Polyelemental (with As, Sn, V, Bi, Ag, Te, Ge, Se, etc.) mineralizations in the Asarel porphyry copper deposit (Bulgaria)

Abstract

The Panagjuri sle ore zone which occupies the central pari of the Srednogorie melall cgm ic zone is known to host two major types of copper deposits formed durirg the Late Crdzccot;s: copper pyrite (volca nog enic) and porphyry copper (pluton cgeni c). The former are of much more varied mineral and met al composition th an the latter. Generally, the two types are quite near each other both in space an d in time of their formation, and in so me cases they are even found together .The Asarel porphyry copper ores occur in secondary quartzites developed in Late Cretaceous medium-acid volcanic an d subvolcanic rocks . The main ore mineral paragenesis is dominated by pyrite and chalcopyrite . It also includes the minerals of polyelemental composition . A lead-zinc mineralization of minor occurrence has been formed later .• At the beginning of the ore-forming process, small oval inclusions of pyrrhotite, chalcopyrite, native gold, ca laverite (?) and bor nite were formed in pyrite. This mineral assembl <ge, whi ch we ca ll copper-gold-tel lurium partial paragenesis, had been formed in a reducing environment. Another partial paragenesis-arsenic-t in -bi smuth-tellurium (with lead, vanadi um and germanium)-was formed in a med i urn of higher oxidation pot en ti al. I t occurs as small impregnations and vein! ets consisl)ng of enargit e, digenite, gold fieldite , aikinitf, colusite, <rs€nosulvanite, sulvanite, ga len a and wi IIi cheni I e. The chemical for mul11s of some mineral s, based on microprobe analyses, are as foll ows: ai ki ni I e (Cu o.9 0 Fe 0 _ 0 g ) 0 _ 9 oPb 0 _ 0 sBi o.9sS 3 ' 14 , gal dfiel di le (Cu 11 • 7 2 Zn 0 . 10 F e 0 . 10 ) 11 _, 2 (Te 1.0 1 As1.1 1 Bi o. 2 9