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Scheelite Dome Gold Project, Yukon
Target | Project Summary | Detailed Description | Appendix | Figures | Related News Releases | Photo Gallery
Target
- Tintina Gold Belt intrusive related gold deposit.
- High grade Pogo look-alike (5.6 million ounce, 0.52 oz. Au/ton); vein or shear zone; high grade skarn.
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Project Summary
Copper Ridge's 100% owned, 11,250 hectare Scheelite Dome Project, located in central Yukon Territory, features one of the largest and strongest gold soil geochemical anomalies in the Tintina Gold Belt. The property is road accessible from the town of Mayo and has a history of placer gold production.
Scheelite Dome is in a geological setting that is similar to that of the Sumitomo-Teck Pogo deposit in Alaska (5.6 million ounce, 0.52 oz. Au/ton). The 10 km long gold soil anomaly at Scheelite Dome occurs over gold mineralization in metamorphic rocks, immediately adjacent to a 90 million year old intrusion, with a classic gold-arsenic-bismuth-antimony geochemical signature. Gold mineralization occurs in veins, stockworks, replacement zones and skarn.
Exploration on the property to date has included geological mapping, grid soil sampling, a reconnaissance Induced Polarization survey, trenching, reverse circulation drilling and 2,610 m of core drilling in 20 holes (Highlights: 7.7 m @ 3.67 gpt gold; 4.6 m @ 3.66 gpt gold; 5.9 m @ 2.46 gpt gold).
Exploration on the property to date has included geological mapping, grid soil sampling, a reconnaissance Induced Polarization survey, trenching, reverse circulation drilling and 2,610 m of core drilling in 20 holes (Highlights: 7.7 m @ 3.67 gpt gold; 4.6 m @ 3.66 gpt gold; 5.9 m @ 2.46 gpt gold). Grab samples of up to 70 gpt gold have been obtained from the Tom Zone, an un-drilled target.
In June, 2003, the property was optioned to Golden Patriot Mining Inc. who carried out a geophysical program, including magnetometer and IP, over the high grade Tom Zone, followed by a 5 hole drill test in September-October. The Project has subsequently been returned to Copper Ridge. The following are highlights of the drill results:
The program was successful not only in confirming high gold grades over significant widths in the Tom calc-silicate zone, it provided a new model for the control of mineralization at Scheelite Dome related to a property-wide thrust fault.
In 2005, Copper Ridge defined a strong gold-arsenic-bismuth-antimony soil geochemical anomaly, the Toby Zone, to the south of the Tom Zone. During the 2006 season, detailed soil geochemical and geophysical surveys were completed over the zone, followed by road building and trenching. A drill test is planned, probably in early 2007.
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Detailed Description - Scheelite Dome Gold Property, Yukon
Copper Ridge owns a 100% interest in the Scheelite Dome Property and has completed the terms of an arm's length Option Agreement dated April 15, 1998 made between La Teko and Kennecott, subsequently assigned by La Teko to Copper Ridge (the "Kennecott Option"), subject to a 2% net smelter return ("NSR") in favour of Rudy Riepe in respect of certain of the claims comprising the property. Pursuant to a further agreement dated June 29, 2000 made between the Company and Kennecott, the Company purchased a back-in right held by Kennecott. On June 23, 2003, the Company announced an agreement with Golden Patriot Mining Inc. whereby Golden Patriot can earn a 51% interest in the Property. Golden Patriot subsequently dropped its option on the property.
Location, Access and Geography
The Scheelite Dome property is located 25 kilometres northwest of Mayo in the central Yukon. The property falls within the Mayo Mining District on NTS map sheets 115P/16, 115P/9 and 105M/13, at latitude 63º47" north and longitude 136º15" west.
Access to the property from Mayo is via the Silver Trail, leading to Elsa and Keno City, and the Minto Lake road, from which the Highet Creek road branches off at 11 kilometres. The Highet Creek road leads to the Morrison Creek and Scheelite Dome roads.
