Kuivisto - Gold Database

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Name	Kuivisto	DATA UPDATED	12.9.2008
Alternative names
Deposit summary	KUIVISTO, in the Ilomantsi greenstone belt, has an in situ resource estimate of 400 kg gold. It is an Archaean orogenic gold deposit comprising two lodes defined by feldspar- and tourmaline-bearing quartz vein networks in intermediate metatuffite, close to the NNW trending Pampalo Shear Zone.
LOCATION
Geological domain	Archaean	Belt	Ilomantsi
Site photo		Regional map
Map sheet	433308
Northing (kkj)	6992900	Easting (kkj)	4560660
Latitude	63.03436N	Longitude	31.19535E
Municipality	Ilomantsi
Nearest town, roads	40 km NE from Ilomantsi, 100 km NE from Joensuu. A sealed road 0.5 km from the area.
MINING
Exploration licence no	5210/1, 5356/5–6	Mining concession no
Present holder	Endomines Oy (1993–)
Previous holders	Geological Survey of Finland (GTK) (–1993)
Mine photo 1		Mine photo 2
Mine photo 3		Mine photo 4
Status of development	Prospect
When mined
Resources	Kuivisto E: inferred 0.1 Mt @ 4 ppm Au [5].
Deposit size (Mt)	0.1	Reference (size)	[5]
Total in-situ gold (kg)	400	Reference (in-situ Au)	[5]
Total gold production (kg)		Reference (gold prod)
Production of other metals
Extent of mineralisation	Kuivisto E is 300–400 m long [5].
Lodes	Two main lodes or lode sets, Kuivisto E and Kuivisto W [5].
Best sections	6 m @ 4.3 ppm, 12 m @ 3.6 ppm, 3 m @ 7.2 ppm, 2.8 m @ 2.5 ppm, 2.1 m @ 4.9 ppm, 1 m @ 35.7 ppm, 1 m @ 43.2 ppm Au [7]. 0.6 m @ 0.6 ppm Au, 0.9 m @ 25.5 ppm Au: Kuivisto East [9].
EXPLORATION
Discovery year	1993
Discovery	By GTK [7]: drilling into structurally favourable location within a localgeochemical anomaly in till.
Exploration history	GTK [1,6,7]: Low-altitude airborne- and ground-magnetic, slingram and IP survey. Detailed geochemical till sampling: sampling grid 250x250 m over the greenstone belt covering 400 km2. Follow-up as till-bedrock interface geochemistry, samples collected across the Au anomaly along traverses 100 m apart with sampling distance 10–30 m. Trenching, diamond drilling. Endomines (1996–) [2,5]: Re-logging of older core, ground-geophysical surveys, diamond-drilling.
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	[1]: No response on magnetic orslingram methods. Magnetic and electric methods do show the structural features of the area, including those which control gold mineralisation. [2]: An IP anomaly indicates the presence of the Au-mineralised zone.
Drilling	GTK: 41 diamond-drill holes, total 2997 m [7]. Endomines: 53 diamond-drill holes [5].
Elements analysed
Primary dispersion
Secondary dispersion	[1]: Regional Au, As and B till anomaly, local Au, Te and Bi anomaly(?). Au content within the till anomaly is from tens of ppb to >1 ppm. Best combination for defining exploration targets: Au + Te + Bi- better than Au alone.
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 [5].
Exploration geologist in charge	Endomines: Jaakko Liikanen.
ORE
Siting of gold
Fineness
Major opaques	Pyrrhotite, pyrite [2].
Minor opaques
Gangue	Quartz, feldspar, scheelite, tourmaline [2].
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
Enriched elements
Ore fluid
Stable isotopes
Pb isotope data
GEOLOGY
Geological setting	The mineralisation is in the northern part of the 2754–2 726 Ma Hattu Schist Belt [8]. The host rocks are intruded by pegmatite dikes, all lithological units show complicated folding [1].
Major host rocks	Mica schist(?).
Minor host rocks
Intrusives
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	[1]: Progressive regional metamorphism on ca. 2750–2700 Ma, apparently peaked soon after gold mineralisation, at a temperature of about 550±50°C. Thermal peak was synchronous or outlasted deformation.
Metamorphic grade	Greenschist-amphibolite facies transition [1].
Metamorphic mineral assemblage
Metamorph photo 1		Metamorph photo 2
STRUCTURE
Structural style	Brittle-ductile [2].
Closest major shear	The Pampalo Shear Zone system? [1].
Controlling structure
Deformation history	Rapid and extensive crustal generation and progressive deformation between 2.76–2.73 Ma, in a transpressional regime [1,8].
