Ontario Geological Survey
Permanent Link to this Record:
MDI42F04SE00010
| Record Name(s) | McGraw Lake Copper Occurrence - 1992 |
|---|---|
| Related Record Type | Simple |
| Related Record(s) | |
| Record Status | Occurrence |
| Date Created | 1996-Dec-20 |
| Date Last Modified | 2022-May-09 |
| Created By | |
| Revised By |
Primary Commodities: Copper
Secondary Commodities: Gold, Silver
Township or Area: Cecil
Latitude: 49° 4' 23.59" Longitude: -85° 35' 32.69"
UTM Zone: 16 Easting: 602801.96 Northing: 5436549.55 UTM Datum: NAD83
Resident Geologist District: Thunder Bay South
NTS Grid: 42F04SE
Point Location Description: Small stripped area and blast pit
Location Method: Field Visit
Access Description: The McGraw Lake copper occurrence is located in Cecil Township approximately 18.6 km east-southeast of Manitouwadge and 0.5 km west of McGraw Lake. The occurrence is accessible via motor vehicle followed by travel on foot. From Manitouwadge, proceed east along the Camp 70 logging road for approximately 4.25 km to the Twist Lake road. Proceed south and east along the Twist Lake road for approximately 17 km to an unnamed, secondary logging road located approximately 100 m south of a small creek which flows into the north end of Faries Lake. Proceed easterly along this unnamed road for approximately 1.2 km to where the road forks. Turn left and proceed on foot for approximately 770 m to where the road forks once again. Sulphide mineralization is exposed on the side of a hill approximately 20 m southeast of the fork in the road.
1964-1965: Geological mapping; V.G. Milne (ODM). 1967: Geological maping; J. F. Giguere (ODM). 1978: Regional lake sediment and water geochemical survey; GSC-MNR. Samples collected in the vicinity of the occurrence did not contain anomalous amounts of gold nor base metals. 1989: Geological mapping; H. Williams and F. Breaks (OGS). Dighem airborne geophysical survey (EM, MAG, VLF-EM); Noranda Exploration Company, Limited and Noranda Minerals Inc. (Geco Division). 1991: Reconnaissance till sampling program; I.M. Kettles (GSC). Samples collected in the vicinity of the occurrence contained slightly anomalous amounts of copper (up to 43 ppm) and gold (12 ppb). 1992: Stripping, blasting, prospecting and lithogeochemical sampling; prospector A. Turner. The occurrence was discovered at this time but the blasting essentially destroyed the original showing and failed to expose any new mineralization. Lithogeochemical sampling; D.B Mckay (OGS). No assessment reports were found on file.
Province: Southern
Subprovince: Wawa
Terrane: Wawa-Abitibi
Belt: Manitouwadge-Hornepayne
Geological Age: Archean
Metamorphism Type: Regional
Metamorphism Grade: Amphibolite
Dec 07, 2005 (D McKay) - The occurrence is located within the Wawa subprovince and is underlain primarily by variably deformed, locally brecciated, strongly foliated (320 degrees /subvertical), amphibolitic, mafic metavolcanic rocks which may represent part of the eastward extension of the south limb of the Manitouwadge greenstone belt (Williams and Breaks 1989, 1990). Mineral assemblages suggest these rocks have experienced upper amphibolite facies-grade regional metamorphism (Williams and Breaks 1989). The mafic metavolcanic rocks in the vicinity of the occurrence have been folded into a narrow (approximately 500 m wide) boot-shaped belt which wraps around the south and west sides of McGraw Lake (Giguere 1972; Williams and Breaks 1990). This folded belt of rocks is surrounded to the east, west and south by tonalitic and granodioritic gneisses of the Black Pic batholith (Williams and Breaks 1990). The Faries Lake-Moshkinabi Lake mafic intrusive complex is located approximately 1 km west of the occurrence (Williams and Breaks 1989, 1990). The occurrence is located along the western contact between the mafic metavolcanic rocks and the surrounding gneisses of the Black-Pic batholith. The occurrence consists of up to 10% fine- to medium-grained, disseminated grains and irregularly shaped patches (up to 1 cm across) of pyrrhotite, pyrite and rare chalcopyrite hosted within strongly deformed, amphibolitic, mafic metavolcanic gneiss.
