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Chalkidiki - Olympias, Madem Lakos, Mavres Petres |
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Greece |
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Zn Pb Au Ag
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Olympias, Madem Lakkos & Mavres Petres Pb-Zn(Au,Ag) sulphide ore deposits are located on the Chalkidiki Peninsular of eastern Greece.
These structurally controlled ores are developed in calcite-rhodochrosite marbles of the Palaeozoic (or older) Kerdilia Formation of the Servo-Macedonian Massif. The host sequence comprises predominantly marbles, biotite-horneblende gneisses and amphibolites which have been regionally deformed and metamorphosed to amphibolite facies with associated anatexis and calc-alkaline magmatism which have in turn produced hornfelsed contact aureoles.
The Olympias deposit is located approximately 15 km NNE of Skouries and is also part of the Kasandra Mining District. It is a massive stratabound polymetallic replacement deposit hosted in the marble-gneiss contact of the Kerdilla Formation. No skarn mineralisation has been identified to date, although it is predicted to occur at deeper levels, closer to the source of the mineralising fluid, believed to be a Tertiary age, sub-alkaline intrusive. Field relationships between the mineralisation and the 30 Ma Stratoni Granodiorite suggest a Tertiary age for the mineralisation.
The deposit is characterised by an assemblage of pyrite, arsenopyrite, sphalerite, galena, tetrahedritetenantite, boulangerite and chalcopyrite, with gold being almost exclusively associated with arsenopyrite and pyrite. Minor amounts of bournonite, pyrrhotite, marcasite, mackinawite, enargite and geocronite are also found. Secondary cerussite, anglesite, chalcocite and covellite are found near the surface, while manganese oxides represent alteration of rhodochrosite. Gangue minerals include quartz, calcite, rhodochrosite, feldspar, kaolinite, chlorite, ankerite and graphite.
The ore is mainly massive in form, although disseminated sulphides are also present. Manganese oxides are found near surface and distally to the sulphides, and are regarded as representing a temperature zonation during deposition. From between 50 and 70 m below the surface, there is a gradual change to mixed sulphides. Kaolinisation is the main alteration type associated with mineralisation. Aplitic intrusions may be sericitised. Hydrothermal brecciation is common and chloritisation and silicification of host rocks immediately is frequently observed around the mineralised zone.
The deposit occurs within two orebodies, namely: i). the West orebody, which is approximately 250 m along strike and persists for 1200 m down plunge to the southwest. It has been intersected from surface to a depth of 500 m and is open down plunge, with a thickness that varies between 5 to 15 m, and dips averaging 30 to 35° east, although the attitude may vary locally from near horizontal to near-vertical. The horizontal width can reach 50 m in the flatter areas. The Upper West orebody comprises remnants left by previous operators who high-graded the lead and zinc mineralisation and left behind gold-rich pockets. ii). The East orebody, which lies some 150 m east of the West orebody. It represents an anticlinal structure, exhibiting axial thickening, with steeper dips toward the peripheries. It dips at 25-30° on average to the southeast, with an average length af thickness of 75 m and 7 m respectively. The mineralisation has been traced for 600 m down plunge.
The total measured + indicated resource at Olympias in 2004 (European Goldfields Ltd) was:
14.5 Mt @ 9.31 g/t Au, 128.6 g/t Ag, 4.2% Pb, 5.6% Zn.
In 1986 the reserves were:
Olympias - 16 Mt @ 3.3% Pb, 5% Zn, 120 g/t Ag and 5.5 g/t Au
Madam Lakkos & Mavres Petres - 4.7 Mt @ 4% Pb, 4% Zn, 110 g/t Ag and 1.5 g/t Au
Madam Lakkos (1986) - 6 Mt of pyritic ore & 4 Mt of mixed sulphide ore:
4% Pb, 4% Zn, 0.15% Cu 110 g/t Ag and 1.6 g/t Au
For detail see the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 1990.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Kalogeropoulos S I, Kilias S P, Bitzios D C 1989 - Genesis of the Olympias Carbonate-hosted Pb-Zn(Au,Ag) Sulfide ore deposit, eastern Chalkidiki Peninsula, northern Greece: in Econ. Geol. v84 pp 1210-1234
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Kilias S P, Kalogeropoulos S I, Konnerup-Madsen J, 1996 - Fluid inclusion evidence for the physicochemical conditions of sulfide deposition in the Olympias carbonate-hosted Pb-Zn (Au, Ag) sulfide ore deposit, E. Chalkidiki peninsula, N. Greece: in Mineralium Deposita v31 pp 394 - 406
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Nebel M L, Hutchinson R W, Zartman R E 1991 - Metamorphism and polygenesis of the Madem Lakkos polymetallic Sulfide deposit, Chalkidiki, Greece: in Econ. Geol. v86 pp 81-105
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Siron, C.R., Rhys, D., Thompson, J.F.H., Baker, T., Veligrakis, T., Camacho, A. and Dalampiras, L., 2018 - Structural Controls on Porphyry Au-Cu and Au-Rich Polymetallic Carbonate-Hosted Replacement Deposits of the Kassandra Mining District, Northern Greece: in Econ. Geol. v.113, pp. 309-345.
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Voudouris, P., Melfos, V., Spry, P.G., Bindi,L., Moritz, R.,Ortelli, M. and Kartal, T., 2013 - Extremely Re-Rich Molybdenite from Porphyry Cu-Mo-Au Prospects in Northeastern Greece: Mode of Occurrence, Causes of Enrichment, and Implications for Gold Exploration: in Minerals (MDPI) v.3, pp. 165-191.
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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