General Information
Primary Commodities: tungsten, tungsten trioxide
Secondary Commodities: gold
Aliases: Garnet, Garnet Skarn Zone, Mar-Tungsten, Ray Gulch
Deposit Type(s): Skarn W
Location(s): 64.027780 N, -135.751110 W
NTS Mapsheet(s): 106D04
Location Comments: .5 Kilometres
Hand Samples Available at YGS: Yes
Capsule
Work History
Staked as Tip Top cl (55220) in Oct/42 by Harvey Ray, examined by Ventures Ltd in 1942, and investigated by the Geological Survey of Canada in 1942-44. Restaked in Aug/51 by R.A. Batty and E. Barker as Batty cl (61878), which were prospected and sampled in 1956 by Stride Exploration and Development Company Ltd. Mayo Silver Mines Ltd staked claims on the east side of the gulch about 1960 and bulldozer trenched in 1963 or 1964.
The first interest in the bulk tonnage tungsten potential commenced in Jun/68 when Pan cl 1-36 (Y27203) were staked by C. Provencher. The Pan claims covered this occurrence and the Potatoe Hills occurrence (Minfile Occurrence #106D 026) located approximately 1.5 km to the north. After 1968 both occurrences were explored simultaneously for tungsten mineralization, however the majority of exploration was directed towards this occurrence.
The property was optioned in 1968 by Great Plains Development Company of Canada Ltd, which conducted bulldozer trenching and added Pan cl 37-68 (Y31528) in Sep/68. Tam Mines Ltd added Arpa cl 29, 31, 39, 40 (Y31715) and Arpa cl 57-96 (Y31727) to the claim group in Feb/69 and bulldozer trenched later in the year. Connaught Mines Ltd optioned all of the claims from 1969 to 1971 but assigned their rights in 1970 and 1971 to Canex Aerial Exploration Ltd. The company carried out bulldozer trenching and an extensive soil geochemical survey on the west side of Ray Gulch in 1970, and in 1971 drilled three holes (457.2 m) across the quartz-scheelite vein system located within the stock. All of the claims reverted early in 1972 to Provencher, who transferred them to a private company, Scheelite Hills Minerals Ltd.
Restaked as Mar cl 1-24 (YA14897) in Mar/77 by Queenstake Resources Ltd, which carried out geological mapping and bulldozer trenching later in the year. In the spring of 1978, Canada Tungsten Mining Corporation Ltd optioned the Mar claims from Queenstake Resources. At approximately the same time Canada Tungsten purchased the adjoining (west) R & D claims (1-16, YA1393) from Dublin Gulch Mining Ltd, staked Dave cl 1-24 (YA17802) to the southwest in Apr/78 and either purchased or optioned a further 389 claims in the Dublin Gulch region. The company explored with extensive geochemical and geophysical surveys in 1978 and 1979 and between July and Sep/79 drilled 21 diamond drill holes (2 423 m) on the Garnet Skarn Zone. In Apr/80 Canada Tungsten released a preliminary resource figure of 4 861 593 tonnes of ore grading 0.48% tungsten oxide (WO3) (Assessment Report #090614 - page 113). This preliminary reserve was listed under the "possible-probable category and is reported for historical purposes and is not compliant with National Instruments 43-101 standards.
Beginning in 1980 Bema Industries assumed project management. They drilled 64 diamond drill holes (11 278 m) in 1980, carried out additional trenching, geochemical and geophysical programs in 1981. In Nov/81 Bema published an updated reserve figure of 3 750 492 tonnes grading 0.555% tungsten oxide (WO3) (Assessment Report #090915 - Table 1 located between pages 26 and 27). This reserve figure is not compliant with National Instruments 43-101 and can only be considered historical. Bema drilled 3 diamond drill holes( 751 m) in 1982 after which no further work was carried out on this occurrence. Cantung dropped its option in 1986 and the claims reverted to Queenstake Resources. After 1982 very little work was carried out on this occurrence.
H-6000 Holdings optioned the entire Dublin Gulch property in 1991 and subsequently optioned it in Sep/91 to Amax Gold Inc, which explored with mapping, geochemistry, geophysics and 16 diamond drillholes totaling 2 500 m. Amax was interested in exploring the property's potential for an intrusive hosted, bulk mineable gold deposit similar to the Fort Knox deposit located near Fairbanks, Alaska.
In 1992, Amax performed 1 129.9 m of reverse circulation drilling on the R & D 2 and 16, Bob 1, Smoky 64, 65, 74 and 76 claims. In late 1992, the property was returned to Ivanhoe Goldfields Ltd (a successor company of H-6000 Holdings). In Sep/93, Ivanhoe drilled 10 reverse circulation drill holes totaling 2 079 m on the Smoky 3 and 4 claims and Smoky 96 fractional claim, and dug several test pits in decomposed bedrock on the R and D claims and the Olive crown grant in Sept/93. Samples were then screened, gravity concentrated and assayed. Ivanhoe also performed a soil survey on the West, Sec and DG claims in Sep/93. In Aug/94 First Dynasty Mines Ltd acquired Ivanhoe Goldfields Ltd and in Oct/94 Queenstake Resources Ltd transferred its interest in the Mar, R and D, DG, Jeff, Bob, and Smoky claims to First Dynasty.
