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Summary
Barker Minerals discovered and is systematically exploring a polymetallic, volcanogenic massive sulphide (VMS) zone located along the southern extension of the 3.7 million ounce historic Cariboo gold district in east-central B.C., Canada (the Ace project). The Company believes that the exploration to-date has defined several exceptional targets that may lead to the discovery of one or more significant mineral deposits on the Ace project.
The mineralization is considered by Major Mining Companies, Strathcona Mineral Services Ltd., the Geological Survey of Canada and the B.C. Geological Survey to be similar to other Besshi-type massive sulphide deposits in B.C., including the high-grade Goldstream deposit and Windy Craggy, one of the largest massive sulphide deposits in the world.
Mineralization
Results from an extensive exploration program on the Ace project have confirmed excellent potential for significant massive sulphide deposits along a zone at least 8 km in length. Most of the work has centered along a 2.7 km interval where well-defined target areas have been defined. Support for this mineralization is from the following:
- Extensive mineralized boulder field
- Coincident bedrock mineralization
- Felsic volcanic rocks with VMS footwall-style alteration
- Well-defined geochemical soil anomaly
- Strong IP/Chargeability geophysical anomaly
- Initial Drill Program
Mineralized Boulder Field
The Company has documented more than 1,000 mineralized boulders within an area 8 km long and up to 2 km wide. Most of the mineralized boulders are angular and many of the associated large blocks of country rock are strongly angular, suggesting minimal transport distance. The mineralized boulders are of two types, quartz-rich, sulphide-bearing vein and massive sulphide. In a geological report prepared for Barker Minerals, John Payne Ph.D. of vancouver Petrographics noted the following:
- The average of 53 samples from widespread float boulders of sulphide-bearing quartz veins is 3.1 g/t gold, with values up to 29 g/t (nearly 1 oz/ton) gold.
- Pyrrhotite-rich massive sulphide boulders contain up to 16% combined zinc and lead, and up to 3 oz/t silver and 0.25% copper.
Coincident Bedrock Mineralization
Due to the lack of bedrock exposed along the mineralized boulder field, preliminary trenching and pitting of several areas were completed. Some of the new bedrock uncovered contained both gold-bearing quartz vein and massive sulphide mineralization only several meters below the surface, further confirming the likely proximity to a possible ore deposit. Grab samples of quartz-rich sulphide veins in bedrock carried values up to 6.0 g/t gold, and several other bedrock zones contained chalcopyrite (copper) and up to 2% combined zinc and lead associated with massive lenses of pyrite and pyrrhotite.
Felsic Volcanic Rocks with VMS footwall-style alteration
From the trenching, mapping and sampling completed in 1997, a significant volume of metamorphosed felsic volcanic rocks was identified along the mineralized boulder field. These rocks show many characteristics of the footwall portion of a volcanogenic massive sulphide (VMS) deposit. The felsic rocks commonly contain 2-5% disseminated pyrite, and locally, in highly altered areas, contain up to 50% sulphides, mainly pyrite and pyrrhotite. Some of the most altered rock consists of a complete replacement of the host rock by massive, fine-grained pyrite and dark green chlorite.
Well-defined Geochemical Soil Anomalies
A total of 4,020 grid-controlled soil samples collected on the Ace project show strong and partially-zoned geochemical anomalies within the boulder field. The copper zone lying to the south of (stratigraphically below) the zinc-lead anomaly is typical of many VMS deposits. The gap in the zinc-lead anomaly is due to the inability to collect soil samples in a swamp. Gold, is coincident with the copper, zinc and lead soil anomalies, further confirming a gold-bearing massive sulphide system.
Strong IP/Chargeability Geophysical Anomaly
Several geophysical surveys have been conducted over various portions of the Ace project. These include: Mag/VLF, E-scan, and IP/Chargeability. Of these, the IP/Chargeability is the most important as it identified a strong anomaly (resistivity low/chargeability high) interpreted as a VMS occurrence running parallel with the east-west bedrock foliation and coincident with the trend of the zinc-lead geochemical anomaly. The follow-up trenching, noted above, further confirmed this association.
