İnebolu şelfi ve kıta yamacı oksik-anoksik sedimentlerinin sedimentolojik ve jeokimyasal incelenmesi

Distribution of major, minor and trace elements in surface sediment of the continental shelf and upper slope of the Turkish continental margin of the southern Black Sea reflect the influences of discharge from the Central Anatolian rivers and oxic-anoxic conditions of the Black Sea. A narrow variety of sediment types (silty clay to silt) was obtained at eighty-five stations on the southern Black Sea shelf and upper slope and analyzed their elemental geochemistry. Concentrations of 30 major, minor and trace elements (Al, As, Ba, Ca, Ce, CI, Cr, Cu, Fe, Ga, K, Mg, Mn, Na, Nb, Ni, P, Pb, Rb, S, Sc, Si, Sr, Th, Ti, U, V, Y, Zn, Zr) were determined in all samples by X-ray flourescence. Distribution of grain size, carbonates, organic carbon and major, minor, trace elements show marked changes in the topography, hydrographic conditions and land geology of the region studied. Sediments constituted up to %48 CaC03, mainly of biogenic origin from the shell remains of benthic organisms and coccoliths. Organic carbon contents of the surface sediments (%0.34-1.77) usually reflect the prevailing primary productivities in the Black Sea although significant terrigenous influences also inferred. Grain size trends in associated with net sediment transport pathways are applied, using some commonly used grain size parameters. The pattern gives apreliminary estimation of sediment transport directions and also main depositional areas of central Black Sea shelf area. The element concentrations largely indicate the influences from the geochemical weathering of terrigenous sources on land. In comparison with the average sedimentary rocks and other modern sediments from the adjacent regions, the concentrations of As, Cr, Cu, Pb and Zn are somehow higher in the surface sediments from the southern Black Sea. This is though to reflect the possible contribution from metal-rich rocks and associated economic mineral deposits in the catchment areas of rivers which drain this part of the coast. Multivariate factor analysis of sediment geochemistry was used to identify three grouping of samples (factors) on the shelf and slope. The first factor is an aluminosilicate factor that represents detrital clastic material. The other factors comprise excess sediment discharges from western streams and anoxic deep water. Multivariate factor analyses also show that uranium concentrations in the sediment appear to be controlled by sand fraction of sediment.