T79 Undergraduate Research Talks: The Next Step in Student Research Projects

Sunday, 27 October 2013
1:00 PM - 5:00 PM
Room 405

GEOARCHAEOLOGY OF THE BAGRATASHEN 1 SITE, NORTHERN ARMENIA: SOIL MINERAL AND CHEMICAL ASSESSMENT

Paper number: T79-16
Program: Technical Sessions
Time: 4:45 PM – 5:00 PM

Authors

Abstract

Soil formation assessment of this Middle Paleolithic site includes x-ray diffraction, pH, and sulfate content analysis of samples taken during archaeological excavations in 2011. Cultural materials at Bagratashen 1 lie within an alluvial terrace of the Debed River. On-site work included mapping of the terrace in which the site resides, and detailed description and sampling of soil profiles in archaeological excavation trenches. The area mapped with differential GPS is approximately 87,000 m2 and includes the site, the terrace, and modern drainages that cut the terrace. Profile descriptions include color, texture, structure, and horizonation. Soils are quartz-rich and contain sulfate accumulations that were historically mined for gypsum.

Laboratory analyses of a composite 4-m profile through the terrace and cultural deposits reveal the bulk mineralogy and chemistry of the soils and paleosols. Soils are basic, with all but the modern A horizon falling between pH 8.4 and 9. Though initial XRD results indicated uncertain mineralogy and low crystallinity, new XRD and chemical data confirm the soil and paleosols' quartz sand parent material and variable accumulations of calcite. Sulfate is present throughout the profile, with the lowest paleosol containing the heaviest sulfate accumulations, although crystalline gypsum remains unidentifiable in XRD spectra.

Our work at this site is part of the Lori Depression Paleoanthropology Project, which aims to elucidate Lower and Middle Paleolithic adaptations in the Southern Caucasus region. These results have implications for the physical and chemical interaction of soil precipitates and artifacts, as well as the relative timing of archaeological site-use, sediment deposition, and soil formation. When combined with planned OSL dating and stable isotope chemistry, this profile will serve as a detailed paleoclimate chronology specific to the Middle Paleolithic at Bagratashen 1.