Initial Drill Results
Preliminary results from an initial drill program confirmed the presence of gold-bearing VMS mineralization on the Ace project. Seven diamond (core) holes were completed totaling 1,260 meters in the central portion of the area. Massive sulfide mineralization was encountered at the top of a thick felsite section in drill hole 98-03. Anomalous base and precious metal values were also encountered in quartz-pyrrhotite viens in drill holes 98-01,02 and 07.
Compelling Evidence for a VMS Deposit
All of the data collected to-date show compelling evidence for the excellent potential of a significant volcanogenic massive sulphide (VMS) deposit. It should also be noted that the Company continues to gain evidence that the mineralization observed in the central portion of the Ace project, may extend for much of the length of the 8 km long boulder field, offering the possibility of numerous mineral deposits. Multiple deposits are typical of VMS districts around the world.
Project History
Mineralized boulder field
During 1993, in the Ace Prospect project area (project area #1) at the outlet of a culvert on the "F" spur, a branch of Weldwood's "8400" logging road, a grab sample of sand collected by Louis Doyle assayed 129 g/t gold. At the end of October, Doyle staked mineral claims on the potential source area. During November of the same year these claims were vended to a newly formed company, Barker Minerals Ltd.
During 1994, the Ace mineral claims were staked on the north-facing slope of Mount Barker. Prospecting, reconnaissance geological mapping and rock sampling, line cutting and soil geochemical sampling conducted during the summer of 1994 helped to locate many glacially transported cobbles and boulders comprised of vein quartz, quartz-pyrite-pyrrhotite and/or semi-massive to massive iron-rich sulphides. Many of the boulders of quartz-rich veins and massive sulphides in the boulder field are subrounded to subangular. Many of the nearby coarse blocks of country rocks are distinctly angular. These features suggest that the as-yet-undiscovered bedrock source of the boulders is probably close by, possibly beneath glacial till deposits located up-ice (opposite direction of the flow ancient glacial ice) from the present locations of the boulders. The mineralization in some of the boulders of Doyle's boulder field has been compared with that of the Goldstream deposit north of Revelstoke and with that of the Vine prospect in southeastern B.C.
The main boulder field, along Weldwood's main "8400" haul road from km 8423 to km 8431, is 8 km long and several hundred metres wide. Many boulders are comprised of quartz veins with minor to moderately abundant amounts of one or more of tourmaline, sphalerite, chalcopyrite, galena and graphite. Grab samples collected from many boulders contained significant concentrations of gold and/or base metals. The average of 53 widespread float boulders comprised of sulphide-bearing quartz veins was 3.1 g/t Au, with concentrations ranging up to 29 g/t Au.  Many of the higher-concentration gold samples contain significant concentrations of lead (1000-2000 ppm), bismuth (100-2500 ppm), selenium (20-50 ppm) and tellurium (10-34 ppm). Several pyrrhotite-rich massive sulphide boulders contain 3-16% Zn+Pb and up to 3 oz/t Ag and Cu stringer material up to 4.1% Cu. Precious and base metals have been, and continue to be, the major economic focuses of exploration.
Government Comments:
"The Ace's host rock lithology and metal content suggest an affinity to well explored gold quartz veins of the Yanks Peak and Cow Mountain (IWA) areas to the north. The geological setting, style of mineralization and geochemistry suggest an analogy to the "Plutonic-associated" or "Pogo-Type" Gold vein model."
Bob Lane and Ken McDonald
April 2000
The 1995 program included prospecting, line cutting, geochemistry, geophysics and geology. This expanded the database and identified geophysical and geochemical targets.
During 1996, Barker Minerals staked 2,590 claim units around the Ace project area and performed limited trenching and geological mapping on the Ace project area. Regional stream sampling and magnetometer surveys were conducted on these claims; this resulted in the discovery of the Big Gulp mineral occurrence.