Ore fabric
Veins	Auriferous, quartz-feldspar-tourmaline veins which form the breccia matrix [6].
Structure photo 1		Vein photo 1
Structure photo 2		Vein photo 2
Structure photo 3		Vein photo 3
ALTERATION
General alteration
Proximal alteration
Intermediate alteration
Distal alteration
Zonation figure		Prox alteration photo 1
Alteration photo 1		Prox alteration photo 2
Alteration photo 2		Intermed alteration photo
Alteration photo 3		Distal alteration photo1
Post-mineralisation modifications	[1]: Probably, an Archaean post-mineralisation metamorphic overprint at about 500±50°C with deformation and porphyroblast overgrowth. On ca. 1800 Ma, a Proterozoic regional metamorphic overprint which is shown by K-Ar and Rb-Sr ages of micas within the schist belt.
TIMING	[1]: Either pre-peak metamorphic and formed under greenschist-facies conditions, or syn-peak metamorphic. Minimum age 2708–2693 Ma (U-Pb of titanite and monazite indicating peakmetamorphism in the schist belt).
GENETIC MODEL	[1]: Formed in a structurally favourable, the most competent lithological units in the area. Precipitation of gold by desulphidation of fluid and, possibly, by decomposition of Au-Te complexes of fluid due to cooling and/or changes in pH and fO2. Probably, gold precipitated just below 500°C with sulphides. The formation of the present low-temperature Te and Bi minerals most probably took place as subsolidus reactions with cooling temperature. Within the schist belt, the combination of arsenopyrite and oxygen isotope thermometry, sphalerite geobarometry, with the dominance of pyrrhotite and calcite instead of pyrite and dolomite, respectively, suggests uppermost-greenschist facies or conditions transitional between greenschist and amphibolite facies for mineralisation: T = 450–500°C, p = 2–3 kbar.
GENETIC TYPE	Orogenic	References	[1]
Alternative genetic type 1		References
Alternative genetic type 2		References
References 1. Nurmi, P. A. & Sorjonen-Ward, P. (eds) 1993. Geological Development, Gold Mineralization and Exploration Methods in the Late Archaean Hattu Schist Belt, Ilomantsi, Eastern Finland. Geol. Surv. Finland, Special Paper 17. 386 p. 2. Liikanen, J. 1999. Ilomantsin Hattuvaaran liuskejakso: Hoskon kultamalmi kooste. Written communication. 3 p. 3. Endomines Oy. 1999. www.endomines.fi on 09/12/99. 4. Korsman, K. (ed.) & Glebovitsky, V. (ed.) 1999. Raahe-Ladoga Zone structure-lithology, metamorphism and metallogeny: a Finnish-Russian cooperation project 1996–1999. Map 2: Metamorphism of the Raahe-Ladoga Zone 1:1000000. Geol. Surv. Finland. 5. Parkkinen, J. 2001. Quality control of mineral resource estimates: Laivakangas, Hosko, Kuivisto E, Other, Osikonmäki, Pirilä, Housuvaara, Pahkalampi. Geol. Surv. Finland, Report. 27 p. 6. Hartikainen, A. & Niskanen, M. 2001. maaperägeokemialliset kultatutkimukset Hatun liuskejaksolla Ilomantsissa vv. 1983-1995. Geol. Surv. Finland, Report S/41/4244/1/2001. 22 p. 7. Heino, T., Hartikainen, A., Koistinen, E. & Niskanen, M. 1995. Tutkimustyöselostus Ilomantsin kunnassa valtausalueilla Sivakko 1 (5188/1), Korpilampi 1–2 (5402/1–2), Korpi 1–4 (5356/1–4), Kuivisto 1 (5210/1), Kuivisto 2–3 (5356/5–6), Pihlajavaara 1–2 (5511/2–3) ja Valkeasuo 1–2 (4853/1, 5511/1) suoritetuista kultamalmitutkimuksista vuosina 1992–1995 sekä neljältä vireillä olevalta valtaukselta (Sivakko 2–3 ja Valkeasuo 3–4). English summary: Report on exploration in Ilomantsi in 1992–1995, within claims Sivakko 1 (Mine Register no. 5188/1), Korpilampi 1–2 (5402/1–2 ), Korpi 1–4 (5356/1–4), Kuivisto 1 (5210/1), Kuivisto 2–3 (5356/5–6), Pihlajavaara 1–2 (5511/2–3) and Valkeasuo 1–2 (4853/1, 5511/1). Geol. Surv. Finland, Report M06/4333/-95/1/10. 17 p. 8. 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, 19-99. 9. Endomines 2008. Press release 16 June 2008.
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