In 1995, First Dynasty and in 1996 its wholly owned subsidiary, New Millennium Mining Ltd carried out a major drilling program to outline a core resource/reserve on the Eagle Zone (Minfile Occurrence #106D 025) located approximately 2.5 km to the west. The companies also carried out diamond drilling on Potato Hills (Minfile Occurrence #106D 026) located 1.5 km to the northeast to test for mineralization under the proposed heap leach pad area. During the 1990's only a minor amount of assessment work was carried out on the tungsten potential of this occurrence and the neighboring Potatoe Hills occurrence.
First Dynasty changed its name to Sterlite Gold Ltd in Jul/2002. In Oct/2004 StrataGold Corporation entered into an agreement to acquire all of Sterlite's interest in Dublin Gulch including this occurrence. In addition, StrataGold purchased Queenstake Resources surviving rights and interest in various claims. Queenstake retained a 1% royalty on ore processed from this occurrence and surrounding leases.
StrataGold renamed this occurrence the Mar-Tungsten Deposit and hired SRK Consulting (US) Inc to calculate a updated resource estimate for the deposit. In Jan/2008 StrataGold announced a National Instruments 43-101 resource estimate for the Mar-Tungsten Deposit of 5.31 million tonnes grading 0.39% tungsten oxide (WO3) in the indicated category and 2.17 million tonnes grading 0.36 % tungsten oxide in the Inferred category. A cut-off grade of 0.10% tungsten oxide was used for the resource estimate (SRK Consulting, Feb 2008).
Stratagold released a positive NI 43-101 preliminary economic assessment on the Mar in a report dated December 01 2008. The report was prepared by SRK Consulting (US) Inc and included an updated resource estimate.
Capsule Geology
The area has not yet been remapped by the Yukon Geological Survey however C. Roots (1997) of the Geological Survey of Canada under contract with the Exploration and Geological Services Division (now part of the Yukon Geological Survey) remapped topographic map sheet 105M located directly to the south in the mid-1990's. In 2003 Gordey and Makepeace released a geological compilation of the Yukon which covered this area. In addition various company geologists have mapped the Dublin Gulch area in detail.
Geological work carried out by Roots, Gordey and Makepeace and various company geologists shows that the Dublin Gulch area is underlain by deformed Upper Proterozoic to Lower Cambrian clastic rocks of the Hyland Group that have been intruded by the Dublin Gulch Stock, a Late Cretaceous medium-grained granodiorite stock assigned to the Tombstone Suite. The stock is cut by minor late dykes. Rare narrow intrusive breccia dykes have also been reported. Alteration, gold and tungsten mineralization is directly associated with these intrusions.
Ray the original staker found large blocks of pale green, coarsely crystalline tremolite skarn float containing 2.7% to 3.3% scheelite. In 1943, the Geological Survey of Canada located an outcropping zone 25 m thick in Late Proterozoic Hyland Group quartz-biotite schist, from which grab samples assayed 0.27% to 0.5% tungsten oxide (WO3).
In the occurrence area interbedded units of gritty quartzite, micaeous (muscovite) quartzite, massive white quartzite, limestone and phyllite locally referred to as the Grit unit are intruded by the Dublin Gulch stock. A hornfels thermal aureole measuring up to 2 km wide developed around the stock as it intruded the metasedimentary rocks and altered them to biotite-quartzite schists, marble, wollastonite-quartz skarn and pyroxene skarn as a result of contact metamorphism and metasomatism. The Ray Gulch tungsten skarn (Mar Tungsten) deposit formed within this hornfels aureole.
Four phases of granitic rocks have been identified in outcrop and drill core. They are, from youngest to oldest: leucocratic granite and aplite, quartz monzonite, quartz diorite and granodiorite. Intrusion of the granodiorite and leucratic granitic phases were likely responsible for the metasomatic alteration and mineralization of the hornfelsed metasedimentary rocks. Two phases of metasomatism in the skarn and scheelite mineralization have been identified. The first phase formed a light green, fine-grained skarn within marble and biotite-quartzite schist units. No tungsten mineralization was associated with this phase. The second phase formed massive dark gree scheelite bearing skarn within marble units and also within previously formed light green skarn. Sulphide mineralization in the tungsten bearing skarn is negligible.
The deposit is located within a roof pendant and the pendant has been sliced in several places by the injection of several sill-like sheets of granodiorite. There are two dominant sheets which are thicker and laterally more continuous than the rest and might have exerted some control on the tungsten mineralization in the pyroxene skarns. The upper sheet averages 10 m in thickness, plunges westerly and pinches out to the south. The lower sheet averages 40 m in thickness, dips southward and like the upper sheet pinches out at the southern extremity of the deposit. The two sheets are separated by six interbedded units of wollastonite-quartz skarn, pyroxene skarn, biotite-quartzite schist and marble. The two sheets connect with the main Dublin Gulch stock to the north, east and possibly the west but pinch out to the south.
Drill-indicated ore reserves and probable reserves are contained within the six skarn zones, all which possess a northerly strike and a westerly 25 degree dip. The number 1 zone is at the highest elevation and the number 6 zone is at the lowest elevation within the metasedimentary units. Zones 1 to 3 are located between the upper granodiorite sheet and the surface in the west central part of the deposit and have been nearly removed by erosion. The number 4 zone lies adjacent to and is cut by the upper granodiorite sheet. The number 5 zone lies between the upper and lower granodiorite sheets and is truncated to the west and south by the lower sheet as it rises to higher levels in these directions. The number 6 zone lies along and just above the lower granodiorite sheet and is also truncated to the west and south by this sheet.
