Location and Access
The Drumheller Property (the “Property”) is situated in central Alberta immediately north of the city of Drumheller, approximately 140 kilometres northeast of Alberta’s largest city, Calgary. The Property is accessed by Highway 9 as well as secondary highways. The Property can also be accessed by well-maintained gravel roads year round. The general location is shown in figure 1.
Figure 1: General location map of the Property
Property and Target Geology
The surface bedrock geology of the Property is comprised entirely of the Horseshoe Canyon Formation.
The Horseshoe Canyon Formation (Edmonton Group) is comprised of deltaic and fluvial deposits. These deposits are complexly interbedded and interlensed fresh and brackish water sandstones, siltstones and shales. Typically, sandstones are soft grey and greenish grey, grey and white weathering, fine grained, bentonitic, and feldspathic. Shales are silty, grey green and brown bentonitic shales. Also included in the shales are coal seams and beds of carbonaceous shale. Bentonite appears throughout the Horseshoe Canyon Formation. Beds containing oyster shot forming coquinas are observed near the base locally. The Horseshoe Canyon Formation are well known for three key features: (1) the lensing of the strata so that no two sections are identical; (2) the great amount of bentonite in the beds; and (3 numerous coal seams which are the main markers for correlating different measured sections. The Horseshoe Canyon Formation is 227 metres thick at the type section. The lower contact of the Horseshoe Canyon Formation is gradational with the underlying Bearpaw shales. At some localities the upper contact is also gradational, as on Bow River, where the uppermost bed is a light grey weathering, argillaceous sandstone or. Along the Red Deer River light grey weathering the upper contact is seen as grey shale grades upward into white weathering, light green-grey shale which underlies typical white weathering clayey sandstone of the Whitemud Formation (Edmonton Group).
Target for Potential Lithium Brines
The target for lithium brines on the Property are the Winterburn Carbonates (the “Target”). Lithium values for the Target were noted in three old wells as shown in figure 2. Of potential interest is an apparent thicking of the Target towards the southeast on the Property as per old well data.
Target 1: Winterburn Group Carbonates (Upper Devonian)
Three formations comprise the Upper Devonian aged Winterburn Group at the type section. These formations are, in ascending order the Nisku, Calmar and Graminia.
Nisku Formation (Winterburn Group)
The Nisku Formation, a key target for lithium brines forms the base of the Winterburn Group. The Nisku is divisible in central Alberta into a lower, carbonate dominated silty dolomite succession deposited in biostromal and restricted bank interior settings. The upper Nisku is a bedded, evaporitic sequence that overlies the lower unit. Locally, most notably in the Stettler area the evaporitic upper phase comprises the majority of the Nisku Formation. To the west, in the West Pembina area the carbonate portion of the Nisku dominates, eventually passing into argillaceous limestones and pinnacle reefs along the east and southeast edge of the basin.
Calmar and Graminia Formations (Winterburn Group)
The mottled red and green siltstones of the Calmar Formation overlies the Nisku Formation. These siltstones are succeeded by anhydrite, silty dolomites and siltstones of the Graminia Formation. To the south and east these two formations become indistinguishable, but west of the Rimbey Meadowbrook trend the Calmar becomes increasingly argillaceous and the Graminia thickens where a carbonate member (Blue Ridge) is developed within the formation.
Thickness and Distribution of the Winterburn Group
At its type section the Winterburn Group measures 76.2 metres in thickness. To the south and southeast the group thins to less than 60 metres, and locally may be less than 30 metres thick where the Winterburn Group overlies Leduc Formation carbonate complexes. To the east and northeast the Winterburn Group has been removed by truncation at the pre-Cretaceous unconformity. West of the Rimbey-Meadowbrook Leduc reef trend the group thickens to 120 to 150 metres as it passes into the adjacent Winterburn shale basin. North and west the Winterburn Group thins onto the Peace River Arch through onlap and is absent on the higher parts. North and west of the Peace River Arch the Winterburn Group averages 70 to 100 metres in thickness, thinning to zero as it passes into the Upper Devonian shale basin in northeastern British Columbia.
Lithium Brines Potential
A total of three (3) old wells drilled on the Property have values for lithium brines (mg/L) according to data available from the Alberta Energy Regulator (“AER”). Also according to the AER two of these have been abandoned. These old wells show potential for Devonian aged carbonbate formations to host lithium brines. All three of these two old wells have data showing lithium beraring horizons in the Winterburn Group as seen in figure 2. Table 3 summarizes formations, their thicknesses and grades of lithium in mg/L.
Table 3: Lithium in Carbonates (mg/L) From Old Well Data
All the above data in table 2 is taken from the Alberta Energy Regulator’s public data sets
Figure 2: Geology and lithium potential of the Drumheller property