О золотоносности мелководной зоны шельфа Юго-Западной Камчатки

Abstract

The materials, obtained from previous (1972-2019) studies of over 300 km of the coastal land strip in Southwestern Kamchatka and the adjoining underwater slope of the Sea of Okhotsk (in the interfluve of the Bolshaya and the Kikhchik rivers) were analyzed. Gold-rich zones (> 60 mg/m3) in the form of subparallel lenses, oriented along the sea shoreline, were identified between 6.3-30 m isobaths in the shallow marine shelf zone. The gold content of the submarine coastal slope correlated directly with the sediments of the upper coastal zone. Higher gold concentrations (up to hundreds of mg/m3) were detected in Holocene marine sediments of the shallow marine shelf in sampling intervals 0 to 2.0 m. They are mostly confined either to the upper, steepest part of the submarine slope or to the first or second terraced level. These are the areas of the most active impact, near the shorelines (modern and submerged), within which glacial and water-glacial formations are often exposed by erosion. Most of the gold concentrate halos related to ancient shorelines, the western boundary of which lies within 25-30 m isobaths, and to paleovalleys, identified by seismoacoustic profiling. In paleovalleys, flooded by the sea and buried under marine sediments, alluvial placers similar to Tikhangou in Primorsky Krai may be revealed. The most promising within the investigated territory was the area of underwater coastal slope within the Severnaya Mitoga - Utka - Khomutina interfluve, between 5.3-30 m isobaths, where concentrate halos with considerable gold concentrations from 60 to 500-1186 mg/m3 had been revealed.