Andesite and obsidian accessibility and distribution during the Holocene in north-west Santa Cruz province (south-central Patagonia), Argentina

This paper discusses different aspects related to the andesite and obsidian availability and circulation routes in different moments of the occupation sequence in the Pueyrredón-Posadas-Salitroso (PPS) Lake Basin in the north, and the Burmeister-Belgrano (BB) Lake Basin to the south (north-west Santa Cruz province, Argentinian Patagonia). The distribution of raw materials - both in space and time - allows us to assert that potential regional circulation routes would have been affected differentially by the palaeolakes present from the Pleistocene up until the mid-Holocene. We are taking into account three sites: Cueva Milodón Norte 1 (CMN1), located in the northeast coast of the Pueyrredón Lake, Cerro de los Indios 1 (CI1) (central portion of the PPS Basin), and Cerro Casa de Piedra 7 (CCP7) (near to the Burmeister Lake). This investigation considers six periods, based on the calibrated ranges from 73 radiocarbon dates: 17 from CI1, 14 from CMN1, and 42 radiocarbon dates from CCP7. As a result of this analysis we can conclude that, in sites with a higher density of occupation such as CI1 and CCP7, the use of obsidian (non-local rock) and andesite or basalt did not vary over time. In the case of CMN1, access to the sources of these raw materials varied according to the presence of large bodies of water, although it does not seem to have influenced the procurement of these rocks