Moukkori - Gold Database

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Name	Moukkori	DATA UPDATED	24.5.2007
Alternative names	Housuvaara
Deposit summary	MOUKKORI, in the Suomussalmi greenstone belt, is a small deposit with gold grades >10 g/t, and with an in situ resource estimate of 220 kg gold. It is an Archaean orogenic gold deposit comprising, at least, three or four parallel, narrow lodes in mafic metavolcanic rock in a second-order D3 fault zone. Chiefly native free gold disseminated in the host rock and in quartz veins. Visible gold is common.
LOCATION
Geological domain	Archaean	Belt	Suomussalmi
Site photo		Regional map
Map sheet	451309
Northing (kkj)	7243900	Easting (kkj)	4480850
Latitude	65.29036N	Longitude	29.58612E
Municipality	Suomussalmi
Nearest town, roads	55 km NE from Suomussalmi. 5 km from sealed road, a gravel road to the area.
MINING
Exploration licence no	4876/1–2, 6950/1, 7980/1–4	Mining concession no
Present holder	Nordic Mines AB (2005–)
Previous holders	Geological Survey of Finland (GTK), Endomines Oy (2000–2 005)
Mine photo 1		Mine photo 2
Mine photo 3		Mine photo 4
Status of development	Prospect
When mined
Resources	0.0034 Mt @ 13.4 ppm Au [5]. Indicated 0.0034 Mt @ 13.4 ppm + inferred 0.017 Mt @ 10 ppm (cutoff 2 ppm) [13].
Deposit size (Mt)	0.024	Reference (size)	[13]
Total in-situ gold (kg)	220	Reference (in-situ Au)	[13]
Total gold production (kg)		Reference (gold prod)
Production of other metals
Extent of mineralisation
Lodes	At least four parallel, subvertical lodes, plunging 42–45° to the S [12,13,15].
Best sections	3.5 m @ 30.9 ppm, 1.3 m @ 15 ppm Au [13,14].
EXPLORATION
Discovery year	1990
Discovery	By GTK: a tiny mineralised outcrop found in a forest road ditch, during exploration for base metals [4,7,12]. First indication for gold in the region were the auriferous glacial erratics found by an amateur prospector in 1989 [15].
Exploration history	GTK (1990–97) [1,4,5,6,7,12]: Bedrock mapping, ground magnetic, slingram, VLF-R, total intensity and IP survey, till geochemical and stratigraphic survey, RC and diamond drilling, trenching, detailed mineralogical study.
Section figure 1		Plan figure 1
Section figure 2		Plan figure 2
Section figure 3		Plan figure 3
Trench fig 1		Trench fig 4
Trench fig 2		Trench fig 5
Trench fig 3		Trench fig 6
Explor site photo 1		Explor site photo 2
Geophysical response
Drilling	GTK: 17 diamond-drill holes, total 1746 m [5,7].
Elements analysed	[9]: Main components, Cl, Sn and Zr by XRF; Ag, As, Au, Bi, Pd, Sb, Se and Te by GFAAS; Hg by wet-chemical method; B by DCP; Ba, Cd, Co, Cr, Ga, La, Li, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Sr, Th, Tl, U, V, W, Y and Zn by ICP; S by Leco.
Primary dispersion
Secondary dispersion
Primary anomaly fig 1		Secondary anomaly fig 1
Primary anomaly fig 2		Secondary anomaly fig 2
Primary anomaly fig 3		Secondary anomaly fig 3
Primary anomaly fig 4		Secondary anomaly fig 4
Primary anomaly fig 5		Secondary anomaly fig 5
Economic evaluations	Resource estimates for Endomines by GTK in 2001 [13].
Exploration geologist in charge	GTK: Erkki Luukkonen.
ORE
Siting of gold	80% of gold occurs as free grains (avg. grain size 25 μm, locally up to millimetres in diameter) with gangue minerals, chiefly with quartz in quartz veins, 15% is as inclusions in practically all sulphides and tellurides, and some gold is in the lattice of the tellurides [1,3,5,12,13,16].
Fineness	6.1–13.4% Ag; inclusions: 18.4–22.4% Ag [1].
Major opaques	Pyrrhotite [1,4,7,12].
Minor opaques	Marcasite, pyrite, galena, sphalerite, chalcopyrite, altaite, hessite, volynskite, tsumoite, petzite, cervellite, gold, rutile, goethite [1,4,7,12].
Gangue	Quartz, scheelite, tourmaline [2,3,7,12].
