Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI42D16SW00028

Record: MDI42D16SW00028

General

Commodities

Primary Commodities: Copper, Iron

Secondary Commodities: Titanium, Vanadium

Location

Township or Area: Seeley Lake Area

Latitude: 48° 48' 58.18"    Longitude: -86° 19' 17.82"

UTM Zone: 16    Easting: 549800.8   Northing: 5407241.54    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 42D16SW

Point Location Description: Precise

Location Method: Conversion from MDI

Access Description: The Marathon property is located on the north shore of Lake Superior approximately 290 km east of Thunder Bay, Ontario and 12 km from the town of Marathon. The Marathon claim group is accessible from Highway 17 by a gravel road.

Exploration History

1954: claims held by Bamoos Lake Mines Ltd., who drilled the gabbros to test the copper potential. 1963: Empire Exploration s Ltd. held the claims and conducted magnetic and self-potential geophysical surveys. 1964: claims were optioned to Anaconda American Brass Ltd, who carried out geological mapping. 1966: claims were held by the Keevil Mining Group Ltd. Exploration has included trenching, detailed mapping, geophysical surveys and diamond drilling. 1976: D. Fairbairn conducted an airborne geophysical survey. 1984-1991: Fleck Resources Ltd. conducted linecutting, trenching, sampling and diamond drilling. 2000: property was staked by M. and S. Stares. 2000-01: Freewest Resources Canada Inc. optioned the property and conducted an airborne magnetometer and TEM survey. 2003: Benton Resources Corp. acquired the property. 2004: Benton drilled 1 DDH. 2005-06: Benton conducted prospecting, sampling, geological mapping, trenching, and drilled 22 DDH totalling 4028.4 m. 2007: Benton conducted geological mapping and drilled 28 DDH totalling 5070.6 m. 2011: Stillwater acquired the leases.

Assessment Work on File

Geology

Province: Superior

Subprovince: Wawa

Terrane: Wawa-Abitibi

Geological Age: Archean  

Geology Comments

Sep 28, 2015 (Therese Pettigrew) - The area is predominantly underlain by gabbro belonging to the Port Coldwell alkalic complex. To the east, the gabbro intrudes rocks belonging to an older metavolcanic-metasedimentary assemblage. Numerous, eastward-dipping dikes of larvikite syenite and younger, lamprophyre dikes intrude the gabbro (Shklanka, 1969).

Lithology

Lithology Comments

Sep 28, 2015 (Therese Pettigrew) - The margin of the Coldwell Complex is composed of two gabbroic phases: an early (olivine gabbro) phase, and a later olivine-biotite gabbro. The later gabbro is discontinuous along the marginal contact, dips moderately westwards, and locally contains disseminated chalcopyrite and pyrrhotite with variable concentrations of Platinum Group Elements. The intrusive rocks of the Coldwell Alkalic Complex consist of an olivine gabbro outer zone and a syenitic core. The mineralized part of the complex is contained within the outer zone olivine gabbro. There, olivine gabbro was intruded by an olivine-biotite gabbro containing sulfide mineralization. This later intrusion is focused along the Complex/metavolcanic contact where it has almost completely displaced the earlier olivine gabbro towards the core of the Complex. The olivine-biotite gabbro intruded parallel to or slightly obliquely to the igneous layering exhibited in the early gabbro. Lateral continuity of this unit ranges from 500 m to 10 km. thickness is on the order of 20 to 100 m. The abundance of olivine-biotite gabbro decreases rapidly up-section, where it becomes a series of thin and discontinuous lenses with minor sulfide mineralization. The Two Duck Lake Gabbro, which contains the Cu-Ni-PGE mineralization, ranges from medium through coarse and very coarse-grained to pegmatitic. The medium-grained unit varies from olivine-biotite to olivine-biotite-hornblende gabbro in composition. Olivine and biotite contents range from 2 to 10 ft. Coarse-grained olivine-biotite gabbro (7c) represents the bulk of the Two Duck Lake intrusion. Olivine content ranges from 1 to 5% and biotite ranges from 5 to 15%. The very coarse-grained olivine-biotite gabbro contains olivine and biotite contents similar to the coarse- grained gabbro but may contain up to 15% Fe-Ti oxides (ferro-gabbro). Pegmatitic, olivine-biotite or olivine-hornblende-biotite gabbro, which may contain variable Fe-Ti oxides (up to 10%), is a volumetrically small unit. This unit is extremely discontinuous and has patchy crosscutting and oblique lenses-like forms (AFRI 42D16SE0021).

