The Lago Cardiel Basin, Argentina (49°S): Origin and evolution revealed by high-resolution multichannel seismic reflection studies

A multichannel, high-resolution seismic reflection survey was conducted with an airgun source in the closed lake system of Lago Cardiel, Argentina (49°S). As part of an ongoing study of interhemispheric correlations in climate change, it was intended to determine the maximum age and depth of the lake sediments and better understand the origin and evolution of the lake basin. In agreement with previous single-channel, 3.5-kHz surveys, six major seismic sequences throughout the lake’s subsurface were mapped. The stronger seismic source of this study allows the deepest sequence (Sequence VI) to be interpreted as folded Cretaceous marls with a highly eroded surface. Further examination of this sequence reveals various stratigraphic signatures and mechanisms of the generally east–west orientation of tectonic compression. The nature and continuity of Sequence VI do not indicate a volcanic or impact-related origin of the lake. The original basin has a maximal depression of 154 ms (∼114 m) deep beneath the modern lake surface and is overlain by an alluvial fan (Sequence V) of likely Pleistocene age in the western portion and late Quaternary lacustrine sediments (Sequences I–IV) everywhere else. The data confirm that southern Patagonia was dominated by extremely contrasting climatic conditions during the Quaternary.