General Information
Secondary Commodities: molybdenum, tungsten
Deposit Type(s): Vein Polymetallic Ag-Pb-Zn+/-Au
Location(s): 61.370830 N, -131.152780 W
NTS Mapsheet(s): 105G06
Location Comments: .5 Kilometres
Hand Samples Available at YGS: No
Capsule
Work History
Staked as Grass cl 1-24 (Y7079) in Apr/66 by Cassiar Asbestos Corporation Ltd on a showing reportedly found in 1954 by Pelly River Explorations Ltd (Pioneer Gold Mines Ltd, American Standard Mines Ltd, New York-Alaska Gold Dredging Corporation and Northwest Ventures Ltd) and investigated by Cassiar in 1961.
Restaked within a large block of Boot claims (approximately 124 - 221, YA33924) in Jul/78 by Chevron Canada Ltd. The entire claim block covered the north-central half of Topographic Map Sheet 105G 06 and was formally called the Grass Project. Chevron explored this occurrence with mapping, geochem sampling and hand trenching in 1978 and 1980.
Restaked as Oz cl 1-30 (YC23138) in Dec/2002 by True North Gems Inc which carried out geological mapping, soil and silt sampling, prospecting and hand pitting later in the year.
Capsule Geology
The area is located in the south-central portion of the Yukon-Tanana Terrane (YTT), northeast of the Tintina Fault. Beginning in 1996 Murphy and others (Murphy et al. 2001) began a systematic geological mapping program to update and unravel the complex geology of the YTT and explain the formation and stratigraphic relationships of the various volcanic-hosted massive sulphide and other deposits present in the YTT. The YTT is a volcanic-plutonic pericratonic arc assemblage that was strongly deformed and metamorphosed by Late Triassic time. Geological mapping shows the region is dominantly underlain by a layered sequence of Devonian to Early Mississippian metavolcanic and metasedimentary rocks belonging to the Grass Lakes Succession. Early Mississippian granitic metaplutonic rocks of the Grass Lakes Plutonic suite intrude the package.
Early geological mapping by Chevron Canada shows that the occurrence area is mainly underlain by augen gneiss. Several isolated outcrops of volcanic schist and interbedded skarn survived the intrusion of the gneiss. Murphy's mapping generally agrees with Chevron Canada work. Murphy's map shows the occurrence area is underlain by voluminous granitic meta-plutonic rocks assigned to the Early Mississippian Grass Lakes suite (Mgag). Murphy's map doe not indicate any volcanic rocks in the area but he indicates that thin intervals of marble and calc-schist not mappable at 1:50 000 scale and assigned to unit (Dq), Upper Devonian occur in the area.
Chevron called this occurrence the Pika showing. Mineralization is described as narrow quartz veins containing pyrite, scheelite, wolframite, molybdenite or arsenopyrite. The veins are erratically distributed. Scheelite also occurs as disseminations in limy bands within calc-silicate schist. Grades are very low in all metals, including traces of tin and gold. Silt sampling in 1978 showed a moderate but even tungsten response along creeks in the area. Quartz veins found previously in this area contain tourmaline with traces of molybdenite and pyrite. Host rocks include Upper Devonian and older(?) schist (Dq) and the gneissic Grass Lakes intrusions.
True North Gems staked the Oz claims for their emerald potential. The company hired Archer, Cathro and Associates (1981) Ltd to lead the exploration program. Archer, Cathro carried out Chevron's earlier exploration program and made the original discovery at Regal Ridge (Minfile Occurrence 105G 147), the Yukon's first commercial emerald deposit. Archer, Cathro used their proprietary database to determine the threshold for various geochemical elements.
Prospecting outlined three zones of alteration (A, B and C), similar to those found at the Regal Ridge emerald deposit. These zones are characterized by rusty to golden weathered muscovite schists bands, recessive gullies, radiating bird's foot tourmaline along foliation planes in the schist and quartz-tourmaline veining. Zone A appears to be the best exposed zone. The zone measures approximately 100m by 100m and within this area orthogneiss (unit Dq) and Fire Lake biotite-chlorite- quartz schist (unit DF) are cut by a undeformed mafic dyke, an aplite dyke and quartz veins. The largest vein is 1.2 m thick and contains tourmaline masses and disseminate silver mica. Pervasive massive, green actinolite is developed in unit Dq up to 2m on either side of the quartz veins.
