Before and after of the Hudson volcano eruption: paleoecological approach by multidisciplinary analysis of camelid coprolites

Abstract

The earliest human occupation evidence in the Pueyrredón-Posadas lake basin (SantaCruz, Argentina) is dated to ca. 8,600 cal BP. However, there are no archaeologicalrecords between ca. 8,100-7,700 cal BP. This hiatus coincides with the H1 Hudsonvolcano eruption about 7,900 cal BP, as indicated by the presence of tephra in thestratigraphy of two archaeological sites in the area. This eruption was recorded as thelargest in the southern of the Andes during the post glacial period. The proposedhypothesis is that this event influenced the permanence of camelids and the humanpopulation in this region. Camelids were the main resource of hunter-gathererpopulations of Patagonia during the Holocene. At regional scale, archaeological studiesshowed variations in lithic technology, styles of projectile points, instrument size androck art among the sets recorded before and after the H1 eruption. The hypothesis willbe tested in part through a multiproxy analysis of camelid coprolites collected fromlayers immediately below and above the Hudson ash level at the Cueva Milodón Norte 1site (47.30ºS 71.89ºW). Silicophytoliths, pollen, plant remains, stable isotopes (C and N)and aDNA of coprolites will be analyzed to evaluate changes in the frequency andabundance of these proxies that may be associated with paleodiet, seasonality in the useof the site before and after the H1 eruption. In the present work, results ofsilicophytoliths, pollen and plant remains in current guanaco feaces collected near thesite are presented as a reference model for the coprolites analyses. Forest taxa such as,Nothofagus spp. (Nothofagaceae) and steppe taxa such as, Caryophyllaceae,Cyperaceae, Poa ligularis (Poaceae subf. Pooideae), Empetrum rubrum (Empetraceae),Mulinum spinosum (Apiaceae), among others, were identified. These results willcontribute to interpreting the changes and interactions in pre- and post-eruptionscenarios.