Summary:
There are a number of mineralizing styles and models in the Republic/Greenwood Districts:
1) Gold and Copper-Gold Skarns: Fe-Cu massive sulfide/oxide horizon in Brooklyn Fm. Present in all major “skarn” deposits in the district. Examples are Phoenix, Motherlode and Crown Jewel (“Buckhorn Mtn”).
2) Mesothermal Quartz Veins with Gold (+/- Ag, Pb, Zn). Examples are Providence Mine, Dentonia, Camp McKinney, May Mac. Polymetallic silver-lead-zinc veins with lesser gold.
3) Epithermal Quartz Veins commonly in the Republic District and often marked by the paleosurface between the Eocene Marron and Kettle River Formations and the overlying Oligocene Klondike. Examples are Mountain Formation Knob Hill Mine, Emanuel Creek, Union Mine and Picture Rock Quarry.
4) Cretaceous – Jurassic Alkalic Intrusives with Cu-Au-Ag (+/- PGE’s) with a strong spatial association between these intrusives and Jurassic thrust faults. Examples are Lexington-Lone Star alkalic porphyry type mineralization, Franklin Camp, Sappho cpy rich shears with PGE’s and Au, Golden Crown, Wildrose and Rossland type veins close spaced, parallel, en-echelon veins of gold in massive pyrrhotite-pyrite-chalcopyrite veins & quartz veins.
5) Gold Mineralization Associated with Serpentinite related to #3, #4 because an association with structure = an association with serpentinite. Known bodies of mineralization have traditionally been small, but often high grade. Examples are Athelstan – Jackpot - gold in massive arsenopyrite + pyrite in listwanite and Lexington-Grenoble Deposit.
6) Gold-bearing volcanogenic magnetite-sulfide mineralization. Syngenetic mineralization within the Triassic Brooklyn Formation. Gold-bearing massive magnetite and sulfides along the same stratigraphic horizon. At least some of the gold is attributed to a late stage epigenetic (Jurassic or Tertiary) event. Examples are Lamefoot and possibly Sylvester K. The vein systems in the Greenwood Camp, in particular those making up the Golden Crown Deposit, are intrusive – related, Au-Cu pyrrhotite veins.
Lexington-Grenoble Mineralization
The Lexington-Grenoble Deposit is composed of multiple shallow to moderately dipping closely spaced overlapping en echelon zones that appear to be confined to a basal pyroclastic unit within the dacite unit. The deposit lies at the contact or just above the lower serpentinite unit following its dip at about 20-30° to the northeast. Over 90 % of the mineralization is hosted in the dacite unit, with only minor mineralization in serpentinite. The footwall of the deposit has a sharp tectonic contact of broken and crushed serpentinite and subordinate gouge. The individual zones comprise a congregation of massive sulfide veins, veinlets and disseminations in a sheeted, roughly foliation-parallel fashion. The massive sulfide veins tend to have a favored dip of between 20° and 35° towards the northeast, east and southeast. Most veins within a zone are foliation parallel, but there appears also to be a subordinate vertical vein orientation present that may represent feeder veins.
Golden Crown Property Mineralization
A corridor of west northwest trending sub parallel and closely spaced, steeply dipping massive sulfide and quartz-sulfide veins occur in the southeastern part of the property as part of a 4 km long gold/copper system defined by drill hole intercepts, trenches, gold soil geochemical anomalies and geophysical (“VLF”) anomalies. The core of the known vein system (the resource) lies within an area 130 m wide by 800 m long. As many as 17 discrete veins have been identified in the heart of the system.
The veins are generally sub parallel and closely spaced (generally 15-25 m apart), trending west northwest and steeply dipping. Veins typically are 0.3-1 m true width, with local developments to 5 m true width near the serpentinite contact. Veins range in sulfide content of 50-90 % sulfides of pyrrhotite-pyrite and lesser chalcopyrite, with very local arsenopyrite in a quartz gangue and carry high gold tenor. According to metallurgical testing, the bulk of the gold is free and associated with pyrite. The vein system appears to be the result of two separate mineralizing events.
Wallrock alteration associated with veins varies in intensity depending on the host rock type. The fine-grained pyroclastics and porphyry hosts, which are regionally strongly sericite-pyrite altered, become more intensely altered adjacent to veins. Diorite, microdiorite, augite and serpentinite hosts exhibit very little wallrock alteration.
Tam O’Shanter Property Mineralization
Numerous areas of gold ± silver, copper and other metal occurrences have been identified during past exploration by different companies and prospectors on the Tam O’Shanter Property. There are four main areas of known mineralization on the Property: the Bengal Zone, Deadwood Zone, Tam O’Shanter, and Iva Lenore in which the latter two zones are Minfile occurrences.
Three or more sub-parallel quartz veins, located in a wide zone of intense shearing and silicification, occurs along the Wild Rose Fault and is collectively known as the Deadwood Zone. The Deadwood Zone lies on Tam O’Shanter Property and extends eastward onto the Wild Rose property owned by others. A number of Eocene syenite dykes occur within the Wild Rose Fault Zone. These dykes usually appear intensely altered and are closely associated with the veining. These Eocene events have not definitively linked the resultant alteration to gold mineralization in the veins.
Widespread silicification, argillic, and phyllic alteration in the rocks located within the hanging wall of the Wild Rose fault (the Deadwood Zone) are accountable for the elevated gold values present in the area.
Phoenix Property Mineralization
The Phoenix Property is extensively mineralized with a variety of types. The Phoenix Property covers 29 past producing mine and in excess of 70 mineral showings.
Boundary Falls Property Mineralization
The Skomac quartz vein system is composed of two principal veins carrying precious metal and polymetallic values and lesser parallel sympathetic weakly mineralized quartz veins. The two principal veins, the Upper and Lower Skomac veins, although somewhat different, may in fact be the same vein, either offset by faulting or folded. There has been insufficient drilling between veins to support a positive correlation. Golden Dawn interprets the Lower Skomac vein to be distinct from the Upper Skomac vein based on its steeper dip, different host rocks and relatively elevated gold content.
The Skomac vein system is traceable on surface, underground drifting and now diamond drilling for a 400 m along strike length. The Upper Skomac vein is traceable for 150 m in the dip direction. The Lower Skomac vein has been traced down dip for 250 m.