General Information
Secondary Commodities: barium, copper, zinc, silver, lead
Deposit Type(s): Volcanogenic Massive Sulphide (VMS) Kuroko Cu-Pb-Zn
Location(s): 61.391940 N, -130.672220 W
NTS Mapsheet(s): 105G07
Location Comments: .5 Kilometres
Hand Samples Available at YGS: No
Capsule
Work History
Staked as Cobb cl 1-88 (YB60092) in Jun/95 by Cominco Ltd to cover stream sediment anomalies detected during a regional geochemical program carried out the previous year. Later in the summer, the company contracted Aerodat Inc to fly a helicopter-borne electromagnetic and magnetic geophysical survey over the claim block. In 1996 Cominco Ltd carried out a short mapping and soil sampling program.
Capsule Geology
Geological mapping (Murphy et al. 2001) shows the area is dominantly underlain by a layered sequence of Devonian to Early Mississippian metavolcanic and metasedimentary rocks belonging to the Yukon-Tanana Terrane (YTT). The YTT is a volcanic-plutonic pericratonic arc assemblage that was strongly deformed and metamorphosed by Late Triassic time. Volcanic-hosted massive sulphide deposits exist at different stratigraphic positions within the YTT including the Fyre Lake deposit (Minfile Occurrence #105G 034) in the Devonian to lower Mississippian(?) Fire Lake mafic metavolcanic unit, the Kudz Ze Kayah deposit (Minfile Occurrence #105G 117) in the Mississippian Kudz Ze Kayah felsic metavolcanic unit, and the Wolverine deposit (Minfile Occurrence #105G 072) within the Lower Mississippian Wolverine Succession.
The occurrence is underlain by biotite-muscovite-feldspar-quartz schist, and micaceous quartzite and marble (unit Dq). These units are overlain by unit DF, (Fire Lake mafic metavolcanic unit) composed of massive to subtly layered biotite-plagioclase-actinolite-chlorite schist and lesser carbonaceous phyllite, quartzite and grey marble. Unit DF is in turn overlain by unit DK, (Kudz Ze Kayah felsic metavolcanic unit), composed of undifferentiated feldspar-muscovite-quartz schist, feldspar and less commonly quartz augen schist. The sequence is intruded by granitic to monzonitic metaplutonic rocks (unit MGg) of the Mississippian Grass Lakes Plutonic Suite. Geological characteristics and stratigraphic relations suggests that the metaplutonic rocks are sills that flowed from dykes lying along the trend of thickness changes in the surrounding metavolcanic and metasedimentary rocks. In the northeast corner of the Cobb claims a small ultramafic body (unit Dum) intrudes unit DF.
Cominco reported that the claim block is mainly underlain by thick felsic crystal meta-tuffs interlayered with felsic meta-flows with lesser interbedded meta-mudstone and meta-siltstone (Bannister). Lithologies are generally strongly foliated and shallow-dipping. Stratigraphically, Cominco suggests that the Cobb claims occur just stratigraphically below or contemporaneous with the Kudz Ze Kayah deposit (Minfile Occurrence #105G 117).
The 1995 airborne geophysical survey delineated two areas with coincident magnetic and EM anomalies (Holroyd, 1996) on the south side of the claim block.
Geological mapping and prospecting located mineralization in some of the flat lying interlayered metasedimentary units, bound by felsic metavolcanics. The best results were returned from the central portion of the claim block, where sphalerite, galena and pyrite occur as fine to blotchy disseminated patches parallel to foliation and as fracture filling. Thin laminae of galena and chalcopyrite were also found within the felsic crystal tuffs. Some of the quartz-biotite schists found on the claim block also display fine-grained chalcopyrite and pyrite +/- magnetite.
Grid soil sampling over the central area of the claim block returned coincident Pb (>75, up to 1003 ppm), Zn (>400, up to 5638 ppm) and moderate Cu (>50, up to 375 ppm) soil anomalies over a distance of 500 m. Additional anomalous values were reported from neighbouring grid lines and included values up to 12 409 ppm Ba and 3.9 ppm Ag. Weak to moderately anomalous Cu-Pb-Zn values were returned over the airborne anomalies.
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.
