234 Economic Geology (Posters)

Wednesday, 31 October 2007
1:30 PM - 5:30 PM

THE MINERALOGY AND GENESIS OF PRECIOUS METAL TELLURIDE DEPOSITS OF GREECE

Paper number: 234-11
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Gold-silver tellurides are hosted in several types of mineralization in Greece, mainly within two ore provinces: the Servomacedonian-Rhodope massifs (SRM) and the Attico-Cycladic metamorphic belt. Both provinces contain pre-Tertiary VMS deposits, ores related to Mesozoic-Miocene shears that were controlled by exhumation of metamorphic domes, and deposits related to Tertiary-Quaternary magmatic activity (skarn and carbonate replacement, porphyry-type, vein-type, epithermal-type). Pre-Tertiary to Tertiary shear-zone-controlled and/or metamorphosed gold mineralization in the SRM occurs in quartz veins and as a replacement-type, irregular pods and as lenses in gneisses, amphibolites, and marbles. The mineralization contains Ag-Au tellurides (hessite, petzite, sylvanite) associated with bismuth sulfosalts and tellurides (joseite-A, joseite-B, pilsenite), native bismuth and native gold. In the Attico-Cycladic Massif, orogenic quartz veins hosted in metamorphic rocks of the Blueschist Unit at Panormos Bay (Tinos Island) and Kallianou area (S. Evia Island) contain electrum, Au-Ag tellurides and silver sulfotellurides.

Au-Ag-tellurides occur in Tertiary porphyry-type and precious metal epithermal assemblages in northern Greece within calcalkaline to alkaline magmatic rocks. The syenite-hosted Skouries porphyry gold-PGE deposit contains Au-Ag tellurides, native gold, merenskyite, and tellurobismuthite. In the dacitic andesite- and monzonite-hosted Pagoni Rachi (W. Thrace) and Fakos (Limnos Island) porphyry Cu±Mo prospects, hessite, stützite, petzite, and electrum are spatially associated with Bi-sulfosalts, base metal sulfides and tennantite in late-stage carbonate-quartz veins. The high-intermediate sulfidation epithermal assemblages at various locations in western Thrace contain precious metal tellurides, Bi-sulfosalts and Bi-tellurides that formed under oxidizing conditions. Submarine epithermal mineralization at Profitis Ilias (Milos Island), which is genetically related to an Upper Pliocene rhyodacite cryptodome, contains hessite, petzite and native gold/electrum. The close spatial relationship among Au-Ag-tellurides, Bi-tellurides and Bi-sulfosalts in deposits that formed at T > 300oC suggests that these minerals were derived from metallic melts.