A 3,300 yr high-resolutioncushion peatlandrecord of climatic and environmental change as recorded in stable isotope proxies from Oxychloe peat (NW Argentina, Jujuy)

SEBASTIAN KOCK; KARSTEN SCHITECK; LILIANA C. LUPO; FRANK SCHÄBITZ

Conferencia; 4th Southern Deserts Conference; 2014

Archivesforpalaeoenvironmental investigationsin the high Andesare very rare and wide scattered.Well-suited for palaeoecological multi-proxy studies and less investigated arehigh-altitude cushion peatlands. The advantages of these geoarchives are their comparability with climatic gradients, their high accumulation rates and the high quality of their peat deposits, which ensures precisely radiocarbon-datings.Beside their keyrole for palaeoenvironmental changes,cushion peatlands represents pastureland and are important water reservoirs (Schittek et al., 2012).Because of increasing grazing intensity the sensitive ecosystems get endanger and need to be protected. We present first results of a multi-proxy approach for the reconstruction of the Holocene climatic and environmental history based on high-altitude peat records. The study area is located in the high Andes of NW Argentina (Jujuy province). The study site (24° 09´ 00.2"S, 66°24´ 01.8"W) represents an extended cushionpeatland, located at an altitude of 4,350 meters, close to the Tuzgle volcano. An 8 m-peat core was extracted by percussion drilling in December 2012. The age depth model is based on 20 AMS dates and reveals the climatic and environmental history of the past 8000 cal years. The dominant peat-accumulating species of the peatland is the Juncaceae Oxychloe andina. We have extracted cellulose fromOxychloe andinaplant parts separated by sieving at 200 μm from the bulk peat sample. The cellulose extraction is based on an improved method starting with sample bleaching with sodium chlorite and followed by cellulose dissolution with cuprammonium([Cu(NH3)4](OH)2) solution (CUAM) and re-precipitation by using sulphuric acid (Wissel et al., 2008). This extraction has the advantage compared toconventional methods (e.g. Ménot and Burns, 2001), that contamination of Oxychloecellulose with small amounts of minerogenic matter like silt and clay could be completely excluded. The separated cellulose is highly homogenous and free of inorganic contaminants ensuring isotopic homogeneity when using small sample amounts for isotope measurements (Moschen et al., 2009). Here we present the results from the first 3m ofthe 8 m master core, showingoscillations in high-resolution stable 18Oand 13Cisotopesover the past ~3300 yr.