- Located in Nevada's Carlin Trend - 2nd richest gold district in the world
- Surrounded by major operators (Barrick, Newmont, Yukon-Nevada, Anglo Gold-Ashanti)
- Has the capability to host a 1 – 5 million ounce deposit
- Potential for greater than 5 million ounces
Nevada now produces 82% of all new gold in America. At the heart of the gold productive region in the State is a 2 mile wide by 20 mile long geographic anomaly bisecting north central Nevada laterally as it migrates south-east and is known as the "
Carlin Trend." This deposit is home to some of the largest mining companies in the world with over 50 million ounces of gold mined to-date and with an estimated potential to produce 200 million ounces -- more gold than all of California ever produced and production has grown exponentially to where it is today -- the second richest gold district in the world, second only to Witwatersrand, South Africa. This is where Ironwood Gold Corp. has entered into an Assignment Agreement with Teck Resources to acquire the undivided 100% right, title and interest in and of the Rock Creek Project located firmly in the
Carlin Trend by making certain expenditures in respect to the exploration and development of the property.
The potential of this strategically situated property can be put into context by realizing that many major companies have worked in the
Carlin Trend (Texas Gulf, Homestake, Barrick, Goldfields, Placer Dome and Newmont) (see map) and all have found extensive gold deposits with alteration and major structures similar to that found in the Rock Creek claims. Similarly, rock sampling in a north/south direction over the claims by Teck Resources found numerous rock chip surface samples with anomalous gold concentration.
This Rock Creek property is in the northern part of the
Carlin Trend and has similar geology and deep seated structures found in the mineralized zones within the more southern part of the trend. Newmont, Barrick and other companies have located and are mining gold deposits that have at least 1-5 million ounces of gold and some, like the Goldstrike mine (Barrick), had 17million ounces of gold reserves in 2005. Newmont has reserves of over 33 million ounces and is the largest land owner in the trend.
Over 50 million ounces of gold has been mined already and it is estimated that the trend has the potential to produce 200 million ounces. Rock Creek with its geographical, geological and structural setting and indications of gold has the capability to host a similar 1 – 5 million ounce deposit with the potential of greater than 5 million ounces. This is exemplified by the Jerritt Canyon gold deposit (10-25 million ounces) owned by Yukon Nevada Gold due east of the Rock Creek property and the Anglo Gold Property (2-5 million ounces) located just to the north of Jerritt Canyon.
The Rock Creek Project area is located in the Tuscarora Mountains of north-central Nevada, in Elko County. (
See Figure 4.1) The center of the Rock Creek project area is approximately about 12 miles northwest of the old mining town of Tuscarora, which in turn is about 38 miles northwest of the town of Elko. Elko is the county seat, and lies on Interstate Highway I-80 about halfway between Reno, Nevada and Salt Lake City, Utah. The property in the project area together add up to 82 unpatented lode mining claims, with each claim covering 20 acres. It is approximately 5 miles by 1 mile (maximum dimensions) and covers an area of about 1640 acres.
As shown in
Figure 4.2, the Rock Creek property consists of 82 unpatented lode mining claims arranged in two groups: The northern group consists of 67 contiguous "Bluto" claims (1340 acres), in the "Red Cow" area (named after Red Cow Creek). The Bluto claims are located in Sections 29 and 32 of T41N, R50E, and in Sections 1 and 2 of T40N, R49E, MDB&M. About half a mile to the south, the second group consists of 15 contiguous "Dry" claims (300 acres), in the "Falcon" area (named after the adjacent Falcon mine). The Dry claims are located in Sections 12 and 13 of T40N, R49E, MDB&M.
Past Production
The Rock Creek Project area is within a historic mining district, where mineralization was first discovered in the 1870's. The Rock Creek mining district produced silver (32,000 ounces), gold (55 ounces), mercury (26 flasks) and antimony, mainly from the old Falcon mine located immediately south of the Dry claim group, and from the Teapot mercury prospect located between the Dry and Bluto claim groups, see
Figures 4.2 and
7.2. The Falcon mine, which exploited a volcanic hosted vein deposit, and the Teapot prospect are not included in Ironwood’s Rock Creek property.
Previous Exploration and Drilling
Industrial scale exploration of the region began in the 1960’s following the discovery of the Carlin deposit, and included: drilling in the Rock Creek property (Red Cow area) in 1983-84 by Shell Oil and in the 1990's by Western States Minerals. At the Rock Creek property, gold mineralization was discovered at Red Cow Creek in 1982 during a reconnaissance exploration program funded by Shell Oil Company.
