Tammasuo - Gold Database

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Name	Tammasuo	DATA UPDATED	24.5.2007
Alternative names	Sika-aho
Deposit summary	TAMMASUO, in the Kuhmo greenstone belt, is an Archaean orogenic gold occurrence with no resource estimate available. It comprises a set of NNE-trending lodes defining a mineralised zone >2 km long, and is hosted by mafic volcanic rocks. The occurrence is controlled by the N- or NNE-trending Tammasuo Shear Zone which may be subsidiary to the main shear zone of the Kuhmo greenstone belt. Native gold associated with arsenopyrite.
LOCATION
Geological domain	Archaean	Belt	Kuhmo
Site photo		Regional map
Map sheet	442110
Northing (kkj)	7168700	Easting (kkj)	4459900
Latitude	64.61404N	Longitude	29.15864E
Municipality	Hyrynsalmi
Nearest town, roads	40 km SE from Suomusalmi. Sealed road along the eastern margin of the area.
MINING
Exploration licence no	8049/7	Mining concession no
Present holder	Kuhmo Metals Oy (2006–)
Previous holders	Geological Survey of Finland (GTK) (1997–1999), Polar Mining (2004–2006)
Mine photo 1		Mine photo 2
Mine photo 3		Mine photo 4
Status of development	Prospect
When mined
Resources
Deposit size (Mt)		Reference (size)
Total in-situ gold (kg)		Reference (in-situ Au)
Total gold production (kg)		Reference (gold prod)
Production of other metals
Extent of mineralisation	Lodes appear to extend for about two kilometres along strike [1].
Lodes	A set of few metres wide, NNE-trending, lodes [1].
Best sections	A few of 1 m @ 2.0–2.5 g/t Au; 4.8 m @ 2.9 ppm, 3 m @ 1.33 ppm Au [1].
EXPLORATION
Discovery year	1994
Discovery	By GTK, by drilling into local regolith (Au-As) anomalies [1].
Exploration history	GTK (1993–1996) [1]: Regional and local till and local regolith geochemical surveys, ground magnetic, electromagnetic and IP survey, bedrock mapping, 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
Drilling	GTK (late 1990's): diamond-drilling [1].
Elements analysed	By ICP-AES: Al, Ba, Ca, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Na, Ni, P, Sc, Sr, Ti, V, Y and Zn; by GAAS: Au and Te [1].
Primary dispersion	Gold consistently shows a strong positive correlation with As and, at least locally, with Te [1].
Secondary dispersion	Regional and local Au, As, Te anomalies related to mineralisation [1].
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
Exploration geologist in charge	GTK: Erkki Luukkonen
ORE
Siting of gold	Associated, at least, with arsenopyrite [1].
Fineness
Major opaques	Arsenopyrite, pyrrhotite(?) [1].
Minor opaques
Gangue
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
Major host rocks	Mafic metavolcanic rock [1]
Minor host rocks	Felsic dykes [1]
Intrusives	NW-trending Palaeoproterozoic dolerite cut arcoss the deformed Archaean rocks in the rergion [1].
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	Upper-greenschist(?) facies [1].
Metamorphic mineral assemblage
Metamorph photo 1		Metamorph photo 2
STRUCTURE
Structural style
Closest major shear	The N-trending main shear zone of the Kuhmo greenstone belt [1].
Controlling structure	The N- or NNE-trending Tammasuo Shear Zone) [1].
Deformation history	At least, six deformation stages during the late Archaean and two deformation stages during the Palaeoproterozoic detected in the area; gold mineralisation is related to the Archaean late D3 and/or D4 stages [2,3]. D2: 2850-2837 Ma, D3: 2701-2697 Ma, D4: peaked at 2657±32 Ma [3]. Age of D2 is probably 2820±15 Ma [1] or 2843±18 Ma [4].
Ore fabric
Veins
Structure photo 1		Vein photo 1
Structure photo 2		Vein photo 3
ALTERATION
General alteration	Silicification (= quartz veins?), carbonation, and sericitisation [1].
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 photo 1
Post-mineralisation modifications
TIMING	During ca. 2720–2650 Ma [1].
GENETIC MODEL
GENETIC TYPE	Orogenic	References	[1]
Alternative genetic type 1		References
Alternative genetic type 2		References
References 1. 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 1992–2 001 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) 2. 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. 3. Luukkonen, E. 2001. Lentiiran kartta-alueen kallioperä. Summary: Pre-Quaternary rock of the Lentiira map-sheet area. Suomen geologinen kartta 1:100 000. Kallioperäkarttojen selitykset, 4414 + 4432 Lentiira. 68 p. 4. 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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