Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52P12NW00003

Record: MDI52P12NW00003

General

Commodities

Primary Commodities: Gold

Location

Township or Area: Collishaw Lake Area

Latitude: 51° 37' 42.42"    Longitude: -89° 55' 52.59"

UTM Zone: 16    Easting: 297125   Northing: 5723784.99    UTM Datum: NAD83

Resident Geologist District: Thunder Bay North

NTS Grid: 52P12NW

Point Location Description: Assessment file maps and DDH database.

Location Method: Conversion from MDI

Exploration History

1947: Prospecting and diamond drilling by Central Patricia Gold Mines and Conwest Explorations on the Little July Falls prospect and the July Falls Mafic Stock occurrence. 1948: Prospecting and diamond drilling by Crowshore Patricia Gold Mines on the July Falls No. 1 prospect. 1972: Geophysical surveys and diamond drilling by Umex on sulphide occurrence 1 km south of July Falls. 1988-1989: Prospecting, geophysical, geological and geochemical surveys, and diamond drilling by Norwin Geological and July Resources Corporation.

Assessment Work on File

Geology

Province: Superior

Subprovince: Uchi

Terrane: North Caribou

Domain: Uchi

Belt: Pickle Lake

Geological Age: Archean  

Geology Comments

Nov 14, 2006 (Mark Puumala) - The July Falls area occurrences are located at the northeast end of the Pickle Lake Greenstone Belt. These occurrences are found within a mafic metavolcanic rock dominated supracrustal sequence identified by Young (2003) as being part of the > 2860 Ma Pickle Crow Assemblage, and within a mafic intrusion referred to by Stott (1996) as the July Falls Mafic Stock. According to Young (2003), the Pickle Crow assemblage is dominated by massive and pillowed mafic metavolcanic flows with subordinate gabbroic sills. The mafic metavolcanics are intercalated with thin, laterally continuous banded iron formation and small, discontinuous lenses of intermediate metavolcanics. All lithologies are intruded by semi-concordant feldspar porphyry dikes. Stratigraphy generally faces toward the northwest, except where asymmetric folding (mainly in the Pickle Crow mine area) has caused reversals in the younging direction (Young 2003). The July Falls Mafic Stock is described by Stott (1996) as a composite mafic stock consisting of phases ranging from quartz diorite to gabbro, pegmatitic gabbro and hornblendite. The structural geology of the July Falls Area is described by McAuley and Winter (1990). The earliest structures in the area appear to parallel the volcanic stratigraphy and strike approximately north-northeast to northeast. These structures are interpreted by McAuley and Winter (1990) to be cross-cut by later 060-striking shears. These shears are in-turn cross-cut by later shear/fault zones that strike approximately 335 and 100-120 respectively. These and the east-west-striking veins observed at the July Falls No. 1 prospect appear to be similar to the structures mapped by MacQueen (1987) at the Pickle Crow mine property. McAuley and Winter (1990) have interpreted mineralization at the three July Falls area gold prospects/occurrences to have a close spatial association with the intersection of the 060 and 335-striking structures.

Lithology

Mineralization

Mineralization Comments

Nov 14, 2006 (Mark Puumala) - McAuley and Winter (1990) indicates that rocks in the vicinity of this prospect are dominated by massive mafic metavolcanic rocks. Exposed outcrop in the main trench consists of fine-grained pillowed flows. The volcanic sequence is reported to strike between 020 to 040, and dips steeply to the northwest. Younging indicators also indicate that the rocks are likely to face northwest. The mafic metavolcanics are intruded by lamprophyre dikes. One of these dikes has been mapped within a late shear that strikes approximately 120. Gold mineralization at this location occurs in two parallel quartz veins that cross-cut the stratigraphy and strike approximately 330 to 335 and dip 60 degrees toward the west. The veins occur within shear zones that are characterized by moderate to strong chloritization, brecciation, shearing, local carbonatization and silicification, and numerous quartz and quartz-carbonate veinlets and veins. The shear zones mapped in this area have been observed to pinch and swell along strike. The two main mineralized veins reach maximum widths of 0.65 and 0.3 m and consist of smoky-grey to milky-white quartz containing disseminated sulphides (1-2% with localized concentrations of up to 5%). Gold is associated with chalcopyrite, bornite, pyrite, pyrrhotite and arsenopyrite, and the highest assays are generally obtained from samples containing the highest sulphide concentrations. Trenching and diamond drilling carried out by Central Patricia Gold Mines/Conwest Explorations (Lytle 1948) and July Resources (McAuley and Winter 1990) has identified gold mineralization over an approximate strike-length of 150 m. Intense northeast-trending cross-fractures and drag folds have been observed in the area between the gold mineralized veins. Quartz veinlets also occur parallel to the cross-fractures, and tend to be most abundant in the area where the two mineralized veins are widest. An assay of 0.181 oz/ton was obtained over 1.28 m from a mineralized quartz vein intersected by July Resources drill hole JR89-4B. Other notable assays reported by July Resources include 0.095 oz/ton (3.25 g/t) over 0.3 m in JL89-03; 0.082 oz/ton (2.8 g/t) over 0.4 m in JL89-05; 0.417 oz/ton from 20 cm channel sample from eastern vein; 0.824 oz/ton from a 60 cm wide sample across the main (western) vein.

Mineral Record Details

References

Map - Geological series, Precambrian geology, Pickle Lake area, eastern part

Publication Number: P3057 Scale: 1:50,000    Date: 1989

Author: Stott G.M., Brown G.H., Coleman V.J., Green G.M., Reilly B.A.

Publisher Name: Ontario Geological Survey

Location:

Map - Cat Lake-Pickle Lake, geological compilation series, Kenora and Thunder Bay districts

Publication Number: M2218 Scale: 1:253,440    Date: 1976

Author: Sage R.P., Breaks F.W., Troup W.R.

Publisher Name: Ontario Division of Mines

Location:

Mono - The Geology and Tectonic History of the Central Uchi Subprovince

Publication Number: OFR5952 Date: 1996

Author: Stott G.M.

Publisher Name: Ontario Geological Survey

Location:

Thesis - New Structural, Geochronological, and Geochemical Constraints on the Tectonic Assembly of the Archean Pickle Lake Greenstone Belt, Uchi Subprovince, Western Superior Province.

Publication Number: MSc Thesis Date: 2003

Author: Young, M.D.

Publisher Name: Queen's University

Location: Thunder Bay RGP

Thesis - Stratigraphy, Structure and Gold Mineralization of the No. 5 Vein/Iron Formation Zone, Pickle Crow Gold Mines, Pickle Lake, Ontario

Publication Number: MSc Thesis Date: 1987

Author: MacQueen, J.K.

Publisher Name: Carleton University

Location: Thunder Bay RGP

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