General Information
Secondary Commodities: iron
Deposit Type(s): Iron Formation
Location(s): 68.479720 N, -136.4725 W
NTS Mapsheet(s): 117A08
Location Comments: .5 Kilometres
Hand Samples Available at YGS: No
Capsule
Work History
First noted by the GSC in 1971 and staked as Mac cl (56531) and Delta cl (YA82503) in May/74 by Welcome North ML and Bethlehem Copper, which performed sampling and evaluation later in the year. The phosphate minerals at this location were subsequently studied extensively by mineralogists and gem collectors.
This area lies within a large area withdrawn from staking in Jul/78 pending creation of a National Wilderness Park, settlement of native land claims, and development of a management plan for the Porcupine Caribou Herd.
Capsule Geology
Thick deposits of siderite and phosphatic ironstone in shale occur in the Rapid Creek Formation, which overlies a thick sequence of turbidite sandstones deposited during the late Early Cretaceous. The Rapid Creek sequence consists of three units of cyclically interbedded siderite, mudstone and shale separated by two grey montmorillonite shale units. The phosphate minerals are thought to have been deposited by cold, northeast-flowing currents upwelling on the flank of a structural high which formed the eastern margin of the Blow Trough. In the Rapid Creek and Lower Big Fish River drainages, the Rapid Creek Formation forms an immense low-grade deposit containing an estimated 91 billion tonnes of Fe2O3 equivalent, and roughly 7 billion tonnes of P2O5 and over 1.162 billion tonnes of MnO in an ore which has an average grade of 33% Fe2O3, 14% P2O5 and 5% MnO. The Rapid Creek iron-manganese horizon is ranked by Laznicka as the world's fourth largest manganese deposit, with 6.5% of the world's total manganese reserves.
The Rapid Creek Formation is the most northerly known phosphorite with a paleolatitude of 75° N. It varies from about 1000 m thick west of Rapid Creek to 60 m at Big Fish River. The phosphatic iron formation is composed of phosphate-siderite pellets and granules, detrital quartz and skeletal fragments in a matrix of sideritic mudstone. The phosphate-siderite pellets appear to have been redeposited and have an unusual chemistry which is more calcium deficient and more iron and magnesium rich than other marine phosphorites. Sampling in 1974 gave a grade of 16.7% total Fe across a thickness of 442 m. A direct reduction test gave 66.7% total Fe concentrate grade and a recovery of 72.5%. Sampling in this area gave a grade of 20.5% total Fe across a thickness of 182 m. A direct reduction test gave a 66.7% total Fe concentrate grade and a recovery of 72.5%.
The Blow River Formation is best known for the secondary minerals, chiefly phosphates, which are found as veins and breccia fillings in the Rapid Creek (Minfile 117A 027) and Big Fish River areas. Phosphate mineralization at the Big Fish River location is largely confined to recrystallized spherulitic replacements of ammonites and pelecypods and oblate concretionary phosphate nodules. The main minerals are pyrite, wolfeite, satterlyite, maricite, vivianite-baricite and varulite.
First noted by the GSC in 1971 and staked as Mac cl (56531) and Delta cl (YA82503) in May/74 by Welcome North ML and Bethlehem Copper, which performed sampling and evaluation later in the year. The phosphate minerals at this location were subsequently studied extensively by mineralogists and gem collectors.
This area lies within a large area withdrawn from staking in Jul/78 pending creation of a National Wilderness Park, settlement of native land claims, and development of a management plan for the Porcupine Caribou Herd.
Capsule Geology
Thick deposits of siderite and phosphatic ironstone in shale occur in the Rapid Creek Formation, which overlies a thick sequence of turbidite sandstones deposited during the late Early Cretaceous. The Rapid Creek sequence consists of three units of cyclically interbedded siderite, mudstone and shale separated by two grey montmorillonite shale units. The phosphate minerals are thought to have been deposited by cold, northeast-flowing currents upwelling on the flank of a structural high which formed the eastern margin of the Blow Trough. In the Rapid Creek and Lower Big Fish River drainages, the Rapid Creek Formation forms an immense low-grade deposit containing an estimated 91 billion tonnes of Fe2O3 equivalent, and roughly 7 billion tonnes of P2O5 and over 1.162 billion tonnes of MnO in an ore which has an average grade of 33% Fe2O3, 14% P2O5 and 5% MnO. The Rapid Creek iron-manganese horizon is ranked by Laznicka as the world's fourth largest manganese deposit, with 6.5% of the world's total manganese reserves.