COMINCO LTD, Apr/98. Assessment Report #093713 by V.L. Bannister.
COMINCO LTD, Apr/96. Assessment Report #093429 by R.D. Holroyd.
HUNT, J.A., 2001. Volcanic-associated massive (VMS) mineralization in the Yukon-Tanana Terrane and coeval strata of the North American miogeocline, in the Yukon and adjacent areas. Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, Bulletin 12, 107 p.
MURPHY, D.C., 1998. Stratigraphic framework for syngenetic mineral occurrences, Yukon Tanana Terrane south of Finlayson Lake: A Progress Report. In: Yukon Exploration and Geology 1997, Exploration and Geological Services Division, Indian and Northern Affairs Canada, p. 51-58.
MURPHY, D.C., AND PIERCEY, S.J., 1999a. Finlayson project: Geological evolution of Yukon-Tanana Terrane and its relationship to Campbell Range belt, northern Wolverine Lake map area, southeastern Yukon. In: Yukon Exploration and Geology 1998, C.F. Roots and D.S. Emond (eds.), Exploration and Geological Services Division, Indian and Northern Affairs Canada, p. 54.
MURPHY, D.C. AND PIERCEY, S.J., 1999b. Geological map 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, 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, 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.
Staked as Cobb cl 1-88 (YB60092) in Jun/95 by Cominco Ltd to cover stream sediment anomalies detected during a regional geochemical program carried out the previous year. Later in the summer, the company contracted Aerodat Inc to fly a helicopter-borne electromagnetic and magnetic geophysical survey over the claim block. In 1996 Cominco Ltd carried out a short mapping and soil sampling program.
Capsule Geology
Geological mapping (Murphy et al. 2001) shows the area is dominantly underlain by a layered sequence of Devonian to Early Mississippian metavolcanic and metasedimentary rocks belonging to the Yukon-Tanana Terrane (YTT). The YTT is a volcanic-plutonic pericratonic arc assemblage that was strongly deformed and metamorphosed by Late Triassic time. Volcanic-hosted massive sulphide deposits exist at different stratigraphic positions within the YTT including the Fyre Lake deposit (Minfile Occurrence #105G 034) in the Devonian to lower Mississippian(?) Fire Lake mafic metavolcanic unit, the Kudz Ze Kayah deposit (Minfile Occurrence #105G 117) in the Mississippian Kudz Ze Kayah felsic metavolcanic unit, and the Wolverine deposit (Minfile Occurrence #105G 072) within the Lower Mississippian Wolverine Succession.
The occurrence is underlain by biotite-muscovite-feldspar-quartz schist, and micaceous quartzite and marble (unit Dq). These units are overlain by unit DF, (Fire Lake mafic metavolcanic unit) composed of massive to subtly layered biotite-plagioclase-actinolite-chlorite schist and lesser carbonaceous phyllite, quartzite and grey marble. Unit DF is in turn overlain by unit DK, (Kudz Ze Kayah felsic metavolcanic unit), composed of undifferentiated feldspar-muscovite-quartz schist, feldspar and less commonly quartz augen schist. The sequence is intruded by granitic to monzonitic metaplutonic rocks (unit MGg) of the Mississippian Grass Lakes Plutonic Suite. Geological characteristics and stratigraphic relations suggests that the metaplutonic rocks are sills that flowed from dykes lying along the trend of thickness changes in the surrounding metavolcanic and metasedimentary rocks. In the northeast corner of the Cobb claims a small ultramafic body (unit Dum) intrudes unit DF.
Cominco reported that the claim block is mainly underlain by thick felsic crystal meta-tuffs interlayered with felsic meta-flows with lesser interbedded meta-mudstone and meta-siltstone (Bannister). Lithologies are generally strongly foliated and shallow-dipping. Stratigraphically, Cominco suggests that the Cobb claims occur just stratigraphically below or contemporaneous with the Kudz Ze Kayah deposit (Minfile Occurrence #105G 117).
The 1995 airborne geophysical survey delineated two areas with coincident magnetic and EM anomalies (Holroyd, 1996) on the south side of the claim block.
