Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52A03SW00018

Record: MDI52A03SW00018

General

Commodities

Primary Commodities: Silver, Copper

Secondary Commodities: Barite

Location

Township or Area: Crooks

Latitude: 48° 3' 34.64"    Longitude: -89° 29' 12.76"

UTM Zone: 16    Easting: 314710   Northing: 5325919    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 52A03SW

Point Location Description: AMIS adit location

Location Method: Conversion from MDI

Access Description: Proceed south on Hwy 61 to Memory Lake Road. Turn left onto Memory Lake Road and proceed 3.4 to a gravel road on the left, just past the gravel pit. Follow the gravel road east 0.3 km to a dead end. A trail at the end of the road leads up a hill for 25 m to a ridge with a lookout point and a statue. Follow a trail along the top of the ridge for about 800 m at a bearing of 60 degrees to the top of a very large hill. Near the apex of the hill the trail is cut by iron sulphide staining and a quartz carbonate vein. Minor workings are located about 15 m downhill along the vein.

Exploration History

Pre-1874: Discovered by the McKellar brothers. 1882-83: stripping and 2 adits, each about 15.2 m long, one 9.1 m below the other, run along the vein. 1966: diamond drilling. 2001: McVicar Minerals Ltd. optioned the property and conducted prospecting and sampling.

Assessment Work on File

Geology

Province: Southern

Formation Group: Animikie Group

Geological Age: Mesoproterozoic  

Geology Comments

Feb 26, 2018 (Therese Pettigrew) - The Mesoproterozoic geology of the Lake Superior region was formed during the development of the Midcontinent Rift (MCR), also known as the Keweenawan Rift, starting about 1110 Ma. The rift originated when a mantle plume arrived at the base of the lithosphere under the central part of what is now the North American continent. The rifting process involved the thinning, extension and subsidence of the overlying crust, accompanied by the production and eruption of a remarkable volume mafic magma. Geophysical modeling of aeromagnetic, gravity and seismic data show the rift to be composed of a deep (-30 km) asymmetric basin, infilled with a lower sequence of volcanic rocks, locally as much as 20 km thick and occupying a volume of over 2 million km2 , and a upper sequence of fluvial sedimentary rocks. The rifting and associated magmatic activity occurred over a relatively short period of approximately 22 million years from 1108-1186 Ma. Typical stratigraphy along the MCR consists of eroded Archean basement rocks, unconformably overlain by Paleoproterozoic sediments of the Animikie Group, ca. 1.8 Ma. It is believed that these rocks were deposited in an elongate depression that bordered an island arc or an orogenic belt. On the northern flank, they drape unconformable on the Archean "basement" rocks and thicken to the south, reaching several kilometres of thickness. The lower part of the Animikie Group is this area is referred as the Gunflint Formation. The Midcontinent Rift (MCR) consists of three major components: 1) a thick edifice of subaerial flood basalt lava flows; 2) local concentrations of intrusive rocks; and 3) an upper sequence of sedimentary rocks. The MCR volcanic sequence is composed predominately of flood basalts, with lesser intermediate to felsic rocks (andesitic and rhyolitic flows). The earliest lava flows erupted under seawater, but soon accumulated to a thickness that allowed them to erupt on dry land or subaerially. MCR intrusions are well-represented on the north shore of Lake Superior, where they are host to a number of nickel-copper, PGE, and Fe-Ti-oxide occurrences (AFRI 52A03SW2008).

Lithology

Mineralization

Mineralization Comments

Feb 26, 2018 (Therese Pettigrew) - Near the inner end of this bay some test work has been done on a vein running in a northwesterly direction and dipping to the northeast at an angle of 70 degrees to 75 degrees. It is about 0.3 m thick, and has definite walls where seen in the workings. It cuts a hill about 91 m high of argillites, capped, as usual, with a diabase sill, and intersected by dykes of the same rock. The work done is near the top of the hill, and shows a vein which, in the usual gangue of coarsely crystallized calcite and barite with a little amethystine quartz, carries pyrite and shows indications of copper in the shape of occasional malachite stains. Around the workings the country rock is entirely trap, which carries a large percentage of pyrite adjacent to the vein (Tanton, 1931). Disseminated to blebby sulphide zones occur along the entire length of the Mount Mollie Dyke (AFRI 52A03SW2008).

Mineral Record Details

References

Publication - Fort William and Port Arthur, and Thunder Cape Map-area, Thunder Bay District, Ontario; Geological Survey of Canada, Memoir 167

Publication Number: GSC Memoir 167 Scale:     Date: 1931

Author: Tanton, T.L.

Publisher Name: Geological Survey of Canada

Location: https://doi.org/10.4095/100799

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