Summary:
Deposit Type
The Palmer Project is host to VMS-style mineralization. As a group, VMS deposits are stratiform accumulations of sulfide minerals that formed on or near the seafloor by precipitation near a discharge site (or vents) of hydrothermal fluids (Franklin et al., 1981. VMS deposits form polymetallic mineralized bodies and commonly contain economic concentrations of zinc, copper, lead, silver, and gold.
The Project most closely resembles the Greens Creek deposit. However, significant differences exist, most notably the much higher copper/zinc and zinc/lead ratios present at Palmer, which more closely resemble deposits in Noranda, Quebec, or at Kidd Creek, Ontario. Zinc is the dominant base metal at both the Greens Creek deposit (Swainbank et al., 2000) and Palmer. Silver grades are locally similarly enriched but are much lower within the mineral resource area at Palmer than at Greens Creek. Gold grades are commonly elevated at Palmer (e.g., 0.5 to 1.5 g/t) but are lower than the average at Greens Creek (0.12 oz/ton (4.11 g/t)). Barite is common in both deposits and is the dominant gangue mineral for parts of the orebody at the Greens Creek deposit. Deformation at the Greens Creek deposit is much more ductile in style than at Palmer, resulting in sometimes tight and complex folding of the mineralized zones and host stratigraphy at Greens Creek.
VMS Mineralization
The Palmer Project hosts two known VMS deposits: the Palmer Deposit, which consists of the SW and RW Zones, and the more recently discovered AG Deposit, located 3 km to the southwest. Numerous other mineralized prospects and occurrences are also present throughout the property. The various prospects and deposits share similar alteration and mineralogical characteristics, suggesting a large-scale, property-wide, Late Triassic mineralizing event with multiple hydrothermal vent centers.
Six VMS mineralization styles have been identified and are grouped according to dominant mineral assemblages and texture.
Barite Mineralization (Zinc-Rich)
Barite-rich ores contain abundant pale honey-brown, low-iron sphalerite with variable amounts of pyrite, locally minor galena, tetrahedrite, arsenopyrite, and variable concentrations of late chalcopyrite. Barite ores contain >50% barite and 30% to 50% sulfides and resemble some types of black ore in Kuroko deposits (Eldridge et al., 1983). Barite is the dominant gangue mineral. Compositional bands dominated by either barite, sphalerite, pyrite, or chalcopyrite occur locally. This compositional banding is likely primary (by comparison with Kuroko analogs) but may have been enhanced by deformation. The barite-rich mineralized rock grades locally into massive pyrite mineralized rock as sulfide content increases and quartz becomes the dominant gangue. Barite mineralized rock also grades into a barite-carbonate mineralized rock at the upper limits and flanks of SW Zones 1 and 2, with carbonate increasing in abundance at the margins of the lens.
Massive Pyrite Mineralization (Copper-Rich)
Massive pyrite mineralization typically occupies the core of the lens and is dominant in SW Zone 1 and parts of SW Zones 2 and 3. This facies is classified as having >50% sulfide content, typically as pyrite and chalcopyrite with lesser sphalerite and associated minor quartz and/or barite gangue. This mineralization unit resembles the yellow ore of the Kuroko deposits (Eldridge et al., 1983). The massive pyrite mineralization commonly exhibits compositional banding with variable amounts of sphalerite and chalcopyrite. This facies also shows fine-grained, dispersed pyrite followed by later, coarser, anhedral pyrite with remobilized intergranular chalcopyrite or sphalerite.
Semi-Massive and Stringer-Style Mineralization
Semi-massive and stringer-style pyrite ± sphalerite ± chalcopyrite zones stratigraphically underlie and form the feeder zones to massive sulfide mineralization. The semi-massive and stringer mineralization zones consist of 30% to 50% by volume (vol%) and 15 to 30 vol% sulfide, respectively. Pyrite grains occur as very fine disseminated grains and as coarser grains within stringers. Sphalerite and chalcopyrite are also disseminated with pyrite and within stringers. Locally, stratigraphically below SW Zone 1 and 2 massive sulfide mineralization and within the alteration zone, stringer-style mineralization is dominated by pyrrhotite-chalcopyrite, rather than pyrite-sphalerite. This facies is characterized by 50 vol% gangue of quartz and muscovite. The chalcopyrite content ranges from 3 to 15 vol%, with pyrrhotite content up to 40 vol%. Trace sphalerite is present in most samples as dark red, anhedral grains.
Massive Pyrrhotite Mineralization
Massive pyrrhotite mineralization occurs both above and below massive pyrite mineralization and barite mineralization within SW Zones 1, 2, and 3 and generally represents a volumetrically small portion of the mineralized zones. The facies contains >50 vol% sulfide with up to 15 vol% chalcopyrite, up to 20 vol% sphalerite, and <1 vol% pyrite. Chalcopyrite and sphalerite occur within massive pyrrhotite and in fractures in pyrrhotite. The dominant gangue minerals are quartz and carbonate with minor very fine-grained muscovite. Trace hematite and rare molybdenite are present within muscovite-rich patches cross-cutting quartz and sulfide grains.
Carbonate Mineralization
Carbonate-rich mineralization is found at the stratigraphic top of SW Zone 1. Carbonate mineralization typically contains 60 vol% coarse-grained carbonate, with minor quartz, muscovite, and dark green chlorite, up to 35 vol% dark red-burgundy sphalerite, and up to 5 vol% chalcopyrite. Trace amounts of partially replaced (barium-potassium (K)) feldspar are also observed. More massive carbonate contains relatively coarse, subhedral to euhedral, interlocking crystals of calcite (up to 3 millimeters (mm)). Late chalcopyrite stringers cross-cut carbonate as thin veinlets, and sphalerite is disseminated throughout, locally as relatively coarse anhedral to euhedral grains (up to 1 mm) forming aggregates. These rocks appear to be highly recrystallized.
Barite-Carbonate Mineralization (Tuffaceous and Re-Sedimented)
At the margins of SW Zones 1 and 2 (and to a lesser extent in SW Zone 3), there is a mix of carbonaterich and sulfide-rich mineralization; these include a finely layered barite-carbonate-sulfide facies, some sulfide-clast and barite crystal-rich facies, and a variably mineralized tuffaceous and cherty facies. Barite mineralized rock grades outward into a barite-carbonate mineralized rock as the disseminated carbonate content increases and gradually becomes more tuffaceous, with interlayered barite and carbonate laminae.
Above this unit is a weakly mineralized, barite-free tuffaceous horizon. This capping tuffaceous horizon overlies the entire lens and is characterized by weak mineralization, barium-potassium-feldspar, barian muscovite, local albite, and cherty patches/layers, and it is strongly calcareous.
Palmer Deposit
The Palmer Deposit area, previously referred to as the Glacier Creek prospect, is host to the SW and RW Zones semi-massive to massive sulfide mineralization (collectively, the Palmer Deposit) and is exposed on flanks of Mount Morlan. The overall structure of the Mount Morlan host rocks is that of a large, overturned, south-verging anticline with an axial plane that dips moderately to the northeast.
AG Deposit
The AG Deposit, previously referred to as the AG Zone and Nunatak prospect, is located approximately 3 km southwest of the Palmer Deposit on a steep Nunatak between two branches of the Saksaia Glacier. The AG Deposit was discovered in 2017 and is defined by 33 drillholes completed from 2017 to 2019. Most of the more recent understanding of the AG Deposit stratigraphy and mineralization is through M.Sc. thesis work completed by Quinn (2024).