Molluscs as evidence for a late Pleistocene and early Holocene humid period in the southern coastal desert of Peru (14.5°S) |
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Authors: | Bertil Mächtle Ingmar Unkel Bernd Kromer |
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Institution: | a Geographical Institute, Heidelberg University, INF 348, D-69120 Heidelberg, Germany b GeoBiosphere Science Centre, Quaternary Sciences, Sölvegatan 12, S-223 62 Lund, Sweden c Heidelberg Academy of Sciences, c/o Institute of Environmental Physics, INF 229, D-69120 Heidelberg, Germany d Institut für Ur- und Frühgeschichte und Archäologie des Mittelalters, Abteilung Ältere Urgeschichte und Quartärökologie, Arbeitsbereich Naturwissenschaftliche Archäologie, Tübingen University, Rümelinstr. 23, D-72070 Tübingen, Germany |
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Abstract: | The southern Peruvian coastal desert around Palpa, southern Peru (14.5°S) is currently characterized by hyper-arid conditions. However, the presence of two species of molluscs (Scutalus, Pupoides) and desert-loess deposits indicates the past development of semi-desert and grassland ecosystems caused by a displacement of the eastern desert margin due to hydrological changes. Radiocarbon dating shows that the transition to a semi-arid climate in the southern Peruvian coastal desert took place during the Greenland interstadial 1, ∼ 13.5 cal ka BP. At the beginning of the Holocene, the mollusc fauna vanished due to increasing humidity and the development of grasslands. Dust particles were fixed by the grasses, as indicated by abundant Poaceae phytoliths, and desert loess was formed. The humid period we observe here is out of phase with the palaeoenvironmental records from the Titicaca region, which indicates dry conditions at that time. This paper offers a new idea for this contradiction: an orbitally driven meridional shift of the Bolivian high might have altered the moisture supply across the Andes. |
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Keywords: | Palaeoenvironment Palaeoclimatic change Mollusc fauna Desert loess Scutalus Pupoides Peruvian coastal desert |
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