Shell Oil took over the "Cow Creek" prospect, interpreted to be "...a bulk-tonnage gold and silver target hosted by Tertiary rhyolite tuffs and Palaeozoic carbonaceous sediments." Shell carried out surface and subsurface exploration in the 1983 and 1984 field seasons: 81 rock-chip samples and 405 soil samples were taken, and 23 drill holes were completed. As shown in
Figure 7.2, 16 of these "CC" drill holes are in Ironwood’s Rock Creek property, including CC-10 and CC-11 that each intersected 100 ft of 0.02 opt gold mineralization. In addition, hole CC-2 bottomed in 135 ft of Palaeozoic basement rocks comprised of pyritized, carbonaceous siltstone, with numerous gold shows in the overlying altered tuff.
In the 1990's Western States Minerals Corporation explored an area mainly east of Shell's area, for volcanic-hosted disseminated gold deposits, with geologic mapping, extensive geochemical sampling, an IP survey, and 13 reverse circulation drill holes. As shown in
Figure 7.2, five of these "RC" holes are in Ironwood’s property. Two of the holes, RC-2 and RC-5, which were drilled outside and to the east of Ironwood’s property, hit strongly altered and strongly gold mineralized Palaeozoic sedimentary rock.
Teck acquired the Bluto and Dry claims in 1999, and interpreted the target to be a classic volcanic-hosted gold-silver epithermal system with the potential for high-grade, underground mineable, gold-silver veins. Teck took 67 rock chip samples along the entire strike length of altered and mineralized volcanics (
see Figure 9.1). Two of the three samples with the highest gold grade, and six of the nine samples with the second highest gold grade, were taken within Ironwood’s Rock Creek property.
According to BLM records, companies that previously held claims covering or included within the Rock Creek property include: Shell Oil Co. 1978-90, Homestake Mining Co. 1981-88, Cruson and Pansze 1983-84, Newmont Mining Co. 1991-94, and Western States Minerals 1994-1998. All of these companies carried out their exploration in a manner using appropriate industry standards at that time.
Carlin type gold deposits are among the most important being mined at present anywhere in the world. Total production from the Carlin Trend, since the original mine began operation in 1964, has now exceeded 50 million troy ounces and there appears to be no end in sight. Many of the gold deposits found in the Carlin Trend fall in the range of 1 to 5 million ounces of gold and several exceed 10 million ounces of gold. Newmont has reserves of 33.3 million ounces. Barrick Gold Corp, as of 2005, had gold reserves of over 17 million ounces at their Goldstrike Mine alone. Clearly, these deposits are worthwhile and attractive targets.
Carlin-type gold deposits are formed in the frontal zone of the Roberts Mountains thrust plate, mostly in autochthonous carbonate rocks of the lower plate, but also in allochthonous rocks of the upper plate, and in igneous rocks (mainly Eocene age feeder dikes) that cut both plates. Most of the deposits are on the flanks of domal uplifts which are exposed as erosional windows in the thrust. These domes are structurally controlled along regional scale fracture zones, and are developed over intrusive bodies that fed overlying volcanic fields (like the Tuscarora Volcanic Field).
It has been speculated that at the time of ore formation, the thrust plate covered the erosional windows and being relatively impermeable, impeded the flow of ore-forming solutions upward and confined them mostly to the lower plate rocks. This combination of permeable and soluble lower plate rocks with impermeable and insoluble upper plate rocks, created stratigraphic and/or structural traps, very much like the traps observed in oil and gas reservoirs. In fact, nearly all Carlin-type deposits contain appreciable amounts of pyrobitumen, the residue of failed oil reservoirs. It is now understood that deep structures acted as channel ways for solutions that have both prepared the ground (by hydrothermal de-calcification or de-carbonitisation of limestones to make them more porous and permeable) and have carried the gold and associated elements from source region (probably the upper mantle) to depositional site.
Many of the more recently discovered deposits are deep, higher grade, and are structurally controlled (i.e., Meikle). It has become evident that these structures often carry significant quantities of the so called "Carlin indicator suite" of elements (As, Sb, Hg and perhaps Th) for considerable distances above and lateral to the gold deposits. And it has also been recognized that many, if not most Carlin type deposits are hosted in what were once petroleum reservoirs (Hulen, 1990). These reservoirs developed in stratigraphic and structural traps along basin de-watering fluid path ways, such as basin margin faults, which have later been exploited as pathways for gold bearing hydrothermal fluids. So, in addition to the traditional suite of indicator elements, oil field brine associated elements (i.e., B, Br, F, I, Pb, Zn, V) are further indicators of permissive areas for blind Carlin-type deposits.