Elevations on the property range from approximately 850 to 1,600 metres. The tree line is at about 1525 metres.
The Scheelite Dome property consists of 549 contiguous unpatented quartz claims including 14 fractional claims covering approximately 11,250 hectares.
The Scheelite Dome property is the subject of an independent consultant's report titled "Summary Report on the Scheelite Dome Gold Project" dated April, 1999, prepared by David A. Caulfield, P.Geo. of Equity Engineering Ltd. (the "Caulfield Report"). The following description of the Scheelite Dome property is derived from the Caulfield Report and internal company reports to incorporate results of subsequent work programs.
Previous History
The earliest activity in the area consisted of small-scale placer mining following the discovery of placer gold in 1884 on Johnson Creek and later in 1903, by John Hiatt, in Highet Creek. Highet Creek has produced the largest amount of placer gold in the Mayo area and remains active. The first recorded lode exploration on the property dates back to 1916 when J.A. Anderson and R. McNeil discovered and located claims over the Hawthorne vein.
The late 1980's saw the acquisition of the Gant and Ade claims by R. Riepe and the staking of the A and B claims by R. Barchan in 1991. Following the discovery of the Fort Knox deposit near Fairbanks, Alaska, H6000 Holdings optioned Reipe's claims and staked a large block of claims over the Scheelite Dome Stock, looking for a similar intrusion-hosted gold deposit. Their exploration included soil sampling, trenching and road building and failed to locate significant gold mineralization within the Scheelite Dome intrusion. After the H6000 claim holdings lapsed, Kennecott staked the SC claims from west of Scheelite Dome, east to beyond Bennett Creek and optioned Mr. Reipe's Gant and Ade claims in 1994-95.
Between 1994 and 1997, Kennecott conducted a series of exploration programs including geological mapping, prospecting, stream sediment and soil sampling, trenching airborne geophysics, core and reverse circulation drilling (8 core holes totaling 1035 m and 13 RC holes totaling 1052 m, all analytical work for the drill program was done by Chemex Labs Ltd.).
In 1998, fieldwork was undertaken by La Teko Resources Ltd. in three stages: A program of reconnaissance soil sampling and prospecting in late May, an IP and resistivity geophysical survey with further soil sampling in June and a core drilling program (7 holes totaling 1268 m) in August and early September. All rock, core and soil samples were analyzed by Chemex Labs Ltd. for gold (30 gm sample -- rocks, 10 gm sample -- soils) and 32-element ICP analysis, using an aqua regia digestion.
In 1999, Copper Ridge completed a structural study, soil sampling, a ground magnetic survey (54 line-km) and core drilling (13 holes totaling 1358 m). All the drill samples were analyzed by Acme Analytical Laboratories Ltd. For gold (30.0 g fire assay) and 32 element ICP analysis using an aqua regia digestion.
In 2003, Golden Patriot completed linecutting, magnetometer and IP surveys over the Tom Zone. This was followed by 310 m of core drilling in 5 holes. The work was managed by Aurum Geological Consultants of Whitehorse. Geophysical work was carried out by Aurora Geosciences, drilling by E. Caron Diamond Drilling and assaying by Acme Analytical Laboratories Ltd.
Geology and Mineralization
Rocks of the Scheelite Dome area are part of western Selwyn Basin, the site of Late Proterozoic and Middle Paleozoic basinal clastic sedimentation. In the Mayo area, Selwyn Basin rocks are imbricated by the Jura-Cretaceous Dawson, Tombstone, and Robert Service thrusts. The Robert Service thrust typically juxtaposes Upper Proterozoic Hyland Group rocks, including those of the Scheelite Dome area, against Mississippian shelf sedimentary shares including the "Keno Hill Quartzite". The underlying Tombstone thrust sheet of Selwyn Basin rocks are juxtaposed against an immediate footwall of Devonian (?) to Late Jurassic clastics of the Earn Group (?). An intense strain zone affects much of the Tombstone thrust sheet and extends upward well into the Robert Service thrust sheet. Hyland Group rocks are underlain in the west by Ordovician to Silurian Road River Group basinal sediments.
