The Anvil district contains the most westerly off-shelf basinal facies of the Cordilleran miogeocline, a prism of sedimentary rocks of Precambrian to Jurassic age deposited along the relatively stable continental margin of western North America. The district is part of Selwyn basin, a large area of central Yukon in which deep water clastic rocks, chert, and minor carbonate accumulated along the ancient North American continental margin during Neoproterozoic and early Paleozoic time (Gabrielse, 1967).

The Anvil Mining District contains the most westerly exposures of the off-shelf basinal facies (Selwyn Basin) of the Cordilleran miogeocline, a prism of sedimentary rocks of Precambrian to Jurassic age deposited along the relatively stable, passive continental margin of western North America. Anvil District is immediately northeast of the Slide Mountain and Yukon-Tanana Terranes, the most easterly of the allochthonous suspect terranes which were amalgamated with North America starting in Jurassic time. The total interpreted stratigraphic thickness of the metasedimentary rocks of North American affinity is greater than 7400 m, ranging in age from latest Precambrian or earliest Cambrian through Devonian. These metasedimentary rocks consist predominantly of fine clastic sediments deposited in an off-shelf marine basin with local occurrence of euxinic carbonaceous shales and coarser sandstones and conglomerates. Extensive Ordovician within-plate basaltic submarine volcanic rocks and associated epiclastic breccias are indicative of localized rifting along the continental margin.

Includes a geological cross section, mineral occurrences, isotopic age dates and fossil samples.

Cambrian (?) schist and phyllite of the Anvil Range, Yukon, host three large stratabound lead-zinc deposits: Faro, Vangorda, and Swim. Because geological exploration is limited by a thick cover of glacial overburden, geochemical techniques were tested in the area. These include bedrock sampling for primary halos and geochemical marker horizons, and glacial overburden sampling for secondary dispersion patterns. Multi-element geochemistry of bedrock indicates that the schist and phyllite are not distinctive in one or any combination of the trace elements analyzed. However, some younger rocks are enhanced in various elements: amphibolite in Ni, Cr, Co, and Cu; rhyolite in Pb and Sn; and granite in Sn. Despite presence of glacial overburden, the trace element content of bedrock is reflected in soils. Soils overlying magnetic greenstones are enriched in Ni and Cu, whereas soils overlying granite are slightly enriched in Sn content. Detailed bedrock, overburden and soil sampling at the Faro deposit reveals that primary Pb, Zn, Mo, and Ba halos exist about the ore zone. Mo parallels the visible alteration envelope, but Pb and Zn extend into the hanging wall and the footwall. Ba extends into the hanging wall but is not detected in the footwall. Secondary dispersion patterns are primarily related to the proximity of the Faro ore zone and type of parent material sampled. Till deposits have higher background and threshold values for Cu, Pb, and Zn than those of glaciofluvial deposits. Bath Pb and Zn distributions in overburden delineate the Faro #2 ore body; Zn extends to surface whereas Pb, in some cases, does not. This is a reflection of the type of overburden sampled. In general, Zn is the more consistent indicator of ore. The Zn anomaly is primarily hydromorphic in origin, cxZn having higher anomalous/threshold contrast than total Zn (11.1 for cxZn vs 4.8 for total Zn). The nature of the Pb anomaly is not understood. This thesis is available online at https://open.library.ubc.ca/cIRcle/collections/ubctheses/831/items/1.0302661. A copy of this thesis is available at the EMR library – TN27.Y8 M677.

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The northeast Anvil area, 15 km north of Mount Mye (NTS 105K/6, 105K/7), is underlain by a conformable Cambrian-Devonian volcanic and sedimentary package with an aggregate thickness of greater than 1600 m. The lowest unit, with an exposed thickness of 120 m, consists of calcareous phyllites of the Cambrian-Ordovician Vangorda formation. Conformably overlying the phyllites is a >900-m-thick Ordovician-Silurian sequence of submarine basalt flows and volcaniclastic sedimentary rocks of the Menzie Creek formation. Volcaniclastic sediments are dominantly coarse, proximal, fragmental breccias with lesser conglomerates, sandstones, and siltstones. Carbonaceous shales with lesser siltstones, limestones, dolostones, and quartzites of the Ordovician-Devonian Road River Group (>450 m) are intercalated with and overlying the basalt flows. The east margin of the map area is a depositional edge of basalt volcanism with only scattered thin flows occurring further to the east. This depositional edge is considered to be a north-trending, west-side-down, Ordovician-Silurian syndepositional, normal fault forming the east margin of a sedimentary sub-basin infilled with volcanic rocks. Hornfelsing on the east margin of the map area indicates a large, shallowly buried, northwest extension of the mid-Cretaceous Orchay Batholith.

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Sphalerite and tetrahedrite occur with arsenopyrite and minor chalcopyrite and galena in a tabular, fault-bounded body which cuts granitic rocks of the Cassiar batholith. Diamond drilling between 1986 and 1988 outlined a deposit 1100 m long and 50-100 m wide containing geological reserves of 12.3 million tonnes grading 6.17% Zn and 26 g/t Ag. These reserves are amenable to open pit mining and the deposit is open to depth.