Pampalo NW - Gold Database

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Name	Pampalo NW	DATA UPDATED	15.1.2008
Alternative names	Pampalonsärkät
Deposit summary	PAMPALO NW, in the Ilomantsi greenstone belt, is an Archaean orogenic gold occurrence with no resource estimate available. It comprises quartz veins in apparently subsidiary shear zones of the Pampalo Shear Zone system, NW from the Pampalo gold deposit and test mine. Gold in quartz veins and their immediate wallrocks.
LOCATION
Geological domain	Archaean	Belt	Ilomantsi
Site photo		Regional map
Map sheet	433307
Northing (kkj)	6988500	Easting (kkj)	4563700
Latitude	62.99437N	Longitude	31.25371E
Municipality	Ilomantsi
Nearest town, roads	40 km NE from Ilomantsi, 100 km NE from Joensuu. A sealed road 1 km from the area.
MINING
Exploration licence no	6653/1, 7559/2	Mining concession no
Present holder	Endomines Oy
Previous holders	Geological Survey of Finland (GTK)
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	At least three lodes [1,8].
Best sections	0.5 m @ 24.4 ppm [1,5]. 10.95 m @ 3.26 Au, 1.2 m @ 3.78 ppm Au [8].
EXPLORATION
Discovery year	1995
Discovery	By GTK; drilling into a combined till-geochemical and IP anomaly [5].
Exploration history	GTK (early 1990's) [1,4,5,6]: Regional bedrock mapping, regional and local till geochemical survey, ground magnetic, slingram and IP survey, diamond drilling. Endomines (1998–) [1,8]: 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: 11 diamond-drill holes, total 1953 m [5]. Endomines (1999): a few diamond-drill holes [2], 2007: two diamond-drill holes, total 223 m [8].
Elements analysed
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	Endomines: Jaakko Liikanen.
ORE
Siting of gold	In quartz veins and their immediate wallrocks [1].
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	The mineralisation is in the central part of the 2754–2726 Ma Hattu Schist Belt [1,7].
Major host rocks	Feldspar porphyry [8].
Minor host rocks
Intrusives	The nearest pluton (Tasanvaara tonalite) predates mineralisation. The age of the tonalitic plutons bounding the schist belt is ca. 2750 Ma [2,7].
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	[2]: 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. Formation of post-mineralisation tremolite porphyroblasts in the metakomatiite. A relatively strong, but unevenly distributed Palaeoproterozoic overprint [3].
Metamorphic grade	Greenschist-amphibolite facies transition [2].
Metamorphic mineral assemblage
Metamorph photo 1		Metamorph photo 2
STRUCTURE
Structural style
Closest major shear	The Pampalo Shear Zone system: a major shear zone on the both sides of the deposit [2].
Controlling structure	Subsidiary shear or fault zones related to the Pampalo Shear Zone system? [2].
Deformation history	Rapid and extensive crustal generation and progressive deformation between 2.76–2.73 Ma, in a transpressional regime [7].
Ore fabric
Veins	Quartz veins [1].
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	An Archaean post-mineralisation metamorphic overprint at about 500±50°C with deformation, sinistral folding, and local remobilisation of gold [2]. During this stage, gold concentrated into axial planes of folds dipping 80° to the south [2]. On ca. 1800 Ma, a Proterozoic regional metamorphic overprint which is shown by K-Ar and Rb-Sr ages of micas [2].
TIMING	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 peak metamorphism) [2].
GENETIC MODEL	[2]: 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-bisulphide, -thiosulphide and -telluride complexes of fluid due to cooling and/or changes in pH and fO2. Probably, gold precipitated just below 500°C with sulphides due to reaction between the mineralising fluid and wall-rock (chiefly by sulphidation). The formation of the present low-temperature Te and Bi minerals probably took place as subsolidus reactions with cooling temperature.
GENETIC TYPE	Orogenic	References	[2]
Alternative genetic type 1		References
Alternative genetic type 2		References
References 1. Endomines Oy. 1999. www.endomines.fi on 09/12/99. 2. 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. 3. 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. 4. Hartikainen, A. & Niskanen, M. 2001. maaperägeokemialliset kultatutkimukset Hatun liuskejaksolla Ilomantsissa vv. 1983–1995. Geol. Surv. Finland, Report S/41/4244/1/2001. 22 p. 5. 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. 6. 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) 7. 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. 8. Endomines 2007. Pressmeddelande den 18 december 2007. (in Swedish)
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