The above rocks and thrust sheets are intruded by the Tombstone Plutonic Suite (TPS) a suite of 90-93 Ma intermediate to felsic intrusions. The TPS are spatially associated with a wide range of base and precious metal occurrences, which in some cases are genetically related to the magmatism. Most intrusions are granodiorite, quartz monzonite, monzogranite, monzonite, quartz syenite or syenite. The smaller bodies, such as the Scheelite Dome and Minto Lake intrusions, typically consist of more felsic to intermediate compositions and are metaluminous. Porphyritic, aplitic and lamprophyre dikes cut both intrusions and the host rocks.
The TPS forms a narrow (50 km wide), east-west trending belt, 550 kilometres long, across north-central Yukon from Dawson City to the Yukon-Northwest Territories border. The TPS is truncated in the west by the Tintina Fault Zone, a Cretaceous-Tertiary dextral strike slip fault with an estimated 450 kilometres of displacement. Restoration of this displacement aligns a similar suite of intrusions, including the Fort Knox intrusion (host to the Fort Knox deposit) in the Fairbanks area, on the west side of the fault zone.
The property is underlain by the Yusezyu Formation, a siliciclastic unit of the Upper Proterozoic-Lower Cambrian Hyland Group. The metasedimentary rocks include highly foliated, interlayered muscovite-chlorite phyllites, quartzo-feldspathic and micaceous psammites ("dirty quartzites"), and gritty psammites that locally form massive outcrops. Rare marble and calc-silicate outcrops are best exposed on the north side of the property although pods and boudins of marble and limy psammites can be found throughout the property. Igneous rocks on the property consist largely of medium- to coarse-grained, hornblende- and biotite-bearing granodiorite, fine-grained diorite, thin lamprophyre dykes and very fine-grained to aphanitic aplite or rhyolite float. The igneous rocks are believed to form part of the early Late Cretaceous Tombstone Plutonic Suite. Older foliated 'diorite' bodies as intersected in drill hole SH98-09 are likely Triassic in age.
Alteration and mineralization on the property is related to the Tombstone Plutonic Suite stocks and smaller intrusive bodies. Gold-bearing zones occur in several different styles and lithologies.
Discordant Mineralization:
- Structurally controlled, quartz-sulphide veins: Discordant mineralization consists primarily of quartz-sulphide veins that crosscut both the metasediments and the Scheelite Dome stock. There appear to be two types of quartz sulphide veins: an earlier set of narrow (<1 cm) quartz±arsenopyrite±pyrite veins and a later, less abundant but wider (>1 cm) set of quartz±arsenopyrite±stibnite veins (e.g. Hawthorne Vein, Aorta Structure in SH98-10, mineralized veins in SH99-23). Brittle fractured rocks, such as more quartzite-rich units or monzonites (as in SH99-24) make excellent hosts for this style of mineralization. Although no bismuth minerals were identified in the drilling, it is clear from the correlation coefficient for 1998 and 1999 core samples that gold correlates better with bismuth (0.595) than arsenic (0.390) or antimony (0.104). Alteration envelopes and selvages associated with this mineralization include sericite, silica, biotite and tourmaline.
- Disseminated sulphides: Disseminated sulphides are hosted in both intrusive and metasedimentary units, although the bulk of disseminated sulphides are found outside of the intrusives. An important occurrence is the mineralized monzonite intersected in RC97-11, SH98-10 and SH99-24. Disseminated arsenopyrite, pyrite and pyrrhotite occur throughout the metasedimentary units in zones of greater permeability, such as in quartzitic units, or in zones of increased fracturing. Phyllitic units adjacent to quartzite-rich units with abundant quartz-sulphide veining as above are commonly cut by close-spaced fractures. Areas of disseminated mineralization are typically altered by sericite and silica or less commonly biotite or muscovite, and are often found enveloping the quartz-sulphide veins described above.
