Geochemistry of trace element in carbonaceous sediments from recent seas and oceans

Abstract

Published and original data on the contents of 50 elements in carbonaceous sediments from seas (Black, Baltic, and Caspian) and fertile oceanic shelves (shelves of Namibia, Peru, Chile, and California) are generalized. The comparison of these results with the average composition of ancient carbonaceous shales reveals both similarities and differences in the distribution of indicator trace elements (Re, Hg, Se, Ag, Cd, Tl, U, Mo, As, Ni, and Zn). Correlation coefficients were analyzed to determine the characteristic element associations. It is established that oceanic carbonaceous sediments are closer in composition to carbonaceous shales than their marine analogues, which is related to the differences in sedimentation conditions, including hydrological, hydrochemical, and biogeochemical factors. The role of anoxic environment in the accumulation of chalcophile elements in sediments is estimated. The comparison of the contents of some mobile trace elements in oceanic water and carbonaceous sediments of modern oceans demonstrates that the water composition affects the composition of carbonaceous sediments and can be used for deciphering the composition of ancient ocean water.