The Santa Fe Project comprises 388 unpatented mining claims, 67 unpatented millsite claims, and 24 patented mining claims in a contiguous block located 12 km east along Nevada State Highway 361 from the town of Luning, Nevada. The claims are held by Gateway Gold (USA) Corp., and Lahontan Gold (US) Corp., wholly owned subsidiaries of Lahontan.
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Summary:
Deposit Types
Gold-silver deposits of the Walker Lane – including those of the Santa Fe Project – fall into the well-known class of epithermal gold-silver deposits (description herein summarized from Hedenquist et al., 2000; John et al., 2018). These deposits form in the upper ~1.5 km of the crust from magmatic hydrothermal systems driven by subvolcanic feederintrusions. Modern active geothermal systems are their present-day analogues. As well as enrichment of the precious metals, Zn, Pb, Cu, Hg, Sb and S typically form subeconomic deposits in these systems but are useful pathfinders to gold and silver. The magmatism in most epithermal districts is subduction-related calc-alkaline and ranges from basaltic to rhyolitic in composition. The epithermal deposits of the Walker Lane mineral belt formed during Cenozoic arc magmatism that resulted from subduction of the Farallon plate beneath North America.
Both the associated volcanism and the hydrothermal systems that form epithermal deposits are typically strongly structurally controlled. Deposit styles vary considerably and include vein, breccia, stockwork, disseminated and replacement, with many individual deposits or districts having multiple styles. Interaction between the causative hydrothermal system and paleo-water tables, as well as chemically and rheologically distinct host rocks, are responsible for much of the observed variation. For example, vein-type deposits with bonanza-grade precious metals may form within a feeder conduit fault while, at the same time, a low-grade disseminated style deposit formed adjacent to the fault within permeable and/or chemically reactive beds.
Copper skarn deposits within Mesozoic basement rocks are a secondary deposit target that has not been widely evaluated at the Santa Fe Project.
Property Mineralisation
Gold-silver mineralisation at the Santa Fe Project is controlled by various interplays of faults (which provided fluid conduits), lithological contrasts (rheological and chemical), intrusive contacts, and structural complexities such as fault intersections and fault jogs. As such, the geometries of individual deposits are variable.
Santa Fe Deposit (Historically Mined)
The Santa Fe deposit is hosted within the Santa Fe Fault Zone in limestone of the Luning Formation. The deposit occurs at the intersection of the Santa Fe Fault Zone and the Calvada fault where the strike of the Santa Fe Fault Zone deflects from northwest to west-northwest. This change in orientation may be controlled by the Todd Mountain stock which seemingly acted as a relatively rigid block and between the contact of the TRl4 and underlying TRl2 and TRl3. Two styles of mineralisation occur at Santa Fe deposit – narrow zones of steely-dipping gold and antimony-rich jasperoid which occurs along faults and dyke contacts, and pyrite-rich siliceous limestone breccia.
The BH Zone is an unmined extension of the Santa Fe deposit southeast of the pit that is suspected to be the down-plunge extension of the deposit. Locally high-grade gold mineralisation is associated with colloform-banded veins containing abundant arsenic-rich pyrite and marcasite that characterize the BH target.
Most of the historically mined portions of the Santa Fe deposit occurred within the oxide and transitional oxide portions of the deposit at depth. Sulphide abundance increases towards the southeast and shallows towards the BH Zone.
Slab Deposit (Historically Mined)
The Calvada West deposit (also known as Slab) occurs in the central part of the property and was (i.e., pre-mining) marked at surface by a north-northeast to north-trending silicified ridge comprised of dark sulfide-bearing jasperoid that replaced basement rocks and exposed Luning limestone. The location of the deposit is controlled by an interplay of the Calvada fault, a subsidiary north to north-northeast fault, and the unconformity between the Luning formation limestone and overlying Tertiary Lavas of the Giroux Valley formation. Post-mineral faulting has also introduced minor offset within portions of the deposit. The Slab deposit is a shallowly dipping antiform that plunges to the northeast at 010°. The Slab deposit consists of three zones: an upper, middle, and lowe zones. Historical mining occurred within the uppermost zone and areas where the mid and upper zones are within proximity to another. The upper zone’s thickness ranges from 3 m to 40 m and averages 10 m thickness. The mid and lower zones are more discontinuous and thinner, ranging from 3 m to 20 m and average 6 m thickness. The Slab deposit occurs as oxide based on ratios of cyanide leach to fire assay ratios and logged sulphide abundance.
Calvada Central Target
The Calvada Central target occurs along the east-west trending Calvada fault midway between Calvada West and East. Mineralisation occurs within the Calvada fault zone and in the Luning limestone in jasperoids focused along the unconformity with the overlying Tertiary Lavas of the Giroux Valley. The Calvada Central target occurs as two jasperoid lenses of variable thickness. The Hangingwall jasperoid lens occurs nearthe unconformity and is generally thicker and higher grade than the footwall lens. Multiple historical drill holes and recent drilling completed by Lahontan at Calvada Central returned anomalous gold results(Table 7-1). The drill hole intervals summarised in Table 7-1 represent 70% to 90% of true thickness. The target dips approximately 50 degrees to the north and has been drill tested along 400 m of strike length with variable width along strike. The Calvada Central target occurs as oxide based on ratios of cyanide leach to fire assay ratios and logged sulphide abundance.
Calvada East Deposit (historically mined)
Calvada East is an east-west trending, steeply dipping arcuate zone marked by gold-bearing dark jasperoid within proximity to the Calvada fault. The hanging-wall is comprised of the Lavas of the Giroux Valley, which overlies or is in contact with the mineralised Triassic Luning formation limestone. Mineralisation occurs near the contact of the two units along the Calvada fault zone. The footwall of the Calvada East deposit consists ofstrong clay-altered quartz monzonite intrusive rocks analogous to the Cretaceous Todd Mountain intrusive suite. The Calvada East deposit measures approximately 500 m along strike and ranges from 3 m to 50 m thickness and averages 20 m in thickness. The Calvada East Deposit occurs as two separate jasperoid lenses that intersect within the central portion of the Calvada East deposit where the thickest portions of the deposit have been historically mined. The deepest drilling at Calvada East has encountered transitional oxide and non-oxide mineralisation based on ratios of cyanide leach to fire assay ratios and logged sulphide abundance.
York Deposit (historically mined)
The York deposit occurs within the Triassic Luning formation that has been locally recrystalised to marble. The historically mined portions of the York deposit occur along a northeast striking, steeply dipping faultsthat is interpreted to be an offset portion of the Calvada fault. The York deposit