Metal-organic matter interactions in the formation of an oil shale deposit

Abstract

An attempt was made to distinguish metal-organic matter interactions in two types of sulfate-reducing environments, mild (MR) and strong sulfate-reducing (SR), in the Aleksinac oil shale deposit (Oligocene-Miocene). Samples from the MR group show (all differences are statistically highly significant): lower organic matter content, compared with the SR group, higher O/C and N/C ratios (0.147 ± 0.054 and 0.041 ± 0.014, respectively, compared with 0.125 ± 0.031 and 0.035 ± 0.008, respectively, in the SR group), and higher Cu, Zn, Pb, Cr, Mo and Co contents than in the SR group. Statistically significant correlations between metals, the N/C and the SiO2/Al2O3 ratio in the MR group only, represent a record of highly interdependent processes of organic-metal-silicate interactions which had been occurring in the mild sulfate-reducing conditions during oil shale formation.