The Finger Lake-Iron Knoll showing is underlain by Lower to Middle Jurassic Hazelton Group andesite, rhyolite, basalt, dacite, crystal tuff, flow and breccia. Minor limestone and limestone breccia with rhyolite flows, located on the south side of Tatuk Lake, indicate a shallow marine environment. Triassic to Jurassic age Brooks Diorites (diorite, monzodiorite, monzonite, amphibolite) intrude the Hazelton Group.
Field mapping by Robin Day in 2001 revealed outcrop, subcrop and float hosting iron-oxide mineralization that continues for about 1000 metres west of Iron Knoll and for 3000 metres east of Iron Knoll, as numerous lenses of unknown dimensions, within a zone 100 to 200 metres wide.
An apparent offset transects the system suggests the presence of a fault on the east side of Iron Knoll. Alternately, there are two separate iron-oxide hydrothermal systems present. Oxide mineralization is characterized by non-magnetic, massive specular hematite, hematite and hematite-quartz, stockworks, breccias and replacements, hosted in andesites and felsic pyroclatics (very coarse fragmental and crystal tuffs). The ore mineral assemblage is dominated by hematite, with rare pyrite and very rare chalcopyrite.
The east-west structure hosting is proximal to the intersection of two district scale lineaments: a large east-west trending structure corridor underlying Finger Lake and the north-south trending Nulki Shear zone (Geological Survey of Canada open file 3631).
Work History
Extensive trenching and stripping was completed in 1921, but with little success. The Geological Survey of Canada noted the iron showing (Geological Survey of Canada map 1131A) now known as “Finger Lake-Iron Mountain” (093F 023). Two old trenches were located on Iron Knoll by Robin Day who, in 2001, explored the extensive newly discovered system and collected a total of 248 till, 2 silt and 48 rock samples. Thin section petrology was performed on 10 rock samples and one fluid inclusion section.
In 2007, a total of 2144 till samples were taken, just north of the Finger Lake iron showing explored in 2001. Results were generally subdued.
