Summary:
The Great Atlantic Salt (GAS) Project is located within the Bay St. George Sub-Basin which represents the northeastern extension of the regional Maritimes Carboniferous Basin of southwest Newfoundland.
The Sub-Basin halite is considered to be a basin-wide, sedimentary salt deposit on the basis of its wide lateral extent and overall stratigraphy which includes sedimentary strata from a range of depositional environments including marine, shallow marine, and salina, to fluvial and deltaic.
Property Geology
The Codroy and Robinsons River formations represent the dominant stratigraphic units within the Project area, with bedrock exposures observed across the Project area including at the quarry workings of the Flat Bay Gypsum Quarry, approximately 3 km southwest of the Project. The mine extracted gypsum and anhydrite of the Codroy Road Formation in the northern portion of the Bay St. George Sub-Basin, including massive and sugary crystallite gypsum, coarse to needle-like and fibrous gypsum, and massive crystalline anhydrite. These evaporites, originating in shallow salinas (salt flats), are found interbedded with fine grained grey to red siliciclastic rocks of shallow marine and lagoonal settings.
Exploration drilling to date has tested the geological succession beneath the Project to a maximum depth of approximately 630 m (in drill hole CC-5), which represents the most complete stratigraphic profile of the GAS halite deposit. The halite deposit has been intersected in a total of seven drill holes between depths of approximately 180 m and 395 m. Excluding two drill holes terminated shorter than planned, the thickness of the halite deposit has been observed to vary between 68 m in the southwest and 340 m in the northeast.
The halite is overlain by a thick succession of sandstones, siltstones, mudstones, and conglomerates, referred to as Red Beds, and is immediately underlain by a basal anhydrite, both of which form relatively sharp boundaries with the major halite horizons. The Red Beds have been intersected to a maximum depth of 394 m in CC-5 with the strata thickening to the north and southeast. Drill holes have generally been terminated after intersecting the base of the halite, and as such the information on the total thickness of this unit in the Project area is limited, although it was intersected to a maximum depth of 604 m in drill hole CC-1.
Discrete interbeds of primarily mudstone with minor potash and anhydrite exist across the Project area and have been intersected in multiple drill holes. These interbeds range from 2 m to 27 m thick and exhibit varying degrees of lateral continuity across the Project area. SLR has opted to correlate these across the deposit for the purpose of excluding this material from the Mineral Resource estimate. SLR has interpreted two major interbed units across the Project as having greater lateral continuity, referred to herein as IB-1 and IB-2, thereby splitting the halite into three main horizons, referred to herein as 1-Salt, 2-Salt, and 3-Salt.
Thinner interbeds with a lower degree of lateral continuity also exist within each of the three halite horizons, interpreted as occurring over localized areas only. It is not possible to confidently correlate these between drill holes and as such these are considered as internal dilution in the Mineral Resource estimate.
Mineralization
Potentially economic mineralization of gypsum, sodium chloride, and minor potassium chloride (potash) occur within the Codroy Formation, in addition to minor coal measure accumulations within the Barachois Group. Economic extraction of gypsum has been undertaken locally since the 1950s, including at the Flat Bay Gypsum Quarry. The Project is, however, focussed on the mineralization of thick, massive halite accumulations primarily of the Robinsons River Formation within the Codroy Group. The massive halite is known to contain laterally continuous mudstone interbeds up to 27 m thick. These interbeds have the effect of separating the halite into three horizons, a sub-division which is also known to exist within the regional Maritimes Basin. Within each of the halite units other minor interbeds of mudstones, shales, potash, and anhydrite also exist but lack lateral continuity.
The GAS halite has been shown from drill core observations to exhibit varying colouration ranging between white, beige, brown, orange, champagne, medium grey, and dark grey. Except for brown and orange colouration, which is attributable to an increased proportion of potash and/or mudstone content, colouration has not been shown to be a reliable indicator of halite quality, with grades typically ranging from 95% NaCl to 99% NaCl.
Sampling of the GAS halite has shown it to range from fine to very coarsely grained, but more commonly medium coarse. Recrystallization of salt within the deposit is evident from drill core with small, centimetre-scale, clear glass-like halite occurring perpendicular or sub-perpendicular to core axes indicating lateral salt flow having occurred after deposition. Another indicator of potential salt flow or deposition is the presence of centimetre-scale inclusions which are common through the drill core and particularly prevalent either near the top or base of the deposit proximal to the overlying red beds or underlying anhydrite. Inclusions of salt fragments occurring within interbedded mudstones is also commonly observed in drill core. Fine, millimetre-scale inclusions of gypsum within the halite have also been observed and interpreted as secondary to original halite formation. Potash interbeds within the deposits typically consist of a mixture of mudstone, salt, and potash.
Potash typically occurs as fine to coarse, clear white to pale orange sylvite disseminated in a halite matrix. Distinct potash beds are less common across the deposit but generally comprise sylvinite with disseminated carnallite.