The mining claims of Kenbridge Project are registered to Canadian Arrow Mines Limited and Kenbridge Nickel Mines Limited, currently wholly-owned subsidiaries of Tartisan Nickel Corp.
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Summary:
DEPOSIT TYPES
Kenbridge is an Archean age gabbro-related magmatic sulphide deposit with geological similarities to the better known and larger deposits, such as the Montcalm Mine Deposit near Timmins, Ontario (Naldrett, 1981).
Magmatic nickel sulphide deposits form when sulphur-undersaturated picrite or high magnesium basalt magma becomes saturated in sulphides, generally as a result of interaction with and assimilation of sulphur-bearing sedimentary rocks. Assimilation of crustal sulphur results in the formation of an immiscible sulphide liquid that segregates toward the base of the flow or sill. Assimilation and concentration may be enhanced by multiple pulses of magma in a dynamic conduit system. The mineralization typically forms lenses or tabular concentrations in the middle or lower parts of the gabbro intrusions. Subsequently, the effects of post-emplacement deformation preferentially concentrate in the incompetent sulphides, resulting in the latter being displaced from their host parental body unit, possibly as breccias, into surrounding rocks.
The Kenbridge Deposit appears to be a breccia pipe that may represent the conduit of a larger magmatic feeder system associated with major regional structure. The sulphide mineral assemblage appears to be relatively high-nickel in composition, with nickel/copper of 2:1 overall. Keast and O’Flaherty (2006) favour a model in which the sulphides were remobilized in a breccia pipe conduit. This interpretation is consistent with the variable grade and less variable nickel/copper ratios of the Deposit. However, the effects of overprinting deformation and metamorphism on the rock textures and sulphide compositions remain to be comprehensively studied and understood.
The Kenbridge Property overlies volcanic rocks and an ovoid-shaped gabbro body, which hosts the Kenbridge Deposit. Interpretation of property-scale geology is complicated by limited rock exposure and the overprinting effects of deformation and upper greenschist facies regional metamorphism and contact metamorphism. Intrusive and extrusive rock types occur on the Property with associated nickel sulphide mineralization.
The Kenbridge Deposit occurs within a vertically dipping, lenticular gabbro and gabbro breccia with surface dimensions of 250 by 60 m. The Deposit and host rocks occur within a regional northeast-trending deformation zone. The gabbro body is surrounded by vertically-dipping volcanic units consisting of andesite flows, fragmental rocks, and volcaniclastic sedimentary rocks.
The host volcanic rocks west of the Kenbridge Deposit are composed mainly of medium-grained green, strongly foliated and sheared, fragmental tuffaceous units. Volcanic rocks to the east of the Deposit are characterized by larger fragments and weak foliation. Most of the fragments are fine-grained volcanics with subtle changes in contents of chlorite and interstitial carbonate, which allows them to be recognized. This “eastern” volcanic unit is logged as a volcanic breccia. The volcanic sequence is intruded by gabbro, granite and quartz diorite plutons and by the mafic-ultramafic breccias that host the Kenbridge Deposit.
The gabbro body that hosts the Kenbridge Deposit consists of several rock types, including fine- to coarse-grained gabbro, quartz-phyric gabbro with 2 to 3% rounded blue quartz grains, and diorite. In the historical literature, terms such as anorthositic gabbro and norite were used, but these names were not recorded during drill core logging. Some of the diorite may be later dykes. Texturally, the rocks range from fine-grained (probable chilled) to medium-grained massive to highly sheared and schistose rock, particularly near the granitoid pluton contacts and fault zones. Contacts between the mineralized gabbro and the surrounding volcanic rocks are marked by a talc schist unit up to 30 m wide, which is tightly folded in places. The talc schist may or may not be mineralized.
MINERALIZATION
The nickel sulphide mineralization at Kenbridge is described by Keast and O’Flaherty (2006). Nickel sulphide mineralization in the Kenbridge Project area is exposed in trenches for a distance of 150 m, but the nickel-copper mineralized zone has a strike length of approximately 250 m in drilling.
Mineralization (pyrrhotite, pentlandite, and chalcopyrite ± pyrite) occurs as massive to nettextured and disseminated sulphide zones, primarily in gabbro with smaller amounts in talc schist. Nickel grades within the Kenbridge Deposit are proportional to the total amount of sulphide present. Massive sulphide zones locally grade higher than 6% Ni. Mineralization undergoes rapid changes in thickness and grades.