Greece hosts a broad variety of magmatic-hydrothermal ore deposits with porphyry- and epithermal styles playing a major role to the total gold endowment of the country. They are mainly clustered in two areas, the Rhodope- and Attico-Cycladic massifs, and were formed from about 33 Ma to the Pleistocene, as a result of back-arc extension in the Aegean Sea, metamorphic core complex formation, and contemporaneous post-collisional and arc magmatism. In the W. Rhodope massif, porphyry Cu-Au deposits include Skouries, Fisoka, Tsikara in the Chalkidiki area, and Vathi and Gerakario in the Kilkis area. Causative intrusives are Oligocene to Miocene granodiorites to monzonites. Mineralization is associated with potassic alteration of the intrusives and by Au and PGE enrichment. An epithermal overprint is very weak or lacking. In the E. Rhodope Massif and the NE Aegean islands of Limnos and Lesvos, porphyry deposits occur at Pagoni Rachi, Maronia, Sapes, Myli, Melitena (W. Thrace), at Fakos, Sardes, Kaspakas (Limnos) and at Stypsi (Lesvos). Mineralization is associated with Oligocene to Miocene subvolcanics of calc-alkaline to shoshonitic affinity. A common feature of these deposits is their very shallow depth of emplacement, the presence of sodic-(potassic-calcic) alteration in the core of the systems, their low Cu content, an extreme Re-enrichment, the multistage introduction of gold, the presence of banded quartz veinlets, and the local presence of tourmaline, thus sharing similarities to porphyry goldonly systems. New discoveries of porphyry-style mineralization at King Arthur, St Philippos and Esymi-Leptokarya, may increase the gold potential in W. Thrace. HS-IS epithermal Au-Ag- polymetallic deposits overprint and/or occur laterally from porphyry-style mineralization, where they are spatially associated with lithocaps of advanced argillic alteration. HS-IS Au-Ag epithermal mineralization at Perama Hill, Mavrokoryfi and Pefka in W. Thrace and at Pterounda, Mesotopos and Megala Therma in Lesvos Island, is controlled by steeply-dipping extensional faults within volcanic rocks, without any obvious genetic relationship to spatially-related porphyry-style mineralization. Polymetallic epithermal deposits and prospects contain critical and energy critical metals (e.g. Te, Se, Bi, Sb, In, Ge and Ga), which may be considered as by-products for future exploitation. In the Attico-Cycladic area, porphyry Mo-W mineralization occurs as sheeted quartz veins and stockworks cutting a potassic- to sericitic-altered Miocene granodiorite stock in the Lavrion district. Bonanza grade Au- and/or Ag-rich veins with epithermal affinities crosscut metamorphic rocks at Lavrion, and at Syros, Tinos, Antiparos and Anafi Islands. Milos Island, is characterized by shallow submarine volcanic-hosted IS-HS epithermal Au-Ag-Te and base metal deposits. Sb-As-Ag-Au deposits at Chios, Samos and Kos Islands in the eastern Aegean Sea, indicate the potential for Carlin-style mineralization in Greece. Several factors are considered to have played a role of the metal endowment in the Aegean porphyry-epithermal systems: magma fertility in source regions, depth of emplacement of causative intrusive, relative contribution of mantle vs crustal material, oxidation state of magma, and physico-chemical fluid conditions at the site of ore deposition.
Porphyry and Epithermal Deposits in Greece: A Review and New Discoveries
Konstantinos Mavrogonatos;
2018-01-01
Abstract
Greece hosts a broad variety of magmatic-hydrothermal ore deposits with porphyry- and epithermal styles playing a major role to the total gold endowment of the country. They are mainly clustered in two areas, the Rhodope- and Attico-Cycladic massifs, and were formed from about 33 Ma to the Pleistocene, as a result of back-arc extension in the Aegean Sea, metamorphic core complex formation, and contemporaneous post-collisional and arc magmatism. In the W. Rhodope massif, porphyry Cu-Au deposits include Skouries, Fisoka, Tsikara in the Chalkidiki area, and Vathi and Gerakario in the Kilkis area. Causative intrusives are Oligocene to Miocene granodiorites to monzonites. Mineralization is associated with potassic alteration of the intrusives and by Au and PGE enrichment. An epithermal overprint is very weak or lacking. In the E. Rhodope Massif and the NE Aegean islands of Limnos and Lesvos, porphyry deposits occur at Pagoni Rachi, Maronia, Sapes, Myli, Melitena (W. Thrace), at Fakos, Sardes, Kaspakas (Limnos) and at Stypsi (Lesvos). Mineralization is associated with Oligocene to Miocene subvolcanics of calc-alkaline to shoshonitic affinity. A common feature of these deposits is their very shallow depth of emplacement, the presence of sodic-(potassic-calcic) alteration in the core of the systems, their low Cu content, an extreme Re-enrichment, the multistage introduction of gold, the presence of banded quartz veinlets, and the local presence of tourmaline, thus sharing similarities to porphyry goldonly systems. New discoveries of porphyry-style mineralization at King Arthur, St Philippos and Esymi-Leptokarya, may increase the gold potential in W. Thrace. HS-IS epithermal Au-Ag- polymetallic deposits overprint and/or occur laterally from porphyry-style mineralization, where they are spatially associated with lithocaps of advanced argillic alteration. HS-IS Au-Ag epithermal mineralization at Perama Hill, Mavrokoryfi and Pefka in W. Thrace and at Pterounda, Mesotopos and Megala Therma in Lesvos Island, is controlled by steeply-dipping extensional faults within volcanic rocks, without any obvious genetic relationship to spatially-related porphyry-style mineralization. Polymetallic epithermal deposits and prospects contain critical and energy critical metals (e.g. Te, Se, Bi, Sb, In, Ge and Ga), which may be considered as by-products for future exploitation. In the Attico-Cycladic area, porphyry Mo-W mineralization occurs as sheeted quartz veins and stockworks cutting a potassic- to sericitic-altered Miocene granodiorite stock in the Lavrion district. Bonanza grade Au- and/or Ag-rich veins with epithermal affinities crosscut metamorphic rocks at Lavrion, and at Syros, Tinos, Antiparos and Anafi Islands. Milos Island, is characterized by shallow submarine volcanic-hosted IS-HS epithermal Au-Ag-Te and base metal deposits. Sb-As-Ag-Au deposits at Chios, Samos and Kos Islands in the eastern Aegean Sea, indicate the potential for Carlin-style mineralization in Greece. Several factors are considered to have played a role of the metal endowment in the Aegean porphyry-epithermal systems: magma fertility in source regions, depth of emplacement of causative intrusive, relative contribution of mantle vs crustal material, oxidation state of magma, and physico-chemical fluid conditions at the site of ore deposition.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