Within the deposit each of the six skarn zones consists of several skarn beds that are in closed proximity to each other. The lateral continuity of individual skarn units varies considerably because of different degrees of replacement by the mineralized pyroxene skarns. Tungsten concentration within individual unit are highly variable but because several skarn units form each zone concentration variations in each unit are smoothed. Thus these generalized zones of mineralization are therefore in most cases laterally continuous and consistent in grades.
Average tungsten grades increase with depth from the number 1 skarn zone nearest the surface of the deposit, to the lower level number 6 skarn zone located some 200 m below surface. Within each zone, grades in pyroxene skarns range from less than 0.10% tungsten oxide (WO3) to greater than 2.0% tungsten oxide. There is no tungsten mineralization in the wollastonite-quartz skarn units within each zone. Massive pyroxene skarn units are more common than wollastonite-quartz skarn units in the number 5 and 6 skarn zones and there is a gradual increase in grade within the pyroxene skarn units themselves from the number 1 to number 6 skarn zones. However it is the greater abundance of the massive pyroxene skarn units in each successive zone that accounts for the higher tenor of these zones.
NI 43-101 compliant resource as reported by StrataGold Corporation on Jan 15 2008 were:
Indicated Resource = 5 310 000 tonnes grading 0.39% tungsten oxide (WO3)
Inferred Resource = 2 100 000 tonnes grading 0.36% tungsten oxide (WO3)
A cut-off grade of 0.10% tungsten oxide (WO3) was used for the resource estimate. Estimate calculated by SRK Consulting (US) Inc and can be found on the SEDAR web site under the StrataGold Corporation company profile dated Feb 26, 2008.
In Oct, 2008, Stratagold released an updated resource for the Mar tungsten deposit: 7.819 mT at 0.381% WO3 in the indicated category and 0.945 mT at 0.410% WO3 in the inferred category.
A preliminary economic assessement report dated December 2008, by SRK, revised the estimate to an Indicated Mineral Resource of 12.7Mt of material with 0.31% WO3 and an additional Inferred Mineral Resource of 1.3Mt of material with 0.30% WO3 both using a 0.1% WO3 cut-off.
References
AMAX GOLD (B.C.) LTD, Nov/92. Assessment Report *#093050 by A.C. Hitchins.
BEMA INDUSTRIES LTD, Mar/81. Assessment Report #090790 by G.D. Nordin.
BEMA INDUSTRIES LTD, Dec/81. Assessment Report #090915 by G.M. Rodgers.
CANADA TUNGSTEN MINING CORPORATION LTD, May/80. Assessment Report #090614 by W.R. Howard and W.A. Gewargis.
CATHRO, R.J., Apr/69. Tungsten in Yukon. Western Miner, p. 32.
EMOND, D.S., 1992. Petrology and geochemistry of tin and tungsten mineralized plutons, McQuesten River region, Central Yukon. In: Yukon Geology Vol. 3, Exploration and Geological Services Division, DIAND, p. 167-195.
EMOND, D.S., and LYNCH, T., 1992. Geology, mineralogy and geochemistry of tin and tungsten mineralized veins, breccias and skarns, McQuesten River Region (115P(North)) and 105 M 13), Yukon. In: Yukon Geology Vol. 3, Exploration and Geological Services Division, DIAND, p. 133-159.
FIRST DYNASTY MINES LTD, Mar/96. Assessment Report #093409 by M. Sieb.
GEOLOGICAL SURVEY OF CANADA, Tungsten Deposits of Canada. Economic Geology Series No. 17, p. 34.
GEORGE CROSS NEWSLETTER, 16 Sep/91; 30 Dec/92.
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).
IVANHOE GOLDFIELDS LTD, Sep/93. Assessment Report #093140 by C.N. Orssich.
IVANHOE GOLDFIELDS LTD, Sep/93. Assessment Report #093141 by C.N. Orssich.
IVANHOE GOLDFIELDS LTD, Sep/93. Assessment Report #093142 by C.N. Orssich.
MCKAY, T., 1943. Assessment Report *#062120 by H.S. Bostock.
MINERAL INDUSTRY REPORT, 1978, p. 14-15.
NORTHERN MINER, 22 Nov/79; 1 May/80.
ORSSICH, C.N., 1981. Geology of the Dublin Gulch Tungsten Deposit. Unpublished B.Sc. Thesis, Carleton University.
QUEENSTAKE RESOURCES LTD, May/92. Assessment Report *#093028 by B. Lennan.
ROOTS, C.F., 1997. Bedrock geology of Mayo area, central Yukon (105M). Exploration and Geological Services Division, Indian and Northern Affairs Canada, Geoscience Map 1997-1, 1:50 000 scale.
ROOTS, C.F., 1997. Geology of the Mayo Map Area, Yukon Territory (105M). Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, Bulletin 7, 82 p.
SEDAR. System for Electronic Document Analysis and Retrieval system - Company Profiles.
SRK CONSULTING (US) INC. Feb/2008. NI 43-101Technical Report on Resources Dublin Gulch Property - Mar Tungsten Zone Mayo District, Yukon Territory, Canada. (Available on Sedar web site under StrataGold Corporation's company profile).