Concordant Mineralization:
- Structurally-controlled, quartz-sulphide veins: Concordant, undeformed quartz arsenopyrite pyrite veins have been noted in the bluffs above the Tom Zone and in the Toby's Creek area where the S2 foliation has opened under tension. Similar veining, with significant gold grades, has been noted in drilling in the Aorta Corridor area and is often accompanied by sulphides, principally arsenopyrite, disseminated along the S2 foliation.
- Replacement: Sulphides, notably arsenopyrite, commonly replace limy bands in the metasediments, and are semi-massive to massive with high gold grades. Examples of this type of mineralization are particularly well developed in the Tom Zone, Highet Creek, and the Rudolph Gulch area.
Skarn Mineralization:
- Zones of auriferous garnet-wollastonite-quartz-tremolite skarn with dissemination and blebs of pyrrhotite, scheelite and chalcopyrite are found on the south side of the Scheelite Dome Stock, the Tom Zone, as well as the north side (Cominco Zone). Contact skarn mineralization consisting of calc-silicate (diopside), biotite, and chlorite is also found associated with biotite lamprophyre dykes (SH99-16).
In addition to the auriferous quartz veining noted above, early quartz-chlorite-pyrrhotite+/-chalcopyrite veins are prevalent throughout the property. These veins are easily identified by the presence of chlorite and are distinguished by their irregular, pinch and swell habit parallel to the foliation. In any of the 1998 drill holes, the percentage of folioform veins exceeds that of the later, gold-bearing, discordant veins. The early quartz veins are not thought to be auriferous.
Mineralization Model
Structure is the key to mineralization at Scheelite Dome, whether the mineralization is hosted in structures or replacing adjacent favourable strata. A newly developed mineralization model, shown schematically below, suggests that potential for a major gold discovery lies along the south-dipping thrust fault to the south of Highet and Sabbath Creeks in an area not yet tested by drilling. This concept is supported by the gold values encountered in 2003 drill hole TOM-04 and the fact that some of the best placer gold in Highet Creek appears to have been derived from a local source, almost in place. Further, the few IP lines that have crossed Sabbath Creek outline a chargeability anomaly that parallels the creek and is reasonably flat lying.
 click on map to view enlarged
The target for ongoing exploration would be along or below the structural trap formed by the south-directed thrust sheet and localized by steep cross structures. Several major cross structures have been mapped on the property, some with known gold showings and anomalous gold geochemistry in the vicinity of the thrust sheet.
Exploration
Soil sampling has proven to be the most effective exploration tool for locating mineralization at Scheelite Dome. Sample results from soil sampling conducted by H6000 Holdings, Kennecott, La Teko Resources and the Issuer, have been compiled and anomalous results for Au, As, Sb and Bi were delineated. Sb and Bi values were not determined by H6000 Holdings; their sampling was concentrated over the Scheelite Dome Stock and the Minto Lake Stock immediately south of the property. Overall, the soil sample results show the coincident nature of As, Sb and Au which lie in an east-west corridor with concentrations in the Harvey-Rudolph Area (3500 by 1500 metres) and the Héon Grid-Bennett Creek West area (4000 by 1500 metres). As the soil samples returned generally low values for bismuth and considering the high detection limit (2 ppm), any Bi results above detection are significant. Interestingly, the highest Bi values are located away from the area of most of the drilling in the Harvey-Rudolph Area, in the area of Toby's Creek and the Héon Grid-Bennett Creek West area.
