Precious-metal distribution and fluid-inclusion petrography of the Elatsite porphyry copper deposit, Bulgaria

摘要: The Elatsite porphyry copper deposit occurs in an island-arc setting hosted by Late Cretaceous monzonitic-monzodioritic stocks which were emplaced into Precambrian-Cambrian phyllites. Trace element data of the intrusive rocks suggest that they are I-type volcanic arc granitoids. Two main ore mineral assemblages distinguished: (1) magnetite–bornite–chalcopyrite, and (2) chalcopyrite–pyrite. first one is linked to potassic-propylitic, second phyllic-argillic alteration. Minor minerals hematite, molybdenite, sphalerite, pyrrhotite, marcasite, hessite, solid solutions linnaeite–siegenite–carrollite, tetrahedrite–tennantite, clausthalite–galena, gold–electrum merenskyite–moncheite. Precious-metal contents relatively high throughout but Au, Pd Pt concentrated more strongly magnetite–bornite–chalcopyrite assemblage. Average grades Ag, calculated for 0.33% Cu body 0.96, 0.19, 0.007 0.002 g/t respectively. Analyses flotation concentrates revealed 25.6% Cu, 33.0, 13.6, 0.72 0.15 mineralisation at took place pressures 120 300 bar, corresponding depths formation 1 3 km under hydrostatic conditions. precious metals probably transported jointly as chloride complexes highly saline magmatic-hydrothermal solutions. fluids had temperatures 340 >700 °C salinities 28 64% NaCl, mixed with meteoric water.