Ore miner. photo 1		Ore miner. photo 5
Ore miner. photo 2		Ore miner. photo 6
Ore miner. photo 3		Ore outcrop photo 1
Ore miner. photo 4		Ore outcrop photo 2
Ore composition	Diamond-drill core [9]: 36.00 ppm Au, 6.90 ppm Ag, 5.2 ppm As, 33 ppm B, 241 ppm Ba, 920 ppm Bi, 26.5 ppm Co, 110 ppm Cu, 13 ppb Hg, 26.2 ppm Li, 2.1 ppm Mo, 26.3 ppm Ni, 124 ppm Pb, 59 ppm Rb, 10700 ppm S, 0.19 ppm Sb, 0.58 ppm Se, 192 ppm Sr, 2.20 ppm Te, 2.1 ppm Th, 0.40 ppm Tl, 1.2 ppm U, 210 ppm V, 2 ppm W, 30 ppm Y, 117 ppm Zn, 108 ppm Zr; 63.3% SiO2, 1.04% TiO2, 10.38% Al2O3, 9.82% Fe2O3, 3.28% MgO, 5.60% CaO, 1.47% Na2O, 1.90% K2O, 0.13% P2O5.
Enriched elements	Au, Ag, As, B, Bi, CO2, K, Pb, S, Te [9].
Ore fluid	Low salinity H2O-CO2±CH4 fluid(s); fluid inclusions: homogenisation T = 195–235°C, min. pressure <2.5 kbar [2,16].
Stable isotopes
Pb isotope data	Pb-Pb data suggest lead originating from upper crust [15].
GEOLOGY
Geological setting	The deposit is in the Tormua Schist Belt which forms the NE part of the late Archaean Suomussalmi Greenstone Belt and is in the rocks of the 3.0–2.8 Ga Luoma Group of the greenstone belt [7,10,11,12].
Major host rocks	"Uralite-porphyrite" [6,12].
Minor host rocks	Intermediate metatuffite [4].
Intrusives	Ca. 2700 Ma granitoids (syn-D3) and Palaeoproterozoic dolerites have intruded into the supracrustal sequence [15].
Regional geol map 1		Outcrop photo 1
Regional geol map 2		Outcrop photo 2
Local geology map 1		Outcrop photo 3
Local geology map 2
METAMORPHISM
Metamorphic history
Metamorphic grade	Amphibolite facies [4].
Metamorphic mineral assemblage	Plagioclase-hornblende-biotite-quartz ± K feldspar, ilmenite [1].
Metamorph photo 1		Metamorph photo 2
STRUCTURE
Structural style	Ductile(-brittle) [2,4,12].
Closest major shear	A NNE-trending shear zone at the eastern boundary of the greenstone belt, 1 km SE from the deposit [12].
Controlling structure	The mineralisation is within asecond-order D3 fault zone, in the axial plane of a chevron-type F3 fold [3,5,7,12].
Deformation history	At least, four deformation stages during the late Archaean and two deformation stages during the Palaeoproterozoic time detected in the area; the controlling structure is related to the third phase (D3) of the regional structural evolution during the Archaean [1,3,7,15]. The latest Archaean stage, D4, has deformed the gold mineralisation [3]. Age of D2 is probably 2820±15 Ma [15] or 2843±18 Ma [17]. The D3 started as a plastic stage, dominantly dextral folding and formation of strong N-trending shear zones; this is partially overprinted by the NW-trending D4 foliation under retrograde conditions [14]. Syn-D3 granodiorite suggests an age of ca. 2718 Ma for the D3 stage [15].
Ore fabric
Veins	Quartz veins with variable amount of sulphides [1,3,6,12].
Structure photo 1		Vein photo 1
Structure photo 2		Vein photo 2
Structure photo 3		Vein photo 3
ALTERATION
General alteration	Formation of the mineral assemblage chlorite-sericite-epidote-calcite-quartz-rutile-ilmenite-pyrrhotite [1,2,12].
Proximal alteration	Mineral assemblage quartz-biotite-epidote(?)-chlorite-plagioclase-K feldspar-sericite-calcite-pyrrhotite [1].
Intermediate alteration
Distal alteration	The most distal alteration is probably indicated by the appearance of tremolite ± epidote and titanite [1].
Zonation figure		Prox alteration photo 1
Alteration photo 1		Prox alteration photo 2
Alteration photo 2		Intermed alteration photo
Alteration photo 3		Distal alteration photo 1
Post-mineralisation modifications	Post-mineralisation(?) D4 deformation [12]. Possibly, a retrograde overprint at greenschist-facies PT conditions [2]. Palaeoproterozoic dolerites have no thermal or alteration effect on their Archaean country rocks [15].
TIMING	[2,15]: Hydrothermal titanite gives an U-Pb age of 2676±20 Ma [2,16]. This timing as the age for mineralisation is supported by structural evidence, and be considered as a minimum age for mineralisation [15].
GENETIC MODEL	[2,12,14,15]: Formed soon(?) after the peak metamorphic event under slightly retrograde conditions near the ductile-brittle and amphibolite-greenschist facies transition zones, in still dominantly ductile regime, during late-Archaean cratonisation. Deposition of gold occurred primarily as a consequence of sulphidation of iron from the mafic country rock. Timing fits with late-D3 or D4 deformation [15]. Fluid inclusions suggest a single-event mineralisation at about 2–3 kbar, 300–350°C [16].