SMIT, H., ET AL. Summary Information on the Dublin Gulch Project, Yukon Territory. In: Yukon Exploration and Geology, 1995, Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, p.33-36.
STRATAGOLD CORPORATION, News Release, 18 Oct/2004; 15 Jan/2008; 1 Dec/2008; 5 Jun/2009.
VICTORIA GOLD CORPORATION, News Release, 5 Jun/2009.
WHITEHORSE STAR, 14 Jun/95; 21 Sep/95.
YUKON EXPLORATION 1985-86, p. 293-294.
YUKON EXPLORATION AND GEOLOGY 1982, p. 180; 1983, p. 27; 1992, p. 2, 4-5; 1995, 8, 33; 1996, p. 13-14, 30, 32; 1997, p. 12, 35.
YUKON GEOLOGY AND EXPLORATION 1979-80, p. 238-240.
Staked as Tip Top cl (55220) in Oct/42 by Harvey Ray, examined by Ventures Ltd in 1942, and investigated by the Geological Survey of Canada in 1942-44. Restaked in Aug/51 by R.A. Batty and E. Barker as Batty cl (61878), which were prospected and sampled in 1956 by Stride Exploration and Development Company Ltd. Mayo Silver Mines Ltd staked claims on the east side of the gulch about 1960 and bulldozer trenched in 1963 or 1964.
The first interest in the bulk tonnage tungsten potential commenced in Jun/68 when Pan cl 1-36 (Y27203) were staked by C. Provencher. The Pan claims covered this occurrence and the Potatoe Hills occurrence (Minfile Occurrence #106D 026) located approximately 1.5 km to the north. After 1968 both occurrences were explored simultaneously for tungsten mineralization, however the majority of exploration was directed towards this occurrence.
The property was optioned in 1968 by Great Plains Development Company of Canada Ltd, which conducted bulldozer trenching and added Pan cl 37-68 (Y31528) in Sep/68. Tam Mines Ltd added Arpa cl 29, 31, 39, 40 (Y31715) and Arpa cl 57-96 (Y31727) to the claim group in Feb/69 and bulldozer trenched later in the year. Connaught Mines Ltd optioned all of the claims from 1969 to 1971 but assigned their rights in 1970 and 1971 to Canex Aerial Exploration Ltd. The company carried out bulldozer trenching and an extensive soil geochemical survey on the west side of Ray Gulch in 1970, and in 1971 drilled three holes (457.2 m) across the quartz-scheelite vein system located within the stock. All of the claims reverted early in 1972 to Provencher, who transferred them to a private company, Scheelite Hills Minerals Ltd.
Restaked as Mar cl 1-24 (YA14897) in Mar/77 by Queenstake Resources Ltd, which carried out geological mapping and bulldozer trenching later in the year. In the spring of 1978, Canada Tungsten Mining Corporation Ltd optioned the Mar claims from Queenstake Resources. At approximately the same time Canada Tungsten purchased the adjoining (west) R & D claims (1-16, YA1393) from Dublin Gulch Mining Ltd, staked Dave cl 1-24 (YA17802) to the southwest in Apr/78 and either purchased or optioned a further 389 claims in the Dublin Gulch region. The company explored with extensive geochemical and geophysical surveys in 1978 and 1979 and between July and Sep/79 drilled 21 diamond drill holes (2 423 m) on the Garnet Skarn Zone. In Apr/80 Canada Tungsten released a preliminary resource figure of 4 861 593 tonnes of ore grading 0.48% tungsten oxide (WO3) (Assessment Report #090614 - page 113). This preliminary reserve was listed under the "possible-probable category and is reported for historical purposes and is not compliant with National Instruments 43-101 standards.
Beginning in 1980 Bema Industries assumed project management. They drilled 64 diamond drill holes (11 278 m) in 1980, carried out additional trenching, geochemical and geophysical programs in 1981. In Nov/81 Bema published an updated reserve figure of 3 750 492 tonnes grading 0.555% tungsten oxide (WO3) (Assessment Report #090915 - Table 1 located between pages 26 and 27). This reserve figure is not compliant with National Instruments 43-101 and can only be considered historical. Bema drilled 3 diamond drill holes( 751 m) in 1982 after which no further work was carried out on this occurrence. Cantung dropped its option in 1986 and the claims reverted to Queenstake Resources. After 1982 very little work was carried out on this occurrence.
H-6000 Holdings optioned the entire Dublin Gulch property in 1991 and subsequently optioned it in Sep/91 to Amax Gold Inc, which explored with mapping, geochemistry, geophysics and 16 diamond drillholes totaling 2 500 m. Amax was interested in exploring the property's potential for an intrusive hosted, bulk mineable gold deposit similar to the Fort Knox deposit located near Fairbanks, Alaska.
In 1992, Amax performed 1 129.9 m of reverse circulation drilling on the R & D 2 and 16, Bob 1, Smoky 64, 65, 74 and 76 claims. In late 1992, the property was returned to Ivanhoe Goldfields Ltd (a successor company of H-6000 Holdings). In Sep/93, Ivanhoe drilled 10 reverse circulation drill holes totaling 2 079 m on the Smoky 3 and 4 claims and Smoky 96 fractional claim, and dug several test pits in decomposed bedrock on the R and D claims and the Olive crown grant in Sept/93. Samples were then screened, gravity concentrated and assayed. Ivanhoe also performed a soil survey on the West, Sec and DG claims in Sep/93. In Aug/94 First Dynasty Mines Ltd acquired Ivanhoe Goldfields Ltd and in Oct/94 Queenstake Resources Ltd transferred its interest in the Mar, R and D, DG, Jeff, Bob, and Smoky claims to First Dynasty.
