Exploration & Geology

During the 2017 field-season, IDM focused exploration on underground and surface resource expansion drilling, targeting near-mine areas with the objective of increasing reserves and resources to potentially extend the mine-life at the Red Mountain property.

IDM also undertook a significant geologic reinterpretation at Red Mountain which will help guide future exploration outside of the areas of known mineralization and reserves. An updated NI 43-101 resource estimate based on the 2017 drilling and reinterpreted geology at Red Mountain is expected in Q2 2018.

Exploration Upside

  • No significant surface work has been completed on the Red Mountain Gold Project since 1996
  • Glacial ice has retreated throughout the property, including areas adjacent to known high-grade showings, opening up new targets for exploration
  • Ongoing surface work identified multiple prospects including the 2016 discovery at Lost Valley
  • Potential to add high-grade underground resources north of JW Zone and at 141 Zone
  • 16 km trend of prospective geology and mineralized showings
  • Geological analogue to KSM: intrusions along early Jurassic growth faults
  • Widespread > 1g/t gold mineralization similar to Snowfield, Mitchell Deposit
  • The Red Mountain Gold Project has numerous mineralized zones and showings which are open for expansion

The Red Mountain Gold Project has excellent exploration upside with numerous mineralized zones and showings across the Property, Including: Rio Blanco, McAdam, Cambria, Marc Extension, Hartley, Mike and Brad Zones.

Glacial retreat in the southern portion of the Property uncovered IDM’s 2016 Lost Valley discovery, ~4 km southwest of the current Red Mountain resource. Lost Valley is comprised of high-grade veins which assay up to 165 g/t Au, 1,048 g/t Ag and 15.5% Cu. The veins vary in thickness from 5 to 100 cm and are traceable up to a kilometre in strike length. The Mitchell Deposit at Seabridge's KSM Property and Pretvim's Brucejack Mine were partially discovered due to retreating glacial ice over the past couple of decades.  

Regional Geology & Tectonic History

  • The Red Mountain Gold Project is located near the western margin of the of the Stikine terrane
  • Later accretion of outlying terranes added to the coast caused regional deformation
  • The Red Mountain mineral zones lie at the core of the Bitter Creek antiform, a northwest-southeast trending structure created during a complex Cretaceous era deformation event.
Structural and Stratigraphic Setting of Gold Mineralization at Red Mountain (Greig et al., 1994) (Banks Island Gold technical report, 2013)
Structural and Stratigraphic Setting of Gold Mineralization at Red Mountain (Greig et al., 1994) (Banks Island Gold technical report, 2013)
Regional Geology and Structure of Red Mountain (Randell, 2016)
Regional Geology and Structure of Red Mountain (Randell, 2016)
Regional Tectonic History of Red Mountain (Randell, 2016)
Regional Tectonic History of Red Mountain (Randell, 2016)

Property Geology

Sedimentary Units

  • Property underlain by Triassic-aged Stuhini Group sediments, and Jurassic-aged sedimentary / volcaniclastic units of the Hazelton Group.
  • Sequence has been folded along the Bitter Creek anticline, which is the focus of the Red Mountain ore deposits
  • Represents a rapid marine transgression forming a relatively deep seaway between the ancestral North American continent and advancing volcanic island chains
  • Increasing volcanic influence moving up through the stratigraphic sequence
Plan view location of Ore Zones and Showings on the Red Mountain Property (Randell, 2016)
Plan view location of Ore Zones and Showings on the Red Mountain Property (Randell, 2016)
Structural and Stratigraphic Setting of Gold Mineralization at Red Mountain (Greig et al., 1994) (Banks Island Gold technical report, 2013)
Stratigraphic log of major lithologies and there outcrop locales at Red Mountain (Randell, 2016)

Jurassic Porphyry Units

  • Two phases of the Early Jurassic intrusions are exposed on the property; the Hillside and Goldslide Porphyries
  • The two phases are differentiated by mineralogy, texture, and geochemistry and likely represent fractionation and depletion of a shared magmatic source over time.
  • The Hillside Porphyry is a fine to medium grained hornblende – plagioclase intrusive which outcrops mainly around the summit of Red Mountain and along the southeasterly ridge.
  • The Goldslide Porphyry is a medium to coarse grained hornblende, biotite ± quartz intrusive, primarily exposed along the Goldslide Creek, and extending east-west across Red Mountain.

