SEDIMENTARY DOSIMETRY FOR ESR DATING AT SARADJ-CHUKO GROTTO: A CAVE IN A LAVA TUBE IN THE NORTH-CENTRAL CAUCASUS, RUSSIA

Saradj-Chuko Grotto lies at 934 m amsl and ~ 30 m above the Saradj-Chuko (Fanduko) River, a tributary to the Кишпек (Baksan) River in Kabardino-Balkaria, between Europe's highest volcanic peaks, Elbrus and Kazbek. The cave sits in Lower Chegem Formation rhyolitic ignimbrites between the Laba-Malka monoclinal uplift and Terek-Caspian Trough. Locally, Baksan (Zayukovo) obsidian occurs in pyroclastic bombs and fluvial sediment. Opening to the southeast, the cave lies 6 km from local obsidian sources. Found in 2016, Saradj-Chuko Grotto has 11 geoarchaeological horizons containing deposits from Anthropocene to Middle Paleolithic (MP). Layer 6A is a grey clay-rich silty sand, but Layer 6B has ignimbrite and tuff pebbles in a dark brown to orangy-brown clay-rich sandy silt that has some organic materials with secondary Fe-hydroxides. Both Layers 6A and 6B have yielded Mousterian (MP) laminar obsidian artefacts made mainly on Baksan obsidian and very rarely on flint. Most artefacts are laminar flakes, but Levallois points, blades, and scrapers do occur, many with tool-thinning. The assemblage is most similar to the early MP assemblages found in the NE Caucasus and Georgia, and to the Zagros Mousterian in Armenia, Azerbaijan, and Iran. Layer 6B (~ 200 artefacts/m²) has an active Neanderthal habitation with obsidian tool production. Layer 6B has yielded Сapra caucasica, Cervus elaphus, Bison sp., Ovis orientalis, Capreolus, rare Equus, Rupicapra, and small carnivores, some with traces of heating. Layer 6B formed under interglacial climates when diverse hazel-elm-hornbeam-oak closed forests grew near the cave. Since ESR can date teeth from 10-30 ka to 2-4 Ma with 2-5% uncertainty, 10 mammalian teeth and > 50 sediment samples were collected in 2018 to date the Middle Paleolithic layers.To measure volumetrically averaged sedimentary dose rates, sediment samples from all layers were analyzed by NAA. Cosmic dose rates were calculated by a ramped box model using paleocover data.