Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI42F05SW00012

Record: MDI42F05SW00012

General

Commodities

Primary Commodities: Sulphur/Pyrite

Secondary Commodities: Gold, Copper

Location

Township or Area: Everest Lake Area

Latitude: 49° 18' 6.27"    Longitude: -85° 46' 20.31"

UTM Zone: 16    Easting: 589251.787   Northing: 5461724.747    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 42F05SW

Point Location Description: Several small pits and stripped areas

Location Method: Field Visit

Access Description: The Otter Lake sulphide occurrence is located approximately 20 km north of Manitouwadge and 8.5 km east-northeast of Everest Lake. The occurrence is situated on level ground approximately 610 m east of Otter Lake and 750 m northeast of Adze Lake. Recent logging operations have removed most of the trees in this area. As a consequence, the occurrence is well exposed and readily accessed. The occurrence is accessible via motor vehicle followed by travel on foot. From Manitouwadge, travel east and then north along the Camp 70 logging road for approximately 31.5 km to the Jim Lake road. Proceed north along the Jim Lake road for approximately 7.85 km to the Husak road. Proceed west along the Husak road for approximately 10.8 km to an unnamed, poorly marked, tertiary logging road. Proceed north along this unnamed road, through a large cut-over area, for approximately 1.0 km to a flagged trail. Proceed east along this trail for approximately 300 m to the vicinity of the occurrence. Sulphide mineralization is exposed in several small pits located near the northern edge of the cut-over area.

Exploration History

1955: Trenching and diamond drilling (6 holes totalling 748 m); Chellew Gold Mines Limited. Although assay data is not available, the results of the drilling are reported to have been disappointing (The Northern Miner, May 31, 1956). 1965: Geological mapping; M.E. Coates (ODM). 1977: Line cutting, soil geochemical sampling, geological mapping and ground geophysical surveys (RADEM and MAG); Noranda Mines Limited (Geco Division). The geophysical surveys indicated that the occurrence was associated with a magnetic, conductive anomaly approximately 15 m wide and 900 m long. 1978-1979: Regional lake sediment and water geochemical survey; GSC-MNR. Samples collected from lakes in the vicinity of the occurrence contained slightly anomalous amounts of Cu and Zn. 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). 1991-1992: Stripping, trenching, prospecting and lithogeochemical sampling; prospectors G. Goodwin and A. Turner. Reconnaissance till sampling survey; GSC. Samples collected in the vicinity of the occurrence contained slightly anomalous amounts of Au, Ni, Cu and Zn. Lithogeochemical sampling; D.B. McKay (OGS).

Assessment Work on File

Geology

Province: Superior

Subprovince: Quetico

Geological Age: Archean  

Metamorphism Type: Regional

Metamorphism Grade: Granulite

Geology Comments

Dec 07, 2005 (D McKay) - The occurrence is located within the Quetico Subprovince approximately 2.5 km north of the Quetico-Wawa subprovince boundary (Williams and Breaks 1990). The rocks in the vicinity of the occurrence are moderately to locally strongly foliated (080 degrees/85 degrees S). An east-trending, regional scale, linear topographic feature referred to as the Little Nama Lake lineament (Coates 1968) is located approximately 180 m north of the occurrence. A northwest-striking fault transects Otter lake and has offset sinistrally, by approximately 150 m, the iron formation hosting the occurrence (Williams and Breaks 1990). This fault is located approximately 600 m west of the occurrence. The occurrence is underlain primarily by an east-trending sequence of migmatitic paragneiss and silicate- and sulphide-facies iron formation. Refolded minor folds in the paragneiss indicate multiple episodes of deformation have occurred. A large (200 m wide by 3.5 km long) northeast-trending, coarse-grained, locally porphyritic, diabase dike is located approximately 1 km south of the occurrence (Williams and Breaks 1990). Several smaller northeast- and northwest-trending diabase dikes occur in the vicinity of the occurrence. The paragneiss is generally light tan- to rusty-weathering, speckled black and white, medium- to coarse-grained, moderately foliated, non-magnetic and crudely laminated. The paragneiss is composed primarily of biotite, quartz and feldspar. Coarse-grained porphyroblasts of purple garnet and rare, dark brown orthopyroxene are present locally. The iron formation is rusty-weathering, medium- to coarse-grained, locally sulphide-rich and locally strongly magnetic. The iron formation varies in width up to approximately 4 m and can be traced along strike for approximately 2 km. Sulphide-rich zones occur discontinuously along the length of the iron formation. The Otter Lake sulphide occurrence is one of these zones.