In 1998, induced polarization and resistivity geophysical surveys were conducted over the Harvey-Rudolph Area to help prioritize drill targets. The survey identified a number of targets exhibiting high chargeability with both low and high resistivity. Although the IP survey was successful in indicating better-mineralized zones in the drilling, the survey's interpretation is complicated by an earlier metamorphic event. Prior to the emplacement of the Cretaceous Scheelite Dome stock, metamorphism and folding was accompanied by widespread quartz-chlorite-pyrrhotite+/-chalcopyrite veining. Pyrrhotite is also present in the hornfels surrounding Scheelite Dome. No gold is thought to be associated with the early phase of quartz veining and it is not known whether gold occurs with the hornfels. Therefore, the higher chargeability and resistivity anomalies should be reviewed in conjunction with magnetic data as pyrrhotite associated with the synmetamorphic veining and hornfelsing may cause some of the chargeability anomalies. Chargeability anomalies do not come to surface on the pseudosections due to weathering of sulphide minerals to depths of >30 metres. Extremely high chargeability anomalies, as in hole SH98-11, are caused by conductive, black argillaceous phyllite. In addition, clay-rich fault zones are the suspected source of the high chargeability in hole SH98-14.
Extensive trenching programs were undertaken in 1995 and 1997; all trenches were mapped and sampled, returning values up to 84300 ppb Au over 4.0 metres (collected along an east-west trending, clay fracture parallel to the Big Time Vein). Most of the trenching was restricted to ridge spurs where bedrock was easily accessible. The bulk of the trenching was conducted in the Harvey-Rudolph Area, revealing Au values similar to the drilling where >100 ppb Au values occur over tens of metres with narrower intersections of >1000 ppb Au. An example of the strength of mineralization in the Harvey-Rudolph corridor is shown by two long excavator trenches on Hawthorne and Harvey ridges that averaged 188 ppb Au over 744 metres and 147 ppb Au over 375.7 metres, respectively.
Five drilling campaigns have been undertaken at Scheelite Dome: 1995 (Kennecott - 8 holes, 1035 m), 1997 (Kennecott - 13 holes, 1052 m), 1998 (La Teko - 7 holes, 1268 m), 1999 (Copper Ridge -- 13 holes, 1358 m) and 2003 (Golden Patriot -- 5 holes, 330 m). The 1995, 1998, 1999 and 2003 drilling utilized core drilling whereas reverse circulation drilling was carried out in 1997.
The Scheelite Dome property belongs to a diverse suite of Yukon and Alaskan plutonic-related gold deposits associated with Cretaceous intrusions including the high grade Pogo deposit (5.2 million ounces Au) and the large tonnage, low grade Fort Knox Mine (7 million ounces Au) in Alaska. More specifically, Scheelite Dome occurs in a narrow, east-west trending belt of lithologically and geochemically distinct intrusions of the 90-93 Ma Tombstone Plutonic Suite (TPS) which stretches 550 kilometres across the north central Yukon. Scheelite Dome differs from the better-recognized TPS-related gold deposits, Brewery Creek Mine and Dublin Gulch deposit, in that the most significant mineralization is situated outside of the intrusion in metasediments of the Hyland Group. The bulk of the mineralization is hosted in structurally controlled quartz-sulphide veins and as dissemination in quartzite-rich lithologies. The veins, soil geochemistry and mineralization define an east-west corridor measuring 1.5 kilometres wide and over 10 kilometres long. The veins typically strike east west and dip moderately to the north.
According to the Caulfield Report, the Scheelite Dome property represents of one the better-mineralized plutonic-related gold targets in the north central Yukon. On the basis of the large alteration/mineralization system, the multiple controls for mineralization and significant drill/trench results, further work is fully justified on the property. The drill and trench sample results provide strong justification to continue drilling the Aorta Structure and other untested targets in the Harvey-Rudolph Area and elsewhere on the property to determine if an economic gold deposit occurs within this large gold-bearing system. Scheelite Dome's potential will be better understood as each of these targets is tested. To date, geological mapping, soil geochemistry, IP and trenching have proven to be effective in targeting drilling.
