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Thompson

Manitoba, Canada

Main commodities: Ni Cu
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The Thompson nickel deposits are located over a NNE trending interval of 130 km within the Thompson Nickel Belt of northern Manitoba, Canada, 660 km north of Winnipeg.
(#Location: T1 - 55° 42' 56"N, 97° 51' 7"W; Mel - 55° 58' 15"N, 97° 46' 34"W; Soab Lake - 55° 12' 39"N, 98° 25' 34"W; Bucko - 54° 52' 41"N, 98° 39' 27"W).

This belt lies on the margin of the 1850 Ma Trans-Hudson Orogen, adjacent to the north-western margin of the Archaean Superior province.

The ore deposits are associated with peridotitic lenses that typically occur in sulphidic meta-pelites, now biotite schists of the Ospwagan Group, a sedimentary-volcanic shelf sequence. This sequence includes siltstone, sandstone, quartzite, shale, phyllite, dolomite, iron formation and pillowed basalts which have been deformed and a pronounced linearity produced. They have been juxtaposed against the upper amphibolite to granulite facies rocks of the Trans-Hudson Orogen further to the north-west.

Several periods of folding and amphibolite facies metamorphism have pervasively reworked the original ore-host relationship in many deposits. Deformation of ores and host rocks at Thompson has been extreme. The parent harzburgite body has been stretched and dismembered into a horizon of ultramafic blocks and boudins that are enclosed in the sulphide rich schist that hosts the ore.

The main Thompson ore zone has a 6 km long surface trace and has been intersected to a depth of >1500 m below the surface. The deposit is generally stratabound and occurs near the top of the pelitic schist unit, the P2 Member of the Pipe Formation. It has undergone six folding phases and sillimanite-garnet-K Feldspar grade metamorphism.

The deposit is found on the limbs of the first order "Thompson Dome". A second order parasitic fold runs along the the strike of the eastern limb, with sulphides commonly concentrated in dilation zones along the hinge of this fold. Third order, sub-horizontal folds have led to the thickening of sulphide zones within this system.

Nickel sulphides occur as massive, semi-massive and as matrix breccias and stringers composed of pyrrhotite-pentlandite with minor chalcopyrite. The pyrrhotite-dominated nickel sulphide ores are zones in the pelitic schists that contain quasi-conformable lenses and stringers of massive sulphide which enclose numerous wall rock inclusions.

The Pipe II deposit is less deformed than the main Thompson ore and extends for approximately 1 km in strike length along the stratigraphic base of a 2 km long, 150 m thick serpentinised ultramafic body, thought to be the boudinaged remnant of a larger sill on the western limb of the main Thompson Dome. This sill lies in a tight, steeply NE plunging F3 synform. The mineralisation in this body also occur as disseminated, network textured interstitial and massive sulphides.

The deposits in the belt, which include Thompson, Mel, Pipe I, Pipe II, Birchtree, Soab Lake, Manibridge, Bucko and Bowden - all show similar though sometimes less extreme deformation. Most of the komatiitic sulphide rich ores of the belt have been deformed to form sulphide matrix breccias enclosing clasts of wall rocks.

The total production plus reserves in the Thompson Belt amounts to approximately 89 Mt @ 2.5% Ni, 0.13% Cu. Proven + probable reserves in 2005 were: 25 Mt @ 1.9% Ni. The total resource (including production) at Thompson is estimated by Naldrett 2004 as 150 Mt @ 2.32% Ni, 0.16% Cu, 0.046% Co.

The most recent source geological information used to prepare this summary was dated: 2000.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.


Thompson T1

Mel

Pipe

Soab Lake

Bucko

  References & Additional Information
   Selected References:
Begg, G.C., Hronsky, J.A.M., Arndt, N.T., Griffin, W.L., O Reilly, S.Y. and Hayward, N.,  2010 - Lithospheric, Cratonic, and Geodynamic Setting of Ni-Cu-PGE Sulfide Deposits: in    Econ. Geol.   v.105, pp. 1057-1070.
Bleeker W  1990 - Thompson Area - General Geology and Ore Deposits: in Galley A G, Bailes A H, Syme E C, Bleeker W, Macek J J, Gordon T S, (Eds),  Geology & Mineral Deposits of the Flin Flon and Thompson Belts, Manitoba, International Association on the Genesis of Ore Deposits Guide Book No. 10 Geological Survey of Canada, Open File 2165    pp 93-136
Bohm C O, Zwanzig H V and Creaser  R A,  2007 - Sm-Nd Isotope Technique as an Exploration Tool: Delineating the Northern Extension of the Thompson Nickel Belt, Manitoba, Canada: in    Econ. Geol.   v102 pp 1217-1231
Galley A G, et. al.,  1990 - Introduction: in Galley A G, Bailes A H, Syme E C, Bleeker W, Macek J J, Gordon T S, (Eds),  Geology & Mineral Deposits of the Flin Flon and Thompson Belts, Manitoba, International Association on the Genesis of Ore Deposits Guide Book No. 10 Geological Survey of Canada,    Open File 2165 pp 1-5
Hulbert L J, Hamilton M A, Horan M F and Scoates R F J  2005 - U-Pb Zircon and Re-Os Isotope Geochronology of Mineralized Ultramafic Intrusions and Associated Nickel Ores from the Thompson Nickel Belt, Manitoba, Canada: in    Econ. Geol.   v100 pp 29-41
Peredery W V, et. al.  1982 - Geology & Nickel Sulfide Deposits of the Thompson Belt, Manitoba: in Hutchinson R W, Spence C D, Franklin J M (Eds),  Precambrian Sulphide Deposits, Geological Association of Canada   Special Paper No. 25 pp 165-209
Scoates, J.S., Scoates, R.F.J., Wall, C.J., Friedman, R.M. and Coueslan, C.J.,  2017 - Direct dating of ultramafic sills and mafic intrusions associated with Ni-sulfide mineralization in the Thompson Nickel Belt, Manitoba, Canada: in    Econ. Geol.   v.112, pp. 675-692.
Song, X., Wang, Y. and Chen, L.,  2011 - Magmatic Ni-Cu-(PGE) deposits in magma plumbing systems: Features, formation and exploration: in    Geoscience Frontiers   v.2, pp. 375-384.
Zwanzig H V, Macek J J and McGregor  C R,    2007 - Lithostratigraphy and Geochemistry of the High-Grade Metasedimentary Rocks in the Thompson Nickel Belt and Adjacent Kisseynew Domain, Manitoba: Implications for Nickel Exploration: in    Econ. Geol.   v102 pp 1197-1216


Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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