The Rapid Creek Formation is the most northerly known phosphorite with a paleolatitude of 75° N. It varies from about 1000 m thick west of Rapid Creek to 60 m at Big Fish River. The phosphatic iron formation is composed of phosphate-siderite pellets and granules, detrital quartz and skeletal fragments in a matrix of sideritic mudstone. The phosphate-siderite pellets appear to have been redeposited and have an unusual chemistry which is more calcium deficient and more iron and magnesium rich than other marine phosphorites. Sampling in 1974 gave a grade of 16.7% total Fe across a thickness of 442 m. A direct reduction test gave 66.7% total Fe concentrate grade and a recovery of 72.5%. Sampling in this area gave a grade of 20.5% total Fe across a thickness of 182 m. A direct reduction test gave a 66.7% total Fe concentrate grade and a recovery of 72.5%.
The Blow River Formation is best known for the secondary minerals, chiefly phosphates, which are found as veins and breccia fillings in the Rapid Creek (Minfile 117A 027) and Big Fish River areas. Phosphate mineralization at the Big Fish River location is largely confined to recrystallized spherulitic replacements of ammonites and pelecypods and oblate concretionary phosphate nodules. The main minerals are pyrite, wolfeite, satterlyite, maricite, vivianite-baricite and varulite.
Location Map
Last Updated: Nov 4, 2019
Work History
| Year | Work Type | Comment |
|---|---|---|
| 1974 | Geochemistry: Rock | |
| 1974 | Lab Work/Physical Studies: Petrographic | Phosphate minerals studied extensively. |
Regional Geology - Terrane
Group: Ancestral North America
Affinity: W Laurentia
Name: North America - basinal strata
Realm: Laurentia
Regional Geology - Bedrock
Supergroup:
Group/Suite:
Formation: Boundary Creek
Member:
Terrane:
Period Max: Cretaceous
Age Max: 100 MA
Period Min: Cretaceous
Age Min: 66 MA
Rock Major: shale/bentonite/ironstone
Rock Minor:
Reference: Norris (1981) - GSC Map 1516A
Geological Unit (1M): KM
Geological Unit (250K): KM6
Related References
| Number | Title | Page(s) | Document Type |
|---|---|---|---|
| 1992GeolVol3_02 | Phosphorites, ironstones, and secondary phosphates in Mid-Cretaceous flysch of the blow trough, northern Yukon | Annual Report Paper |
| Citations |
|---|
| Coleman, L.C. and Robertson, B.T., 1981. Nahpoite Na2HPO4, a new mineral from the Big Fish River area, Yukon Territory. Canadian Mineralogist, vol. 19, p. 373-376. |
| Gordey, S.P., 1981. Assessment of mineral and fuel resource potential of the proposed northern Yukon national park and adjacent areas (Phase 1). Geological Survey of Canada, Open File 760. |
| Mandarino, J.A. and Sturman, B.D., 1976. Kulanite, a new barium iron aluminum phosphate from the Yukon Territory. Canadian Mineralogist, vol. 14, p. 127-131. |
| Mandarino, J.A., Sturman, B.D. and Corlett, M.I., 1977. Penikisite, the magnesium analogue of kulanite, from Yukon. Canadian Mineralogist, vol. 15, p. 393-395. |
| Mandarino, J.A., Sturman, B.D. and Corlett, M.I., 1978. Satterlyite, a new hydroxyl-bearing ferrous phosphate from the Big Fish River area, Yukon. Canadian Mineralogist, vol. 16, p. 411-413. |
| Norris, D.K. (ed), 1997. The geology, mineral and hydrocarbon potential of northern Yukon Territory and northwestern District of Mackenzie. Geological Survey of Canada, Bulletin 422. |
| Norris, D.K., 1980. Geology, northern Yukon Territory and northwestern District of Mackenzie. Geological Survey of Canada, Open File 715. |
| ROBERTSON, 1980. Stratigraphic setting of some new and rare phosphatic minerals in the Yukon Territory. Unpublished M.Sc. thesis, University of Saskatchewan. |
| Robertson, B.T., 1982. Occurrence of epigenetic phosphate minerals in a phosphatic iron-formation, Yukon Territory. Canadian Mineralogist, vol. 20, p. 177-187. |
| Young, F.G., 1972. Cretaceous stratigraphy between Blow and Fish rivers, Yukon Territory, In: Report of activities, part A: April to October, 1971. Geological Survey of Canada, Paper no. 72-1A, p. 229-235. |
