Jousijärvi - Gold Database

Back to Gold map			Alphabetical list
Name	Jousijärvi	DATA UPDATED	24.5.2007
Alternative names
Deposit summary	JOUSIJÄRVI, in the Kuhmo greenstone belt, is an Archaean orogenic gold occurrence with no resource estimate available. It is hosted by intermediate metatuffite in the eastern margin of the main, N-trending shear zone of the greenstone belt.
LOCATION
Geological domain	Archaean	Belt	Kuhmo
Site photo		Regional map
Map sheet	441211
Northing (kkj)	7141740	Easting (kkj)	4455730
Latitude	64.37172N	Longitude	29.07969E
Municipality	Kuhmo
Nearest town, roads	40 km NW from Kuhmo. 100 m from a sealed road, seven km from railway.
MINING
Exploration licence no	4876/1, 5333/1	Mining concession no
Present holder	GTK (2004–2005)
Previous holders	Geological Survey of Finland (GTK) (1994–1999), Ilmari Exploration (2002–2003)
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
Best sections	2.6 m @ 3.5 ppm Au [7].
EXPLORATION
Discovery year	1994
Discovery	By GTK: regional Au anomaly in till was the first indication; also the high-grade boulder found at and the potential extensions of magnetic and IP anomalies from the Mujesuo prospect near Jousijärvi were seen as good indicators; the mineralisation was detected by diamond drilling into bedrock covered by a local Au anomaly in till [1,7].
Exploration history	GTK [1,7,9]: bedrock mapping, diamond drilling, ground magnetic, electromagnetic and IP survey, till geochemical and stratigraphy survey.
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 [7]: nine diamond-drill holes, total 382 m.
Elements analysed
Primary dispersion	Au-As anomaly following the regional N-trending shear zone [9].
Secondary dispersion	Regional and local Au and As anomalies in till [7].
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
Primary anomaly fig 6		Secondary anomaly fig 6
Economic evaluations
Exploration geologist in charge	GTK: Erkki Luukkonen, Timo Heino.
ORE
Siting of gold
Fineness
Major opaques
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	Located in the central part of the Late-Archaean Kuhmo Greenstone Belt, in a sequence dominated by mafic metavolcanic rocks [2,4,7].
Major host rocks	Intermediate tuffite [9].
Minor host rocks
Intrusives	The greenstone belt is largely bounded by 2739–2697 Ga tonalites and trondhjemites [4]. NW-trending Palaeoproterozoic dolerite cut arcoss the deformed Archaean rocks in the rergion [9].
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	A very weak, unevenly distributed Palaeoproterozoic overprint [5].
Metamorphic grade	Transitional between upper-greenschist and lower-amphibolite facies [2].
Metamorphic mineral assemblage
Metamorph photo 1		Metamorph photo 2
STRUCTURE
Structural style	Ductile(-brittle) [2].
Closest major shear	A N-S trending, ductile, subvertical, several hundreds of metres wide shear zone = the main shear zone of the Kuhmo greenstone belt [2,8].
Controlling structure	The mineralisation is in the eastern margin of the major shear zone in the area [2].
Deformation history	At least, six deformation stages during the late Archaean and two deformation stages during the Palaeoproterozoic time detected in the area; gold mineralisation is related to the Archaean late D3 and/or D4 stages [3,7]. D2: 2850–2837 Ma, D3: 2701–2697 Ma, D4: peaked at 2657±32 Ma [7,8]. Age of D2 is probably 2820±15 Ma [9] or 2843±18 Ma [10].
Ore fabric
Veins	Extensional quartz(-baryte) veins [2].
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 photo 1
Post-mineralisation modifications
TIMING	During ca. 2700–2650 Ma [7,8].
GENETIC MODEL	Orogenic "mesothermal" deposit formed during late-Archaean cratonisation [6].
Genetic type	Orogenic	References	[6]
Alternative genetic type 1		References
Alternative genetic type 2		References
References 1. Pietikäinen, K. 1998. Personal communication 14/9/1998. 2. Luukkonen, E. 1998. Personal communication 27/10/98. 3. Luukkonen, E., Pajunen, M. & Poutiainen, M. 1992. Kuhmo–Suomussalmen alueen arkeeisen kallioperä rakenne-evoluutio ja Au-aiheet. In: E. Ekdahl (ed.) Suomen kallioperän kehitys ja raaka-ainevarat. Vuorimiesyhdistys, Sarja B, 51, 11–12. (in Finnish) 4. 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. 5. 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. 6. 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. 7. Tenhola, M. & Niskanen, M. 2001. Tutkimustyöselostus Kuhmon kaupungissa valtausalueilla Aitto 1 (Kaivosrekisteri No 5032/1), Mujesuo 1 (Kaivosrekisteri No 5412/1), Jousijärvi 1 (Kaivosrekisteri No 5333/1) sekä Härmäkangas 1 (Kaivosrekisteri No 6108/1) suoritetuista kulta- ja sinkkimalmitutkimuksista vuosina 1992–1999. English summary: The gold and zinc prospects in Kuhmo, Eastern Finland in 1992–1999 (register number of claims: Aitto 1, 5032/1; Mujesuo 1, 5412/1; Jousijärvi 1, 5333/1; Härmäkangas 1, 6108/1) Geol. Surv. Finland, Report M 06/4412/2001/3/10. 8 p. (in Finnish, 3.7 MB) 8. 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. 9. 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) 10. 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.
Back to Gold map			Alphabetical list