The Big Ten project is located along the northern margin of the of the Walker Lane belt in west-central Nevada. It occurs in an extensional, Tertiary-aged rhyolite volcanic centre analogous in age and setting to the Round Mountain gold mine located approximately 50 km’s to the northwest where cumulative and ongoing mine production now exceeds 18 million ounces of gold (Kinross Gold Corporation), and to the past producing Paradise Peak gold deposit located 110 km’s to the northwest, operated by FMC Mining Corp. between 1986 and 1994.
Based on reconnaissance surface exploration and airborne magnetic, radiometric and hyperspectral surveys, the Company now owns seven properties along the 20 km length of a structural corridor and mineral trend which transects the entire Big Ten caldera, and is parallel to the eastern margin of the Walker Lane belt. There is ample evidence for focused alteration and gold and silver mineralization along the entire 20 km length of the controlling structure. As such, the Big Ten volcanic center is clearly fertile for gold, and its potential is underscored by the gold endowment of the next volcanic center to the north at Round Mountain. VR’s land position on the Big Ten trend affords the unusual opportunity to explore and evaluate a complete epithermal gold system, both laterally and vertically.
There are scattered historic workings in the region, active between the 1900’s and 1930’s, but modern exploration is limited to early-stage surface sampling and a reverse-circulation drilling program in the early 1980’s by Amselco at the Danbo and Amsel properties. Overall, the properties in the Big Ten project are remote and underexplored using modern epithermal gold exploration technologies, but there is road access for cost-effective exploration.
The Big Ten project is located in Nye County in west-central Nevada. It is in the southern part of the Monitor Range, approximately 50 kilometres northeast of Tonopah.
Cost effective exploration is afforded by road access to the property on Highway 82, with actively used historic ranch and mine roads throughout the property connecting it to the highway.
Topography is mountainous. The main workings at the Danbo property are at an elevation of 7,900 feet, with surrounding ridges and rounded peaks exceeding 8,800 feet. Sub-alpine bowls are grassy rangeland with scattered sage and stunted pine and juniper in some places.
Outcrop is extensive in the sub-alpine areas. Where there is cover, colluvium is interpreted to be thin and local in nature. Soil profiles are poorly developed; fine, light brown colluvium normally gives way to more rubbly-weathered outcrop material within a metre of depth, or less.
The Company now owns seven properties along the 20 km length of the Big Ten mineral trend. The properties comprise 117 claims in total, covering 2,417 acres. Each property is a single, contiguous claim block. The individual properties include:
- Hat Peak: 4 claims, 83 acres; large sericite/pyrite alteration halo; surface gold geochemistry; possible large-scale porphyry root.
- Kano: 3 claims, 62 acres; distinct hyperspectral anomaly occurring on USGS mapped rhyolite intrusive; surface gold geochemistry.
- Fisher: 4 claims, 83 acres; historic gold production in caldera-rim volcanic meg-breccia.
- Amsel: 66 claims, 1,363 acres; large airborne radiometric anomaly (potassium) 2 x 3 kms in size with a robust gold-silver-tungsten-moly’ soil anomaly occurring in the southwest quadrant and correlated with an integrated IP and resistivity anomaly covering 700 x 900 metres; overall, Amsel is a hilltop of silica-adularia altered volcanic tuff and tuffisite with gold and silver - bearing quartz vein stockworks and quartz vein breccia with the potential for a large tonnage epithermal gold system comparable to the Round Mtn. deposit which occurs below and within adularia alteration of rhyolite volcanic rocks that are the same age as Big Ten, in the next volcanic caldera located 45 kms to the north.
- Danbo: 21 claims, 434 acres; gold at surface in 3 quartz vein sets with 1.3 km strike.
- Clipper: 17 claims, 328 acres; gold in multiple quartz vein sets across 1.5 km width.
- Little Joe: 2 claims; 41 acres; southern extension of gold-bearing quartz veins at Danbo and Clipper properties
The properties are on federal land (BLM), within the Toiyabe National Forest managed by the federal National Forest Service. The properties are outside of the BLM’s broadly defined area of sage grouse protection.
The properties are owned 100% by VR, registered to the Company’s wholly-owned, Nevada-registered US subsidiary Renntiger Resources USA Ltd. There are no underlying annual lease payments on the property, nor are there any joint venture or carried interests on the property. There is a 3% net smelter returns royalty on the Danbo property, and a 2% net smelter returns royalty on the Amsel property.
Overall, the Company continues to synthesize and integrate regional and property-scale data from the Big Ten corridor for ongoing exploration targeting.
