The stratigraphic record of changing hyperaridity in the Atacama desert over the last 10 Ma

摘要: New radiometric and magnetostratigraphic data from Quillagua Calama basins (Atacama desert) indicate that the stratigraphic record over last 10 Ma includes two hiatuses, lasting approximately 2 4 million years respectively. These sedimentary gaps are thought to represent prolonged periods of hyperaridity in region, with absence sediment production accumulation central depressions. Their remarkable synchrony Antarctic Patagonian glacial stages, Humboldt cold current enhancement upwelling waters lead us suggest long-term climate forcing. Higher frequency (orbital precession eccentricity) forcing is control sequential arrangement lacustrine units deposited at times lower aridity. Hyperaridity trends appear be modulated by activity South American Summer Monsoon, which drives precipitation along high altitude areas east Atacama. This increase combined eastward enlargement regional drainage during late Pleistocene enabled water transfer these low lying closed basin resulted deposition widespread saline deposits this depression, before its was open Pacific Ocean.