FINE GOLD IN THE BOTTOM DEPOSITS OF THE DNIEPER SUBMARINE VALLEY (THE NW BLACK SEA SHELF): PROSPECTS, MORPHOLOGY, GENESIS

Abstract

The area of the Dnieper Trench is the most promising for thin and fine gold among the manifested manifestations of the northwest shelf of the Black Sea. Favorable hydrological and sedimentation conditions, the presence of paleo coastal stripes, geological structure and neotectonic development of the area cause the presence of the largest manifestation of gold mineralization in the area among those dis covered to date. In addition, the area of the Dnieper Trench is interesting for other promising minerals, including hydrocarbons and peloids. More than 500 sediment samples were collected on a 2.4 ´ 0.8 km grid vibrating piston tube. A granulometric analysis was performed on all samples, mineralogical analysis of the heavy fraction was made on a part of the samples. Samples were enriched on screw gateways. The content of gold in the primary samples and concentrates was determined by several methods — atomic adsorption, assay, amalgamation and the like. The morphology, mineralogical features and com position of the gold were studied using a binocular optical microscope and a scanning electron microscope with an integrated electron probe system. The results of investigations of the forms, surface and composition of gold, which showed the polygenic terrigenous autogenous character of gold in deposits, are presented. Holocene shelf deposits are more enriched in gold than the Upper Pleistocene, which were formed under conditions of the Paleo Dnieper estuary complex. The accumulation of gold in shelf deposits is caused not only by terrigenous runoff, but also by the imposition of purely marine sedimentation processes. Offshore shelf facies deposits may be conducive to the accumulation of fine gold at high concentrations. The manifestations of gold mineralization in the Upper Pleistocene Holocene bottom sediments of the Dnipro Trench provide the basis for predicting the complex use of this section of shelf in the case of concomitant gold production.

Keywords

• fine gold
• nw black sea shelf
• dnieper submarine valley
• morphology of gold