Summary:
The Goliath Gold Complex is comprised of three projects, namely: the Goliath project, Goldlund project and Miller project.
Deposit Types
The Goliath Project hosts a hybrid deposit-type model, also known as a “Pre-orogenic Atypical Greenstone Belt Gold Model” as a promising genetic model to explain the geology, structures and mineralisation observed within the Goliath deposit. In this model, early gold-rich volcanogenic sulphide mineralisation is overprinted by subsequent deformation and alteration events which can contribute to further concentration and/or remobilising of both precious and base metals. This model also integrates potential VMS and Magmatic Hydrothermal Archean Lode Gold Deposit (“Magmatic Hydrothermal”) models in the formation of the deposit. It is likely that the Goliath deposit does not fit into any one idealised model and neither should be discounted.
The Goldlund Project hosts Archean, shear zone-hosted quartz vein mineralisation (Archean lode- gold), occurring as extensional quartz vein systems, particularly between rocks with high competency contrast. Archean lode-gold deposits occur in a broad range of structural settings, and at different crustal levels, but they share a similarity in ore fluid characteristics. Mineralisation is typically late tectonic, occurring after the main phases of regional thrusting and folding, and generally late-syn to post-peak metamorphism with most of the significant deposits in areas of greenschist facies. Many deposits are related to the reactivation of earlier structures.
Gold mineralization at Miller is similar to Archean shear Zone hosted quartz vein model (Archean lode gold). The Archean lode gold occurrences are common in the Sandy Beach Lake – Sioux Lookout area and are concentrated in the Southern and Central volcanic belts.
Goliath Deposit Mineralization
At Goliath, the gold-bearing zones all strike from 090° to 072° with dips that are consistently 72° to 78° toward the south or southeast. The main area of gold, silver and sulphide mineralization and alteration occurs up to a maximum drill-tested vertical depth of approximately 805 m (TL135) below the surface, over a drill-tested strike-length of approximately 3,000 m within the current defined resource area. Gold mineralized zones remain open at depth.
Native gold and silver are associated with finely disseminated sulphides, coarse-grained pyrite and very narrow light grey translucent “ribbon” quartz veining. The main sulphide phases are pyrite, sphalerite, galena, pyrrhotite, minor chalcopyrite and arsenopyrite and dark grey needles of stibnite. The alteration consists of primarily sericitisation and silicification in association with the gold mineralisation.
The mineralized zones are tabular composite units defined on the basis of moderate to strongly altered rock units, anomalous to strongly elevated gold concentrations, and increased sulphide content and are concordant to the local stratigraphic units.
In the Goliath deposit, high-grade gold mineralization and silver occur in shoots with relatively short strike-lengths (up to 50 m) that plunge steeply to the west.
Goldlund Project Mineralization
Gold occurs in essentially two types of deposits in the Goldlund area. The most important gold mineralization is associated with quartz vein and stock-work structures, which are found in albite-trondhjemite sills, as well as in porphyry sills and mafic metavolcanic rocks. Trace to minor quantities of gold (and silver) are found in disseminated and massive sulphide deposits (copper-nickel, copper-zinc) in metavolcanic rocks.
Gold mineralization is hosted by zones of northeast-trending and gently to moderately northwest-dipping quartz stockworks, comprised of numerous quartz veinlets less than 1 to 20 cm thick. These stockwork zones form bands within the sills that intrude the east-northeast-trending mafic metavolcanic rocks. The quartz veins and veinlets contain occasional fine-grained to coarse-grained pyrite. The intervening areas between the quartz veinlets exhibit strong to moderate feldspathic alteration associated with common fine to medium-grained pyrite and magnetite.
The mineralized sills strike generally northeast (065°) and dip steeply to the southeast. The quartz stockwork veins at Goldlund consist of two synchronous sets of veins, referred to as the 20 set and the 70 set (Pettigrew, 2012). The gold bearing veins display a remarkable consistency in form across the project. Although locally they may differ by up to ± 20° in strike and dip, overall, they are a very consistent 239°/58°N (70 set) and 189°/53°W (20 set) orientation.
Miller Project Mineralization
The Miller project is situated approximately 8 km northeast and along strike of the Goldlund project. Similar to the Goldlund deposit, the gold mineralization at the Miller deposit “is hosted by zones of northeast-trending and gently to moderately northwest-dipping quartz stockworks, comprising of numerous quartz veinlets less than 1 to 20 cm thick. These stockwork zones form bands within the sills that intrude the east-northeast-trending mafic metavolcanic rocks. The quartz veins and veinlets contain occasional fine-grained to coarse-grained pyrite. The intervening areas between the quartz veinlets exhibit strong to moderate feldspathic alteration associated with common fine to medium-grained pyrite and magnetite” (WSP, 2020).
The gold mineralisation has been interpreted as a series of nine northeast-trending subparallel zone wireframes, considering a nominal 0.1 g/t Au threshold. Wireframes of Zones 1, 7, and 5 consist principally of gold mineralisation associated with the stockwork veins in the large granodiorite sills, while wireframes of Zones 2, 3, 4, 6, 8, and 9 consist of gold mineralisation associated with stockwork veins that are hosted in several lithologies including andesite, and felsic to intermediate porphyries, with only a minor contribution from the granodiorite sills.