Summary:
Gold-bearing quartz veins at the property are hosted by Ordovician metavolcanic and metasedimentary rocks of the Catchers Pond Group. The style of veining, mineralization, alteration, host rock, and tectonism most closely resemble other mesothermal volcanic-hosted (greenstone belt) gold deposits throughout the world.
The most important and well-defined gold deposits include the Hammerdown, Rumbullion, Muddy Shag and Orion deposits, which all occur within the Hammerdown Deformation Zone (HDZ). The HDZ is described has a 100 m to 250 m wide structural corridor of strong ductile to brittle shearing hosted in the uppermost units of the Catchers Pond Group. The historic Lochinvar VMS base metal deposit also occurs in the HDZ along with the Golden Anchor gold veins and Beetle Pond VMS alteration zone.
Hammerdown-Rumbullion-Muddy Shag Vein System
The Hammerdown-Rumbullion-Muddy Shag-Wisteria gold systems consist of both a series of stacked gold veins as well as a zone of broadly disseminated to veinlet hosted gold and pyrite mineralization. Both styles of mineralization are hosted within an 1,800 m long shear zone informally referred to as the HDZ. The vein system is now considered to be a single deposit however, historical definition drilling has identified internal faults that have served to segregate the veins into several mineralized domains.
Geologically, the Hammerdown deposit is situated close to the contact of a Lower Ordovician mafic sequence of ophiolitic origin with an overlying felsic island arc sequence. The contact area was uplifted, folded and intensely sheared, then invaded by early Silurian quartz feldspar porphyry dykes, which were closely followed by the gold-bearing quartz-sulphide veins.
A structural interpretation by Szybinski (internal unpublished report 2003), defined the deposits as being located within a high-strain shear zone that has experienced a prolonged and intense deformational history. At least four major deformational events were determined that shaped the present geometry of this shear zone. Detailed interpretation of the deposits concluded that the Captain Nemo Fault and the Rumbullion Fault represent only smaller segments of much larger and complex fault system. This fault system is characterized by an intricate pattern of en-echelon faults and shears that step right and are oblique to the general trend of the entire system, producing a number of fault-bounded panels containing different slices of the host stratigraphy.
Szybinski described the complex pattern of faults and veins as similar to the strike-slip duplexes of Woodcock and Fisher (1986), which form in 3-D in releasing and restraining bends along faults. The overall geometry of the fault system is characteristic of a contractional duplex or fan formed in a dextral strike slip.
At depth, the entire shear zone, including most gold zones, are cut off by the extensive Captain Nemo Fault, which is a north dipping, normal fault with some strike slip movement. Geological interpretation indicates down drop of the Hammerdown area to be several hundred metres. As the Captain Nemo Fault cuts through the Hammerdown shear at an oblique angle, veins are cut off at depths varying from 150 m to 250 m. Several of the veins appear to pinch out naturally before reaching the fault. During Richmont mining operation (2000 to 2004) cataclastized mineralized material was partly mined from the fault zone.
The Rumbullion Fault, a north-easterly trending right lateral fault, defines the boundary of the Hammerdown designated veins from the Rumbullion veins to the east. To the west, the Hammerdown vein system pinches out at a strong flexure in the shear zone which rotates the shear from east-west at Hammerdown to the southwest. This southwest trending shear extends for several hundred metres and hosts the Muddy Shag gold zone.
The more robust veins in the Hammerdown zone are closely associated with the most extensive of the late quartz feldspar porphyry (QFP) dykes near the top of the hanging wall overturned mafic sequence. Hanging wall veins are hosted in the mafic rocks, and limited drilling into the footwall has identified mineralization hosted in older footwall felsic units. Younger porphyry dykes are only erratically associated with mineralized veins in both footwall and hanging wall locations.
In the Rumbullion and Muddy Shag zones veins at this stage appear to be less numerous and narrower, possibly due to the lack of more extensive QFP intrusions.
The gold-bearing veins throughout the mineralized system consist essentially of vein quartz with 5% to 20% pyrite occurring as massive stringers and dense disseminations. Base metal sulphides total about 1%, with zinc content equaling combined copper and lead values. Minor bismuth occurs as native metal as well as the sulphosalt hammarite.
Gold is intimately associated with all sulphide phases, occurring as discrete grains within sulphides, at sulphide grain boundaries and, occasionally in quartz fractures near sulphide grains. There is a direct relationship between sulphide content and gold grade in veins. The gold is always fine grained, with 80% being of grain size less than 20 µm. The largest grain size is slightly over 100 µm along the long axis; relatively little visual gold occurs in the deposit.
In addition to quartz, gangue minerals include chlorite and carbonate (calcite and ankerite) with minor rutile. Hydrothermal alteration of mafic wall rocks consists mainly of muscovite/sericite and calcite, with minor rutile, creating a light bleaching halo usually similar in thickness to the gold-bearing vein.
Hammerdown Gold Veins
At Hammerdown, the more robust main veins are located along the north and south contacts of a fairly continuous, sill-like felsic porphyry body intruding the sheared mafic volcanic host. The veins dip predominantly to the north although at depth they rotate to a steep southerly dip due to drag folding has they near the Captain Nemo Fault. The veins also appear to plunge to the west but high-grade shoots within the plane of the vein plunge steeply to the east. These larger veins were the target for the 2000 to 2004 cut and fill mining phase by Richmont and have therefore been predominantly mined out, however the updated wireframes in this report have determined that some of the veins remain at the peripheral edges of the historical mining, probably due to the higher cut-off grade used at the time in defining mining blocks.
The Hammerdown hanging wall veins to the main veins mostly occur in less deformed mafic volcanics with a minor iron formation component and leucoxene-bearing mafic dykes. Felsic porphyry sills are present but smaller and do not seem to influence the location of the veins like the larger QFP associated with the larger main veins. The hanging wall veins generally do not have the same depth extension as the larger vein system therefore they do not reach the Captain Nemo Fault. They do exhibit merging and/or bifurcation both along strike and vertically. Dips progressively shallow from south to north but are still quite steep (80°). High-grade shoots within individual veins have steep easterly plunges.
The footwall veins to the main veins are hosted by strongly sheared mafic and felsic volcanics and volcaniclastics intruded by felsic porphyry sills. As with the Main Zone, the porphyries play a significant role in localizing the veining, with the strongest veins occurring along the southern contact of the sills. Dips are near vertical and all footwall veins are truncated by the Captain Nemo Fault.