General Information
Secondary Commodities: barite, thallium, silver
Aliases: Thallium, Twin Zone
Deposit Type(s): Sediment hosted Sedimentary Exhalative Zn-Pb-Ag (Sedex)
Location(s): 63.300650 N, -131.103550 W
NTS Mapsheet(s): 105O06
Location Comments: Location verified by Colorado Resources Ltd during 2012 geological mapping program.
Hand Samples Available at YGS: No
Last Reviewed: Feb 24, 2014
Capsule
Last Updated: Feb 24, 2014Work History
*In February 2014 the occurrence location was moved approximately 880 m northwest to a site verified by Colorado Resources Ltd.
Staked as TH cl 1-86 (YA38074) in Aug/78 by the Mackenzie Joint Venture (British Newfoundland Exploration Ltd, A.M. & S. Canada Minerals Ltd & C.L. Smith), which explored with mapping and geochemical sampling later in the year.
Restaked as Andy cl 1-32 (YA41392) in Nov/79 by Ventures West Minerals Ltd, which performed mapping and geochemical sampling in 1980.
Restaked within OS cl 1-532 (YE42001) in Apr/2011 by Colorado Resources Ltd. The claims were added to the larger Oro property located to the east. During the 2011 exploration season Colorado Resources flew a helicopter-borne magnetic and electromagnetic survey over the entire Oro property and carried out regional scale soil and silt sampling over the occurrence area.
In 2012 Colorado Resources carried out geological mapping and collected addition soil samples over the occurrence area.
In May/2013 Colorado Resources optioned the Oro property to Gold Fields Selwyn Exploration Corporation a wholly owned subsidiary of Gold Fields Ltd. Under the agreement Gold Fields could acquire up to a 71% interest in the property subject to certain payments, work commitments and share issuances.
During the 2013 exploration program Gold Fields collared 13 diamond drill holes (1 614 m) and undertook a proprietary analysis of more than 20 000 soil and rock samples previously collected by Colorado Resources to identify areas to be highly prospective for “Carlin style mineralization”. None of the drill holes were collared on or in the vicinity of this occurrence.
In Nov/2013 Gold Fields terminated its option on the Oro claims
Capsule Geology
The occurrence area is located approximately 45 km west of the Macmillan Pass Airstrip near the central-east boundary of the Yukon. Access to the occurrence area is via helicopter from the airstrip or the camp/staging areas located along the North Canol Highway located approximately 10 km to the south of the airstrip.
The area was regionally mapped throughout the 1980’s by G. Abbott who was employed by Exploration and Geological Services Division of the Department of Indian and Northern Affairs, Yukon. In April 2003 Abbott and the division was devolved to the Yukon Government and is now part of the Yukon Geological Survey. In 2013 Abbott released an updated version of the geology of the Macmillan Pass area based on his 30 year career in the Yukon. Beginning in 2011 Colorado Resources began remapping their Oro property in detail. In the first year the company mapped in detail the area surrounding the J.O. – Saddle – Canol zones (Minfile Occurrence 105O 032) located 5 km to the east, where mineralization had been previously discovered by AGIP. In the second year the company expanded eastward and regionally mapped the central portion of their large property, including the area surrounding this occurrence. Although Colorado Resources mapping differs somewhat from Abbott’s in terms of the composition of individual geological units and their stratigraphic location, Colorado’s mapping generally mirrors Abbott’s work.
The TH claims were staked on an anomalous lead and zinc silt anomaly collected from a small creek (original occurrence location ~ 393791 W 7020398 N) draining the central portion of the claim block. The anomaly was likely originally discovered by Atlas Explorations Ltd during their Hess River Project, a large regional silt sampling program carried out in 1967-68. C.L. Smith, a principal participant in the Mackenzie Joint Venture was the chief geologist for Atlas Explorations’ (see title page of Assessment Report # 018947). No records can be found regarding the results obtained by the joint venture group and it appears the TH claims were allowed to lapse the following year.