Soil sampling returned enriched beryllium levels but only weakly to moderately anomalous chromium values leading the company to speculate whether there was sufficient chromium enrichment to form emeralds. Further investigation of Zone A was suggested.
References
BOND, J.D., MURPHY, D.C., COLPRON, M., GORDEY, S.P., PLOUFFE, A., ROOTS, C.F., LIPOVSKY, P.S., STRONGHILL, G., AND ABBOTT, J.G., 2002. Digital compilation of bedrock geology and till geochemistry, northern Finlayson Lake map area, Southeastern Yukon (105G), Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, Open File Report, 2002-7(D) and Geological Survey of Canada Open File 4243.
GORDEY, S.P. AND MAKEPEACE, A.J., 2003. Yukon Digital Geology, version 2.0, S.P. Gordey and A.J. Makepeace (comp); Geological Survey of Canada, Open File 1749 and Yukon Geological Survey, Open File 2003-9 (D).
MURPHY, D.C. and PIERCEY, S.J., 1999. Geological map of parts of Finlayson Lake (105G/7, 8 and parts of 1, 2, and 9) and Frances Lake (parts of 105H/5 and 12) map areas, southeastern Yukon (1:100 000-scale). Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, Open File 1999-4.
MURPHY, D.C. AND PIERCEY, S.J., 2000. Syn-mineralization faults and their re-activation, Finlayson Lake massive sulphide district, Yukon-Tanana Terrane, southeastern Yukon. In: Yukon Exploration and Geology 1999, D.S. Emond and L.H. Weston (eds.), Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, p. 55-66.
MURPHY, D.C., COLPRON, M., GORDEY, S.P., ROOTS, C.F., ABBOTT, G., AND LIPOVSKY, P.S., 2001. Preliminary bedrock geological map of northern Finlayson Lake area (NTS 105 G) Yukon Territory (1:100 000 scale). Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, Open File 2001-33.
MURPHY, D.C., COLPRON, M., ROOTS, C.F., GORDEY, S.P. AND ABBOTT, J.G., 2002. Finlayson Lake Targeted Geoscience Initiative (southeastern Yukon) , Part 1: Bedrock geology. In: Yukon Exploration and Geology 2001, D.S. Emond, L.H. Weston and L.L. Lewis (eds.), Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, p. 189-207.
CHEVRON CANADA LTD, Feb/79. Assessment Report #090439 by R.J. Cathro and U. Schmidt.
CHEVRON CANADA LTD, Feb/81. Assessment Report #090728 by R.J. Cathro and U. Schmidt.
MINERAL INDUSTRY REPORT 1978, p. 65.
TRUE NORTH GEMS INC, Aug/2004. Assessment Report #094469 by W. Wengzynowski.
Staked as Grass cl 1-24 (Y7079) in Apr/66 by Cassiar Asbestos Corporation Ltd on a showing reportedly found in 1954 by Pelly River Explorations Ltd (Pioneer Gold Mines Ltd, American Standard Mines Ltd, New York-Alaska Gold Dredging Corporation and Northwest Ventures Ltd) and investigated by Cassiar in 1961.
Restaked within a large block of Boot claims (approximately 124 - 221, YA33924) in Jul/78 by Chevron Canada Ltd. The entire claim block covered the north-central half of Topographic Map Sheet 105G 06 and was formally called the Grass Project. Chevron explored this occurrence with mapping, geochem sampling and hand trenching in 1978 and 1980.
Restaked as Oz cl 1-30 (YC23138) in Dec/2002 by True North Gems Inc which carried out geological mapping, soil and silt sampling, prospecting and hand pitting later in the year.