A test I.P. Survey was conducted on the central part of Doyle's boulder field by Scott Geophysics of Vancouver, B.C., to improve definition of geophysical targets outlined by the 1995 magnetic and VLF-EM studies. Several shallow, discrete targets have been outlined, mainly trending parallel to the regional stratigraphy and mainly indicated represented by coincident resistivity lows, chargeability highs and mag highs.
An experimental "E-Scan" 3-dimensional resistivity survey was done by Premier Geophysics of Vancouver, B.C., on part of the Ace (Kloo) grid southeast from the GSC2 fault on lines spaced at 100 m. The survey outlines a prominent near-surface resistivity low centred at 10E-36S that extends to depth.
1995 and 1996 GSM-19 magnetometer surveys defined several, narrow, linear, near-surface anomalies associated with areas of high chargeability. Some magnetic anomalies occur in a circular zone about a magnetic low in the Ace 86 claim in the central part of the property. This low coincides with moderately anomalous values in gold, arsenic and boron in soil samples. As well, this area contains a circular area containing sinuous and irregular VLF-EM high readings.
In 1995 and 1996 on the Ace grid, 4,420 soil samples were collected from the top of the "B" soil horizon, or as close to that horizon as could be determined. In general, the top of the B horizon was reached at depths between 0.2 and 0.7 m. Threshold concentrations used were as follows: Cu - 50 ppm, Zn - 100 ppm, and Pb - 25 ppm. The 1996 results compliment the patterns in the 1995 survey results, and show the more extensive nature of the Pb and Zn anomalies situated along the northern margin of Doyle's boulder field between the GSC-1 and GSC-2 faults.
During October, 1996, preliminary excavator/backhoe trenching in and near Doyle's boulder field was conducted. Thirty-six trenches totaling 260 m were excavated. The average depth was 4 m, and a few trenches reached 5.5 m in depth. These exposed bedrock at scattered points within the central part of the boulder field. Acme Analytical Laboratories analyzed 107 grab specimens of host rocks and mineralized zones by ICP, whole-rock and hydride methods. Gold concentrations in rock samples collected from four trenches are anomalous. Two grab samples collected from Trench 30 near the "F" road, contained 1065 ppb and 1386 ppb Au. Grab samples of two siliceous rocks collected from Trench A contained 296 ppb and 77 ppb Au. Two grab samples collected from Trench G contained 213 ppb and 50 ppb Au. Concentrations of gold greater than trace correlate positively with Cu, Pb, Fe, Te and SiO2, and to a lesser degree with As, Bi and Hg. A negative correlation exists between Au and Zn.
During 1997, surface mapping was begun in an area of 2 sq. km in the core of Ace project area. Detailed geological mapping and sampling were conducted in 20 trenches totaling 1084 m in length and in 46 test pits. The average depth was 4 m, and a few trenches reached 5.5 m in depth.
The 1997 program shows the continuity over a length of a few km of a belt of metamorphosed, felsic volcanic rocks dominated by plagioclase, and containing 1-5% disseminated pyrite and/or pyrrhotite. In this belt, trenches have exposed zones up to 10 m thick of semi-massive sulphide containing 20-50% pyrite and/or pyrrhotite. In the VMS model, this unit is in the footwall of the
massive sulphide deposits. Less abundant units include muscovite-quartz, quartz-muscovite-biotite schist, and slightly graphitic phyllite. In the felsic volcanic unit, two main alteration assemblages were recognized in the field. The first consists of semi-massive to massive sulfide dominated by granular pyrite intergrown with abundant dark green chlorite and much less abundant sericite and quartz. The other consists of felsite containing 20-30% disseminated pyrrhotite. Both types of altered rocks contain anomalous values in base and precious metals.