C.L. Smith restaked the anomaly within the Andy claims and immediately optioned the claims to Ventures West Minerals Ltd. Smith carried out 5 days of geological mapping in 1980 during which he discovered a barren barite bed, described as “several feet thick, massive to finely laminated and conformable with bedding”. The barite bed is enclosed by a silvery weathering carbonaceous shale described by Smith as interbedded with black chert and minor barite. This description suggests the barite bed likely belongs to the Fuller Lake Member of the Upper Devonian Portrait Lake Formation, a silver grey bedded siliceous shale/argillite unit. This unit is known to host minor barite beds. The location of the bed was re-discovered and verified by Colorado Resources during their 2012 geological mapping program (new occurrence location).
Regional and follow-up soil sampling carried out in 2011 and 2012 by Colorado Resources outlined two sub-parallel thallium soil geochemical anomalies (called the Twin Zone) which trend to the west from the Oro Main zone (5 km to the east). Both anomalies contain core thallium values of over 15 ppm, a pathfinder element commonly associated with gold mineralization in the Carlin district in Nevada, USA. The northernmost anomaly (location ~7021090 N, 394560 W = ~ center point of anomaly) measures approximately 3 300 m long and 400 m wide. Geological mapping suggests that it is underlain by silver grey bedded siliceous shales-argillites assigned to the Fuller Pass Member of the Upper Devonian (?) Portrait Lake Formation and carbonaceous silty limestones of the mid Devonian Sapper Formation. The thallium likely originates from within the limestones.
The southernmost anomaly lies approximately 1.25 km to the south, (location ~7019485 N, 393880 W, = ~ center point of anomaly) and measures approximately 2 100 m long by 350 m wide. The anomaly appears to be underlain by buff weathering bioturbated cherty shales assigned to the upper Silurian (?) Steel Formation. This unit likely lies overtop carbonaceous silty limestones assigned to the mid Devonian Sapper Formation, the likely source of the thallium. A thrust fault separates the southern anomaly from the northern anomaly. The southern anomaly also hosts a 1 000 m long by 250 m wide >95th percentile silver (>3.3 ppm to 20.1 ppm) anomaly.
*In February 2014 the occurrence location was moved approximately 880 m northwest to a site verified by Colorado Resources Ltd.
Staked as TH cl 1-86 (YA38074) in Aug/78 by the Mackenzie Joint Venture (British Newfoundland Exploration Ltd, A.M. & S. Canada Minerals Ltd & C.L. Smith), which explored with mapping and geochemical sampling later in the year.
Restaked as Andy cl 1-32 (YA41392) in Nov/79 by Ventures West Minerals Ltd, which performed mapping and geochemical sampling in 1980.
Restaked within OS cl 1-532 (YE42001) in Apr/2011 by Colorado Resources Ltd. The claims were added to the larger Oro property located to the east. During the 2011 exploration season Colorado Resources flew a helicopter-borne magnetic and electromagnetic survey over the entire Oro property and carried out regional scale soil and silt sampling over the occurrence area.
In 2012 Colorado Resources carried out geological mapping and collected addition soil samples over the occurrence area.
In May/2013 Colorado Resources optioned the Oro property to Gold Fields Selwyn Exploration Corporation a wholly owned subsidiary of Gold Fields Ltd. Under the agreement Gold Fields could acquire up to a 71% interest in the property subject to certain payments, work commitments and share issuances.
During the 2013 exploration program Gold Fields collared 13 diamond drill holes (1 614 m) and undertook a proprietary analysis of more than 20 000 soil and rock samples previously collected by Colorado Resources to identify areas to be highly prospective for “Carlin style mineralization”. None of the drill holes were collared on or in the vicinity of this occurrence.
In Nov/2013 Gold Fields terminated its option on the Oro claims
Capsule Geology
The occurrence area is located approximately 45 km west of the Macmillan Pass Airstrip near the central-east boundary of the Yukon. Access to the occurrence area is via helicopter from the airstrip or the camp/staging areas located along the North Canol Highway located approximately 10 km to the south of the airstrip.
The area was regionally mapped throughout the 1980’s by G. Abbott who was employed by Exploration and Geological Services Division of the Department of Indian and Northern Affairs, Yukon. In April 2003 Abbott and the division was devolved to the Yukon Government and is now part of the Yukon Geological Survey. In 2013 Abbott released an updated version of the geology of the Macmillan Pass area based on his 30 year career in the Yukon. Beginning in 2011 Colorado Resources began remapping their Oro property in detail. In the first year the company mapped in detail the area surrounding the J.O. – Saddle – Canol zones (Minfile Occurrence 105O 032) located 5 km to the east, where mineralization had been previously discovered by AGIP. In the second year the company expanded eastward and regionally mapped the central portion of their large property, including the area surrounding this occurrence. Although Colorado Resources mapping differs somewhat from Abbott’s in terms of the composition of individual geological units and their stratigraphic location, Colorado’s mapping generally mirrors Abbott’s work.
