Ontario Geological Survey
Permanent Link to this Record:
MDI52O07SW00008
| Record Name(s) | Sudbury Point - 1995, Wright Lake #6 - 9999, Ontario Gold Joint Venture - 9999, Dempster Lake - 9999 |
|---|---|
| Related Record Type | Simple |
| Related Record(s) | |
| Record Status | Occurrence |
| Date Created | 1995-May-25 |
| Date Last Modified | 2023-Aug-03 |
| Created By | |
| Revised By |
Primary Commodities: Gold
Township or Area: Wright Lake Area
Latitude: 51° 15' 49.6" Longitude: -90° 55' 32.07"
UTM Zone: 15 Easting: 644727.785 Northing: 5681202.834 UTM Datum: NAD83
Resident Geologist District: Thunder Bay North
NTS Grid: 52O07SW
Point Location Description: Mid point between samples ED-R-18 and YD-R-17 on sample location map (AF 52O/06SE-0032).
Location Method: Data Compilation
Access Description: The Sudbury Point occurrence is located about 55 km southwest of Pickle Lake across the south portion of a small peninsula located on the northwest shore of Dempster Lake. Access to Dempster Lake is by appropriately equipped aircraft.
1984: Dunlop Explorations working for Ontario Gold Joint Venture (Northern Dynasty Explorations Ltd, and Newfield Minerals Inc.) conducted a prospecting and sampling program in the Dempster Lake area and discovered the Sudbury Point occurrence. 1985 to 1988: The Ontario Gold Joint Venture (Northern Dynasty Explorations Ltd, and Newfield Minerals Inc.) conducted an exploration program on a large block of claims in the Dempster Lake area. The multi-phased program included geological mapping, stripping and trenching, rock and soil geochemistry and airborne mag and EM surveys, ground mag and EM surveys and diamond-drilling. 1986: St. Joe Canada Inc. commissioned airborne mag and EM surveys which included the area of this occurrence.
Province: Superior
Subprovince: Uchi
Terrane: North Caribou
Domain: Uchi
Belt: Meen-Dempster
Geological Age: Neoarchean
Dec 07, 2005 (B Nelson) - Northern Dynasty Explorations Ltd. found gold mineralization in quartz-tourmaline veins at Sudbury Point in 1984. The outcrop on the point has been trenched and channel sampled, and 3 diamond-drill holes have been drilled. Felsic metavolcanics, quartz-feldspar porphyry dykes and intermediate dykes with chlorite porphyroblasts are exposed on the point. Dykes of quartz-feldspar porphyry make up 50 percent of rock exposure on Sudbury Point. They are up to 3 m thick and trend 070 degrees to 080 degrees subparallel to the S1 schistosity. The dykes contain many (up to 10%) quartz-tourmaline veins. The veins filled tension gashes in the dykes. Strike measurements on 100 of the tension gashes show two ranges in strike direction, 300 degrees to 317 degrees and 336 degrees to 010 degrees. The tension gashes do not appear to have a conjugate set. The dykes are also penetrated by the S3 fracture cleavage. Four narrow (less than 1 m) intermediate dykes cross Sudbury Point. They strike 070 degreess to 080 degrees in the trenches, but are difficult to trace between trenches. The intermediate dykes contain up to 30%, 1 to 3 mm lenticular chlorite porphyroblasts in an intensely carbonatized feldspathic matrix. Iron carbonate is estimated to comprise up to 50% of the intermediate dykes. The gold mineralization at Sudbury Point is associated with the quartz-tourmaline veins filling tension gashes in the porphyry dykes. Some of the veins have pyritic rims.