Geological mapping and prospecting located mineralization in some of the flat lying interlayered metasedimentary units, bound by felsic metavolcanics. The best results were returned from the central portion of the claim block, where sphalerite, galena and pyrite occur as fine to blotchy disseminated patches parallel to foliation and as fracture filling. Thin laminae of galena and chalcopyrite were also found within the felsic crystal tuffs. Some of the quartz-biotite schists found on the claim block also display fine-grained chalcopyrite and pyrite +/- magnetite.
Grid soil sampling over the central area of the claim block returned coincident Pb (>75, up to 1003 ppm), Zn (>400, up to 5638 ppm) and moderate Cu (>50, up to 375 ppm) soil anomalies over a distance of 500 m. Additional anomalous values were reported from neighbouring grid lines and included values up to 12 409 ppm Ba and 3.9 ppm Ag. Weak to moderately anomalous Cu-Pb-Zn values were returned over the airborne anomalies.
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.
COMINCO LTD, Apr/98. Assessment Report #093713 by V.L. Bannister.
COMINCO LTD, Apr/96. Assessment Report #093429 by R.D. Holroyd.
HUNT, J.A., 2001. Volcanic-associated massive (VMS) mineralization in the Yukon-Tanana Terrane and coeval strata of the North American miogeocline, in the Yukon and adjacent areas. Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, Bulletin 12, 107 p.
MURPHY, D.C., 1998. Stratigraphic framework for syngenetic mineral occurrences, Yukon Tanana Terrane south of Finlayson Lake: A Progress Report. In: Yukon Exploration and Geology 1997, Exploration and Geological Services Division, Indian and Northern Affairs Canada, p. 51-58.
MURPHY, D.C., AND PIERCEY, S.J., 1999a. Finlayson project: Geological evolution of Yukon-Tanana Terrane and its relationship to Campbell Range belt, northern Wolverine Lake map area, southeastern Yukon. In: Yukon Exploration and Geology 1998, C.F. Roots and D.S. Emond (eds.), Exploration and Geological Services Division, Indian and Northern Affairs Canada, p. 54.
MURPHY, D.C. AND PIERCEY, S.J., 1999b. Geological map 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, 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, 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.
Location Map
Last Updated: Jul 30, 2018
Work History
| Year | Work Type | Comment |
|---|---|---|
| 1996 | Geochemistry: Soil | |
| 1996 | Geology: Bedrock Mapping | |
| 1995 | Airborne Geophysics: Electromagnetic | Also magnetic survey. |
| 1995 | Geochemistry: Silt | |
| 1994 | Geochemistry: Silt | Regional program. |
Regional Geology - Terrane
Group: Intermontane
Affinity: W Laurentia
Name: Yukon-Tanana
Realm: peri-Laurentian
Regional Geology - Bedrock
Supergroup:
Group/Suite: Grass Lakes
Formation: Kudz Ze Kayah
Member: carbonaceous phyllite
Terrane: Yukon-Tanana
Period Max: Devonian
Age Max: 365 MA
Period Min: Carboniferous
Age Min: 355 MA
Rock Major: carbonaceous phyllite
Rock Minor:
Reference: Murphy et al. (2001) - YGS OF 2001-33
Geological Unit (1M): DMF
Geological Unit (250K): DMF3
Assessment Reports that overlap occurrence
| Report Number | Year | Title | Worktypes | Holes Drilled | Meters Drilled |
|---|---|---|---|---|---|
| 093848 | 1997 | 1997 Assessment Report Tag Property (KZK Project) and Cobb Property Diamond Drilling and Minor Geological Mapping and Soil/Rock Geochemistry | Diamond - Drilling, Soil - Geochemistry, Bedrock Mapping - Geology, EM - Ground Geophysics, Gravity Survey - Ground Geophysics, Magnetics - Ground Geophysics, Line Cutting - Other | 17 | 3566 |
| 093713 | 1996 | 1996 Assessment Report Cobb Property Geological Mapping/Prospecting and Geochemistry | Soil - Geochemistry, Bedrock Mapping - Geology, Prospecting - Other | ||
| 093429 | 1995 | Combined Helicopter-Borne Magnetic and Electromagnetic Survey of the Cobb Claims, Pelly Mountain Project, Yukon Territory | Electromagnetic - Airborne Geophysics, Magnetic - Airborne Geophysics |