Lost Valley Monzonite

  • Later intrusion, very latest Cretaceous to Early Eocene, exposed in the southern portion of the property
  • Medium to coarse-grained biotite-bearing quartz monzonite, ringed by hornfelsed sediments, which intruded into sulphide-rich Hillside Porphyry
  • Multiple phases of quartz veining have been identified within the intrusion and surrounding hornfels, with abundant coarse-grained pyrite and commonly found along with molybdenite, local chalcopyrite and sphalerite mineralization.
Lost Valley, Red Mountain Property
Lost Valley, Red Mountain Property
K-Fedspar Megacryst in Lost Valley Monzonite Outcrop
K-Feldspar Megacryst in Lost Valley Monzonite Outcrop
Lost Valley Handsamples
Lost Valley Handsamples
Lost Valley Handsamples
Lost Valley Handsamples

Structural Deformation

  • Deformation at property scale is consistent with regional levels
  • Triassic-Jurassic successions are folded, and post-Cretaceous faulting affects all the rock units at Red Mountain
  • The recognition of high-amplitude, post-mineralization, repeating folds has opened up multiple areas to resource expansion
  • Observations in the Lost Valley area indicate a series of north-south trending, low offset, property spanning strike-slip faults that offset and shear a late set of lamprophyre dykes, which are associated with mineralizing structures associated with Reidel Shears and reverse faults.
  • Structures in the main zones (Rick Fault) are regionally accommodated by the findings in Lost Valley.

Mineralized Zones

Marc, AV, JW and NK Zones

  • The Marc, AV, JW and SF Zones are found at the core of the Bitter Creek Antiform
  • Tracing gold-silver ore bodies are crudely tabular with sulphide-rich stockwork vein systems
  • Tracing the folded pattern of the brecciated contact zone, which hosts high-grade, bulk mineable gold mineralization has connected most of our reserves along a continuous horizon
  • Main ore bearing sulphide is pyrite, with gold occurring in its native form, electrum, petzite, and Au-tellurides and locked within sulphosalts
  • Ore zones are generally marked by pyrrhotite and sphalerite halos
  • Pyrite veins typically carry gold grades ranging from 3 g/t to greater than 100 g/t
Coarse Grained Pyrite Veins
Coarse Grained Pyrite Veins
Pyrite Microveins
Pyrite Microveins
Breccia Matrix Pipe
Breccia Matrix Pipe

Alteration Zones of the Hillside and Goldslide Porphyry

  • Alteration is overlapping and gradational
  • Alteration assemblages on the property range from actinolite dominant to quartz stockwork molybdenum copper
  • Alteration weakens in intensity laterally to the southwest
Alteration Thickness Veins Mineralogy of pervasive alteration
Actinolite dominant alteration >150 m Chlorite + Pyrite + Actinolite + Calcite Green to grey K-feldspar + actinolite + chlorite + titanite + albite + pyrite ± pyrrhotite
Tourmaline stockwork 100-300 m Tourmaline + Pyrite + Chlorite + Pyrrhotite Grey K-feldspar + chlorite + titanite + pyrite + tourmaline + pyrrhotite
Pyrrhotite dominant alteration 100-200 m Pyrrhotite + Pyrite ± chalcopyrite ± chlorite ± calcite ± quartz ± sphalerite ± galena Grey to brown-grey K-feldspar + sericite + pyrrhotite + pyrite + chlorite ± tourmaline
Auriferous pyrite + pyrrhotite stockwork 10-50 m Pyrite ± pyrrhotite ± quartz ± chlorite Intense grey sericite + pyrite; mantled by disseminated and veinlet sphalerite + pyrrhotite + pyrite
Pyrite-dominant alteration 100-200 m Pyrite ± calcite ± quartz ± chlorite Cream to tan sericite, pyrite ± calcite ± chlorite ± tourmaline
Gypsum Stockwork <5-100 m Gypsum + pyrite + calcite ± quartz Pale grey sericite + pyrite ± quartz ± K-feldspar
Quartz Stockwork, molybdenum-copper >200 m Quartz + pyrite ± chlorite ± epidote ± magnetite ± molybdenite ± chalcopyrite Green to grey sericite + quartz + pyrite + chlorite + K-feldspar ± epidote ± tourmaline ± magnetite ± hematite
(Rhys et al, 1995, and Thompson, 1994)

Ore and Alteration Formation

  • Alteration and mineralization at Red Mountain were due to influence from hydrothermal systems
  • Development occurred over the following steps:
    • Pre-ore tourmaline alteration
    • Pre/Early-ore stockwork vein development
    • Syn-ore fracture-controlled alteration and mineralization
    • Late/Post-ore fracture-controlled mineralization/alteration
  • Textures and structures developed during these stages are directly related to ore bodies

Deposit Model

Deposit Model

Red Mountain Mineralized Zone Model

Red Mountain Mineralized Zone Model

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