Holocene environmental changes in the northern Atacama desert, southern Peru (14°3O'S) and their impact on the rise and fall of Pre-Columbian cultures

摘要

Holocene palaeoenvironmental history of the northern Atacama desert, southern Peru, is widely unknown. On the basis of geomorphologic studies and chronometric data, palaeoenviron-ments were reconstructed in an area with wide-spread archaeological sites of the Nasca culture, famous for their geoglyphs, and their ancestors. The distribution and the age of desert loess, alluvial sediments and snail shells give evidence of a steppe-like palaeoenvironment from at least ~ 10.500 B.C. until the 2nc millenium B.C.. A subsequent aridification is related to the onset of sedentariness in the river oases of the Andean footzone. Advanced civilisations developed, periodically pressured by water shortage, especially during the Paracas (after ~ 800 B.C.) and Nasca period (~200 B.C. - ~ 600 A.D.). After 600 A.D. the Nasca civilisation collapsed, most likely due to extreme aridity. Between the 13l' and 1411 century the precipitation increased in the eastern Atacama desert again and led to urban centers even outside of the river oases and in mountain areas. During the Little Ice Age, the environment became more arid, typically associated with more accentuated environmental conditions, forcing sedimentation in the river oases and formation of debris fans (see UNKEL et al, in prep.). After the Little Ice Age drier conditions threatened the region, prevailing until at present in the hyper-arid Atacama desert.The studies show, that flood events during El Nina events have had no impact on the rise and fall of the Para-cas-Nasca civilisation, but monsoonally controlled shifting of the eastern Atacama desert margin, which was an important trigger of environmental and cultural changes in the study area.