In 1995, First Dynasty and in 1996 its wholly owned subsidiary, New Millennium Mining Ltd carried out a major drilling program to outline a core resource/reserve on the Eagle Zone (Minfile Occurrence #106D 025) located approximately 2.5 km to the west. The companies also carried out diamond drilling on Potato Hills (Minfile Occurrence #106D 026) located 1.5 km to the northeast to test for mineralization under the proposed heap leach pad area. During the 1990's only a minor amount of assessment work was carried out on the tungsten potential of this occurrence and the neighboring Potatoe Hills occurrence.
First Dynasty changed its name to Sterlite Gold Ltd in Jul/2002. In Oct/2004 StrataGold Corporation entered into an agreement to acquire all of Sterlite's interest in Dublin Gulch including this occurrence. In addition, StrataGold purchased Queenstake Resources surviving rights and interest in various claims. Queenstake retained a 1% royalty on ore processed from this occurrence and surrounding leases.
StrataGold renamed this occurrence the Mar-Tungsten Deposit and hired SRK Consulting (US) Inc to calculate a updated resource estimate for the deposit. In Jan/2008 StrataGold announced a National Instruments 43-101 resource estimate for the Mar-Tungsten Deposit of 5.31 million tonnes grading 0.39% tungsten oxide (WO3) in the indicated category and 2.17 million tonnes grading 0.36 % tungsten oxide in the Inferred category. A cut-off grade of 0.10% tungsten oxide was used for the resource estimate (SRK Consulting, Feb 2008).
Stratagold released a positive NI 43-101 preliminary economic assessment on the Mar in a report dated December 01 2008. The report was prepared by SRK Consulting (US) Inc and included an updated resource estimate.
Capsule Geology
The area has not yet been remapped by the Yukon Geological Survey however C. Roots (1997) of the Geological Survey of Canada under contract with the Exploration and Geological Services Division (now part of the Yukon Geological Survey) remapped topographic map sheet 105M located directly to the south in the mid-1990's. In 2003 Gordey and Makepeace released a geological compilation of the Yukon which covered this area. In addition various company geologists have mapped the Dublin Gulch area in detail.
Geological work carried out by Roots, Gordey and Makepeace and various company geologists shows that the Dublin Gulch area is underlain by deformed Upper Proterozoic to Lower Cambrian clastic rocks of the Hyland Group that have been intruded by the Dublin Gulch Stock, a Late Cretaceous medium-grained granodiorite stock assigned to the Tombstone Suite. The stock is cut by minor late dykes. Rare narrow intrusive breccia dykes have also been reported. Alteration, gold and tungsten mineralization is directly associated with these intrusions.
Ray the original staker found large blocks of pale green, coarsely crystalline tremolite skarn float containing 2.7% to 3.3% scheelite. In 1943, the Geological Survey of Canada located an outcropping zone 25 m thick in Late Proterozoic Hyland Group quartz-biotite schist, from which grab samples assayed 0.27% to 0.5% tungsten oxide (WO3).
In the occurrence area interbedded units of gritty quartzite, micaeous (muscovite) quartzite, massive white quartzite, limestone and phyllite locally referred to as the Grit unit are intruded by the Dublin Gulch stock. A hornfels thermal aureole measuring up to 2 km wide developed around the stock as it intruded the metasedimentary rocks and altered them to biotite-quartzite schists, marble, wollastonite-quartz skarn and pyroxene skarn as a result of contact metamorphism and metasomatism. The Ray Gulch tungsten skarn (Mar Tungsten) deposit formed within this hornfels aureole.
Four phases of granitic rocks have been identified in outcrop and drill core. They are, from youngest to oldest: leucocratic granite and aplite, quartz monzonite, quartz diorite and granodiorite. Intrusion of the granodiorite and leucratic granitic phases were likely responsible for the metasomatic alteration and mineralization of the hornfelsed metasedimentary rocks. Two phases of metasomatism in the skarn and scheelite mineralization have been identified. The first phase formed a light green, fine-grained skarn within marble and biotite-quartzite schist units. No tungsten mineralization was associated with this phase. The second phase formed massive dark gree scheelite bearing skarn within marble units and also within previously formed light green skarn. Sulphide mineralization in the tungsten bearing skarn is negligible.
The deposit is located within a roof pendant and the pendant has been sliced in several places by the injection of several sill-like sheets of granodiorite. There are two dominant sheets which are thicker and laterally more continuous than the rest and might have exerted some control on the tungsten mineralization in the pyroxene skarns. The upper sheet averages 10 m in thickness, plunges westerly and pinches out to the south. The lower sheet averages 40 m in thickness, dips southward and like the upper sheet pinches out at the southern extremity of the deposit. The two sheets are separated by six interbedded units of wollastonite-quartz skarn, pyroxene skarn, biotite-quartzite schist and marble. The two sheets connect with the main Dublin Gulch stock to the north, east and possibly the west but pinch out to the south.
