The Tad/Toro Property was originally targeted to explore for silver-lead-zinc mineralzation in the early 1920s. However, the lode gold potential of the property had not been fully recognized, despite presence of several gold placer producers, until the results of recent exploration programs.
Extensive work was undertaken including geological mapping, sampling, geophysics, trenching and diamond drilling. It was not until 1986 that the potential of a supergene oxide gold mineralized zone was identified and briefly explored by Noranda Exploration Inc. Samples collected from previously drilled holes were assayed and these, coupled with earlier results, established that a potential gold zone exists within a supergene oxide horizon within a Cretaceous aged quartz-monzonite porphyry intrusive.
Encouraging gold values were found in three holes: T-2 gave 0.51 g/t gold over 37.0 m (including 1.0 g/t gold over 8.2 m); T-12 gave 1.23 g/t gold over 4.9 m; and drill hole T-14 gave 1.68 g/t gold over 7.0 m. Other potential economic metals (silver, zinc and molybdenum) also exist in substantial amounts in other underexplored zones.
Additional work carried out by subsequent companies and property owners involved soil sampling, VLF-EM and magnetometer surveys. This work outlined strong Au-Ag-Zn-As soil geochemical anomalies. Compilation of geophysical and geochemical data outlined a 750 m NWSE trending Au-As anomaly with coincidental magnetic lows and variable chargeability responses that have not been adequately tested by previous drilling. Parallel structures to this anomaly are also indicated by the magnetometer shade plot.
View southwesterly over the Tad property, showing the location of the gold-in-soil geochemical anomaly
identified by Noranda in 1987. This anomaly likely represents the intersection of supergene gold horizon
with the present erosion surface.
Location and Access
The Tad/Toro Property is located 100 km northwest of Carmacks and 275 km northwest of Whitehorse on NTS map sheet 115 I/12 and 115J/9 at latitude 62o 33'N and longitude 137o57'W in the west central Yukon Territory. The property can be accessed via helicopter, plane, or winter road. The Casino Trail passes through the Property, but the section accessible to four wheel drive vehicles ends 15 km to the east. The easily upgradable winter road is well established and has often been used for haulage of equipment and supplies by placer miners and exploration companies.
Dawson Range Mineral Belt
Since the late 1960's numerous copper-molybdenum-gold porphyry deposits and occurrences have been discovered along a northwest-trending linear belt that forms the Dawson Range mineral belt. The majority of these occurrences have copper and some combination of gold and molybdenum as their chief commodities. The largest deposit is the Casino copper-molybdenum-gold-porphyry located approximately 50 km to the northwest of the Tad/Toro claims in the Dawson Range mineral belt.
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The region is dominated by metamorphic rocks of the Yukon Tanana Terrane which are intruded by batholiths of Early Jurassic and mid-Cretaceous age. Like most of the porphyry occurrences of the Dawson Range, the Tad porphyry is located immediately southwest of the Big Creek Fault - a prominent structural feature that appears to control the distribution of mineralization in the Dawson Range. A second northtrending fault is thought to exist beneath the Hayes Creek Valley. At least four small northeast-trending faults have been recognized cutting the Tad porphyry. Placer gold has been mined periodically from Hayes Creek and its tributaries.
Property Geology and Mineralization
The Tad Property (minfile 31 and 32) is centred on a felsic porphyry stock which measures approximately three by two km and intrudes coarse-grained, pink quartz monzonite that hosts pendants of Yukon-Tanana Terrane metamorphic rocks.
Mineralization has been oxidized to depths of up to 80 m. The gold bearing oxide zone lies in brecciated and intensely altered quartz monzonite porphyry. Strong manganese staining and limonite is present with higher gold grades. A narrow supergene zone sometimes lies above the hypogene zone.
The best target for gold mineralization is the oxidized breccias, structures and alteration zones in the quartz monzonite porphyry. The underlying hypogene zone may contain gold bearing quartz arsenopyrite veins. Sulphide mineralization consist of up to 10% pyrite disseminated in the granite porphyry and in alteration zones. Narrow quartz sulphide veins in breccias and structures containing sphalerite, galena and aresonpyrite bearing quartz veins are present along shear zones.
Three primary mineralization types are recognized:
Target Model and Proposed Programs
- Porphyry Cu-Mo
- Porphyry Breccia
- Shear hosted and Mesothermal Quartz Veins
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A radiometric survey over the Tad Property indicates that it has a
large area with a low Th/K ratio. This signature is similar to, although
larger and slightly less intense than, the Casino copper-molybdenum-
The target model for the Tad/Toro Property is structurally controlled oxide gold mineralization occurring in the periphery of a small intrusive body with similarities to both porphyry and plutonic gold deposits.
Noranda first examined the bulk tonnage potential for structurally controlled oxide gold deposits. After performing a brief program and locating a promising gold-bearing oxide breccia zone Noranda left the property after four widely spaced drill holes produced weak gold values.
Compilation work following Noranda's work produced several coincidental anomalies located upslope of earlier drill holes. New plots of the magentics delineate linear lows that may outline mineralized structures responsible for the high geochemical values.
This work outlined a 750 m soil anomaly (Au-As-Pb-Zn) which is coincidental with several linear magnetic lows and moderate to high chargeability responses. This area was originally drilled in six holes targeting the main Pb-Zn anomaly. Three holes contained gold values greater than 1 gpt. Two other holes intersected breccia with weak gold values. Additional drilling is proposed to test the upslope portion of the main soil anomaly.
One peak area of Au-As values in the southeast portion of the anomaly was drill tested. Two holes intersected anomalous gold values in the oxide zone in a limonitic and manganese stained breccia to the northeast and downslope of the core of the anomaly. Additional drilling is proposed to test this area.
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Diamond drill core (NQ-size) of the Tad porphyry from the oxide zone. Light-coloured
phenocrysts are quartz and alkali feldspar; dark specks are altered plagioclase.