Dissertation committee:
Dr Panagiotis Voudouris, Professor
Faculty of Geology and Geoenvironment, University of Athens, Greece
Dr Paul G. Spry, Professor
Department of Geological and Atmospheric Sciences, Iowa State University, USA
Dr Vasilios Melfos, Associate Professor
Faculty of Geology, Aristotle University of Thessaloniki, Greece
Dr Federica Zaccarini, Senior Scientist
Department of Applied Geosciences and Geophysics, University of Leoben, Austria
Dr Andreas Magganas, Professor
Faculty of Geology and Geoenvironment, University of Athens, Greece
Dr Konstantinos Kyriakopoulos, Professor
Faculty of Geology and Geoenvironment, University of Athens, Greece
Dr Christina Stouraiti, Assistant Professor
Faculty of Geology and Geoenvironment, University of Athens, Greece
Original Title:
Mineralogical, petrographic and geochemical study of hydrothermal alteration zones and related porphyry-epithermal mineralization at Sapes-Kirki area, NE Greece.
Translated title:
Mineralogical, petrographic and geochemical study of hydrothermal alteration zones and related porphyry-epithermal mineralization at Sapes-Kirki area, NE Greece.
Summary:
Detailed field mapping in the Sapes-Kirki area in northeastern Greece, resulted in new discoveries of porphyry-, and epithermal-style mineralization in addition to the already known Konos Hill and Pagoni Rachi prospects. Porphyry Cu-Mo-Re±Au systems and associated high/intermediate sulphidation epithermal ores are hosted in Oligocene post-collisional intermediate-to-acidic intrusives with high-K calc-alkaline affinities. The porphyry mineralization at Konos Hill, Pagoni Rachi and the newly discovered Papadokoryphi prospect, is temporally related to sodic/potassic-calcic, sodic/potassic and phyllic alteration of the host rocks, and propylitic alteration in the periphery of the systems. All three porphyry prospects are characterized by several generation of quartz stockwork veins with various amounts of magnetite, pyrite, chalcopyrite, molybdenite and native gold. High- and intermediate-sulphidation epithermal-style mineralization at Konos Hill and Pagoni Rachi is spatially associated with zunyite-alunite-APS minerals-diaspore-bearing lithocaps and underlying sericitic alteration zones, respectively, and resulted in significant overprinting of the former sodic/potassic-calcic and sodic/potassic assemblages. Enargite-colusite and tetrahedrite/tennantite-tellurides are the main metallic minerals characterizing the HS and IS epithermal ore, respectively. Mineral-chemical analyses revealed a significant presence of F ( up to 5.67 wt%) and Cl (up to 0.36 wt%) in hydrothermal biotite (phlogopite), compared to its magmatic counterpart. K- and Na-rich (orthoclase, albite to oligoclase) feldspar varieties dominate the sodic/potassic-calcic and sodic/potassic alteration assemblages respectively, while propylitic-related feldspar share a compositional range from albite to oligoclase as well. Secondary amphiboles incorporate F in their structure (up to 0.8 apfu), compared to their magmatic precursors. Epidote and chlorite do not display significant chemical variation between the various alteration styles. Rheniite is presente in both Konos Hill and Pagoni Rachi prospect. Molybdenite in both areas is extremely Re-enriched (values up to 2 wt% and 3.15 wt% respectively). Geochemical data suggest significant enrichment of porphyry-epithermal ores in several precious and critical metals including Au, Ag, Bi, Te, Se, Mo, Re, In, Sn, and V. Close correlations between Mo-Re and Au-Se, suggest the contemporaneous introduction of these metals to the ore systems. In contrast to the low gold content in the Konos Hill porphyry system, in the exposed parts of the deposit, significant gold introduction in the Pagoni Rachi was related to at least three types of alteration and associated porphyry mineralization: early sodic-calcic/potassic assemblages (avrg. 0.15 g/t); Quartz stockworks associated with sodic alteration and late massive pyrite veins associated with phyllic alteration display significant enrichment in gold (average of 0.20 g/t and 3.68 g/t respectively), combined with highest content of Se. Epithermal-style mineralization at Pagoni Rachi and Konos Hill is characterized by an enrichment in Ag, Ga, In, Sn, Te, Bi, Se, and V. A classification of the studied porphyry systems is a matter of further research, as they display several features that are not common to any other known type of porphyry deposit, with an extreme enrichment in Re being the most prominent.
