The East Bell project is located 40 miles southeast of Fallon and 20 miles north of Gabbs. Access is via US Highway 50 then eleven miles south from Middlegate via Nevada Highway 361 to the turnoff to where good dirt roads lead to the property three miles west of the pavement.
The property is made up of thirty unpatented lode claims that include 24 claims in the “Flats Zone” and six claims to the west that cover bedrock exposures at the “Hillside Zone”. Land is administered by the U.S. Bureau of Land Management, Carson City Field Office. Elevations range from 5535 feet to 6415 feet (1687-1955 m) at the project.
Gold occurrences at East Bell are characteristic of low sulfidation, epithermal mineralization hosted in Tertiary volcanic rocks. A train of gold-bearing boulders of rhyolite porphyry form a well- mineralized zone in surface sampling; this zone coincides with a resistivity-high suggesting silicification in the near-surface bedrock. This is known as the “Flats Zone” where the resistivity anomaly and mineralized samples occur in a zone over 350 meters (1100 ft) wide and along a strike length of 1700 m (5600 ft). A second zone, situated a mile (1600m) west, is known as the “Hillside Zone”. Gold mineralization at the Hillside Zone is associated with silicification and adularization of outcropping, felsic volcanic host rocks. A six-hole drilling program is planned to test the two target zones.
Regional Geologic Setting
The East Bell Project is situated near the inferred southeast margin of the 19 m.y. Fairview Peak Caldera. The Nevada Bureau of Mines and Geology mapping (Field Studies Maps 11 and 12, 1996) describes the map units as a complex assemblage of ash-flow tuff, lavas, lava domes, debris deposits, and small intrusions accumulated in and around the Fairview Peak caldera during a brief period between 19.3 and 18.5 Ma. Four distinct sequences are present; only three of which are well represented in the near vicinity to the East Bell Project. These are (1) the tuff of Fairview Peak and related megabreccia/debris deposits, (2) the informally named lavas of Bell Canyon with related dikes and pyroclastic deposits, and (3) late intracaldera dikes. Rhyolitic lava domes are abundant in the Bell Mountain Quadrangle. Late-dike rocks are thought to be one of the host rocks to the gold mineralization at East Bell. The late intracaldera dikes are thought to have migrated along deep-seated conduits that also provided pathways for the mineralizing fluids at the project. The figure below shows the regional setting of the historic mining camps in relation to the Fairview caldera and the East Bell project location.
District Styles of Mineralization
Mineralization in the Fairview and Bell Mountain Districts was mined from veins with high silver and lesser gold. It is thought that there may be a zonation in a broad intrusive complex where the margin of the caldera has been affected by the influence of the ground-water contribution to the hydrothermal system driven by multi-stage intrusive activity related to the Fairview Peak caldera emplacement, eruption and resurgence.
Precious metals in the area influenced by the Fairview Peak caldera occur in veins and breccias that are related to silicification as flooding and infilling breccias. At the Bell Mountain mine, tuffs of the Fairview Peak caldera locally exhibit intense silicification proximal to the veins. In places along the vein, calcite is an important constituent and has been partly replaced by quartz. Gangue minerals include minor adularia, barite, fluorite, clays and Mn-bearing calcite along with rhodochrosite. It is notable that some intervals of carbonate-veining are logged in the 1995 East Bell drilling but were not submitted for assay.
Less-developed, historic mines are observed to occur at the margin of intracaldera dikes that cut the nearly contemporaneous tuffs. The tuffs are propylitized and the margin where silver mineralization occurs is kaolinized and silicified. A third style of hydrothermal alteration is that of hydrothermal breccias where fragments of bedded tuffs, flow-banded rhyolite, angular rock fragments and pumice are included in an intensely silicified matrix and has pyrite associated with the precious metals mineralization.
Model of Mineralization
The project lies along the southeasterly trend that includes the historically productive Fairview District and the Bell Mountain silver and gold resource. The model for mineralization at the East Bell Project is illustrated in the sketch below (after Cas and Wright, 1987). In silicic volcanic centers, such as the Fairview Peak caldera, hydrothermal alteration and metals concentrations may be developed in relation to late-stage, resurgence volcanic activity. Deep-seated structural zones provide pathways for migration of resurgent magma phases. These same deep-seated conduits may also provide for migration of hydrothermal fluids that in turn, create alteration zones in and peripheral to the resurgent intrusive phases. It is thought that the current level of erosion at the East Bell Project results in exposure of a gold-bearing, late-phase rhyolite porphyry related to the Fairview Peak caldera.
Map units exposed at the East Bell claims include tuffs, volcanic sediments, lavas and lava domes related to the Fairview Peak caldera. In the “Flats Zone”, gold-bearing rocks are present below a particular horizon in a sedimentary package interpreted to be post-mineral. Gold-bearing rocks in the “Hillside Zone” are associated with adularia and quartz veining in an ash-flow tuff and breccias erupted during the main event of the caldera.
The primary exploration target, the “Flats Zone” is in the gravel deposits that are thought to be in close proximity to the source rocks. Evidence for the gravels to be nearly in place include scarce mineralized samples west (upslope) of target zone and the coincidence of a distinct CSAMT anomaly in two lines, separated by 3000 feet, over the top of the gold samples. The surrounding hills have been prospected for other rock that could have supplied the mineralized material to the area of interest. No similar gold mineralization in the present-day drainage basin. The boulders and cobbles sampled are not rounded and structural control of the mineralized fractures is evident in large boulders and is sheeted in nature.
A second target, the “Hillside Zone” is situated uphill and west of the near-source gravel target. Gold values are present in silicified and brecciated rhyolitic tuffs.
In 1995, Cordex Exploration completed drilling of nine reverse-circulation holes and a geophysical survey. Five vertical holes were drilled “in the flat” in a north-south fence pattern. The holes are 1000 feet (300 m) west of the mineralized surface samples in the “Flats Zone”. The intervals assayed in these five holes were unmineralized. To the west, and including the “Hillside Zone”, four holes were completed to test the potential of mineralization associated with the range-front fault. These holes successfully confirmed the fault target and intersected anomalous gold in two of the drill holes. The best value was 0.43 g/t in hole BE-006. The 1995 drilling was not close enough to intersect the mineralization at shallow depths.
An geophysical survey was conducted in 1995 and consisted of two, widely-separated lines of CSAMT (controlled-source audio-frequency magnetotelluric). The technique of CSAMT measures resistivities but uses a source transmitter located distant to the survey lines. Data from the CSAMT survey has been reprocessed in 2013, using current, state of the art techniques of analysis. Pseudo-sections generated for the two CSAMT lines reveal a resistivity high that is thought to be related to silicification in the bedrock. The resistivity high clearly is coincident with a zone of gold in surface samples and a fault mapped by NBMG personnel.
To date, a total of 164 rock chip samples have been collected at the property. Gold values range from null to 40.8 g/t gold. Ninety-one samples carry less than 0.1 g/t gold; nineteen samples carry greater than 3.0 g/t gold. Only a handful of samples have been analyzed for trace elements. Other than a tendency for silver to be elevated in samples with higher gold, there are no strongly anomalous trace element associations. The figures below include the details of the rock chip sampling and the proposed drill sites to test the Flats and the Hillside target zones.
Sixteen new claims were located at the property in September 2017. The permitting process has been initiated to commence a phased-drilling program in Fall, 2017. The proposed drilling will test the 300-m wide corridor where anomalous surface gold and resistivity-highs are coincident. Drilling is also proposed to further test the west target where gold mineralization is identified at the surface and in deep drill intercepts are thought to be the down-dip extension of mineralized bedrock.