Tulisilmä - Gold Database

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Name	Tulisilmä	DATA UPDATED	12.1.2007
Alternative names	Sikakangas, Hoikkamäki 1
Deposit summary	TULISILMÄ, in Southern Ostrobothnia, is a Palaeoproterozoic orogenic gold occurrence with no resource estimate available. It is hosted by plagioclase porphyry, formed by a NE-trending set of mineralised lenses comprising quartz-tourmaline veins in altered host rock. The occurrence is located between two major NW-trending shear zones. Native gold in quartz veins.
LOCATION
Geological domain	Svecofennian	Belt	Southern Ostrobothnia
Site photo		Regional map
Map sheet	222207
Northing (kkj)	6956500	Easting (kkj)	2444000
Latitude	62.70838N	Longitude	22.90223E
Municipality	Seinäjoki
Nearest town, roads	5 km south from Seinäjoki. A sealed road at the W margin of the area, a gravel road across the area.
MINING
Exploration licence no	4667/1, 7817/1	Mining concession no
Present holder	Geological Survey of Finland (GTK) (2003–)
Previous holders	Geological Survey of Finland (GTK) (1975–1982, 1989–9 3)
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	The NE-striking mineralised area is 200 m x 700 m at the present surface [4].
Lodes	A set of small mineralised lenses with a width of 2–3 m [1,2,4].
Best sections	5 m @ 2 ppm Au, 1 m @ 11.8 ppm Au [1,2].
EXPLORATION
Discovery year	1989
Discovery	First indication by gold-rich erratic boulders and outcrop found by an amateur prospector. This lead to the discovery of the deposit in outcrop by GTK [1,2].
Exploration history	GTK (1975–1982, 1989–93) [1,2,3,4,5]: Detailed bedrock mapping, trenching, channel sampling from outcrop, diamond drilling, till stratigraphic and geochemical studies, IP ground 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	None by IP, others not tested [1].
Drilling	GTK (1989–93) [1,2]: 19 diamond-drill holes, total 658 m; drilled 1–3 holes per profile, distance between the profiles is 50 m.
Elements analysed
Primary dispersion
Secondary dispersion	Extensive Au anomalies in the region in till, also a local As anomaly enveloping the mineralisation; the regional Sb and As anomalies in till are, apparently, unrelated to gold mineralisation [4].
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: Paunu Oivanen 1975–1982, Niilo Kärkkäinen 1989–1 993.
ORE
Siting of gold
Fineness
Major opaques	Arsenopyrite [1].
Minor opaques	Pyrrhotite, pyrite, gold [1].
Gangue	Quartz, scheelite, tourmaline, calc-silicates [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
Enriched elements
Ore fluid
Stable isotopes
Pb isotope data
GEOLOGY
Geological setting	A sequence of Palaeoproterozoic metapelites and metagreywackes intruded by the intermediate plagioclase and plagioclase-uralite porphyry sills(?) [1,2,3,4].
Major host rocks	Plagioclase porphyry [1,2]
Minor host rocks
Intrusives	Post-mineralisation(?) pegmatite dikes within the host rock, also present in the auriferous shear zone [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	Amphibolite facies [1].
Metamorphic mineral assemblage	Plagioclase-hornblende-quartz-biotite±cummingtonite [3].
Metamorph photo 1		Metamorph photo 2
STRUCTURE
Structural style	Ductile(-brittle) [1].
Closest major shear	The mineralisation is between two NNW-trending, major shear zones which can be traced for tens of kilometres [6].
Controlling structure	Subconformable, minor shear zones near the contact between the plagioclase porphyry and the underlying metapelitic rocks [1].
Deformation history
Ore fabric
Veins	Quartz-tourmaline veins, 1–10 cm in width; these tend to contain 1–20 ppm Au [1].
Structure photo 1		Vein photo 1
Structure photo 2		Vein photo 2
Structure photo 3		Vein photo 3
ALTERATION
General alteration	Calc-silicate alteration and weak sulphidation in on about 20 m wide zone containing most of the shear zones [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
GENETIC MODEL	Orogenic "mesothermal" deposit.
GENETIC TYPE	Orogenic	References
Alternative genetic type 1		References
Alternative genetic type 2		References
References 1. Kärkkäinen, N. 1993. Tutkimustyöseloste Seinäjoen kaupungin Tulisilmän alueen malmitutkimuksista, koskien valtausaluetta Tulisilmänmäki 1, kaiv.rek.nro 4667/1. Geol. Surv. Finland, Report M06/2222/-93/1/10. 9 p. (in Finnish, 4.3 MB) 2. Kärkkäinen, N. & Huuskonen, M. 1992. Kultamalminetsintää Seinäjoen Tulisilmän alueella vuosina 1989–1990. Geol. Surv. Finland, Report M06/2222/-92/1/10. 7 p. (in Finnish, 10.3 MB) 3. Oivanen, P. 1982. Antimonitutkimukset Seinäjoen-Nurmon alueella vuosina 1975–1982. Geol. Surv. Finland, Report M19/2222/-82/1/10. 123 p. (in Finnish, 109 MB) 4. Lestinen, P., Kontas, E., Niskavaara, H. & Virtasalo, J. 1991. Till geochemistry of gold, arsenic and antimony in the Seinäjoki district, western Finland. Journal of Geochemical Exploration 39, 343–361. 5. Lestinen, P. 1988. Seinäjoen alueen geokemialliset tutkimukset vuosina 1983–1986. Geol. Surv. Finland, Report. S/41/2222/1/1988. 40 p. (in Finnish, 1.4 MB) 6. Korsman, K., Koistinen, T., Kohonen, J., Wennerström, M., Ekdahl, E., Honkamo, M., Idman, H. & Pekkala, Y. (eds.) 1997. Suomen Kallioperäkartta = Berggrundskarta över Finland = Bedrock map of Finland 1:1 000 000. Geol. Surv. Finland.
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