Karvosenvaara - Gold Database

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Name	Karvosenvaara	DATA UPDATED	24.5.2007
Alternative names	Pahasuo 1
Deposit summary	KARVOSENVAARA, in the southern part of the Kuhmo greenstone belt, is an Archaean orogenic gold occurrence with no resource estimate available. It comprises auriferous quartz and quartz-carbonate veins in mafic volcanic rock. The controlling structure may be a NW-trending branch of the main shear zone of the greenstone belt.
LOCATION
Geological domain	Archaean	Belt	Kuhmo
Site photo		Regional map
Map sheet	441301
Northing (kkj)	7109500	Easting (kkj)	4466100
Latitude	64.08374N	Longitude	29.30179E
Municipality	Kuhmo
Nearest town, roads	17 km W from Kuhmo. Two km to a sealed road, gravel road to the area.
MINING
Exploration licence no	7468/1	Mining concession no
Present holder	Geological Survey of Finland (GTK) (2001–)
Previous holders
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	2.3 m @ 2.6 ppm, 2 m @ 1.3 ppm, 1 m @ 3.6 ppm, 1 m @ 2.90 ppm, 1 m @ 1.88 ppm, 1 m @ 1.39 ppm Au [1,3].
EXPLORATION
Discovery year	2001
Discovery	By GTK [1,3]: First indication were Au-anomalies in till detected in regional geochemical exploration campaign in 1990's: Auriferous glacial erratics and outrcops were detected during regional exploration in 2001-2002.
Exploration history	GTK (1990's, 2001–2003) [1,2,3]: bedrock mapping, low-altitude airborne magnetic, electric and rediometric survey, regional and local till geochemical survey, 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 (2002–2003): six diamond-drill holes, total 478 m [1,3].
Elements analysed	ICP-AES and GFAAS analyses [3].
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
Exploration geologist in charge	GTK: Aimo Hartikainen
ORE
Siting of gold
Fineness
Major opaques	Pyrrhotite, pyrite, arsenopyrite [1].
Minor opaques	Stibnite, chalcopyrite, galena, sphalerite, gold [1].
Gangue	Quartz, tourmaline, scheelite, carbonate [1].
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
Ore composition table 1	Click here	Ore composition table 2
Enriched elements
Ore fluid
Stable isotopes
Pb isotope data
GEOLOGY
Geological setting	The local bedrock is dominated by mica schist and metavolcanic rocks. These are in the southern part of the Late-Archaean Kuhmo Greenstone Belt, in a sequence dominated by mica schists, phyllites, chert, BIF and mafic tholeiitic metavolcanic rocks, in the Ontojärvi synform [1,2,3].
Major host rocks	Mafic metavolcanic rock [1].
Minor host rocks
Intrusives	The hosting sequence is intruded by Palaeoproterozoic, 2.2-2.1 Ga wehritic dykes [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
Metamorphic mineral assemblage	Mica schist: quartz-K feldspar-plagioclase-biotite-muscovite ± garnet, hornblende [1].
Metamorph photo 1		Metamorph photo 2
STRUCTURE
Structural style
Closest major shear
Controlling structure
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; D2: 2850–2837 Ma, D3: 2701–2697 Ma, D4: peaked at 2657±32 Ma; age of D2 is probably 2820±15 Ma [2] or 2843±18 Ma [4].
Ore fabric
Veins	Auriferous quartz and quartz-carbonate veins [1].
Structure photo 1		Vein photo 1
Structure photo 2		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
GENETIC MODEL
GENETIC TYPE	Orogenic	References	[1]
Alternative genetic type 1		References
Alternative genetic type 2		References
References 1. Hartikainen, A. & Pietikäinen, K. & Niskanen, M. 2004. Tutkimustyöselostus Kuhmon kaupungin länsipuolella sijaitsevien valtausten Pahasuo 1 ja 2 (kaivosrekisterinumerot 7468/1 ja 7486/1) alueilla tehdyistä kultatutkimuksista. English summary: A research report of studies concerning the claims Pahasuo 1 and 2 (register numbers of the claims 7468/1 and 7486/1), located 15 km west of Kuhmo, eastern Finland. Geol. Surv. Finland, Report M06/4413/2004/1/10. 16 p. (1.8 MB) 2. 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) 3. Pietikäinen, K., Halkoaho, T., Hartikainen, A., Niskanen, M. & Tenhola, M. 2005. Itä-Suomen arkeeiset alueet II-hankkeen (2105000) toiminta vuosina 2001–2004 Kuhmon, Nurmeksen, Lieksan ja Hyrynsalmen alueilla. Geol. Surv. Finland, Report M 19/4411/2005/1. 84 p. (in Finnish, 23 MB) 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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