VR has completed numerous reconnaissance surveys and detailed field programs on the various properties within the Big Ten project, starting in the fall of 2016. Work includes:
2016 (Danbo Property)
- Geological mapping of Tertiary volcanic stratigraphy, and structural mapping of the gold-bearing epithermal quartz vein system;
- Alteration mapping in the field, aided by systematic collection of 43 samples of vein outcrops for SWIR spectral analyses (TerraSpec mineral reflectance alteration mapping);
- Soil sampling: 96 samples on 50 metre stations on 6 lines covering 800 m strike length of the vein system;
- Ground magnetic survey: 16 lines, 600 m long, on 100 spacing, for 9.6 line-kilometres covering an overall area of approximately 1.6 kilometer by 600 metres, covering the entire known vein system.
2017 (Danbo Property)
- Airborne Hyperspectral survey for mineral alteration mapping covering 3 x 1.5 km area: 3 metre pixel resolution; Level III processing and interpretation;
- Soil Sampling: 49 additional samples to extend and infill existing samples; and
- Rock sampling for geochemistry: 59 samples
2018 (Big Ten Project)
An airborne magnetic and radiometric survey, and an airborne hyperspectral survey used to map alteration minerals were completed in June 2018, covering the Amsel property and the northern part of the Big Ten mineral trend:
- Helicopter-borne, high resolution magnetic and radiometric survey covering 8 x 10 km block: 108 lines at 100 m spacing for 912 line-kms;
- Fixed-wing hyperspectral survey covering 10 x 12 km block centered over the airborne magnetic survey block; 15 flight lines, 1m pixel resolution, Level III processing and interpretation;
- Based on the results of the airborne surveys, VR completed a nine-day field program of reconnaissance – level and detailed geological mapping, prospecting and rock sampling along the Big Ten trend (54 samples).
A one-week follow-up program of geological mapping and prospecting was completed later in the fall of 2018, during which an additional 28 rock samples were collected.
2019 (Big Ten Project)
VR completed a one-week surface program of grid-based geological mapping and grid-based sampling over the entire silicified hill top and radiometric anomaly at the Amsel property in August, and again in October, 2019. Work included:
- Outcrop-scale, grid-based geological mapping and sampling of quartz veins and fractures
- 57 samples for geochemistry;
- 7 samples for plain light and reflected light petrography;
- 2 samples for geochronology.
- Grid-based soil geochemistry for gold, silver and epithermal trace element indicators: 165 samples from 100 metre-spaced stations on 10 lines covering the 1.8 x 2.2 km are centered on the airborne potassium anomaly and coincident silicified hill top;
- Rock geochemistry and alteration mineral mapping by SWIR and LWIR mineral reflectance on individual rock samples from 135 stations on the soil grid, by TerraCore based in Reno, Nevada.
Geochemical data obtained from this work identify robust, integrated anomalies in gold and silver, trace element indicators arsenic and antimony, and high temperature elements molybdenum, tungsten and lead. Together with occurrences of the high temperature alteration minerals adularia and muscovite, there is a clear exploration vector for the center of the overall hydrothermal gold-silver mineralizing system at Amsel in the southwest quadrant of the 2 x 3 km airborne radiometric anomaly and corresponding surface alteration zone.
Because gold is associated with fine-grained sulfide in epithermal quartz veins and quartz vein breccia throughout the Big Ten mineral trend, the Company designed and executed a 3D, DCIP ground geophysical survey in November, 2019, to cover the entire airborne radiometric anomaly and related multi-element geochemical anomaly and quartz-adularia alteration cap at Amsel:
- 6 lines @ 3.2 kms long and 200m line-spacing for 19 line-kms in total in a grid area of 3.2 x 1.2 kms
- 100 m stations, with separate surveys run on pole-dipole & dipole-dipole configurations;
The IP survey images resistivity and chargeability features to a depth of 500 m below the hilltop at Amsel, within a 3D modeling space of 2.2 sq-kms. Changes in resistivity are related to secondary quartz and adularia alteration, and chargeability anomalies are targeted for pyrite-bearing gold-silver epithermal quartz veins and quartz vein breccia stockworks.
The results of the IP survey are clear. There is a large, near-surface high resistivity anomaly covering a 700 x 900 m area in the southwest quadrant of the 2 x 3 km radiometric anomaly and surface alteration zone at Amsel. It is directly co-spatial with high temperature adularia and sericite alteration minerals in rocks mapped on surface, and with the strongest multi-element soil geochemical anomaly in gold and silver within the 2x3 km survey grid, and including high temperature minerals such as rubidium, tungsten and molybdenum. Further, the high resistivity cap is directly above an underlying IP anomaly which extends from surface through the 500 m vertical extent of the 3-D inversion block model. The target at Amsel is a large volume of pyrite - bearing quartz vein stockwork and quartz vein breccia with gold and silver mineralization extending from surface to depth in altered rhyolite tuff and tuffisite.
