Koillismaa
Koillismaa Layered Intrusions
The Early Proterozoic Koillismaa layered intrusions are among
the largest group of such intrusions (50km x 20km area), which occur
over the northern portions of the Fennoscandian Shield of Finland and
Russia. Three of the largest are 20 to 30km long and 7 to 8km wide. The
intrusions are 2.44 Ga in age and intrude the major structural rift
zone within a portion of Archean terrain in NE Finland. These
intrusions are similar in age and type to the famous Great Dyke of
Zimbabwe, Stillwater Complex of Montana, and the Penikat intrusions in
NW Finland where deposits hosting several million ounces of PGE’s have
been defined and are currently being developed by North American
Palladium in JV with the Arctic Platinum Project.
Limited past exploration has outlined large, low-grade Ni-Cu-PGE zones
in the basal sections of the seven Koillismaa intrusions. Recent work
at Koillismaa by the GTK has indicated high-grade Cu-Ni-PGE
mineralization crosscutting zones within the footwall gneisses, similar
to those that host the rich footwall deposits in the Sudbury Nickel
Camp in Canada.
Magnus Minerals has claim applications covering 15km of the basal
mineralization of the Kuusijärvi Intrusion, 9km of the known
mineralization in the Porttivaara Intrusion, 2km portion of known
mineralization in the footwall of the Syöte Intrusion, and over a 1km
long EM-magnetic anomaly in a poorly-tested massive nickeliferous
sulfide zone. Magnus also holds claim reservations over the Tilsa
and Murtolampi intrusions.
An example of the typical Marginal Zone mineralization in the Koillismaa Area is the Porttivaara
Intrusion, which was extensively explored by Outokumpu in the 1960’s
& 1970’s. Trench samples and seventy-five holes totalling 11,700m
outlined 69 Mt of 0.2% Cu + 0.16% Ni in three deposits. The mineralized
zone is 23 to 29m thick along 4km of the marginal zone from Baabeli to
Rusamo to Porttivaara. PGE’s +Au average from 0.5-1.0 g/t with maximums
of 2–3 g/t in individual samples.
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Exploration by GTK in a JV with North Atlantic Resources in 2001 to
2003 over the entire Koillismaa area resulted in the discovery of
several new prospects and targets. Basal zone mineralization was
detected in the smaller intrusions as well, with some of the more
promising results at Tilsa and Murtolampi. An important discovery by
GTK was the high-grade, cross-cutting, vein-type, massive sulfide
mineralization in the footwall portion of the Syöte Intrusion where
assays up to 1.87% Cu, 1.4% Ni, 4.72 g/t Pd, 1.91g/t Pt & 1.78 g/t
Au were obtained.
Potential
Zones of higher-grade mineralization exist within the known basal sections of the intrusions. An example is Pärjänoja,
where trenching by Lapin Malmi in the 1980’s, totalling 165m, yielded
values of 4m of 0.44% Cu, 0.4% Ni, 0.37 g/t Au, 0.4 g/t Pt & 0.9
g/t Pd; and 17m of 0.44% Cu, 0.33% Ni, 0.14 g/t Au, 0.36 g/t Pt &
0.69 g/t Pd.
Massive nickeliferous sulfides are known in the rocks in the
vicinity of the intrusions as well and remain untested. In addition,
the discovery of off-set dike settings in the footwall structural zones
containing high-grade vein-type mineralization such as the prospect at
Syöte have not been explored for in the past and offer potential
for the discovery of important deposits.
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