Mineral Deposit Inventory for Ontario

Ministry of Energy, Northern Development and Mines

Permanent Link to this Record: MDI000000000284

Deposit: MDI000000000284


Mineral Deposit Identification
Deposit Name(s) North Flexure Zone - 1991, East Bay Property - North Flexure - 2015
Deposit Status prospect
Date Created 2007-Mar-29
Date Last Modified 2019-Sep-26
Created By M A Puumala
Revised By T Pettigrew


Primary Commodities: gold


Township or Area: McVicar Lake Area

Latitude: 51° 34' 10.7"    Longitude: -91° 24' 4.4"

UTM Zone: 15    Easting: 610803   Northing: 5714385    UTM Datum: NAD83

Resident Geologist District: Thunder Bay North

NTS Grid: 52O11SW

Point Location Description: Map in Assessment file 52O11SW0003

Location Method: data compilation

Access Description: ccessible year round via fixed-wing aircraft or helicopter from the town of Pickle Lake. A winter road from Pickle Lake to the First Nation community of Cat Lake is situated approximately 3 km south of the property. A backhoe trail leads from the winter road to the eastern portion of the property.

Exploration and Mining History

1989: BHP drilled 1 DDH totalling 133.84 m. 1991: BHP drilled 6 DDH totalling 613.9 m. 1992: BHP drilled 2 DDH totalling 249.3 m. 2003: Continuum Resources Ltd. drilled 1 DDH totalling 168 m. 2016: Reliant Gold Corp. carried out prospecting and sampling.

Assessment Work on File

Assessment Work on File
Office File Number   Online Assessment File Identifier   Online Assessment File Directory  
2.27178     52O11SW2003     Open
OM91-026     52O11SW0015     Open Open
OM92-008     52O11SW0006     Open
37     52O11SW0009     Open
63.6043     52O11SW0003     Open
39     20000004964     Open
2.57366     20000013886     Open
2.14173     52O11SW0027     Open Open


Province: Superior

Subprovince: Uchi

Belt: Lang Lake

Geological Age: Neoarchean   

Tectonic Assemblage: Confederation

Structure Name Scale Strike Dip Trend Plunge
Altered Zone East Of Flexure regional 300 40
Altered Zone West Of Flexure regional 280 40

Mineral Deposit Lithology

Lithology Data
Rock Type Rank Composition Texture Relationship
vein 1 quartz veins, veinlets, breccia host
mafic metavolcanics 2 sheared and altered adjacent
gabbro 2 anorthositic sheared and altered adjacent
iron formation 4 near


Deposit Mineralization and Alteration
Rank Mineral Name Class Economic Mineral Type Alteration Mineral Type Alteration Ranking Alteration Intensity Habit Description
1 gold economic ore
2 chalcopyrite economic ore
2 pyrite economic ore
3 pyrrhotite economic ore
5 tetrahedrite economic ore
carbonate alteration carbonatization 1 strong replacement
fuchsite alteration carbonatization 2 medium disseminated
sericite alteration potassic 3 strong massive
silica alteration silicification 4 medium replacement

Mineralization Comments

03/29/2007 (M A Puumala) - The North Flexure Zone is a gold mineralized portion of the Altered Zone Fault that is located where this structure refracts parallel to the contact between mafic metavolcanics to the north and gabbro to the south, creating a zone of dilation favourable for the deposition of gold (Bonner 1991a). The metavolcanics are reported to be intercalated with narrow intervals of iron formation, while the gabbro is often described as being anorthositic. To the east of the flexure, the fault zone strikes approximately WNW-ESE (i.e., McKay [2004] reports that foliations at the Altered Zone prospect range between 294-310/36-51), while to the west, the fault is oriented approximately east-west (i.e., Bonner [1991a] reports an orientation of 280/40). The deformation zone at the North Flexure is described by Bonner (1991a) as consisting of intensely foliated and altered equivalents of basalt and/or gabbro. The sheared material is reported to be enveloped by a hydro-breccia zone of variable width. Bonner (1991a) indicates that alteration at this location occurs in distinct propylitic, potassic and argillic zones. The outermost zone consists of propylitic alteration that includes fine light green silica veinlets, chloritic fracture coatings, minor disseminated pyrite and pervasive Ca-carbonate alteration. Potassic alteration consisting of sericite, pyrite, carbonate, apple green mica and quartz typically occurs within 5 m of the fault. Argillic alteration is relatively minor and sporadic, occurring as kaolinitization of plagioclase in anorthositic gabbro. Bonner (1991a) indicates that gold mineralization is associated with quartz veining and pyrite mineralization (i.e., near the center of the deformation zone), with the highest assays obtained from locations with the highest sulphide concentration (up to 30%). Minor chalcopyrite and pyrrhotite mineralization has also been noted, but is interpreted by Bonner (1991a) to be related to primary sulphides present in the gabbro intrusion. Gold and tetrahedrite grains have been observed in thin section and occur within or adjacent to pyrite grains. The mineralized zone has been interpreted by Bonner (1992) consist of an approximately 500 x 25 metre dilation zone in the Altered Zone Fault that plunges to the northwest. Although the zone remains open at depth, Bonner (1991b) has suggested that similarities with the nearby Altered Zone prospect suggest that the North Flexure Zone may not extend more than 250 m down-plunge. Significant assays reported from this zone are tabulated by McKay (2004), with the most notable being 9.3 g/t Au over 2.02 m from drill hole ML-91-54.

09/26/2019 (T Pettigrew) - DDH ML-92-78 intersected 22.3 m of intensely altered and sheared apple green mica with pyritic quartz veins and reports gold assays up to 1.3 ppm (Assessment report 52O11SW0006). DDH ML-03-03 asasyed up to 3.063 ppm Au over 0.39 m (Assessment report 52O11SW2004). DDH ML-91-54 returned assays of 0.174 opt Au over 3.4, 0.376 opt Au over 3.2 and 0.139 opt Au over 1 (5.96 g/t Au over 1 m, 12.9 g/t Au over 1 m, and 4.76 g/t Au over 0.3 m). DDH ML-91-57 returned 2.411 ppm Au over 1.4 m and 1.093 ppm over 1.19 m (Assessment report 52O11SW0003).

Mineral Deposit Details

Deposit Classification
Rank Classification            
1 lode (gold)
Deposit Characteristics
Rank Characteristic            
1 vein
2 sheared
3 breccia


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

Publication Number: P3794     Scale: 1:20 000    Date: 2016

Author: Magnus, S. J.

Publisher Name: OGS

Digital Map - Satellite Image Map, Lake St. Joseph Area Northwest, Northwestern Ontario

Publication Number: P3498     Scale: 1:100 000    Date: 2002

Publisher Name: OGS

Digital Map - Geological, Geochemical, Geophysical, Geochronological and Petrographic Data from the Lang Lake Greenstone Belt, Central Uchi Domain, Superior Province

Publication Number: MRD328     Date: 2016

Author: Magnus, S.J.

Publisher Name: OGS

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