Lithology

Lithology Comments

Dec 07, 2005 (D McKay) - The paragneiss is generally light tan- to rusty-weathering, speckled black and white, medium- to coarse-grained, moderately foliated, non-magnetic and crudely laminated. The paragneiss is composed primarily of biotite, quartz and feldspar. Coarse-grained porphyroblasts of purple garnet and rare, dark brown orthopyroxene are present locally. The iron formation is rusty-weathering, medium- to coarse-grained, locally sulphide-rich and locally strongly magnetic. The iron formation varies in width up to approximately 4 m and can be traced along strike for approximately 2 km. Sulphide-rich zones occur discontinuously along the length of the iron formation. The Otter Lake sulphide occurrence is one of these zones.

Mineralization

Mineralization Comments

Dec 07, 2005 (D McKay) - The sulphides consist primarily of coarse-grained, massive to disseminated, subhedral grains of pyrite, pyrrhotite and rare chalcopyrite. Although local concentrations of up to 80% sulphides occur, the sulphides generally constitute 5 to 10% of the mineralized portions of iron formation. Triple junctions in pyrite and numerous, rounded, sulphide-supported quartz clasts suggest the sulphides have undergone recrystallization and remobilization. A thick, rusty gossan has developed on the surface of the occurrence. Supergene processes have led to the development of localized, surficial deposits of crustiform pyrite and marcasite. Locally derived regolith has been recemented with hematite and limonite. Prominent, narrowly spaced, horizontal joints occur within the iron formation but were not observed in the surrounding migmatite. The iron formation varies from being weakly to locally, strongly magnetic, reflecting variations in pyrrhotite content. Narrow, gray-white quartz veins and pods occur locally in the migmatite surrounding the iron formation. The northern contact between the iron formation and the surrounding migmatite is locally sheared. Channel samples collected from the occurrence in 1991 by D.B. McKay for the OGS returned assay values up to 0.021 ounce Au/ton, 0.1585% Cu and 0.0076% Zn over 1 m widths. Similar sulphide occurrences, some copper-bearing, are located in the general vicinity of the Otter Lake sulphide occurrence. These include the Lovlien and Little Nama Lake sulphide occurrences located approximately 1 and 3 km to the west of the Otter Lake sulphide occurrence respectively. These occurrences are hosted in metasedimentary rocks which may represent the westward extension of the iron formation hosting the Otter Lake sulphide occurrence. To date, none of these occurrences have been found to contain economic amounts of gold nor base metals.

Alteration Comments

Dec 07, 2005 (D McKay) - Supergene processes have led to the development of localized, surficial deposits of crustiform pyrite and marcasite. Locally derived regolith has been recemented with hematite and limonite.

Mineral Record Details

References

Map - Stevens-Kagiano Lake area, District of Thunder Bay

Publication Number: P0362 Scale: 1:63,360    Date: 1997

Author: Coates M.E.

Publisher Name: Ontario Dept. of Mines

Location:

Mono - Mineral Occurrences in the Manitouwadge Area, Volumes 1, 2 and 3

Publication Number: OFR5906 Date: 1994

Author: McKay D.B.

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 - Stevens sheet, Thunder Bay District

Publication Number: M2141 Scale: 1:63,360    Date: 1967

Author: Coates M.E.

Publisher Name: Ontario Dept. of Mines

Location:

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

Location:

MonoMap - Geology of Stevens-Kagiano Lake area, District of Thunder Bay

Publication Number: R068 Date: 1968

Author: Coates M.E.

Publisher Name: Ontario Dept. of Mines

Location:

Compend - Report of activities, 1991, Resident Geologists

Publication Number: MP158 Page: 121-163  Date: 1992

Author: Fenwick K.G., Newsome J.W., Pitts A.E.

Publisher Name: Ontario Geological Survey

Location:

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:

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