Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52O11SW00007

Record: MDI52O11SW00007

General

Commodities

Primary Commodities: Gold

Location

Township or Area: McVicar Lake Area

Latitude: 51° 34' 30.81"    Longitude: -91° 27' 6.68"

UTM Zone: 15    Easting: 607281   Northing: 5714931    UTM Datum: NAD83

Resident Geologist District: Thunder Bay North

NTS Grid: 52O11SW

Point Location Description: McVicar Lake Area - Shonia #1

Location Method: Field Visit with GPS

Exploration History

1950: Chellow Gold Mines Ltd. Conducted geological mapping, trenching and diamond drilling in the Lower McVicar Lake area. 1959-1961: Kenlew Mines Ltd conducted geological mapping, stripping, trenching and diamond drilling in the lower McVicar Lake area and the area to the east of McVicar Lake. 1968-1969: New Jersey Zinc Exploration Company (Canada) Limited conducted geological mapping, geophysics, trenching and limited diamond drilling for VMS mineralization in the area north of north of McVicar Lake. 1971: Hoey Syndicate conducted geological mapping, trenching and geophysics for Cu-Ni-PGE mineralization in the lower half of the McVicar Lake area. 1977-1981, 1987, 1991: Cominco Ltd conducted extensive airborne geophysical surveys as well as diamond drilling over the McVicar Lake and Andy lake areas, well as limited diamond drilling in McVicar and Cannon Lake areas for gold and base metals.1985-1994: Utah Mines, later BHP-Utah Mines, and then simply BHP conducted extensive grid mapping, geophysics and diamond drilling on the area surrounding McVicar Lake resulting in the discovery of the Altered Zone and Lower McVicar Lake structural zones and several associated gold showings. Utah Mines also conducted extensive work in the western Lang Lake area. 2001-2003: Prospector Consolidated Inc. and Continuum Resources Ltd conducted extensive trenching and limited diamond drilling for gold on the old BHP-Utah Mines property in the McVicar Lake area. 2011: Wildcat Exploration Ltd. conducted prospecting and channel sampling.

Assessment Work on File

Geology

Province: Superior

Subprovince: Uchi

Terrane: North Caribou

Domain: Uchi

Belt: Lang Lake

Geological Age: Neoarchean  

Geology Comments

Mar 28, 2007 (Mark Puumala) - Stott and Corfu (1991) describe the Lang Lake greenstone belt as being dominated by tholeiitic basalt flows and calc-alkalic pyroclastic deposits, with the eastern portion of the belt containing a significant clastic metasedimentary sequence that also includes iron formation horizons. The supracrustal rocks of this belt have been provisionally assigned to the Confederation Assemblage by Stott and Corfu (1991) based on a single age determination from a dacitic tuff in the lowermost (i.e., interpreted to be oldest) portion of the supracrustal rock sequence. The entire belt has been isoclinally folded into an east-trending and east-plunging syncline (Thomas 1988). Thomas (1988) also indicates that the belt contains two significant intrusions, including an east-west trending mafic stock in the Sor-McVicar Lakes area, and a later north-south trending felsic intrusion in the Shonia-McVicar Lakes area. The mafic intrusion has a number of Cu-Ni-PGE occurrences that have been documented near its northern contact, while the felsic intrusion hosts several gold occurrences. The dominant structural feature in the area is the Bear Head Fault Zone, which is located immediately to the southwest. This is an approximately northwest-southeast striking, regional-scale, dextral shear zone that has been classified by Stott and Corfu (1991) as a transcrustal megafault. This fault zone extends approximately 515 km from Lake Winnipeg to the northern boundary of the Meen-Dempster Greenstone Belt (Osmani and Stott 1988). Two additional WNW-ESE trending deformation zones referred to as the Lower McVicar Fault and Altered Zone Fault (McKay 2004) are also present in the area and are associated with a number of gold occurrences. Fumerton (1997) suggests a relationship between the Altered Zone Fault and the axial plane of the regional syncline. Fumerton (1997) indicates that supracrustal rocks between the Bear Head and Lower McVicar Faults have been folded into sigmoidal S-folds, and that a number of splay faults also exist in this area. The geometry of these structures has been interpreted as being consistent with a dextral sense of displacement.