Proposed Exploration and Development Program
Copper Ridge plans and exploration program over its newly defined Toby gold-silver zone, south of the Tom Zone, in 2006. This program will consist of geological mapping, prospecting and magnetometer and Induced Polarization geophysical surveys, followed by road building and trenching.
APPENDIX
SCHEELITE DOME
TINTINA GOLD BELT SIMILARITIES
The most notable similarities that Scheelite Dome gold deposit shares with other Tintina Gold Belt deposits are:
- a proximity to Early to Late Cretaceous granitic intrusions, which are typically granodiorite to granite in composition, calc-alkaline, and multi-phase with ages ranging from 85-110 Ma in Yukon and east-Central Alaska and from 50-70 Ma in western Alaska. They typically intrude miogeosynclinal sediments and their metamorphosed equivalents. The Late Cretaceous Scheelite Dome and Minto Lake stocks are quartz monzonite to granodiorite in composition;
- a range of gold mineralization styles hosted within the intrusion or within the thermal metamorphic aureole of the intrusion. At Scheelite Dome, these include gold hosted in sheeted quartz veins and stockworks, low-sulphide fissure veins, shear veins, breccias, disseminated replacements, and skarns;
- a suite of alteration assemblages dominated by quartz, biotite, sericite, carbonate or feldspar alteration;
- a geochemical association of gold with lithophile elements Bi, As, Sb, W, Te, and Ag, (Au correlates most strongly with Bi in drill core);
- indications that magmatic fluids are associated with gold mineralization; and
- a significant component of structural control on mineralization.
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Related News Releases
| February 20, 2007 |
Copper Ridge Options Out Scheelite Dome Gold Property |
| November 16, 2006 |
New Gold Discovery On Copper Ridge's Scheelite Dome Property |
| August 18, 2006 |
Copper Ridge Field Program Update |
| June 22, 2006 |
Exploration Commences On Copper Ridge's Scheelite Dome Gold Project, Yukon |
| May 17, 2006 |
Copper Ridge Closes Brokered Private Placement |
| May 05, 2006 |
Copper Ridge Brokered Private Placement Increased To $2.4 Million |
| April 11, 2006 |
Copper Ridge Arranges $2.04 Million Brokered Private Placement |
| December 22, 2005 |
Copper Ridge - Project Update |
| August 05, 2005 |
Final Drill Results from Lucky Joe Project |
| November 19, 2003 |
Golden Patriot Reports the Balance of Results From Scheelite Dome Project, Yukon |
| November 06, 2003 |
Excellent Gold Values Reported From Scheelite Dome Project in Yukon |
| October 09, 2003 |
Drill Program Begins on High Grade Surface Showings At Scheelite Dome |
| September 30, 2003 |
Sampling Program Returns Excellent Gold Values At Scheelite Dome Project |
| September 22, 2003 |
Extensive Geophysical Anomaly Identified Over High Grade Tom Zone |
| June 23, 2003 |
Scheelite Dome Gold Project Farm-Out |
| May 07, 2003 |
Scheelite Dome Exploration Planned High Grade Tom Zone Gold Targeted |
| September 12, 2000 |
Scheelite Dome property (Yukon) Back-in right Agreement Completed |
| March 27, 2000 |
Scheelite Dome - Purchase of Back-in Right |
| November 16, 1999 |
1999 Scheelite Dome Exploration Summary |
| November 08, 1999 |
Positive Scheelite Dome Drill Results |
| October 20, 1999 |
Initial Scheelite Dome Results |
| September 28, 1999 |
Scheelite Dome Drilling Underway |
| September 22, 1999 |
$1.275 Million Financing Closed - Scheelite Dome Drilling to Commence |
| June 02, 1999 |
Kinross Signs Agreement with Copper Ridge |
| March 09, 1999 |
Agreement with KGE Management Ltd. |
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