Features of Chromite-Containing Placers in the Lukoyanov Placer District (Nizhny Novgorod Region) and Their Formation Conditions

Chromites are a common component of the heavy fraction of sedimentary cover deposits in the platform areas, and their contents usually do not exceed some percents. Commonly, economic chromite placers are formed in vicinity of bedrock sources. Within the Lukoyanov placer district (Nizhny Novgorod region), high chromite contents (up to 100 kg/m3) were found in Middle Jurassic complex coastal-marine rare metal–titanium placers of economic importance. Placer bodies are localized on the periphery of domes in the sedimentary cover. The placers can be sourced from Upper Permian and Lower Jurassic rocks, which were eroded in the zone of positive tectonic structures of the cover and platform basement and within the adjacent land. The revealed patterns can serve as a basis for forecasting similar deposits within promising areas.