Drill-indicated ore reserves and probable reserves are contained within the six skarn zones, all which possess a northerly strike and a westerly 25 degree dip. The number 1 zone is at the highest elevation and the number 6 zone is at the lowest elevation within the metasedimentary units. Zones 1 to 3 are located between the upper granodiorite sheet and the surface in the west central part of the deposit and have been nearly removed by erosion. The number 4 zone lies adjacent to and is cut by the upper granodiorite sheet. The number 5 zone lies between the upper and lower granodiorite sheets and is truncated to the west and south by the lower sheet as it rises to higher levels in these directions. The number 6 zone lies along and just above the lower granodiorite sheet and is also truncated to the west and south by this sheet.
Within the deposit each of the six skarn zones consists of several skarn beds that are in closed proximity to each other. The lateral continuity of individual skarn units varies considerably because of different degrees of replacement by the mineralized pyroxene skarns. Tungsten concentration within individual unit are highly variable but because several skarn units form each zone concentration variations in each unit are smoothed. Thus these generalized zones of mineralization are therefore in most cases laterally continuous and consistent in grades.
Average tungsten grades increase with depth from the number 1 skarn zone nearest the surface of the deposit, to the lower level number 6 skarn zone located some 200 m below surface. Within each zone, grades in pyroxene skarns range from less than 0.10% tungsten oxide (WO3) to greater than 2.0% tungsten oxide. There is no tungsten mineralization in the wollastonite-quartz skarn units within each zone. Massive pyroxene skarn units are more common than wollastonite-quartz skarn units in the number 5 and 6 skarn zones and there is a gradual increase in grade within the pyroxene skarn units themselves from the number 1 to number 6 skarn zones. However it is the greater abundance of the massive pyroxene skarn units in each successive zone that accounts for the higher tenor of these zones.
NI 43-101 compliant resource as reported by StrataGold Corporation on Jan 15 2008 were:
Indicated Resource = 5 310 000 tonnes grading 0.39% tungsten oxide (WO3)
Inferred Resource = 2 100 000 tonnes grading 0.36% tungsten oxide (WO3)
A cut-off grade of 0.10% tungsten oxide (WO3) was used for the resource estimate. Estimate calculated by SRK Consulting (US) Inc and can be found on the SEDAR web site under the StrataGold Corporation company profile dated Feb 26, 2008.
In Oct, 2008, Stratagold released an updated resource for the Mar tungsten deposit: 7.819 mT at 0.381% WO3 in the indicated category and 0.945 mT at 0.410% WO3 in the inferred category.
A preliminary economic assessement report dated December 2008, by SRK, revised the estimate to an Indicated Mineral Resource of 12.7Mt of material with 0.31% WO3 and an additional Inferred Mineral Resource of 1.3Mt of material with 0.30% WO3 both using a 0.1% WO3 cut-off.
References
AMAX GOLD (B.C.) LTD, Nov/92. Assessment Report *#093050 by A.C. Hitchins.
BEMA INDUSTRIES LTD, Mar/81. Assessment Report #090790 by G.D. Nordin.
BEMA INDUSTRIES LTD, Dec/81. Assessment Report #090915 by G.M. Rodgers.
CANADA TUNGSTEN MINING CORPORATION LTD, May/80. Assessment Report #090614 by W.R. Howard and W.A. Gewargis.
CATHRO, R.J., Apr/69. Tungsten in Yukon. Western Miner, p. 32.
EMOND, D.S., 1992. Petrology and geochemistry of tin and tungsten mineralized plutons, McQuesten River region, Central Yukon. In: Yukon Geology Vol. 3, Exploration and Geological Services Division, DIAND, p. 167-195.
EMOND, D.S., and LYNCH, T., 1992. Geology, mineralogy and geochemistry of tin and tungsten mineralized veins, breccias and skarns, McQuesten River Region (115P(North)) and 105 M 13), Yukon. In: Yukon Geology Vol. 3, Exploration and Geological Services Division, DIAND, p. 133-159.
FIRST DYNASTY MINES LTD, Mar/96. Assessment Report #093409 by M. Sieb.
GEOLOGICAL SURVEY OF CANADA, Tungsten Deposits of Canada. Economic Geology Series No. 17, p. 34.
GEORGE CROSS NEWSLETTER, 16 Sep/91; 30 Dec/92.
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).
IVANHOE GOLDFIELDS LTD, Sep/93. Assessment Report #093140 by C.N. Orssich.
IVANHOE GOLDFIELDS LTD, Sep/93. Assessment Report #093141 by C.N. Orssich.
IVANHOE GOLDFIELDS LTD, Sep/93. Assessment Report #093142 by C.N. Orssich.
MCKAY, T., 1943. Assessment Report *#062120 by H.S. Bostock.
MINERAL INDUSTRY REPORT, 1978, p. 14-15.
NORTHERN MINER, 22 Nov/79; 1 May/80.
ORSSICH, C.N., 1981. Geology of the Dublin Gulch Tungsten Deposit. Unpublished B.Sc. Thesis, Carleton University.
QUEENSTAKE RESOURCES LTD, May/92. Assessment Report *#093028 by B. Lennan.
ROOTS, C.F., 1997. Bedrock geology of Mayo area, central Yukon (105M). Exploration and Geological Services Division, Indian and Northern Affairs Canada, Geoscience Map 1997-1, 1:50 000 scale.
ROOTS, C.F., 1997. Geology of the Mayo Map Area, Yukon Territory (105M). Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, Bulletin 7, 82 p.
