As a result of field mapping, radiometric age determinations, and lithoprobe surveys conducted in the area, Chiarenzelli et al. (1997) suggested that the Glennie Domain overlies the apex of a largely buried Archaean micro-continent named the Sask Craton. The Sask Craton likely provided the thick lithospheric keel required for diamonds to remain stable prior to the eruption of the kimberlites.
The Phanerozoic cover consists of a 450 metre-thick basal unit of Cambro–Ordovician dolomitic carbonate rocks and clastic sedimentary rocks, succeeded by 170 metres of Cretaceous shale and sandstone. The entire project area is overlain by Quaternary glacial deposits ranging from 40 metres thickness close to the Saskatchewan River to as thick as 120 metres elsewhere (Figure 6.2).
Figure 6-2: Schematic stratigraphic column of the Fort à la Corne area
The sedimentary formations dip gently to the south-southwest bringing progressively younger strata into contact with the Quaternary glacial till towards the southwest. In the FALC area, the Cretaceous rocks comprise three distinct formational units, in descending succession from southwest to northeast as depicted in Table 6.1.
Table 6.1: Cretaceous-aged rocks hosting the Star Kimberlite
Upper Colorado Group, Favel Formation (Second White Speckled Shale)
Lower Colorado Group, Joli Fou and Westgate formations (shale and lesser sandstone) Mannville Group, Cantuar and Pense formations (continental to marginal marine sandstone and shale)
Note: Rock units are arranged in descending order, from southwest to northeast.
P&E Mining Consultants Inc. NI 43-101 Technical Report No 159 Shore Gold Inc. - Star Diamond Project Resource Estimate Update
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