Holocene vegetational and climatic history inferred from palaeopalynological-palaeoecological studies in northwestern Argentina.

SCHITTEK, K., FLORES, F.F., MORALES, M.R., OXMAN, B., RUTHSATZ, B., SANCHEZ, A.C., SPERANZA, F., TORRES, G.R. & LUPO, L.C.

Bonn, Alemania

Congreso; International conferences in paleobotany and palynology, the 12th; 2008

Universidad de Bonn, Alemania y Organizacion de paleobotanicos y palinologicos alemanes, bajo el auspicio de Arbeitskreis für Palaeobotanik und Palynologie.

The study area comprises palaeoecological investigations performed in lakes, peatlands, river-bed profiles, present time pollen transects and archaeological sites in the highlands of Jujuy province and the lowlands of Chaco province, Argentina. The climatic regime is semiarid to subarid, with predominantly summer precipitation. The study area is at the cross-roads of moisture laden summer air masses originating over the Amazon basin to the east and much drier winter air masses originating westwards over the Pacific Ocean. The source and duration of moist air masses is influenced by El Niño Southern Oscillations1. The study work focusses on 3 sectors: 1- Northeastern humid Puna, 2- Southwestern arid Puna and 3- Chaco. Altitudinal vegetation variations are observed between 4500 and 600 masl (High-Andean, Puna, Prepuna, Yungas and Chaco vegetation). The Puna shrub steppe occurs between 3600 and 4000 masl, the High Andean herbaceous steppe with zonal units like cushion mire, riparian and rocky surface vegetation.2 Objectives: There still is scarce evidence in northern Argentina about landscape evolution and human use of the landscape during the Holocene. Interdisciplinary research was performed in order to reconstruct the palaeoenvironments during the Holocene at different time-scales in the Argentine Andes, recently expanding to Chaco area. Our objective is to contribute to the discussion about natural environmental changes and anthropogenic influences in Andean ecosystems applying multi-proxy analysis. Database: Pollen atlas, modern pollen rain analysis. Systematic sampling was performed for surface pollen rain in 3 sectors. The lab techniques are standard for quaternary pollen, and pollen counting, diagrams and statistical analyses were completed with the Tilia Graph program.  Cores and river-bed profile samples are investigated applying multi-proxy methods (pollen, macrofossiles, charcoal, diatoms, sediments) at different time-scales.