| Rock Type | Rank | Composition | Texture | Relationship | Gneiss-Unsubdivided | 1 | Amphibolitic Gneiss | Host |
|---|---|---|---|---|
| Tonalite | 2 | Tonalitic To Granodioritic | Dikes/Sills, Locally Pegmatitic | Near |
Dec 07, 2005 (D McKay) - The mafic metavolcanic gneiss is typically dark green, medium- grained, moderately foliated and locally sheared. Intrusion of coarse-grained tonalitic and granodioritic magma from the Black Pic batholith has locally brecciated the mafic metavolcanic gneiss into numerous, variably-sized, subangular to angular xenoliths. One of these, approximately 50 cm long by 20 cm wide, hosts the sulphide mineralization discovered by prospector A. Turner. Although many xenoliths of mafic metavolcanic gneiss occur in the vicinity of the occurrence, the sulphide mineralization appears to be confined to the single xenolith discovered by A. Turner. A narrow (up to 20 cm wide), locally pegmatitic, quartz- and feldspar- phyric, felsic dike is located immediately west of the occurrence. This dike strikes approximately 345 degrees , dips 55 degrees E, and contains 1 to 2% fine-grained, disseminated subhedral grains of pyrite and rare molybdenite.
| Rank | Mineral Name | Class | Economic Mineral Type | Alteration Mineral Type | Alteration Ranking | Alteration Intensity | Alteration Style |
|---|---|---|---|---|---|---|---|
| 1 | Chalcopyrite | Economic | Ore | ||||
| 2 | Pyrite | Economic | Ore | ||||
| 3 | Pyrrhotite | Economic | Ore |
Dec 07, 2005 (D McKay) - The occurrence consists of up to 10% fine- to medium-grained, disseminated grains and irregularly shaped patches (up to 1 cm across) of pyrrhotite, pyrite and rare chalcopyrite hosted within strongly deformed, amphibolitic, mafic metavolcanic gneiss. Grab samples collected from the occurrence in 1992 by D.B. McKay for the OGS returned assay results which varied from nil to 0.003 ounce Au/ton, trace to 0.36 ounce Ag/ton, 69 to 3560 ppm Cu, <10 ppm Pb, <10 ppm Pd and 27 to78 ppm Zn. The economic potential of the McGraw Lake copper occurrence is limited by its small size, low metal content, and apparent association to a single xenolith. Pyritic, felsic dikes in the area may warrant exploration to determine their potential to host gold mineralization.
| Rank | Classification |
|---|---|
| 1 | Unknown |
| Rank | Characteristic |
|---|---|
| 1 | Disseminated |
Article - Geological studies in the Manitouwadge-Hornpayne area
Publication Number: MP146.014 Page: 79-91 Date: 1997
Author: Williams H.R., Breaks F.W.
Publisher Name: Ontario Geological Survey
Location:
File - Schreiber-Hemlo Resident Geologist Mineral Deposit Files
Publication Number: Min Dep Date:
Author:
Publisher Name:
Location: Thunder Bay RGP
Map - Geology of the Manitouwadge-Hornepayne area
Publication Number: OFM0142 Scale: 1:50,000 Date: 1990
Author: Williams H.R., Breaks F.W.
Publisher Name: Ontario Geological Survey
Location:
Article - Geological studies in the Manitouwadge-Hornepayne region
Publication Number: MP151.006 Page: 41-47 Date: 1997
Author: Williams H.R., Breaks F.W.
Publisher Name: Ontario Geological Survey
Location:
Mono - Mineral Occurrences in the Manitouwadge Area, Volumes 1, 2 and 3
Publication Number: OFR5906 Page: 349-354 Date: 1994
Author: McKay D.B.
Publisher Name: Ontario Geological Survey
Location:
Compend - Report of Activities 1992, Resident Geologists
Publication Number: MP161 Page: 144-145 Date: 1993
Author: Fenwick K.G., Pitts A.E., Newsome J.W.
Publisher Name: Ontario Geological Survey
Location:
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