Obsidians circulation and use in the northern coast of San Jorge Gulf (Chubut province, Argentina) during the Late Holocene: first results

Resumen:
This paper presents the results of the geochemical (ED-XRF) and technological analysis of 21 obsidian artifacts from the north coast of San Jorge Gulf. Five chemical groups representing four different secondary sources located between 435 and 280 km away from the study area were identified. Three sources have a known location: Pampa del Asador (PSA1) to the South, and Sacanana (S1) and Telsen/Sierra Negra (T/SN 1 y T/SN2) to the North. The fourth, Meseta de Somuncura (MS), still unknown, is probably also located to the North. Two radiocarbon dates -1950 14C AP and 1640 14C AP- indicate that obsidians circulated at least since the Late Holocene. In the lithic samples, obsidians present low frequency, in contrast to the abundant local rocks (silica, petrified wood, and chalcedony), of excellent flaking quality. Artifacts are mainly small, half of them preserve the cortex, and flakes are slightly more frequent than blades. Artifacts include debris, tools, and one core. Evidence suggests the exploitation of small pebbles and the presence of all the lithic production stages at the sites. These results are discussed and compared with those of other obsidian assemblages from central Argentinian Patagonia.

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