The question then becomes where exactly to look for such blind targets; and the answer is to look in the place(s) where there is the greatest opportunity to discover these targets.
Figure 8.1 is a contour map of district gold endowment and regional structures of northern Nevada. It is fairly obvious, even to the casual observer that the most prospective area for finding such blind targets would be to the north of the Carlin District. The alteration zones at Rock Creek (RC) lies within the 5 to10 Million oz contour, and lies along and at, or near, the intersection of major regional structures, all of which are known to have channeled gold bearing fluids elsewhere in the region. These alteration zones are in Eocene age volcanics, which were in place at the time Carlin-type hydrothermal fluids discharged to the surface. The Rock Creek property is situated at the edge of the Tuscarora volcanic field, where the volcanic pile is the thinnest, and thus in the areas where the underlying Palaeozoic basement is within reasonable distance from the surface (<2,500 feet). (
See Fig 8.1)
The mineralization of interest on the Rock Creek Property is within the structures that control the alteration haloes in Eocene volcanic rocks and the alteration observed in outcropping Paleozoic rocks (caldera slide blocks, or horsts). Generally, this mineralization is typical high level, volcanic hosted, epithermal systems.
Mineralization and alteration can be divided into the south and north parts of the property, the Falcon and Red Cow structural zones (or vein systems) respectively (
Figures 7.2 and
7.3).
In the Falcon area, mineralization hosted by andesitic flows is strongly controlled by a series of sub parallel north-northwest, mostly steeply west dipping faults. Within the Falcon mine area; these faults are occupied by fine-grained quartz to chalcedony veins, often with banded textures. Rare quartz after bladed calcite occurs locally. The zone of sub-parallel veins locally reaches widths of at least 100 feet and extends northwards from the Falcon mine for 1 mile. Surface samples of vein silicification typically carry 100 to 1000 ppb Au and 1 to 200 ppm Ag.
In the Red Cow area, a series of steeply east to west dipping fault zones strike north-south to northeast for an aggregate strike length of at least 3 miles (
Fig 7.2). These faults, mostly within lithic rhyolite tuffs, contain locally extensive silicified breccias, fine-grained quartz-barite stockworks, and irregular zones of banded quartz to chalcedony veins. These silicified zones vary along strike in width from 3 to greater than 15 feet. Samples indicate that the silicified zones carry minor anomalous gold (50 – 250 ppb) with local samples up to 2.1 ppm Au (
see Figure 9.1). Unlike the Falcon area, silver is only weakly anomalous, although As, Hg and Sb are strongly anomalous. Previous shallow drilling has intersected up to 20m averaging 0.5 ppm Au. Most of the anomalous gold is near the bottom of these 500 ft. (150m) holes.
Limited soil and rock sampling has revealed large areas highly anomalous in As, Sb, Hg, Ag, and Au. Wide spread drilling has detected thick intercepts of enriched gold and silver values. Two holes (CC-10 and CC-11) encountered approximately 100 feet of economically significant gold mineralization.
The objective on the Rock Creek property is to define a deep drilling target that may lead to the discovery of Carlin-type gold mineralization hosted in Palaeozoic sediments, preferably in the “lower plate” rocks. This property has already been the subject of several concerted exploration efforts. And although these efforts were directed primarily at discovering near-surface gold/silver resources, the data already collected could substantially aid in the campaign of exploring for deeper Carlin-type targets.
The Rock Creek area is underlain by a classic epithermal volcanic-hosted gold-silver epithermal system. The extensive alteration and total sized of the system, at greater than 9km in strike length, indicate high potential for discovery of significant mineralization.
In the northern Falcon and Red Cow areas, alteration and textural features suggest that the current surface may lie above potential high-grade Au-Ag mineralization at depth. Given these features and its location in gold-rich north central Nevada and proximity and similarity to the Midas high-grade epithermal vein discoveries, the Rock Creek property has strong potential for the discovery of similar high grade, underground mineable, bonanza Au-Ag vein systems.
Ironwood Gold proposes to develop and complete a thorough exploration program and to drill test the project in preparation for further development.
Source: abridged and adapted from “Technical Report Rock Creek Project” by Russell Crosby., M.Sc., P.Geo.