Local Factors of the Formation of Coastal-Marine Rare Metal–Titanium Placers

Local factors of the formation of coastal-marine rare metal–titanium placers were analyzed for creating the prospecting-oriented geological-dynamic model that allows to predict the prospects of rare metal–titanium placer mineralization. Their influence on the structure, composition, localization of placer concentrations within sedimentation basins, and dynamic interaction during the formation of productive sediments was investigated. Based on the works of previous researchers devoted to the historical-geological and regional tectonic factors controlling the formation of these placers, we developed a qualitative model of the formation of placer concentrations in different rank areas (districts, clusters, fields, and specified placer bodies), which can serve as a basis for the creation of prospecting-orientated model of the deposit and planning the exploration and evaluation work. Among the factors controlling the formation of placers, we can identify: hydrodynamic processes characterizing the types and mechanisms of placer concentrations (littoral and sublittoral) within the dynamically active coastal zone; lithodynamic processes depending on the abrasion-accumulative setting of the coast and parameters of the alongshore sediment flow; structural-dynamic processes controlling the formation of economically significant productive deposits and their localization; and the transgressive-regressive setting of a basin that determines the structure of placer bodies and their transformation at the postsedimentary stage. Large economically significant rare metal–titanium placer deposits are only formed under conditions of a joint realization of the positive potential of these factors. The developed qualitative model can serve as a basis for digitizing the forecasting of rare metal–titanium placer mineralization.