Archaeological ash deposits and soils formed on ash in the south of the East European Plain

摘要

Ash as an anthropogenic substrate is widely found at archaeological sites in the south of the East European Plain. Investigations of archaeological ashes, the results of which are presented here, have been conducted in three regions that differ in climate and extent of forest cover (from 29 to 1.5%): 1) typical forest-steppe; 2) piedmont forest-steppe with islands of groves; 3) steppe, almost woodless landscapes. Using spectrometry and X-ray analysis, the present study investigates the chemical composition of ancient ash and ash experimentally produced from different sorts of fuel, as well as the geochemistry of soils developed on ash deposits. For ashing, 25 samples of plants that potentially might have been used as fuel were selected, as well as dung from cattle and horses. Using the geometric mean values of concentrations of diagnostic elements, a formula was proposed for evaluating the pedogenetic transformation of ash, which is based on the ratio of accumulation elements (Cu, As, SiO2, Al2O3 and Pb) and dispersion elements (Sr, Ca, Co, Mg and Na2O). The procedure makes it possible to date the pedogenetically transformed ash through the stable associations of chemical elements diagnostic of the geochemical accumulation and dispersion in the soils formed on ash. Geochemical criteria were established for identifying ash that results from the combustion of dung, wood or a combination of different fuels. This study opens prospects for further research into archaeological ash deposits in varying cultural, temporal and environmental conditions.