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A new record of palaeo dust deposition from Argentina’s Altiplano

James Hooper 1, Samuel Marx1, Jan-Hendrik May2, Henk Heijnis3
1GeoQuEST Research Centre - School of Earth and Environmental Sciences, University of Wollongong, Australia, 2Institute of Geology, Albert Ludwig University of Freiburg, Fahnenbergplatz, Freiburg im Breisgau, Germany, 3Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, PMB 1 Menai, Australia

Rates of palaeo-dust deposition have been shown in a number of studies to track environmental variability and land use change. However, globally there is still a paucity of records which record changing rates of dust output through time. Argentina’s Altiplano represents an ideal setting to examine dust deposition as it is positioned between the hyper-arid Atacama Desert to the west and the subtropical lowlands to the east. The Altiplano experiences a strongly seasonal climate, being influenced by the easterly trade winds during the winter and the Chaco low during the summer. As a result, records from this location are well placed to record changes in the strength or position of these synoptic features through time. In addition this region has a long and varied land-use history which includes pre-Inca agriculture, Spanish colonization and significant recent land –clearing. Here, we present the first record of dust deposition from a peat core extracted from the Altiplano of northern Argentina. A 60 cm core was collected from an ombrotrophic peat bog located at ~4300 m a.s.l. on the eastern cordillera of Santa Victoria province bordering the lowlands.  Dust and volcanic deposition in the core are reconstructed based on loss on ignition and high resolution major and trace element data produced by the ITRAX core scanner, while the core chronology is based on 14C AMS and 210Pb. Spanning ~4000 years, the core contains four distinct periods of mineral accumulation representing separate periods of dust deposition, the bottom of which is probably associated with the transition of the bog from a mineralogenic to an ombrotrophic state. In addition, the core provides a record of significant volcanic events. The most recent period of high dust deposition coincides with the Little Ice Age, suggesting changes in climate have driven increased dust emissions at this time. Alternatively, however, it also coincides with the arrival of the Spanish colonists in the region; implying increased dust deposition could also result from cultural change which in turn has driven land use change. Overall the studied core demonstrates that dust emissions in the region have varied significantly over the last 4000 years seemingly in response to both climate variability and potentially human activity.