Summary:
The Joyce Lake DSO Project (Project) is located on the western margin of the Labrador Trough, a Proterozoic volcanosedimentary sequence wedged between Archean basement gneisses. The Labrador Trough, otherwise known as the Labrador-Québec Fold Belt, extends for more than 1,000 km along the eastern margin of the Superior Craton from the Ungava Bay to Lake Pletipi, Québec. The belt is about 100 km wide in its central part and narrows considerably to the north and south.
In the vicinity of the Joyce Lake DSO Project, the Knob Lake Group is subdivided into eight formal geological units. The lowermost unit rests unconformably over Archean gneisses of the Ashuanipi Complex. From oldest to youngest, the rock units are the Seward, Le Fer, Denault, Fleming, Dolly, Wishart, Sokoman and Menihek formations.
The iron formations of the Sokoman formation are classified as Lake Superior type. They consist of a banded sedimentary unit composed principally of bands of magnetite and hematite within chert-rich rocks and variable amounts of silicate-carbonatesulphide.
The iron formation occurring on the Property consists mostly of subunits of the Sokoman formation characterized by recrystallized chert and jasper with bands and disseminations of magnetite, hematite and martite; a type of hematite pseudomorph after magnetite and specularite. Other gangue minerals are a series of iron silicates comprised of minnesotaite, pyrolusite and stilpnomelane and iron carbonate, mainly siderite.
Field mapping done by Century geologists indicates that the fold structure at Joyce Lake is trending NW-SE. There are zones of minimal strain and the units appear undeformed. These lowstrain zones are particularly interesting because they would represent unshortened, and therefore thicker, iron beds outside the nose of the fold. It was observed in the field, especially from the massive hematite units on one limb of the fold structure, that there were specularite and hematite veinlets and tension gashes (ranging between 1 mm and 3 mm) oriented obliquely to the strike of the perceived bedding. These brittle features likely helped to accommodate the volume change during shortening and thus the shortening to be oriented along a strike of NE-SW. It was deduced that the fold was trending at approximately 135° with a dip of approximately 42°.
The Ruth shale provides an impermeable layer at depth to cap the down flow of meteoric water and therefore encourage leaching of silica and the deposition of enriched hematite as a Direct Shipping Ore (“DSO”) type deposit. This enrichment is expected to be most significant where there is the greatest brittle deformation and would carry the greater tonnage where the massive hematite units are thicker. These conditions are satisfied within the nose of the fold structure and within the minimal strain zones identified in the field. The fold structure plunges to the Southeast and one would expect the hematite beds to thicken. Eventually, the strata should be capped by the impermeable Menihek Shale unit. Thus, by moving away from the zone of brittle deformation where being capped by an impermeable layer retards the percolation of meteoric water, it therefore reduces the potential of enrichment and DSO formation along this trend.
The mineralization is an iron enrichment.
The Joyce Lake deposit is an enrichment zone along the nose of the main fold of the Joyce Lake syncline. This enrichment extends laterally within the iron formation, forming a vase (or bowl) shape with significant thickness in the hinge of the syncline.