Dec 16, 2015 (Robert Cundari) - The visited occurrences lie within the Lang Lake greenstone belt, which is dominated by tholeiitic basalt flows and calc-alkalic pyroclastic deposits; the eastern portion of the belt contains a significant clastic metasedimentary sequence that also includes iron formation horizons (Stott and Corfu 1991). The supracrustal rocks of this belt were provisionally assigned to the Confederation assemblage by Stott and Corfu (1991) based on a single age determination from a dacitic tuff in the lowermost (i.e., interpreted to be oldest) portion of the supracrustal sequence. The entire belt was isoclinally folded into an east-trending and east-plunging syncline (BHP–Utah Mines 1988). BHP–Utah Mines (1988) also indicated that the belt contains 2 significant intrusions, including a mafic stock in the Sor–McVicar lakes area, and a later felsic intrusion in the Shonia–McVicar lakes area that hosts several gold occurrences. The Shonia #1 prospect is located where the Altered Zone fault intersects the Shonia Lake tonalite sill (Puumala 2009). The stripped area exposes strongly fractured and variably altered, coarse-grained, unfoliated tonalitic rocks, intruded locally by narrow mafic and felsic dikes (McKay 2004). An older gabbro is represented as xenoliths within the tonalite. Alteration minerals are reported to include iron carbonate, sericite, silica and pyrite (McKay 2004).Many of the stockwork fractures are filled with quartz – sericite ± iron carbonate veins. These veins have varying orientations and are typically narrow (< 70 cm wide), discontinuous and boudinaged. Some veins are barren, whereas others contain significant amounts of pyrite. McKay (2004) indicated that there is typically a strong positive correlation between the pyrite content of the veins and gold grades. The auriferous, pyrite-mineralized veins are also reported to have similar orientations, averaging 035/40. Channel sampling of these veins reported by D.B. McKay (2004) included an assay of 15 926 ppb Au from a 50 cm section across a 40 cm wide pyritic (5 to 7%) vein. A grab sample of wall rock containing massive sulphides was reported by Janes, Seim and Storey (1989) to have returned 3750 ppb Au. 09 MSH-01 Shonia #1 607281E, 5714931N Altered tonalite rusty-weathering, non-magnetic, grey-green, mediumgrained, equigranular, recrystallized, Fe-carbonatized tonalite with disseminated subhedral to euhedral pyrite 1% <0.01 oz/ton Au

Lithology

Mineralization

Mineralization Comments

Mar 28, 2007 (Mark Puumala) - McKay (2004) indicates that the Shonia #1 prospect is located where the Altered Zone Fault intersects the Shonia Lake tonalite sill. The Altered Zone Fault is described by Allen (1986) as a generally WNW-ESE-striking, relatively shallow dipping (<50 degrees to the NE) structure characterized by intense alteration and brittle-ductile deformation. Alteration minerals in this deformation zone include sericite, carbonate, chlorite and silica (including quartz veins and silica flooding). Allen (1986) also indicates that a hydrothermal carbonate breccia commonly envelops the deformation zone. The geology of the surface exposure of the Shonia #1 zone is described by McKay (2004) as consisting of strongly fractured and variably altered coarse-grained tonalitic rocks intruded locally by narrow mafic and felsic dikes. Alteration minerals are reported to include iron carbonate, sericite, silica and pyrite. Many of the fractures are filled with quartz +/- Fe-carbonate veins. These veins have variable orientation sand are typically narrow (<70 cm wide), discontinuous, and boudinaged. Some veins are barren, while others contain significant amounts of pyrite. McKay (2004) indicates that there is typically a strong positive correlation between the pyrite content of the veins and gold grades. The auriferous pyrite-mineralized veins are also reported to have similar orientations, averaging 035/40. Channel sampling of these veins reported by McKay (2004) included an assay of 15,926 ppb Au from a 50 cm section across a 40 cm wide pyritic (5 to 7%) vein. Although the pyritiferous veins typically return the highest gold assays, McKay (2004) reported a grab sample assay of 26,221 ppb Au from a poorly-mineralized 25 cm wide quartz vein that is oriented 120/45. A grab sample of wall rock containing massive sulphides was reported by Janes et al. (1989) to have assayed 3750 ppb Au. The results of a 1992 BHP Minerals diamond drilling program reported by Bonner (1992a) indicated that the Shonia #1 gold mineralization occurs within an approximately 200 m quartz vein halo. Information provided by McKay (2004), further indicates that the diamond drilling defined a smaller high-grade quartz vein envelope within the alteration halo (characterized by seicite, F-carbonate and chlorite alteration). Bonner's (1992a) interpretation of the 1992 diamond drilling results indicated the existence of one set of narrow auriferous quartz veins having average orientations of 068/76, and a second set of potentially-auriferous veins having average orientations of 039/50. The second set appears to correspond with the auriferous veins mapped on surface by McKay (2004). Significant gold assays from 9 drill holes advanced during the 1992 BHP Minerals and 2003 Prospector Consolidated Resources diamond drilling programs are tabulated by McKay (2004). Notable intersections include 24.5 g/t Au over 1.1 m in ML-92-66, 11.9 g/t Au over 1.22 m in ML-92-76 and 11.7 g/t Au over 1.50 m in ML-92-82.

Mineral Record Details

References

Part - Geology of the Shonia Lake area, District of Kenora (Patricia Portion)

Publication Number: ARV39-03.001 Scale:     Date: 1998

Author: Laird H.C.

Publisher Name: Ontario Dept. of Mines

Location:

Map - Geological series, Lang-Cannon lakes area (central part), District of Kenora (Patricia Portion)

Publication Number: P0665 Scale: 1:31,680    Date: 1997

Author: Fenwick K.G.

Publisher Name: Ontario Dept. of Mines and Northern Affairs

Location:

Article - Regional-scale shear zones in Sachigo Subprovince and their economic significance

Publication Number: MP141.006 Scale:     Date: 1997

Author: Osmani I.A., Stott G.M.

Publisher Name: Ontario Geological Survey

Location:

Article - Uchi subprovince

Publication Number: SV04-01.006 Scale:     Date: 1997

Author: Stott G.M., Corfu F.

Publisher Name: Ontario Geological Survey

Location:

Map - Precambrian Geology of the Lang Lake Greenstone Belt (West Half)

Publication Number: P3794 Scale: 1:20,000    Date: 2015

Author: Magnus S.J.

Publisher Name: Ontario Geological Survey

Location:

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