Summary:
The Shovelnose Property is underlain by late Triassic Nicola Group volcanic and equivalent-aged intrusive rocks and early-late Cretaceous Spences Bridge Group volcanic rocks of the Pimainus Formation, unconformably overlain by resistive mafic volcanic rocks of the Eocene Princeton Group exposed to the northeast. A series of small potassium feldspar-phyric syenite bodies and mafic dykes intrude into and cross-cut the volcanic stratigraphy. Outcrops are generally small and most abundant on topographic highs.
Deposit Type
The Shovelnose Gold Property hosts high-grade low sulphidation epithermal gold and silver mineralization within subaerial volcanics of the 215 km long north-northwest trending mid-Cretaceous Spences Bridge Group.
The Franz, FMN, Tower, South and Othello Zones represent an expression of the primary vein system, which extends for >4 km. Immediately adjacent to this feature, and fairly well tested by drilling, are the Alpine, Lear, Line 6 and Mik Zones. Other zones of current exploration interest, that are situated farther from the primary vein system, are Romeo (4 km to the east) and Certes (6 km to the southeast). Mineralization in these zones occurs as structurally controlled gold-silver bearing quartz vein and quartz breccia zones.
Franz Zone
The Franz Zone is located to the northwest of the FMN Zone, 2.8 km west-northwest of the South Zone. Surface exposures represent an 80 m x 20 m outcrop of quartz veined rhyolite oriented at 110°/290°). The veining dips steeply to the southwest, similar to other veins in the general Franz-FMN-South Zone trend.
The Franz Zone is comprised of mineralized hydrothermal quartz breccia, hosted in a sub-vertical rhyolite dyke cutting through a rhyolite tuff underlain by a dacite/andesite flow package. At depth, a lower sequence of epiclastic conglomerate marks the contact between the overlying Spences Bridge Group and the basement, composed of granodiorite of the Nicola Group.
FMN Zone
The FMN (Forget Me Not) Zone is located northwest of the Tower Zone. FMN was identified initially during prospecting activities undertaken by a past operator (Strongbow) as being of potential exploration interest, based on a local weak soil anomaly. FMN appears to have developed along the major northwest-southeast trending strike-slip structure hosting South Zone, and is interpreted to be an extension of that vein system.
Tower Zone
The Tower Zone is located northwest of the South Zone and west of the Alpine Zone, ~1,200 m south of the cell/radio tower on the summit of Shovelnose Mountain. Tower consists of a near-surface flat-lying permeable lithology comprising limonite-stained felsic crystal lithic tuffs that have been intensely silicified from surface to a depth of ~60 m. These tuffs are underlain by non-mineralized heterolithic tuffs and rhyolite flows. Silicification is pervasive and (or) localized along fractures and vuggy/drusy cavity fillings to the west, and occurs within stockwork and veins to the east.
South Zone
The South Zone is located near the southeast end of the main mineralized trend on the Property. Host lithologies are rhyolite tuffs and flows, and mafic basement rocks (heterolithic tuff, andesite tuff and andesite flow). The highest-grade gold mineralization occurs over a 300 m vertical range in a shallow paleo-horizon (~1,050 to 1,325 masl) of boiling that features colloform-cruciform banded quartz veins containing adularia bands and selvages, bladed quartz after calcite, ginguro, and electrum. Deeper veining (below ~1,050 masl) features barren massive to weakly banded quartz with crystalline potassium feldspar.
Othello Zone
The Othello Zone (formerly Southeast Extension) lies immediately southeast of the South Zone and hosts the interpreted extension of Vein Zone 1a. Surface occurrences of hydrothermal brecciation and quartz veining identified during past field programs are underlain by two vein zones ~40 m wide consisting of quartz ± adularia veinlets hosted in fault-bounded blocks of rhyolite tuff, andesite and minor rhyolite. Where mineralized, these vein zones feature high silver to gold ratios suggesting deeper depths of formation below the horizon of boiling and dominant gold precipitation.
Mineralization
Mineralization at the Shovelnose Gold Property - South Zone is typical of low-sulphidation epithermal systems in subaerial volcanic rocks.
Mineralization in the Vein Zones of the South Zone is dominated by ginguro, a cryptocrystalline, unsorted, amalgamated sulphide dust that precipitates as black, mm-scale bands along crustiform and colloform bands in vein zones. Ginguro typically occurs as black bands, and locally may be discreet amalgamations of crystals. Sulphides present are chalcopyrite, electrum, naumannite, sphalerite, galena, pyrite and marcasite, with minor amounts of acanthite, aguilarite, tetrahedrite, greenockite (or hawleyite), Au-Ag selenide, hessite, pyrargite and miargyrite. Pyrite ± marcasite occur in association with veining, however, generally occur peripheral to main vein zones and are limited in extent. Visible massive or crystalline sulphides are very rare at the South Zone.
Primary mineralization textures are typical of epithermal vein systems with crustiform-colloform chalcedony and quartz textures. Crustiform components are the successive bands oriented parallel to vein walls, defined and distinguished by contrasting mineralogy, texture, and (or) colour. This banding is due to fluctuating contents of metals in solution and fluctuating fluid conditions during precipitation, caused by periodic boiling. The colloform components are fine rhythmic bands with a lobed, reniform (kidney-shaped) surface, and commonly an internally radiating form. Strong surface tension of the silica gel is responsible for the lobed, reniform external surface that is characteristic of colloform veins. Cockade textures are also observed locally and the terminology is restricted to crustiform bands that surround isolated rock (breccia) fragments. The comb texture is manifest by open-space growth and unidirectional growth of individual crystals nucleated on vein wall(s), giving rise to syntaxial or monotaxial veins. Moss texture is a recrystallization texture, whereby an original spheroidal gel texture recrystallized to chalcedony or quartz, and is indicative of very high degrees of silica supersaturation.
The electrum is intergrown with pyrite, chalcopyrite, sphalerite, galena and a variety of sulphosalts in trace amounts. The silver selenide naumannite (Ag2Se) is the most common sulphosalt observed with electrum. Aguilarite (Ag4SeS) was also observed. Native silver was observed enclosing electrum. These minerals all occur as complex composite grains generally <50 um in size and commonly much finer grained. Numerous grains <1 um in size occur around larger grains, in the ginguro bands, and in the more diffuse clots.
Galena can contain a small amount of silver, or possibly includes a silver phase too fine-grained to observe. Enargite (Cu3AsS4) is the main sulphosalt phase. Eckerite (Ag2CuAsS3) and a silver telluride, possibly hessite (Ag2Te), were also observed.
In addition to the precious metal mineral phases, fluorapatite was observed to be intimately intergrown with sulphides, specifically pyrite in several samples. Selenium, mostly the arsenic end-member with minor antimony substitution in a few analyses, occurs in naummanite and aguilarite with electrum throughout the system. Vein carbonate is ferroan dolomite, with very minor Mn content. Clay and sericite occur as < 10 um size masses of scaly flakes interstitial to quartz in cloudy bands.