163-A 1.4

An important rain-shadow on the lee side of the southern Andes,in northwestern Argentina, extends along the Valles Calchaquíes (Eastern Cordillera). The onset of desertification is assumed to have existed ~24-15 Ma based on limited sedimentological, paleontological and isotopic evidence. However, a more accurate picture of the past climatic trends is lacking mainly because quantitative analyses based on the fossil record are rarely conducted using climatically key-sensitive species. In this project we aim at estimating climatic conditions and plant richness for the late Miocene-Pliocene based on the study and bioclimatic analysis of terrestrially derived spore-pollen assemblages preserved in the Palo Pintado and San Felipe Formations (Salta Province, NW Argentina) for which we will establish a precise chronostratigraphic scheme. We also aim at collaborating with a group of German researchers from the Institute of Earth and Environmental Science sin Potsdam who has long been contributing to the knowledge of the Tectonics, topography and climate of the southern central Andes. Understanding the timing of the establishment of this tectonically-induced dry region is crucial for documenting both the onset and the cause of the aridity. The multidisciplinary nature of this project will result in bidirectional transfer of knowledge between Argentina and Germany. Both countries will greatly benefit from exchanges and will enhance the capacity of each counterpart in future projects, together or with others.