Genetic type	Orogenic	References	[14]
Alternative genetic type 1		References
Alternative genetic type 2		References
References 1. Chernet, T. 1994. Ore mineralogy of the Moukkori gold prospect. Geol. Surv. Finland, Report M19/4513/-94/1/42. 16 p. (6.2 MB) 2. Poutiainen, M. & Luukkonen, E. 1994. The geology and fluid inclusion studies of some epigenetic gold deposits in the Archean Kuhmo and Suomussalmi greenstone belts, eastern Finland. In: M. G. Izquierdo, A. M. C. Suarez, G. M. Guevara, D. Vanko & G. J. C. Viaggio (eds) Fifth Biennial Pan-American Conference on Research on Fluid Inclusions, Cuernavaca, Morelos, Mexico, May 19–21, 1994. Abstracts, 77–78. 3. Luukkonen, E. 1993. Kultamineralisaatio Suomussalmen ja Kuhmon vihreäkivivyöhykkeellä. In: P. Nurmi (ed.) Itä-Suomen kultaesiintymät. Ekskursio-opas. Vuorimiesyhdistys, Sarja B, no. 54, 33–3 5. (in Finnish) 4. Pietikäinen, K. 1998. Personal communication 14/9/1998. 5. Ministry of Trade and Industry 1998. International tender notice. Tormua gold prospect, Suomussalmi, Finland. Press release 6/10/1998. 6. Luukkonen, E. 1998. Personal communication 27/10/98. 7. Luukkonen, E., Heino, T., Tenhola, M., Niskanen, M. & Hartikainen, A. 1997. Tutkimustyöselostus Suomussalmen kunnassa valtausalueella Saarilampi 1 (kaivosrekisteri 5351/1), Housuvaara 1–2 (kaivosrekisteri 4876/1–2), Mullikko 1 (kaivosrekisteri 5029/1), Pahka 1 (kaivosrekisteri 5029/2/1) ja Pahkalampi 1 (kaivosrekisteri 5232/1) suoritetuista kultamalmitutkimuksista vuosina 1990–1997. Geol. Surv. Finland, Report M06/4513/-97/1/10. 21 p. (in Finnish) 8. Luukkonen, E., Pajunen, M. & Poutiainen, M. 1992. Kuhmo–Suomussalmen alueen arkeeisen kallioperän rakenne-evoluutio ja Au-aiheet. In: E. Ekdahl (ed.) Suomen kallioperän kehitys ja raaka-ainevarat. Vuorimiesyhdistys, Sarja B, 51, 11–12. 9. Bornhorst, T. & Nurmi, P. (1999) Personal communication 20/1/1999. 10. Luukkonen, E. 1992. Late Archaean and Early Proterozoic structural evolution in the Kuhmo-Suomussalmi Terrain, eastern Finland. Annales universitatis Turkuensis. Ser. A. II 78, 1–37. 11. Sorjonen-Ward, P., Nironen, M. & Luukkonen, E. 1997. Greenstone associations in Finland. In: M. J. de Wit and L. D. Ashwal (eds) Greenstone Belts. Clarendon Press, Oxford. 677–6 98. 12. Luukkonen, E. (ed.) 1998. Suomussalmen, Kuhmon ja Kostamuksen arkeeiset vihreäkivivyöhykkeet ja niihihn liittyvä malminmuodostus. Ekskursio-opas. Vuorimiesyhdistys, Sarja B, No 66, 40 p. (in Finnish) 13. Parkkinen, J. 2001. Quality control of mineral resource estimates: Laivakangas, Hosko, Kuivisto E, Other, Osikonmäki, Pirilä, Housuvaara, Pahkalampi. Geol. Surv. Finland, Report. 27 p. 14. Papunen, H., Halkoaho, T., Liimatainen, J. & Luukkonen, E. 2001. Metallogeny of the Archaean Tipasjärvi–Kuhmo–Suomussalmi greenstone belt, Finland. AGSO – Geoscience Australia, Record 2001/37, 456–458. 15. Luukkonen, E., Halkoaho, T., Hartikainen, A., Heino, T., Niskanen, M., Pietikäinen, K. & Tenhola, M. 2002. Itä-Suomen arkeeiset alueet –hankkeen (12201 ja 210 5000) toiminta vuosina 1992–2001 Suomussalmen, Hyrynsalmen, Kuhmon, Nurmeksen, Rautavaaran, Valtimon, Lieksan, Ilomantsin, Kiihtelysvaaran, Enon, Kontiolahden, Tohmajärven ja Tuupovaaran alueella. Geol. Surv. Finland, Report M19/4513/2002/1. 265 p. (in Finnish, 130 MB) 16. Poutiainen, M. and Partamies, S. 2003. Fluid inclusion characteristics of auriferous quartz veins in Archean and Paleoproterozoic greenstone belts of eastern and southern Finland. Econ. Geol. 98, 1355–1369. 17. Sorjonen-Ward, P. & Luukkonen, E.J. 2005. Archean rocks. In: Precambrian Geology of Finland – Key to the Evolution of The Fennoscandian Shield. Elsevier Science B.V., Amsterdam, 19–9 9.
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