Summary:
Deposit types present in the Toodoggone Region include low and high-sulfidation epithermal gold-silver mineralization, calc-alkalic porphyry copper-gold mineralization, and minor iron or copper (±gold-silver) skarn mineralization.
Low Sulfidation Epithermal Deposits
The epithermal system(s) present at the Lawyers Area is(are) structurally related. Most of the significant epithermal style mineralization occurs associated within a series of deep-rooted subvertical north-northwest trending faults with pervasive zoned wall rock alteration. The Lawyers Group Prospects (Cliff Creek, AGB and Dukes Ridge), also referred to as the Lawyers Area Mineral Resource Zones, generally exhibit low-sulfidation characteristics with intense quartzadularia-sericite alteration within the mineralized zone. Hematite alteration is common within and surrounding the main mineralized and Dukes Ridge and AGB Zones. The mineralization defined at Lawyers lacks the base metal-Au-Ag zonation pattern described by Lane et al. (2018). Base metal minerals and metals are spatially confined to the Cliff Creek deep and Pheonix zones, forming only a minor component of the Lawyers area deposits. The alteration patterns of epithermal veins also do not show regular broad scale chlorite-calcite, smectite, sericite/illite alteration zonation patterns. At Lawyers, potassic (K-feldspar) and silica alteration is generally closely associated with the moderate-high grade gold-silver mineralized zones. Additionally, there is a notable absence of the “chalcedonic blanket” that is typically present in classic low-sulfidation deposits, although this could be due to post-depositional erosion.
High Sulfidation Epithermal Deposits
Historically, it was suggested that the Silver Pond Prospects on the Lawyers Area of the Property hosted high sulfidation style mineralization. However, based on current mapping and prospecting by Thesis, no clear evidence of high sulfidation mineralization has been observed. The mineralization in the Silver Pond North and Silver Pond West Areas appear to be restricted to narrow translucent and banded grey silica veinlets, not unlike those observed at Cliff Creek. Extensive advanced argillic and high sulfidation-style alteration and gangue minerals occur over Silver Pond, including alunite, pyrophyllite, vuggy quartz, and bladed barite. This could suggest the potential for a future discovery of high sulfidation mineralization in this area. A leach zone, which corresponds to extensive clay alteration at surface, appears to be transported down paleo-surface. At lower elevations, the advanced argillic zones occur as discrete northwesttrending subparallel zones. Discrete m-scale secondary silica lineaments, defined by pervasive secondary silica, breccias and goethite/jarosite stockworks and stringers, also occur in northwest-trending zones through the Silver Pond Clay Zone mineralization.
Porphyry Deposits
The Lawyers Area southeast zone displays zonation consistent with porphyry systems as identified in the 2019 soil program, with a Cu-Au core surrounded by Mo halo, VTEM survey radiometric response patterns, high K% results, coincide with the zonation displayed in the soil data, which warrants further investigation.
Skarn Deposits
The Black Lake Alteration Corridor (BLAC) exploration target has been identified as a potential skarn deposit during the 2021 rock sampling and mapping program. Skarn deposits are characterized by hydrothermal fluid interaction with carbonate-bearing host rock regionally associated with porphyries, greisen or other intrusions like those observed on adjacent properties.
Skarns are formed by metasomatism of limestones and dolomites. They are characterized by calc-silicate mineral assemblages and may contain Cu-Au and Zn-Pb-Ag minerals, from Ridley (2013).
Lawyers Area Mineralization
Mineralization in the Lawyers Area is hosted in a sequence of intermediate porphyritic rocks that are divided into mappable units based on volcanic textures and phenocryst assemblage. Key mineralogical identifiers of the mapped units are quartz “eyes”, hornblende with variable modal abundance, and fine-medium grained K-feldspar and biotite. Additional surface mineralization hosted in lapilli tuffs of the Saunder Member in the east-central portion of the Lawyers Area was identified by previous historical work and mapping.
Low to intermediate sulfidation epithermal-style alteration and associated mineralization is most common in the Lawyers Area. The most extensive low sulfidation footprint is in the central and eastern parts of the Lawyers Area, though banded epithermal-style quartz veining is visible sporadically at many of the prospects described above. A km-scale advanced argillic alteration zone, the Silver Pond Clay Zone, occurs northwest of Cliff Creek, amongst the historical work areas of Silver Pond North and Silver Pond West. Mineralization is not observed in the clay at surface; however, zonation of the clays could indicate a possible porphyry center or potential for high sulfidation mineralization at depth.
Low sulfidation style mineralization present in the Lawyers Area trend is structurally controlled, with the main northwest to north-northwest trending faults considered to be fluid conduits and localities of deposition. These faults are interpreted to be syn-volcanic and reflect the volcanic basin geometry in the Jurassic. Dilation during extension and displacement along fault structures resulted in the targeted high-grade mineralized vein shoots, such as those observed at the Dukes Ridge, Cliff Creek and Phoenix Zones. Intersecting fault planes appear to result in a convergence of fluid conduits and concentration of high-grade mineralization processes. Deposits are variably truncated and offset, due to a series of post-mineralization faults.
High-grade mineralization in the Lawyers Area deposit is associated with hydrothermal breccia zones composed of translucent to milky/opaque quartz-chalcedony veins and veinlets with varying concentrations of sooty metallic grey fine-grained sulphides (acanthite, sphalerite, pyrite). The hydrothermal breccia zones generally display intense pervasive potassic alteration that resulted in complete replacement of visible phenocrysts.
Low- to moderate-grade mineralization in the Lawyers Area is associated with quartz veins and veinlets that crosscut the host porphyritic volcanic rocks. The mineralized veins are often banded with quartz, fine-grained sulphides, sometimes with hematite, and rarely native silver, gold, or electrum. Mineralized veins are associated with potassic alteration halos that vary from mm to cm in thickness.
Ranch Area Mineralization
High-sulfidation systems are defined by a direct connection between surficial alteration and acidic, high-salinity, hightemperature fluids derived from underlying magmatic intrusions (Hedenquist and Houghton, 1987).
High-grade mineralization appears to be restricted to zones of intense vuggy silica alteration and hydrothermal brecciation. Hydrothermal breccias are dominated by barite-silica cement and clasts of silicified volcanics. Gold mineralization is strongly correlated to the presence of barite and displays weak to moderate correlation to common trace elements, such as tellurium, bismuth, antimony, arsenic, lead and zinc. The gold-bearing zones have a crudely elliptical shape, which are open-ended along the controlling fault systems for follow-up expansion drilling. In the Bonanza Deposit, some of the gold-bearing zones are considered to have formed by selective replacement/silicification of more permeable tuff units within the volcanic strata. Gold mineralization at Ranch Area is known to occur over a vertical depth range of approximately 200 m, extending from approximately 1,700 m at surface in the Bonanza Zone to approximately 1,400 m in elevation in the Thesis III Zone and is open at depth in several areas.