| Rock Type | Rank | Composition | Texture | Relationship | Vein | 1 | Quartz-Tourmaline | Contains |
|---|---|---|---|---|
| Quartz-Feldspar Porphyry | 2 | Quartz-Feldspar Porphyry | Host | |
| Felsic lava flow-unsubdivided | 3 | Near | ||
| Granitoid-Unsubdivided | 4 | Near |
Dec 07, 2005 (B Nelson) - The felsic metavolcanic may have once been a lapilli tuff, but alteration and deformation have all but destroyed the original textures. The resultant rock is a very fine-grained sericite, weakly chloritized, carbonatized schist that weathers light-grey to buff. It contains many quartz and quartz-tourmaline veins aligned parallel to the S2 shear direction. The quartz-feldspar porphyry is composed of 60 to 70% cream-colored, round 1 to 3 mm feldspar phenocrysts and less than 10% quartz phenocrysts of the same size and shape. The ground mass is composed mainly of very fine-grained, red, feldspar crystals. Some of the dykes contain chlorite spots.
| Rank | Mineral Name | Class | Economic Mineral Type | Alteration Mineral Type | Alteration Ranking | Alteration Intensity | Alteration Style |
|---|---|---|---|---|---|---|---|
| 1 | Pyrite | Economic | Ore | ||||
| Unspecified | Alteration | Carbonatization | 1 | ||||
| Chlorite | Alteration | Unknown | 2 | ||||
| Sericite | Alteration | Unknown | 3 |
Dec 07, 2005 (B Nelson) - The best assay values reported by Northern Dynasty Explorations Ltd are two grab samples that assayed 0.28 oz/ton Au and 0.29 oz/ton Au , and a 0.5 m by 1.0 m panel sample over an 89 cm wide chlorite-spotted, quartz-feldspar porphyry dyke that assayed 0.56 oz/ton Au. The following assay results are from diamond-drilling performed by the Ontario Gold Joint Venture in 1987: Hole DH-87-01: From 83.38 m to 88.00 m (0.62 m total), 1120 ppb Au. From 138.34 m to 139.34 m (1.00 m total), 1040 ppb Au. The Sioux Lookout Staff Geologist examined this occurrence in 1989 and took 2 grab samples. One returned an assay value of 520 ppb Au.
| Rank | Classification |
|---|---|
| 1 | Lode (Gold) |
| Rank | Characteristic |
|---|---|
| 1 | Vein |
Map - Cat River-Kawinogans Lake area, District of Kenora (Patricia Portion), Ontario
Publication Number: ARM44F Scale: 1:126,720 Date: 1997
Author: Harding W.D.
Publisher Name: Ontario Dept. of Mines
Location:
Part - Geology of the Cat River-Kawinogans Lake area
Publication Number: ARV44-06.002 Date: 1997
Author: Harding W.D.
Publisher Name: Ontario Dept. of Mines
Location:
Map - Cat Lake-Pickle Lake, geological compilation series, Kenora and Thunder Bay districts
Publication Number: M2218 Scale: 1:253,440 Date: 1976
Author: Sage R.P., Breaks F.W., Troup W.R.
Publisher Name: Ontario Division of Mines
Location:
MonoMap - Geology of the Cat Lake-Pickle Lake area, districts of Kenora and Thunder Bay
Publication Number: R207 Date: 1982
Author: Sage R.P., Breaks F.W.
Publisher Name: Ontario Geological Survey
Location:
Article - Sioux Lookout Resident Geologist's District - 1989
Publication Number: MP147.004 Page: 86 Date: 1997
Author: Janes D.A., Seim G.Wm., Storey C.C.
Publisher Name: Ontario Geological Survey
Location:
Map - Precambrian geology, Muskegsagagen-Bancroft lakes area, District of Kenora (Patricia Portion)
Publication Number: M2507 Scale: 1:50,000 Date: 1986
Author: Stott G.M., Wilson A.C.
Publisher Name: Ontario Geological Survey
Location:
Mono - Mineral Deposits of the Central Portion of Uchi Subprovince, Volume 1, Meen Lake to Kesagiminnis Lake Portion
Publication Number: OFR5869 Page: 357 Date: 1993
Author: Seim G.Wm.
Publisher Name: Ontario Geological Survey
Location:
We are continuously updating our assessment file / technical report information. If you notice errors in the data, please contact us.
Please review our Terms of Use agreement for this data product.
For detailed information regarding this mineral record please contact the Thunder Bay North Resident Geologist District Office