratigraphic units SU1-SU5 separated by regional unconformities D1-D4 above the acoustic basement (D0). LF: Lakefloor; multiple: water-bottom reverberation (noise). The data image the position of the subaqueous ACR-age Puerto Bandera 2 moraines that correlate with their mapped locations on land27. To the east, the glaciolacustrine deposits preserve a buried erosional structure (scarp) and a double crested moraine that predate s the ACR within SU2 and SU1, respectively (b); (c) Glaciotectonic thrust complex uninterpreted, and (d) interpreted. The complex contains imbricate thrusts extending east of the Puerto Bandera 2 moraine for 4 km length and up to 140 m in height, an aspect ratio of 1:28 that is typical of wide push moraines48. Decollement surfaces separate the glaciotectonically disturbed material above from undisturbed material below. These structures are likely to form within weak layers49 and in settings where substratum loading rates greatly outpace pressure dissipation rates, resulting in a rapid increase of pore fluid pressure and reduction of the effective and shear stress, which facilitate brittle failure that can propagate far from the glacial front (e.g., refs.49,50). The presence of a thrust complex here suggests rapid advance of the glacier front during the ACR advance.