The TH claims were staked on an anomalous lead and zinc silt anomaly collected from a small creek (original occurrence location ~ 393791 W 7020398 N) draining the central portion of the claim block. The anomaly was likely originally discovered by Atlas Explorations Ltd during their Hess River Project, a large regional silt sampling program carried out in 1967-68. C.L. Smith, a principal participant in the Mackenzie Joint Venture was the chief geologist for Atlas Explorations’ (see title page of Assessment Report # 018947). No records can be found regarding the results obtained by the joint venture group and it appears the TH claims were allowed to lapse the following year.
C.L. Smith restaked the anomaly within the Andy claims and immediately optioned the claims to Ventures West Minerals Ltd. Smith carried out 5 days of geological mapping in 1980 during which he discovered a barren barite bed, described as “several feet thick, massive to finely laminated and conformable with bedding”. The barite bed is enclosed by a silvery weathering carbonaceous shale described by Smith as interbedded with black chert and minor barite. This description suggests the barite bed likely belongs to the Fuller Lake Member of the Upper Devonian Portrait Lake Formation, a silver grey bedded siliceous shale/argillite unit. This unit is known to host minor barite beds. The location of the bed was re-discovered and verified by Colorado Resources during their 2012 geological mapping program (new occurrence location).
Regional and follow-up soil sampling carried out in 2011 and 2012 by Colorado Resources outlined two sub-parallel thallium soil geochemical anomalies (called the Twin Zone) which trend to the west from the Oro Main zone (5 km to the east). Both anomalies contain core thallium values of over 15 ppm, a pathfinder element commonly associated with gold mineralization in the Carlin district in Nevada, USA. The northernmost anomaly (location ~7021090 N, 394560 W = ~ center point of anomaly) measures approximately 3 300 m long and 400 m wide. Geological mapping suggests that it is underlain by silver grey bedded siliceous shales-argillites assigned to the Fuller Pass Member of the Upper Devonian (?) Portrait Lake Formation and carbonaceous silty limestones of the mid Devonian Sapper Formation. The thallium likely originates from within the limestones.
The southernmost anomaly lies approximately 1.25 km to the south, (location ~7019485 N, 393880 W, = ~ center point of anomaly) and measures approximately 2 100 m long by 350 m wide. The anomaly appears to be underlain by buff weathering bioturbated cherty shales assigned to the upper Silurian (?) Steel Formation. This unit likely lies overtop carbonaceous silty limestones assigned to the mid Devonian Sapper Formation, the likely source of the thallium. A thrust fault separates the southern anomaly from the northern anomaly. The southern anomaly also hosts a 1 000 m long by 250 m wide >95th percentile silver (>3.3 ppm to 20.1 ppm) anomaly.
Location Map
Last Updated: Oct 20, 2020
Work History
Year | Work Type | Comment |
---|---|---|
2012 | Geochemistry: Soil | Infill sampling carried out refine size of anomaly. |
2012 | Geology: Regional Bedrock Mapping | Carried out over anomaly. |
2011 | Airborne Geophysics: Electromagnetic | Also collected magnetics. |
2011 | Geochemistry: Silt | Regional program. |
2011 | Geochemistry: Soil | Regional program, samples collected along claim lines. |
1980 | Geology: Bedrock Mapping | |
1980 | Other: Prospecting | |
1978 | Geochemistry: Silt | Regional program. |
1978 | Geology: Bedrock Mapping |
Regional Geology - Terrane
Group: Ancestral North America
Affinity: W Laurentia
Name: North America - basinal strata
Realm: Laurentia
Regional Geology - Bedrock
Supergroup:
Group/Suite: Earn
Formation: Portrait Lk/Prevost/L Devonian beds?