SEDAR. System for Electronic Document Analysis and Retrieval system - Company Profiles.
SRK CONSULTING (US) INC. Feb/2008. NI 43-101Technical Report on Resources Dublin Gulch Property - Mar Tungsten Zone Mayo District, Yukon Territory, Canada. (Available on Sedar web site under StrataGold Corporation's company profile).
SMIT, H., ET AL. Summary Information on the Dublin Gulch Project, Yukon Territory. In: Yukon Exploration and Geology, 1995, Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, p.33-36.
STRATAGOLD CORPORATION, News Release, 18 Oct/2004; 15 Jan/2008; 1 Dec/2008; 5 Jun/2009.
VICTORIA GOLD CORPORATION, News Release, 5 Jun/2009.
WHITEHORSE STAR, 14 Jun/95; 21 Sep/95.
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YUKON EXPLORATION AND GEOLOGY 1982, p. 180; 1983, p. 27; 1992, p. 2, 4-5; 1995, 8, 33; 1996, p. 13-14, 30, 32; 1997, p. 12, 35.
YUKON GEOLOGY AND EXPLORATION 1979-80, p. 238-240.
Location Map
Last Updated: Jul 24, 2018
Work History
| Year | Work Type | Comment |
|---|---|---|
| 2008 | Studies: Preliminary Economic Assessment | SRK Consulting, December 1 2008. Includes revised resource estimate. |
| 2008 | Studies: Resource Estimate | SRK Consulting, Feb 2008, effective date Dec 2007. |
| 1996 | Studies: Feasibility | All work undertaken to evaluate Dublin Gulch property. |
| 1995 | Studies: Feasibility | All work undertaken to evaluate Dublin Gulch property. |
| 1993 | Drilling: Rotary | Ten holes, 2,079 m. Drilling was reverse circulation, completed on Smoky claims. |
| 1993 | Geochemistry: Soil | |
| 1993 | Trenching: Mechanical | |
| 1992 | Drilling: Reverse Circulation | Nine holes, 1,129.9 m. Amax drilled a total of 5 639 m in the Dublin Gulch and Haggart Creek areas. |
| 1991 | Drilling: Diamond | Six holes, 2,500 m. |
| 1991 | Geochemistry: Soil | Also rock sampling. |
| 1991 | Geology: Bedrock Mapping | |
| 1982 | Drilling: Diamond | Three holes, 738.2 m. |
| 1982 | Geochemistry: Rock | |
| 1982 | Geochemistry: Soil | |
| 1982 | Geology: Bedrock Mapping | |
| 1982 | Ground Geophysics: Magnetics | Also VLF-EM and radiometric surveys. |
| 1981 | Geochemistry: Soil | Also rock sampling. |
| 1981 | Geology: Bedrock Mapping | |
| 1981 | Trenching: Mechanical | |
| 1980 | Drilling: Diamond | Sixty-one holes, 11,315 m. |
| 1980 | Trenching: Mechanical | |
| 1979 | Drilling: Diamond | Twenty-one holes, 2,421.9 m. |
| 1979 | Geochemistry: Rock | |
| 1979 | Geochemistry: Soil | |
| 1979 | Geology: Bedrock Mapping | |
| 1979 | Ground Geophysics: Magnetics | |
| 1978 | Geochemistry: Silt | |
| 1978 | Geochemistry: Soil | |
| 1978 | Geology: Bedrock Mapping | |
| 1978 | Other: Prospecting | |
| 1978 | Ground Geophysics: Magnetics | |
| 1977 | Geology: Bedrock Mapping | |
| 1977 | Trenching: Mechanical | |
| 1971 | Drilling: Diamond | Three holes, 457.2 m. |
| 1971 | Geochemistry: Soil | |
| 1971 | Trenching: Mechanical | |
| 1970 | Geochemistry: Soil | |
| 1970 | Trenching: Mechanical | |
| 1969 | Trenching: Mechanical | |
| 1956 | Geochemistry: Rock | |
| 1956 | Other: Prospecting |
Regional Geology - Terrane
Group: Ancestral North America
Affinity: W Laurentia
Name: North America - basinal strata
Realm: Laurentia
Regional Geology - Bedrock
Supergroup: Windermere
Group/Suite: Hyland
Formation: Yusezyu
Member:
Terrane: Laurentia
Period Max: Ediacaran
Age Max: 635 MA
Period Min: Ediacaran
Age Min: 542 MA
Rock Major: phyllite/shale/sandstone/grit/conglomerate/limestone
Rock Minor: marble
Reference: Green & Roddick (1972) - GSC Map 1283A
Geological Unit (1M): PCH
Geological Unit (250K): PCH6
Assessment Reports that overlap occurrence
| Report Number | Year | Title | Worktypes | Holes Drilled | Meters Drilled |
|---|---|---|---|---|---|
| 097130 | 2017 | Assessment Report on the VBW Claims: Geological, Geochemical and Remote Sensing Exploration Program - 2017 | Magnetic - Airborne Geophysics, Rock - Geochemistry, Soil - Geochemistry, Bedrock Mapping - Geology, LIDAR - Remote Sensing | ||
