Depositional and post-depositional processes in human-modified cave contexts of west-central Patagonia (Southernmost South America)

Abstract

This contribution aims to analyse depositional and post-depositional processes from two volcanic caves (Baño Nuevo 1 and Cueva de la Vieja) from west-central Patagonia, in order to evaluate if natural and anthropogenic processes recorded therein are representative of basin-scale processes. For this purpose, geomorphological, sedimentological, micromorphological, petrographic, magnetic, paleontological and archaeological data are integrated. Results allow correlating the Baño Nuevo 1 and Cueva de la Vieja sequences, comprising a record of ca. 19,000 years. In the first place, the distinction between endogenous and exogenous detritus input, mainly recorded by the mineralogy and lithotypes, provided environmental data related to landscape stability (i.e., vegetation cover). The latter, in turn, could be interpreted as part of a complex feedback associated with major climatic changes. On the other hand, cave weathering rates observed through vertical variations of the gravel fraction, along with bioactivity recorded by percentages of Total Organic Carbon and micromorphological analysis, provided constraints on temperature and/or humidity, being in agreement with available regional information. Main regional palaeoenvironmental changes observed in the sequences were the deglaciation processes, the Pleistocene-Holocene transition, the Holocene amelioration and the Anthropocene. Although no distinctive variations were observed within Holocene deposits, biological processes mainly resultant of the human occupations could have obliterated such finer scale distinctions.