Geological SettingRegional Setting
The regional geology of the Western Brooks Range area is structurally complex. The sedimentary rocks of the area have been disrupted by thrust sheets or allochthons. The term "allochthon" describes an assemblage of stratigraphically related rocks that overlies a large displacement thrust fault. The LIK property and the other zinc-lead deposits of the Brooks Range, including Red Dog, are hosted in the Kuna Formation of the Lisburne Group. In the Western Brooks Range, the Lisburne Group includes both deep and shallow water sedimentary facies and local volcanic rocks. The rocks have been extensively disrupted by thrusting. The deep water facies of the Lisburne Group, the Kuna Formation, are exposed chiefly in the Endicott Mountains and the structurally higher Picnic Creek allochthons.
In the Red Dog plate of the Endicott Mountains allochthon, the Kuna Formation is divided into two units, the Kivilina Unit and the Ikalukrok Unit, and consists of at least 122 m of thinly interbedded calcareous shale, calcareous spiculite and bioclastic supportstone overlain by 30 m to 240 m of siliceous shale, mudstone, calcareous radiolarite and calcareous lithic turbidite. The Ikalukrok Unit in the Red Dog plate hosts all of the massive sulphide deposits in the area.
The LIK property is hosted in the Red Dog plate of the Endicott Mountains allochthon. The stratigraphically lowest rocks within the Red Dog plate belong to the Kayak Shale. The top of the Kayak Shale is interbedded with rocks of the Kuna Formation.
In a district sense, the Kivalina Unit is up to 122 m thick and may have been deposited in a local fault-bounded depression. It includes laminated, black calcareous shale and thick-bedded, grey micritic limestone, grainstone and packstone. The Ikalukrok Unit varies in thickness across the district from 29 m to greater than 240 m. The unit has been divided into a lower laminated black shale sub-unit and an upper medium-to thick-bedded black chert sub-unit.
The LIK property is hosted in the upper part of the Ikalukrok Unit of the Kuna Formation. At the LIK property, the immediate host rocks are carbonaceous and siliceous black shale, with subordinate black chert and fine-grained limestone. These rocks strike broadly north-south and dip at about 25º to 40º to the west. The massive sulphides are overlain conformably by rocks of the Siksikpuk Formation. The sequence is overridden by allochthonous rocks that form high hills north and west of the deposits.
The mineralized sequence is cut by a number of faults. The most significant disruption is the Main Break Fault, which drops the northern end of the LIK deposit down about 150 m. It is unclear whether there is a change in strike north of the fault, or whether the change is more apparent due to topography. The Main Break Fault strikes east-west and dips north at about 60º. There is another group of steeper faults that tend to strike northerly or northwesterly and which are interpreted as being both normal and reverse with throws of up to 100 m.
There had been no recent drilling on the LIK property before 2007. Details of pre-2007 drilling campaigns are discussed above under the heading "Mineral Project - History".