| 096246 | 2012 | 2011 Dublin Gulch Exploration, Drilling, Regional Surface Sampling, Engineering and Environmental Programs | Diamond - Drilling, Diamond - Drilling, Reverse Circulation - Drilling, Reverse Circulation - Drilling, Drill Core - Geochemistry, Drill Core - Geochemistry, Drill Cuttings - Geochemistry, Drill Cuttings - Geochemistry, Rock - Geochemistry, Rock - Geochemistry, Regional Bedrock Mapping - Geology, Regional Bedrock Mapping - Geology, Bulk Sample - Lab Work/Physical Studies, Bulk Sample - Lab Work/Physical Studies, Environmental Assessment/Impact - Studies, Environmental Assessment/Impact - Studies, Geotechnical - Studies, Geotechnical - Studies, Backhoe - Trenching, Backhoe - Trenching | 268 | 35882.36 |
| 095654 | 2008 | Dublin Gulch, Assessment Report 2008 | Diamond - Drilling, Drill Core - Geochemistry, Rock - Geochemistry, Soil - Geochemistry, Environmental Assessment/Impact - Studies, Backhoe - Trenching | 48 | 8301.23 |
| 095592 | 2006 | 2006 Dublin Gulch Exploration Program | Diamond - Drilling, Drill Core - Geochemistry, Rock - Geochemistry, Soil - Geochemistry, Hand - Trenching | 10 | 4281.51 |
| 094788 | 2004 | 2004 [Dublin Gulch] Geophysical Survey | Electromagnetic - Airborne Geophysics, Magnetic - Airborne Geophysics | ||
| 091387 | 1982 | Dublin Gulch 1982 Assessment Dill Logs & Trench Geology | Diamond - Drilling, Drill Core - Geochemistry, Rock - Geochemistry, Mechanical - Trenching | 3 | 738.24 |
| 090915 | 1981 | 1981 Exploration Program, Dublin Gulch | Rock - Geochemistry, Silt - Geochemistry, Soil - Geochemistry, Bedrock Mapping - Geology, Prospecting - Other, Mechanical - Trenching | ||
| 090790 | 1980 | 1980 Assessment Report on the Dublin Gulch Property | Diamond - Drilling, Drill Core - Geochemistry, Rock - Geochemistry, Bedrock Mapping - Geology, Backhoe - Trenching, Mechanical - Trenching | 65 | 11315.09 |
| 090564 | 1979 | Geological, Geochemical, and Geophysical Report | Rock - Geochemistry, Silt - Geochemistry, Soil - Geochemistry, Bedrock Mapping - Geology, EM - Ground Geophysics, Seismic - Ground Geophysics, Research/Summarize - Pre-existing Data | ||
| 090614 | 1979 | 1979 - Project Report - Dublin Gulch Property Claim Groups A-L & Ungrouped Claims Geology, Geochemistry, Geophysics, Diamond Drilling | Diamond - Drilling, Drill Core - Geochemistry, Rock - Geochemistry, Silt - Geochemistry, Soil - Geochemistry, Bedrock Mapping - Geology, Magnetics - Ground Geophysics, Prospecting - Other, Backhoe - Trenching | 28 | 3114.20 |
| 090482 | 1978 | 1978 Project Report on the Secret Creek Property | Orthophoto - Airphotography, Silt - Geochemistry, Soil - Geochemistry, Bedrock Mapping - Geology, Detailed Bedrock Mapping - Geology, Line Cutting - Other, Prospecting - Other, Surveying - Other, Mechanical - Trenching | ||
| 090471 | 1978 | 1978 Project Report on the Dublin Gulch Property | Orthophoto - Airphotography, Rock - Geochemistry, Silt - Geochemistry, Soil - Geochemistry, Bedrock Mapping - Geology, Magnetics - Ground Geophysics, Prospecting - Other | ||
| 060841 | 1970 | Summary Report on Potato Hills Tungsten | Research/Summarize - Pre-existing Data | ||
| 060185 | 1969 | Tungsten Prospect Dublin Gulch and Haggart Creek Property Evaluation | Rock - Geochemistry, Detailed Surficial Mapping - Geology, Prospecting - Other, Research/Summarize - Pre-existing Data, Preliminary Economic Assessment - Studies | ||
| 062258 | 1965 | [Summary of the Peso Silver Mines Ltd. Properties] | Data Compilation - Pre-existing Data, Research/Summarize - Pre-existing Data, Resource Estimate - Studies | ||
| 092069 | 1964 | Prospectus on the Mayo Silver Mines Ltd. | Property Evaluation - Other, Preliminary Economic Assessment - Studies | ||
| 062120 | 1943 | [Geological and Geochemical Assessment at Cement Creek] | Rock - Geochemistry, Bedrock Mapping - Geology, Prospecting - Other |
Related References
| Number | Title | Page(s) | Document Type |
|---|---|---|---|
| ARMC014781 | Final report 1964 - Mayo Silver Mines Ltd. (N.P.L.) - Mayo, Yukon | Report |
| Citations |
|---|
| SRK Consulting, December 1 2008. NI 43-101 Preliminary Assessment, Dublin Gulch Property- Mar-tungsten Zone, Mayo District, Yukon Territory, Canada, for StrataGold Corporation. |
| SRK Consulting, Feb 22 2008 (effective date Dec 21 2007). NI 43-101 Technical Report on Resources, Dublin Gulch Property- Mar Tungsten Zone, Mayo District, Yukon Territory, Canada, for StrataGold Corporation. |