The Big Ten caldera is a Tertiary-aged volcanic complex some 20 kilometres in diameter and located near the eastern limit of Tertiary-aged extension, volcanism, plutonism and faulting which define the Walker Lane Belt in west-central Nevada. The Round Mountain (18 M oz gold) and Manhattan (800,000 oz gold) epithermal gold deposits occur in similarly aged rhyolite caldera centers immediately to the northwest of Big Ten. The low-sulfidation character of the hydrothermal gold-silver quartz veins at Big Ten is also similar to Round Mountain.
The various properties occur along/within a northwest-southeast trending structural corridor which transects the entire Big Ten caldera. The trend of occurrences of epithermal gold-bearing quartz veins is referred to as the Big Ten mineral trend.
There is a consistent volcanic stratigraphy of welded and non-welded rhyolite tuff common to the mineral properties along the Big Ten trend. Certain tuff units are prospective for quartz vein deposition based on relative permeability. Aphanitic and porphyritic rhyolite and trachyite dykes and plugs are mapped at the Amsel and Hat Peak properties. Some dykes are coeval with epithermal alteration and mineralization, and some dykes post-date the epithermal fluid event.
There are common elements to the various occurrences of alteration and mineralization along the Big Ten trend. These attributes collectively strengthen the exploration model for the Big Ten mineral trend, and enable VR to explore and evaluate a complete epithermal gold system, both laterally and vertically. Salient features of the trend include:
- The three central properties all occur near regional-scale discordances, that is, offsets in the northwest-southeast trending Big ten structural corridor;
- Individual quartz veins on all three properties are subvertical and northwesterly striking, parallel to the Big Ten trend itself;
- The style of mineralization is that of a low-sulfidation epithermal system, but gold and silver values are commonly highest in samples with visible sulfide (pyrite): 1-5%; fine grained; disseminated to blebby; bright coloured and commonly euhedral;
- Evidence for multiple phases of hydrothermal fluid pulsing is common and includes quartz veins with open space vugs lined by drusy quartz, banded quartz-adularia veins with colloform texture, and quartz-sulfide linings on vein breccia fragments or lithic tuff fragments in vein breccia and/or tuffisite with a pervasive quartz-adularia alteration of groundmass and fragments, and sericite overprint;
- Quartz veins do not occur in isolation, but in quartz vein sets across several hundred metres, with greater than one kilometre of strike length at Danbo and Clipper;
- Quartz vein sets are commonly associated with obvious zones of silicification, including a broad topographic hill of quartz-adularia-sericite alteration in bleached rhyolite tuff at Amsel, and distinctive, resistant ribs silicified rhyolite northwest of Amsel and at Clipper.
Danbo is an epithermal gold prospect hosted in a sub-horizontal Tertiary pyroclastic sequence of rhyolite lapilli tuff and ash flow tuff. The volcanic stratigraphy exposed on the Danbo property consists of 4 well-defined felsic pyroclastic units. The pyroclastic units are sub-horizontal and do not show evidence of major faulting. No vertical or horizontal translations are evident across the major veins transecting the property.
A series of northwest-striking epithermal quartz veins can be traced across a north-trending valley incised into the pyroclastic sequence for approximately 1,500 m of strike. Three or four distinct zones of veined tuff are mapped across an overall width of 300 to 400 metres, with an additional zone inferred from soil geochemistry and hyperspectral surface alteration data implying a width of 1.1 kilometres. Individual veins are centimetres to decimetres wide, with metre-scale zones of quartz vein breccia in the central part of the property. Narrow (less than one meter), white weathering, crystalline mica-bearing argillic alteration halos are evident at most vein outcrops.
Drusy quartz in open space is nearly ubiquitous along the 1,500 m strike length. Bladed quartz after carbonate is also common, evidence of hydrothermal boiling in the high-level, low-sulfidation epithermal vein system at Danbo. Banded, colloform textures, vuggy open space with drusy quartz, and vein breccia with quartz-lined fragments are observed in the topographically lowest, central part of the property.
The quartz veins generally contain trace to 1%, fine grained sulfide minerals as disseminated grains and blebs, most commonly a bright coloured euhedral to subhedral pyrite. Base metals are not present in Big Ten quartz veins. Gold-silver ratios in mineralized samples with visible sulfide are typically 10:1 or less. At Amsel, the gold-silver quartz veins are within a large silica-sericite alteration cap which is anomalous in gold and silver, the epithermal trace element indicators arsenic and antimony, and the high temperature elements bismuth, tungsten, lead and molybdenum.