From the Ace project area, 433 rock samples were collected, of which 343 were analyzed by ICP, whole-rock and Au-assay methods. From the remainder of the property, 151 rock samples were collected, of which 27 were analyzed by ICP, whole-rock and Au-assay methods. Petrographic examinations were made on 49 rock samples collected from the surface of the Ace project area and 7 from various locations in the eastern half of the property.
During the stream-sediment (silt) survey, 201 samples were collected from the Ace project area and analyzed, and 130 samples were collected from the remainder of the property and analyzed. During 1997, 336 soil samples, which had been collected from a grid on part of the Ace project area in 1996, were analyzed. As well, 30 soil profiles at various locations were logged, sampled and analyzed.
At the west end and northeast corners of the Ace grid, 31 km of additional grid lines were cut. The location of the grid cut during previous exploration was partly rectified by surveying junctions of grid lines with roads and with the Little River. This work continued into 1998. On the Ace project area, geophysical surveys included 11.9 km of magnetometer surveying and 8.7 km of beep-mat surveying.
During 1998, geological mapping continued and seven diamond drill holes totaling 1260 m were drilled in the center of the Ace project area. The results were used to help identify a VMS environment containing massive sulphide mineralization as indicated by three intersections of massive and semi-massive sulphide mineralization measuring up to 0.36 m at or near the top of a pile of felsic volcanic rocks reaching 81.5 m thick. A footwall alteration zone that extends up to a few tens of metres below the massive sulphide zones contains geochemically anomalous concentrations of base metals and precious metals. Forty-five polished thin sections from drill core were examined.
Barker Minerals' initial diamond drilling program targeted felsic strata and geophysical anomalies (chargeability highs, resistivity lows and magnetic highs) located within a zone suspected to be underlain partly by felsic rocks having exploration potential for massive sulphide deposits. The holes were drilled between the main trench area and Colleen Road. Most of the holes were drilled to the south, dipping at -45º, which is approximately perpendicular to the regional trend of the metamorphic foliation. Two holes were drilled more steeply at -60ºand -70º in order to attempt to penetrate specific geophysical anomalies. In some instances, it appears that the holes were not long enough to have reached the intended geophysical targets.
All drill holes except 98-05 intersected felsite, whose thickness ranged from 3.5 to 81.5 m. As the holes were drilled perpendicular or nearly so to the regional foliation, all thickness intervals are close to true thickness relative to the metamorphic event. Because of the complex folding in the region, it is impossible to estimate true, pre-metamorphic thicknesses. At the top of the main felsic section in DDH 98-03, a mineralized zone was intersected for 0.75 m, containing two intersections of massive sulphide mineralization, 0.25 m and 0.20 m long, separated by an intersection of calcite (probably limestone) 0.30 m thick. The massive sulphide mineralization carries apparently anomalous concentrations of Au, Ag, Cu, Zn, As, Se, Te, Sb, Bi, Mo and Cd, as determined by non-statistical consideration of the analytical data. The footwall alteration zone below the massive sulphide is anomalous in many of the same elements, generally with smaller concentrations than in the massive sulphide. As well, the footwall zone carries anomalous concentrations of Mo. Anomalous metal concentrations in the footwall decrease moderately to rapidly away from the top of the section of felsic rocks. Deeper in the footwall, many samples contain anomalous concentrations of Ag, Mo and Zn. In the centre of the felsite section, hole 98-07 intersected semi-massive sulphide mineralization for 0.36 m, containing anomalous concentrations of Ag, Cu, Bi and Se. Above and below this, the rocks contain anomalous concentrations of Ag, Zn, Mo, Bi and Se.
Felsic volcanic rocks encountered during this drilling program consist mainly of extremely fine-grained plagioclase with minor biotite and/or muscovite. Many contain minor to abundant replacement and recrystallized patches of coarser grained plagioclase, with or without minor to abundant quartz, ankerite, muscovite and pyrite. Some surface samples, previously described as metamorphosed diorite, were reinterpreted as recrystallized and replaced felsic volcanic rocks. Some felsic volcanic rocks contain zones up to several metres wide of weak to strong biotitic alteration, some of which occur in broad, diffuse envelopes about quartz-sulphide veins. In these zones, pyrrhotite is replaced by coarser-grained porphyroblasts and lenses of pyrite.
