Holocene paleoenvironments from the Tafí Valley (northwest Argentina) through morpho-sedimentary and geoarchaeological record analyses

Abstract

The Tafí Valley is a small basin located in the northern sector of the Sierras Pampeanas in Northwest Argentina. The geomorphological studies made in the area showed the presence of very representative Holocene morpho-sedimentary records, which are useful for regional paleoenvironmental reconstruction. The study of the main slope accumulations, fluvial terraces, and alluvial fans provided several geoarchaeological records, paleontological remains, and volcanic ash layers as well as radiocarbon and thermoluminescence datings. We used all these data to construct a paleoenvironmental sequence. This sequence was also accompanied by some previously obtained data and detailed geomorphological cartography. Four morphosedimentary units were identified. The oldest unit (H1) comprises the Early and Middle Holocene (ca. 13000 - ca. 4200 BP). It could be divided into two sub-stages (H1a and H1b), with different environmental signs. They appear separated by a tephra layer (V0) dated ca. 10000 BP. The end of sub-stage H1b is limited by another ash layer (V1) dated ca. 4200 BP. By that time, an incision process had already started separating this substage from the next one. Stage H2 spans from ca. 4200 BP to ca. 630 BP, and extends vastly throughout the valley. It was possible to identify several features of human settlements (Tafí and Santa María Cultures) corresponding to that period. The characteristics of the sediments indicate a strong anthropogenic influence during its formation. Finally, two minor units (H3 and H4) cover the last centuries of the Holocene sequence, separated by incision phases. The Holocene set was related to the regional and global paleoclimatic evolution.