ОСОБЕННОСТИ РАССЕЯННОЙ МИНЕРАЛИЗАЦИИ ДУКАТСКОГО РУДНОГО РАЙОНА (СЕВЕРО-ВОСТОК РОССИИ)

Abstract

Mineral and chemical composition, Rb-Sr and Sm-Nd isotopic systems of microaggregates of the postmag-matic disseminated multimetal mineralization, country Ascold rhyolites (Askoldinskaya series) and adularia suggest that the gold-silver ore bodies of Dukat deposit were formed in the upper crust magmatic-hydrothermal system under action of a mantle diapir folding in the rifting geodynamic conditions. The postmagmatic microaggregates are enriched in chalcophile elements and contain anatase-chlorite-bitumen, anatase-mica-jarozite mineral associations and quartz-feldspar-chlorite microaggregates with fine grains and nanoparticles of native Pb, Sn, Cu, Zn, Ag, their alloys, sulfides, oxides. These finely dispersed aggregates show sNd values from -0.1 to +0.8, Th/La ratio from 0.1 to 0.15, and Ba/Nb from < 0.05 to 2. The latter assumes postmagmatic mineral-forming from small volumes of the highly differentiated melt separated from basic source with geochemical parameters close to the mantle regions - HIMU OBI, EMII OBI sources. The same three parameters of Ascold rhyolites vary from-0.1 to+3.1, from 0.2 to 0.7 and from 6.8 to 64.7, respectively; they suggest that acid magma was formed at the partial upper crust melting due to heat of a mantle diapir and differentially basic melts with geochemical parameters close to depleted mantle - MORB sources. Adularias of Ducat ore bodies show eNd, Th/La and Ba/Nb values within ranges from +1.1 to +5.9, 0.04 to 0.15, and > 100, respectively. These values suggest that the ore-bearing hydrothermal solutions could borrow some components from the country Ascold rhyolites and mineralized postmagmatic fluids.