Capsule Geology
The area is located in the south-central portion of the Yukon-Tanana Terrane (YTT), northeast of the Tintina Fault. Beginning in 1996 Murphy and others (Murphy et al. 2001) began a systematic geological mapping program to update and unravel the complex geology of the YTT and explain the formation and stratigraphic relationships of the various volcanic-hosted massive sulphide and other deposits present in the YTT. The YTT is a volcanic-plutonic pericratonic arc assemblage that was strongly deformed and metamorphosed by Late Triassic time. Geological mapping shows the region is dominantly underlain by a layered sequence of Devonian to Early Mississippian metavolcanic and metasedimentary rocks belonging to the Grass Lakes Succession. Early Mississippian granitic metaplutonic rocks of the Grass Lakes Plutonic suite intrude the package.
Early geological mapping by Chevron Canada shows that the occurrence area is mainly underlain by augen gneiss. Several isolated outcrops of volcanic schist and interbedded skarn survived the intrusion of the gneiss. Murphy's mapping generally agrees with Chevron Canada work. Murphy's map shows the occurrence area is underlain by voluminous granitic meta-plutonic rocks assigned to the Early Mississippian Grass Lakes suite (Mgag). Murphy's map doe not indicate any volcanic rocks in the area but he indicates that thin intervals of marble and calc-schist not mappable at 1:50 000 scale and assigned to unit (Dq), Upper Devonian occur in the area.
Chevron called this occurrence the Pika showing. Mineralization is described as narrow quartz veins containing pyrite, scheelite, wolframite, molybdenite or arsenopyrite. The veins are erratically distributed. Scheelite also occurs as disseminations in limy bands within calc-silicate schist. Grades are very low in all metals, including traces of tin and gold. Silt sampling in 1978 showed a moderate but even tungsten response along creeks in the area. Quartz veins found previously in this area contain tourmaline with traces of molybdenite and pyrite. Host rocks include Upper Devonian and older(?) schist (Dq) and the gneissic Grass Lakes intrusions.
True North Gems staked the Oz claims for their emerald potential. The company hired Archer, Cathro and Associates (1981) Ltd to lead the exploration program. Archer, Cathro carried out Chevron's earlier exploration program and made the original discovery at Regal Ridge (Minfile Occurrence 105G 147), the Yukon's first commercial emerald deposit. Archer, Cathro used their proprietary database to determine the threshold for various geochemical elements.
Prospecting outlined three zones of alteration (A, B and C), similar to those found at the Regal Ridge emerald deposit. These zones are characterized by rusty to golden weathered muscovite schists bands, recessive gullies, radiating bird's foot tourmaline along foliation planes in the schist and quartz-tourmaline veining. Zone A appears to be the best exposed zone. The zone measures approximately 100m by 100m and within this area orthogneiss (unit Dq) and Fire Lake biotite-chlorite- quartz schist (unit DF) are cut by a undeformed mafic dyke, an aplite dyke and quartz veins. The largest vein is 1.2 m thick and contains tourmaline masses and disseminate silver mica. Pervasive massive, green actinolite is developed in unit Dq up to 2m on either side of the quartz veins.
Soil sampling returned enriched beryllium levels but only weakly to moderately anomalous chromium values leading the company to speculate whether there was sufficient chromium enrichment to form emeralds. Further investigation of Zone A was suggested.
References
BOND, J.D., MURPHY, D.C., COLPRON, M., GORDEY, S.P., PLOUFFE, A., ROOTS, C.F., LIPOVSKY, P.S., STRONGHILL, G., AND ABBOTT, J.G., 2002. Digital compilation of bedrock geology and till geochemistry, northern Finlayson Lake map area, Southeastern Yukon (105G), Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, Open File Report, 2002-7(D) and Geological Survey of Canada Open File 4243.
GORDEY, S.P. AND MAKEPEACE, A.J., 2003. Yukon Digital Geology, version 2.0, S.P. Gordey and A.J. Makepeace (comp); Geological Survey of Canada, Open File 1749 and Yukon Geological Survey, Open File 2003-9 (D).