Member:
Terrane: Laurentia
Period Max: Devonian
Age Max: 410 MA
Period Min: Devonian
Age Min: 359 MA
Rock Major: chert/shale/argillite
Rock Minor: barite/limestone
Reference: Cecile & Abbott (1989) - GSC OF 2076
Geological Unit (1M): DME
Geological Unit (250K): DME2
Assessment Reports that overlap occurrence
Report Number | Year | Title | Worktypes | Holes Drilled | Meters Drilled |
---|---|---|---|---|---|
096656 | 2013 | 2013 Geological, Geochemical and Diamond Drilling Report on the Oro Property | Diamond - Drilling, Drill Core - Geochemistry, Rock - Geochemistry, Prospecting - Other | 13 | 2614.36 |
096293 | 2012 | 2012 Geological, Geochemical and Trenching Report on the Oro Property | Rock - Geochemistry, Soil - Geochemistry, Bedrock Mapping - Geology, Prospecting - Other, Backhoe - Trenching | ||
095744 | 2011 | Geological, Geochemical, Geophysical and Trenching Report on the Oro Property | Electromagnetic - Airborne Geophysics, Magnetic - Airborne Geophysics, Interpretation - Airphotography, Rock - Geochemistry, Silt - Geochemistry, Soil - Geochemistry, Detailed Bedrock Mapping - Geology, Prospecting - Other, Backhoe - Trenching | ||
093827 | 1997 | 1997 Geological Assessment Report on Emerald Lake Claims | Rock - Geochemistry, Silt - Geochemistry, Soil - Geochemistry | ||
090833 | 1980 | Geological Report, Andy 1-32 Claims | Bedrock Mapping - Geology | ||
019809 | 1968 | Hess Area Project Proposed Property Follow-Up 1968 Field Season | Research/Summarize - Pre-existing Data | ||
019033 | 1968 | Atlas Explorations Limited Project Report 1968 Hess River Area | Silt - Geochemistry, Soil - Geochemistry, Regional Bedrock Mapping - Geology | ||
018947 | 1967 | Hess River Project Report | Rock - Geochemistry, Soil - Geochemistry, Detailed Bedrock Mapping - Geology | ||
019032 | 1967 | Hess River Project Report | Data Compilation - Pre-existing Data |
Related References
Number | Title | Page(s) | Document Type |
---|---|---|---|
ARMC008212 | Detail map area - geochem values - Cu, Pb, Zn, Ba - MacMillan project - 105-O-6 | Geochemical Map | |
ARMC008213 | Detail area map - MacMillan project - 105-O-6 | Geochemical Map | |
ARMC008033 | Geochemical results and claim group map of sheet 105-O-7 - Ross River | Geochemical Map | |
YEG1981 | Yukon Exploration and Geology 1981 | 177. | Annual Report |
1983-1 | Structure and Stratigraphy of the MacMillan Fold Belt: Evidence for Devonian Faulting | 15-21. | Open File (Geological - Bedrock) |
YEG2011_OV | Yukon Exploration and Geology Overview 2011 | 26-27, 66. | Annual Report |
YEG2012_OV | Yukon Exploration and Geology Overview 2012 | 36-37, 62. | Annual Report |
YEG2013_OV | Yukon Exploration and Geology Overview 2013 | 27-28, 43, 47. | Annual Report |
GM2013-1 | Bedrock geology of the Macmillan Pass area, Yukon and adjacent Northwest Territories | Geoscience Map (Geological - Bedrock) | |
BROCK000090 | Geology map - Geochemical results and claim group map of sheet 105-O-6 - Fig. 19 | Geoscience Map (Geological - Bedrock) |
Citations |
---|
COLORADO RESOURCES LTD, Feb/2012. Assessment Report #095744 by L. Dandy. |
COLORADO RESOURCES LTD, Feb/2014. Web Site: www.coloradoresources.com. |
COLORADO RESOURCES LTD, Jan/2013. Assessment Report #096293 by L. Dandy and Jessica Norris. |
COLORADO RESOURCES LTD, News Release. 22 Nov/2010, 12 Jan/2011, 12 Aug/2011, 17 Aug/2011, 19 Jan/2012, 18 Oct/2012, 7 May/2013, 22 Nov/2013. |
GEOLOGICAL SURVEY OF CANADA Open File 1118. |