Veins containing anomalous metal concentrations are of three types. Quartz-pyrrhotite veins in DDH 98-01 carry anomalous concentrations of Cu, Ag and Bi. Quartz-pyrrhotite-tourmaline veins in DDH 98-02 carry anomalous concentrations of Au, Ag, Cu, Zn, Bi, Se and Te. A quartz-pyrrhotite vein in DDH 98-07 carries anomalous concentrations of Au, Ag, Cu, Pb, Bi and Se. Numerous barren quartz and barren quartz-chlorite veins are present in drill core in many rock types and are particularly abundant in some intervals of quartzite and quartz-rich schist.
Comparison of drill-core data with previous analyses of boulders indicates that the massive sulphides and auriferous quartz-sulphide veins in the boulders and corresponding materials in the drill cores have come from the same environment. This and the general angular appearance of the boulders and other large blocks of bedrock with which they occur in the overburden suggest strongly that the boulders are from a nearby bedrock source, probably slightly up-ice from their present locations.
During 2000, a BSc. thesis by Dan Tutt was completed on the Ace Project titled "Geology and Geochemistry Of The Ace Cu-Au-Ag-Zn-(Pb) Property, Barkerville Subterrane, East-Central B.C. (093A/NW)". This thesis was co-sponsored by the Geological Survey of Canada, NATMAP and Barker Minerals Ltd. Interpretations of the Ace Property setting compared favourably with the Yukon / Tanana and Kootenay Terranes and the Bathurst District of New Brunswick.
During 2000, 42 km of new grid line were cut and Max-min HLEM surveys (57.5 km) and magnetometer surveys (42 km) were conducted by Peter Walcott and Associates, Vancouver, B. C., resulting in the detection of three new indicated conductors A, B and C.
The HLEM survey indicated one major east-west trending conductor (Conductor A) 1200 m long and open to the east. Conductor A is coincident with the significant conductor outlined in the previous 1996 E-Scan survey. Conductivity is poor to moderate. It is associated with a magnetic high on the south side of a broad magnetic low. A one-line, broadly indicated conductor (Conductor B) of poor to moderate conductivity is indicated at the northwest corner of the grid and extends off the grid. It is coincident with the east end of the resistivity low located in the 1996 survey of the area to the west. Conductor C is indicated as a weak electro-magnetic anomaly situated near the end of two grid lines 200 m north of indicated Conductor B.
Magnetometer readings were taken over the entire grid at 25 m intervals on lines spaced 100 m apart. The locations of base lines and several other grid points were determined by GPS. The results of the magnetometer survey correlate well with previous data generated by Barker Minerals in 1996. Broad variations in magnetism trend east-west and probably reflect differences in bedrock lithology, which also trend in that direction. A few local dipoles may represent small bodies of a magnetite-bearing rock such as diorite. Sixteen rock samples were collected from the Ace project area and assayed.
Till Study With B.C.G.S.
Barker Minerals oriented and supported a study of glacial till on the Ace project area being conducted by Peter Bobrowsky (2000) of the British Columbia Geological Survey, with the goal of determining the direction(s) of ancient glacial ice movement in order to assist with locating the bedrock source of mineralized boulders found in previous programs.
Geology
The Ace property is underlain mainly by a section of metamorphosed sedimentary and volcanic rocks. The most important sedimentary types are quartz-muscovite schist, quartz-chlorite-muscovite schist, quartzite, quartz-rich schist and quartz-muscovite-biotite schist. In the eastern half of the property, garnet is common, especially in muscovite-rich and biotite-rich schist. Minor argillite, calcareous argillite and limestone are most common directly above the massive sulphide lenses. Deeper in the section on Barker Mountain and along Ishkloo Creek are minor amphibolite and biotite amphibolite.
