Precious Metals in the Holocene Sediments of the Chukchi Sea

Abstract

––We studied the distribution of gold, silver, and platinum group elements (Pd, Pt, Rh, Ir, and Ru) in two bottom sediment cores of the southern Chukchi Sea. It is shown that the Holocene pelite–silty sediments with an age of up to 4.0 ka BP are significantly enriched in these elements, except for Ru and Rh, relative to their clarkes. Native silver minerals were found in all samples by probe microanalysis, whereas gold minerals were revealed only in the surface layer of the sediment core closest to the Chukchi Sea coast. Multicomponent statistical analysis of the chemical composition and grain size of the sediments and the content of organic matter in them has led to the conclusion about the accumulation of clastogenic and chemogenic forms of precious metals. The abnormally high content of gold (0.3 ppm) in the recent sediments near the Chukchi Peninsula coast might be due to its additional removal from the continent as a result of the placer mining there.