Mineralization

Mineralization Comments

Sep 28, 2015 (Therese Pettigrew) - Sulphide mineralization is scattered throughout the banded gabbro unit but becomes significantly concentrated in some widely separated localities. Higher copper values are about 0.5 percent (Milne, 1967). Pyrrhotite, pyrite and chalcopyrite occur as interstitial fillings, and are associated with the coarser grained, ilmenomagnetite-rich phase of the Two Duck Lake gabbro. Assays indicate a variation in copper from 0.05% to about 2% (Shklanka, 1969). The sulfide mineralized zone lies close to the marginal contact of the Complex and the highly deformed metavolcanics. Sulfide content is variable, generally pyrrhotite-rich and chalcopyrite-poor. Massive sulfides, up to 0.5 m thick, may occur in this unit near the basal contact. Sulfides; chalcopyrite, pyrrhotite, and voilarite, occur mostly as interstitial composite grains. Biotite and Fe-Ti oxides may be closely associated with sulfides, especially where sulfide patches or clots occur; such as in very coarse and pegmatitic material. Apatite is often present in the coarse to pegmatitic material (with or without sulfides). Platinum Group Elements (PGE) occur as discrete Platinum Group Minerals (PGM) in and attached to the sulfides and/or Fe-Ti oxides. Platinum, palladium, and minor rhodium occur. The Pd/Pt is approximately 6/1 (AFRI 42D16SE0021). Early investigations were directed toward the ilmenomagnetite layers. Analysis of a chip sample taken from a trench contained 40% iron, 7.35% titanium oxide, 0.56% sulphur, and 0.33% phosphorus. Other assays show that iron content was up to 27% (Puskas, 1967).

Mineral Record Details

References

MonoMap - Geology of Cirrus Lake-Bamoos Lake area, District of Thunder Bay

Publication Number: R043 Scale:     Date: 1997

Author: Milne V.G.

Publisher Name: Ontario Dept. of Mines

MonoMap - Geology of the Port Coldwell area, District of Thunder Bay

Publication Number: OFR5014 Scale:     Date: 1997

Author: Puskas F.P.

Publisher Name: Ontario Dept. of Mines

Mono - Copper, nickel, lead and zinc deposits of Ontario

Publication Number: MDC012 Scale:     Date: 1969

Author: Shklanka R.

Publisher Name: Ontario Dept. of Mines

Map - Bamoos Lake sheet, Thunder Bay District

Publication Number: M2099 Scale:     Date: 1997

Author: Milne V.G.

Publisher Name: Ontario Dept. of Mines

Map - Manitouwadge sheet, districts of Thunder Bay and Algoma, geological compilation series

Publication Number: P0494 Scale: 1:126,720    Date: 1997

Author: Milne V.G.

Publisher Name: Ontario Dept. of Mines

Map - Precambrian Geology, Port Coldwell Complex, East Half

Publication Number: P3233 Scale: 1:20,000    Date: 1993

Author: Walker E.C., Sutcliffe R.H., Shaw C.S.J., Shore G.T., Penczak R.S.

Publisher Name: Ontario Geological Survey

Map - Port Coldwell area, District of Thunder Bay

Publication Number: P0114 Scale: 1:31,680    Date: 1997

Author: Puskas F.P.

Publisher Name: Ontario Dept. of Mines

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For detailed information regarding this mineral record please contact the Thunder Bay South Resident Geologist District Office