A volcanogenic massive-sulphide environment is associated with metamorphosed felsic volcanic rocks along the trend of Doyle's boulder field, where many boulders containing gold-bearing quartz veins and gold-bearing massive sulphides have been found. Drill holes intersected a zone of metamorphosed felsic volcanic rocks up to several km long and 80 m thick. These felsic rocks are dominated by plagioclase with minor to moderately abundant quartz, muscovite and biotite. At the top of the main felsic section in DDH 98-03 is a zone 0.75 m thick, containing two intersections of massive sulphide mineralization 0.20 m thick and 0.25 m thick, separated by an intersection of calcite 0.30 m thick. The massive sulphide mineralization carries anomalous concentrations of Au, Ag, Cu, Zn, Bi, Se and Mn, as determined by non-statistical consideration of the analytical data.
A few massive sulphide samples collected from trenches in this zone contain up to 2% Zn. A similar zone of semi-massive sulphides 0.35 m thick occurs in the centre of the section of felsic volcanic rocks in DDH 98-07. Massive sulphide boulders containing large concentrations of Pb and Zn occur in the Colleen Road area, but their bedrock source has not been found.
In some strongly altered footwall rocks, the host rock was replaced completely by massive, fine-grained pyrite and dark green chlorite. Others contain 20-30% disseminated, very fine-grained pyrrhotite. Many altered felsic rocks contain anomalous concentrations of base metals and precious metals, in part associated with recrystallized and/or replaced patches dominated by one or more of plagioclase, quartz, ankerite and sulphides. Anomalous concentrations increase in footwall rocks near the stratigraphic top of the main felsic section. These patterns show characteristics of footwall rocks beneath a typical VMS deposit.
The drill cores contain a few important faults up to a few metres wide. Because of the wide spacing of the drill holes, these could not be correlated between holes. The moderate to high graphite content of many of these makes them potentially significant conductors.
Most of the geophysical anomalies obtained in earlier studies have yet to be tested or explained. The main geophysical and geochemical anomaly at the western end of the main trench area is open to the west in an area that is interpreted to be underlain by felsic volcanic rocks. This extends west of the massive sulphide occurrence in DDH 98-03. Vectors in the thickness of massive sulphides, intensity of alteration and geochemical anomalies and thickness of the felsic volcanic section indicate that the area west of DDH 98-03 may contain an important exploration target. Another exploration target is indicated by a broad geophysical resistivity anomaly situated northeast of the area of drilling. On surface, this area contains rubble of felsic volcanic rocks and abundant boulders of quartz veins containing anomalous concentrations of base and precious metals. A third important target is the elongate HLEM anomaly in the southeastern part of the project area (Conductor A).
Gold-bearing quartz veins occur in two main modes. The first are as early veins that were deformed strongly with the enclosing host rock. The second are as late crosscutting veins, many of which trend northeasterly. Many of the quartz veins occur in the same general area as the felsic rocks and boulders of massive sulphide.
Exploration Plans
Geological mapping will continue in order to improve understanding of the regional structure and the local geology of areas of felsic volcanic rocks that have not yet been examined. This additional mapping will be integrated with that being done between the Ace and Frank Creek areas by Ferri of the B.C. Geological Survey.
The HLEM and geochemical surveys will be extended to the west and to the east of the present surveys along the trend of the felsic volcanic rocks. Similar surveys will be conducted over the belt of felsic volcanic rocks north of Little River. The main HLEM electromagnetic anomaly discovered during 2000 will be tested by a few gravity profiles. Similar gravity profiles will be run across the core of the altered felsic volcanic rocks defined in the 1998 drill program. Trenching will be conducted on anomalous zones where the thickness of the glacial overburden allows.
Diamond drilling will test targets identified by the geological, geophysical, geochemical and trenching work that will be conducted in the next phase of proposed programs.
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