MURPHY, D.C. and PIERCEY, S.J., 1999. Geological map of parts of Finlayson Lake (105G/7, 8 and parts of 1, 2, and 9) and Frances Lake (parts of 105H/5 and 12) map areas, southeastern Yukon (1:100 000-scale). Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, Open File 1999-4.
MURPHY, D.C. AND PIERCEY, S.J., 2000. Syn-mineralization faults and their re-activation, Finlayson Lake massive sulphide district, Yukon-Tanana Terrane, southeastern Yukon. In: Yukon Exploration and Geology 1999, D.S. Emond and L.H. Weston (eds.), Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, p. 55-66.
MURPHY, D.C., COLPRON, M., GORDEY, S.P., ROOTS, C.F., ABBOTT, G., AND LIPOVSKY, P.S., 2001. Preliminary bedrock geological map of northern Finlayson Lake area (NTS 105 G) Yukon Territory (1:100 000 scale). Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, Open File 2001-33.
MURPHY, D.C., COLPRON, M., ROOTS, C.F., GORDEY, S.P. AND ABBOTT, J.G., 2002. Finlayson Lake Targeted Geoscience Initiative (southeastern Yukon) , Part 1: Bedrock geology. In: Yukon Exploration and Geology 2001, D.S. Emond, L.H. Weston and L.L. Lewis (eds.), Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, p. 189-207.
CHEVRON CANADA LTD, Feb/79. Assessment Report #090439 by R.J. Cathro and U. Schmidt.
CHEVRON CANADA LTD, Feb/81. Assessment Report #090728 by R.J. Cathro and U. Schmidt.
MINERAL INDUSTRY REPORT 1978, p. 65.
TRUE NORTH GEMS INC, Aug/2004. Assessment Report #094469 by W. Wengzynowski.
Location Map
Last Updated: Sep 15, 2011
Work History
| Year | Work Type | Comment |
|---|---|---|
| 2003 | Geochemistry: Silt | |
| 2003 | Geochemistry: Soil | |
| 2003 | Geology: Bedrock Mapping | |
| 2003 | Other | |
| 1980 | Geology: Bedrock Mapping | |
| 1980 | Other | |
| 1980 | Trenching: Hand | |
| 1978 | Geology: Bedrock Mapping | |
| 1978 | Other | |
| 1978 | Trenching: Hand |
Regional Geology - Terrane
Group: Intermontane
Affinity: W Laurentia
Name: Yukon-Tanana
Realm: peri-Laurentian
Regional Geology - Bedrock
Supergroup:
Group/Suite: Grass Lakes
Formation:
Member:
Terrane: Yukon-Tanana
Period Max: Devonian
Age Max: 365 MA
Period Min: Carboniferous
Age Min: 357 MA
Rock Major: augen granite
Rock Minor:
Reference: Murphy et al. (2001) - YGS OF 2001-33
Geological Unit (1M): DMG
Geological Unit (250K): DMqG
Assessment Reports that overlap occurrence
| Report Number | Year | Title | Worktypes | Holes Drilled | Meters Drilled |
|---|---|---|---|---|---|
| 094469 | 2003 | Assessment Report Describing Geology, Mineralogy and Geochemistry at the Oz Property | Silt - Geochemistry, Soil - Geochemistry, Detailed Bedrock Mapping - Geology, Prospecting - Other, Hand - Trenching | ||
| 090728 | 1980 | Report on Geological Mapping and Diamond Drilling on the Boot 1-284 & Marmot 1-24 Claims | Diamond - Drilling, Soil - Geochemistry, Detailed Bedrock Mapping - Geology | 10 | 1232 |
| 019115 | 1966 | Northlake Mines Limited, Gee Group of Claims: Report on Airborne Geophysical Surveys | Electromagnetic - Airborne Geophysics, Magnetic - Airborne Geophysics |
Related References
| Number | Title | Page(s) | Document Type |
|---|---|---|---|
| ARMC016586 | Geochemical map - 105G/6 - Upper Hoole River | Geochemical Map | |
| ARMC016576 | Geology map - 105G/6 - Upper Hoole River | Geoscience Map (Geological - Bedrock) |
| Citations |
|---|
