Summary:
Jerritt Canyon consists of the SSX Mine, Smith Mine, West Generator Mine, Murray Mine. The majority of production has come from the SSX and Smith deposits. The drift is connecting the SSX and Steer mines.
Deposit Type
Jerritt Canyon is a Carlin-type gold deposit, hydrothermal in origin and usually structurally controlled.
Jerritt Canyon is hosted by silty carbonate or carbonaceous siliciclastic rocks originally deposited as shelf sedimentary rocks during the Paleozoic age. The Paleozoic host rocks have been imbricated, faulted, and folded through several orogenic events in the Paleozoic and Mesozoic. An early phase of intrusive igneous activity is represented by west-northwest mafic igneous dikes of Paleozoic age.
Mineralization
The occurrence and distribution of gold mineralization at Jerritt Canyon is controlled both by lithology and structure. Gold mineralization at Jerritt Canyon is hosted by the Hanson Creek Formation units I to III and the lower part of the Roberts Mountains Formation. The Saval discontinuity, being the contact between the Hanson Creek and the Roberts Mountain Formations, is interpreted as a primary control on gold mineralization at Jerritt Canyon.
Gold mineralization is hosted by, or spatially associated, with high-angle west-northwest and north northeast-trending structures. Much of the more continuous gold mineralization occurs within favourable stratigraphic intervals along the limbs or hinge zones of large anticlinal folds, and at the intersection of the two sets of high-angle structures. The mineralized zones form along well defined structural and mineralization trends as stratigraphically controlled tabular pods that are locally stacked upon one another resulting from the presence of more than one favourable stratigraphic unit and/or local thrust and/or high angled-fault intersection controls.
The sediment-hosted gold mineralization is hosted within carbonaceous sediments. Gold occurs as very fine-grained micron-sized particles as grain boundaries or inclusions in arsenic-rich pyrite rims, and as free grains in carbonaceous-rich and fine-grained, calcareous, clastic sedimentary rocks.
SSX Mine
the mineralized zones are more continuous in the SSX area ranging from 200 ft to 2,000 ft in length along the northwest strike and 50 ft to 200 ft in width, with thickness ranging from 10 ft to 100 ft.
SSX mineralization occurs predominantly in the micritic unit III of the Hanson Creek Formation. A smaller portion of the mineralization occurs in calcareous siltstone at the base of the Roberts Mountains Formation or in the upper two cherty and dolomitic members of the Hanson Creek Formation. Mineralized zones are localized in and near west-northwest-trending steeply dipping dikes (e.g., South Boundary Dike); however, dike material is a minor component of the mineralized material at SSX. Mineralization is also localized along cross-cutting northeast-trending faults. Folding of the mineralized horizons is apparent along axes parallel to the west-northwest dike trend and, more prominently, parallel to the northeast fault set. Gold occurs in decarbonatized rock, commonly in association with variable amounts of orpiment and realgar. Silicification with stibnite can also be associated with gold in portions of the upper cherty member of the Hanson Creek Formation.
Mineralization at Steer is less continuous ranging from 50 ft to 500 ft in strike length and 50 ft to 300 ft in width, with thickness ranging from 20 ft up to 100 ft. The depth to mineralization ranges from near surface at the west end of Steer to a depth of approximately 800 ft below the surface for most of the SSX deposit. Most of the mineralization occurs between 600 ft and 1,000 ft below the surface.
Gold mineralization in the Steer portion of the SSX complex has been identified in an area stretching approximately 3,000 ft east from the old Steer pit to halfway along the connection drift to SSX Zone 5. Most gold mineralization at Steer is associated with gently dipping structures cutting through the Hanson Creek Formation unit III. These structures strike northeast and dip southeast, offsetting strata. Zones of mineralization typically follow the structures and tend to be broad and relatively thin. The mineralized zones are usually at the contact between the Hanson Creek Formation units III and IV and occasionally follow the structures up through unit III. Both within the Steer portion and the western side of SSX, several low-angle features have been observed. These features are at least partly responsible for the gold mineralization at the contact of the Hanson Creek Formation units III and IV.
Smith Mine
The mineralization at Smith generally trends northwest with minor northeast trends along minor structures. Mineralization is continuous along the northwest trend ranging from 200 ft to 2,500 ft. The width of the mineralization ranges from 20 ft to 400 ft and the thickness ranges from 10 ft to 100 ft. The depth of the mineralization ranges from near surface at the Dash open pit to 1,200 ft below the surface to the south and east.
In Smith Zone 1, high-grade gold mineralization is hosted in the upper and middle portions of Hanson Creek Formation unit III within a northwest-trending horst block between the South Graben Fault and the 170 fault. Mineralization in Zones 2 and 3 is directly associated with west-northwest-trending dikes. Highgrade mineralization occurs within Hanson Creek Formation units II and III along the steeply dipping dikes. Lesser amounts of mineralization exist at higher levels where the dikes intersect favourable beds in the Roberts Mountains Formation. An exception to the tight elevation controls on mineralization is observed at the intersection of the west-northwest-trending dikes and the Coulee Fault. Here, high-grade mineralization blows out into Hanson Creek Formation unit III along the west plunging intersection of the dikes and the fault for a down-dip depth of 600 ft.