USING PLEISTOCENE PALEOSOLS TO RECONSTRUCT PALEOENVIRONMENTS IN THE HRAZDAN VALLEY OF THE SOUTHERN CAUCASUS OF ARMENIA

The Hrazdan Valley of central Armenia contains several Lower to Middle Paleolithic archaeological sites and is situated at the intersection of Africa, Europe, and Asia making it a critical area to understand the technological evolution of stone tool production and hominin population dynamics. Two related projects are studying this region, the Hrazdan Gorge Palaeolithic Project (HGPP) and the Pleistocene Archaeology, Geochronology and Environment of the Southern Caucasus (PAGES), in order to better understand the environmental and climatic context of this region. Preliminary data indicate that this region has a complex history of repeated basin infill comprised of sediments, volcaniclastics, and lava, and channel incision by the Hrazdan River, which drains Lake Sevan, one of the largest freshwater and high-altitude lakes in Eurasia. These ongoing projects are mapping and characterizing the lavas erupted from the western Gegham Range that sandwich fluvial and lacustrine sediments and preserve Lower to Middle Paleolithic archaeological sites. Paleosols are crucial to the paleoenvironmental reconstruction and have been identified at six sites: Solak, Alapars, Bird Farm, Music House, and Ptghni, as well as the archaeological site of Nor Geghi where several thousand obsidian artifacts have been excavated. ⁴⁰Ar/³⁹Ar dating for all sites other than Bird Farm and Nor Geghi is ongoing. The latter is dated to between 440 and 308 ka and contains four paleo-Inceptisols formed on the paleo-floodplain of the Hrazdan River. These paleosols are moderately well developed with carbonate and FeMn rhizoliths, subangular blocky ped structure, and zones of clay accumulation (Bt horizons) and in some cases eluvial horizons. Ongoing micromorphology, bulk geochemistry, stable isotopic, and grain size analysis for the 23 total paleosols identified in the Hrzadan Valley will provide valuable paleoenvironmental context for hominins occupying this landscape and the first high-resolution paleoenvironmental reconstruction for the Pleistocene in this region.