THERMODYNAMIC INVESTIGATION OF PEDOGENIC MINERALS AT THE PTGHAVAN 4 SITE, NORTHERN ARMENIA

Precipitate masses found in the paleosols of Northern Armenia's Debed River Valley were formerly thought to consist of gypsum; however, powder x-ray diffraction analysis has shown that similar precipitates at two Paleolithic sites (Bagratashen 1 and Haghtanakh 3) are predominantly composed of the phosphate alternative, brushite. The aim of our current research is to determine the thermodynamic and geologic processes which would favor brushite precipitation, and confirm the regional nature of these soil relationships through analysis of samples from a third site, Ptghavan 4.

Our work at these three sites is part of the Lori Depression Paleoanthropology Project, which aims to understand Lower Paleolithic adaptations in this region. Soil laboratory analyses will continue to address the bulk mineralogy and chemistry of deposits at all three sites, and attend to the relationship between hydrology and pedogenesis. Overall our findings will inform the landscape context and environment of archaeological occupation. Increased understanding of the pedo-chemical environment in particular, via mineral thermodynamics, elucidates the potential for bone preservation in these site contexts.