Element contents and organic matter-element relationship of the Tertiary oil shale deposits in northwest Anatolia, Turkey

Major-element and trace-element content of oil shales in northwest Anatolia and their enrichment with respect to average shale have been investigated as well as the relationship between the total organic carbon (TOC) and different elements and the correlation between the different fields. The trace-element contents of the oil shales are generally similar, although the concentrations of some elements, such as As, B, Ba, Cr, Hg, Mo, Ni, and V, show a few differences. The contents of Ag, Au, B, Ba, Hg, Pb, Sb, Sn, Th, V, and Zn in the oil shales arc lower than those of average shale. Only the Re concentration in all of the fields studied is greater than that in average shale. On the basis of the low-enrichment factors (<1) calculated for the trace elements, depletion of As, B, Ba, Cr, Hg, Ni, Pb, Sb, Sn, and Th in the Bahcecik field, Hg and Sn in the Golpazari field, and Sb in the Himmetoglu field has been detected with respect to the average shale. Re shows the largest trace-element enrichment in all of the fields. In comparison to other elements, As, Mo, Ni, Se, Sr, U, Co, and Cr have higher enrichment values. The largest element enrichments have been generally observed in the Beypazari and Seyitomer fields, whereas the lowest enrichments are typical of the Bahcecik field. Regarding the correlations between the elements and TOC, positive correlations with TOC at a significance level of p <= 0.05 or p <= 0.01 have been obtained as follows: Se in five fields, Cd in four fields, U in three fields, Th, Mo, Cu, Co, S, and Re in two fields, and Sb, P, Ca, K, Hg, Fe, and Zn in one of the fields. On the basis of the results from cluster analysis Se, U, and Mo in four fields, Th and Re in three fields, P and Ba in two fields., and Cd, K, V, Sr, Ca, Mn, Mg, B, and Ti in one of the fields comprise a group with TOC.