Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI000000002245

Record: MDI000000002245

General

Commodities

Primary Commodities: Copper

Secondary Commodities: Platinum Metals

Location

Township or Area: Seeley Lake Area

Latitude: 48° 49' 50.92"    Longitude: -86° 20' 41.28"

UTM Zone: 16    Easting: 548085   Northing: 5408855    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 42D16SW

Point Location Description: DDH FD-13-33 location from Assessment file 20000014536

Location Method: Data Compilation

Access Description: The property can be accessed via an all-season gravel road for 12 km and another 2 km seasonal drill trail, or by helicopter.

Exploration History

1965: Anaconda American Brass Ltd. drilled 1 DDH totaling 211.1 m. 1979-80: Placer Development Ltd. carried out line cutting, geological mapping, soil sampling, and magnetic and surveys. 2001: Freewest Resources Canada Inc. carried out line cutting, soil sampling, mapping, prospecting, trenching, sampling, and airborne geophysics. 2005-6: Benton Resources Corp carried out EM surveys and drilled 18 DDH totalling 4618.03 m. 2013: Stillwater Canada drilled 35 DDH totaling 3999 m.

Assessment Work on File

Geology

Province: Superior

Subprovince: Wawa

Terrane: Wawa-Abitibi

Geological Age: Archean  

Geology Comments

Dec 05, 2018 (Therese Pettigrew) - The Four Dams region of the Bermuda property is situated along the north-eastern margin of the Proterozoic (1.1 Ga) Coldwell Alkaline Complex. The Coldwell Complex was emplaced into Archean age felsic to mafic metavolcanic, clastic metasedimentary and granite intrusive rocks. The Coldwell complex is part of the Keweenawan group igneous rocks that were emplaced along the Midcontinent Rift System, a triple junction located in the Nipigon area of the Superior Province. The Coldwell Complex is composed of six major lithologies that have been grouped into three intrusive centers. The general stratigraphy of the intrusion consists of Archean footwall rocks to the east, intruded by Center I, II and III of the Coldwell Alkaline Complex. Footwall xenoliths of mafic to felsic metavolcanics and clastic metasedimentary rocks have been observed in Center I rocks. 1) Center I includes the 700-2000 m thick Eastern Border Gabbro which has been intruded by augite/olivine-augite syenite, intruded again by amphibole syenite. 2) Center II is composed of massive alkalic (Ca-rich) gabbro and a layered nepheline syenite. 3) Center III is composed of barkevikite syenite, quartz syenite and granite. The Coldwell Complex Center I unit has been intruded along the north, north-eastern and eastern contact by the Four Dams Lake Gabbro on the northern and north-eastern contact and the Two Duck Lake gabbro on the eastern contact. The Two Duck Lake and Four Dams Lake gabbro are similar in composition, grain size and texture (Assessment file 20000001980).

Lithology

Lithology Comments

Dec 05, 2018 (Therese Pettigrew) - The Four Dams Lake gabbro is thought to be analogous in composition, grain size, and textural variation to the Two Duck Lake Gabbro. The Two Duck Lake Gabbro has been subdivided into an older phase 1 gabbro and a younger phase 2 gabbro characterized by: 1) Fine- to medium-grained, massive, equigranular, medium to dark mauve feldspar colour and commonly strongly magnetic unit. 2) Coarse-grained, locally pegmatitic (vari-textured), massive, generally equigranular, medium to dark mauve feldspar colour, locally with a blue sub-metallic luster (Labradorite bearing), moderate to strongly magnetic unit. Both phases often exhibit a plagioclase cumulate texture, with mafic minerals intercumulus to the plagioclase feldspar. Mafic mineral phases include olivine (rare), orthopyroxene (bronzite), clinopyroxene (augite), hornblende and biotite. Magnetite and minor ilmenite occur as oxide phases and locally form layers within the gabbro. Accessory phases include apatite, phlogopite, quartz and molybdenum. Intervals of Labradorite-bearing gabbro are uncommon, easily identifiable by the blue sheen on the feldspar surface and restricted to the coarse-grained phase. Cu-PGE mineralization is abundant in, but not restricted to, the coarse-grained phase of this unit. This unit exhibits an irregular contact with the EBG. Augite syenite and augite-olivine syenite units are generally medium-grained, massive, equigranular with light cream to pink feldspars and dark green commonly intercumulus mafic phases. These units are generally weakly to non-magnetic. These rocks rim the gabbroic phases to the west and southwest of the property. Dykes of amphibole syenite have been encountered in drilling and cross-cut the Two Duck Lake Gabbro. This unit does not host Cu-PGE mineralization (Assessment file 20000014536).

Mineralization

Mineralization Comments

Dec 05, 2018 (Therese Pettigrew) - The Four Dams North mineralization occurs in a 100 m thick lens of Marathon Series ultramafic rocks that strikes northwesterly for 350 m and dips 60 degrees to the southwest. The intrusion has a thin marginal zone of melagabbro and a core of apatitic clinopyroxenite to apatitic wehrlite. Sulphides in the Four Dams North zone include disseminated to blebby chalcopyrite with lesser pyrrhotite and trace bornite. The mineralization includes intervals such as 0.16 g/t PGM and 0.39% Cu over 74 m and 0.23 g/t PGM and 0.40% Cu over 85 m. Higher PGM grades occur in the central apatitic wehrlite zone. The Four Dams South mineralization is hosted by the Layered Series rocks, located approximately 150 m south of the Four Dams North mineralization. The mineralization occurs in homogeneous or modally layered olivine gabbro inter layered with magnetite rich lenses. The Four Dams South zone is continuous for 700 m along strike, dips 40 degrees to the southwest and pinches and swells from thicknesses of up to 50 m and down to 4 m. The zone was defined by 32 short diamond drill holes in 2013. Best intersections include 0.33% Cu over 48 m, but the zone contains only trace Pd. The sulphide minerals consist of fine- to medium-grained disseminated pyrrhotite and chalcopyrite and are associated with actinolite and albite alteration. The Four Dams South mineralization is believed to be a result of hydrothermal remobilization (Assessment file 20000014536). Assays from Benton’s 2005-6 drill program were up to 0.97% Cu and 0.13% Ni (although most Ni assays were around 0.03% Ni), 207.29 ppb Au, 311.85 ppb Pd, and 162.1 ppb Pt (Assessment file 20000001980). The 2001 sampling program returned assays from 2040 ppm to 1.25% cu, 650 to 1330 ppm V, 56 to 115 ppb Pd, and up to 78 ppb Pt and 97 ppb Au (Assessment file 42D16SW2006).

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