Summary:
The geology of the Paradox Formation indicates a restricted marine basin, marked by 29 evaporite sequences. Brines that host bromine and lithium mineralization occur within the saline facies of the Paradox Formation and are generally hosted in the more permeable dolomite sediments.
Controls on the spatial distribution of certain salts (boron, bromine, lithium, magnesium, etc.) within the clastic aquifers of the Paradox Basin is poorly understood but believed to be in part dictated by the geochemistry of the surrounding depositional cycles, with each likely associated with a unique geochemical signature.
The conceptual hydrogeological model for the brine aquifers within the clastic zones has four extensively fractured geological units comprising of the following interbedded units (from top to bottom).
• Anhydrite (upper layer);
• Black Shale;
• Dolomite; and
• Anhydrite (lower layer).
Anson has re-entered historic oil wells to depths of up to 2,600 metres in the Paradox Lithium Project area. The wells have an average spacing of 1.6km (ranging between 1.3km and 3.0km). The bores have delineated aquifers containing hyper-saline brine with total dissolved solids (TDS) ranging between 350,000 mg/L and 410,000 mg/L. The brine is enriched with respect to lithium, bromine, and other recoverable minerals. The sampling of the supersaturated brines from these aquifers within the Project area have yielded concentrations of up to 253 ppm lithium and 5,041 ppm bromine.
The planned 23-year production is supported by the lithium in the Indicated category. The lithium that will be extracted will then be processed into lithium carbonate (Li2CO3). Clastic Zones 17, 19, 29 and 33 have no historical assays on the western side of the Project area resulting in the lithium resource being restricted to the eastern side of the project. The Mississippian units have been reentered in the Long Canyon Unit 2 well only, so the lithium resource is restricted to the area surrounding the well.
To date the large exploration target for Clastic Zones 17, 19, 29, 31, 33 & Mississippian Units is due to the fact that there are no historical assays or new drilling on the western side of the Project area to extend the Indicated and Inferred Resources category estimates. With the addition of one re-entry, the Inferred Resource would probably be converted to the Indicated category in Clastic Zone 31 and the Exploration Target estimate to an Indicated and Inferred category for the Clastic Zones 17, 19, 29, 33 and Mississippian Units. This would result in an increase in the block model tonnages and grades for the additional brine horizons as there has been no recorded assays in those locations. Assay data and effective porosity values in those areas would increase both the Indicated and Inferred Resource estimates.
Most of the clastic intervals within the Paradox Formation are a mix of anhydrite, shale, and dolomitic siltstone. These clastic intervals represent sea level highs, and the transition from transgressive to regressive phases. Intervening salt deposition occurred at sea level lows and the transition from regressive to transgressive sequences. These cycles can be readily identified in geophysical logs by combining interpretations of natural gamma and neutron density.
All the drilling programs completed by Anson have intersected hypersaline brines in all the clastic zone horizons sampled (CZ 17, 19, 29, 31 & 33). The clastic intervals are typically interbedded dolomite, dolomitic siltstone, anhydrite, and black shale. Clastic intervals typically range in thickness from 3 to 60 m. And are generally overlain by a salt sequence of 60 to 122 m. Within the Project area, the evaporite section in the Paradox Formation ranges from 875 to 1165 meters in thickness. Potentially economic mineral-bearing brines are not confined to the clastic intervals in Paradox Formation. Within the Paradox Basin, the supersaturated brines of the Clastic Zones that host known lithium and bromine mineralization occur within the saline facies of the Paradox Formation. The saline facies consist of 29 identified evaporitic cycles.
The Mississippian units were cored in the Paradox Lithium Project area during oil and gas exploration programs. Significantly the diamond core shows fracturing & “vugs” throughout the limestone and dolomite units demonstrating the high porosity required for the storage of brine. This confirms the geophysical logs and porosity calculation.
The limestones and dolomites in south-eastern Utah are noted for vuggy and intracrystalline porosity. It has been noted in some of the well files that drilling tools have dropped in apparent cavernous porosity zones resulting in a loss of circulation in the Leadville Formation, Mississippian Unit. This is an indication of high porosity zones.
The deposit model for the Paradox Basin is similar to brine deposits located in the Jurassic age Smackover Formation in Arkansas, USA. The Smackover Formation is predominantly made up of oolitic and silty limestones. Brines recovered from these wells supplies the vast majority of bromine produced in the U.S.
Pumping tests have allowed determination of the hydraulic properties of this aquifer. Four separate flow tests have been completed at rates ranging between 3L/s and 12L/s, for periods of 4 to 12 hours. No pumping was required due to the artesian flow. Flow tests allowed determination of the aquifer permeability and associated potential parameters for brine-abstraction.
Spinner-flowmeter logging carried out on some re-entered wells show that the brine flows not just from the dolomite, but also from the anhydrite and shale units due to a secondary porosity.
Anson completed build-up tests to estimate production interval permeability with the data analysed to determine the formation permeability (from the Horner Plot).
The permeability’s ranged from 1,698 to 6,543 millidarcies (mD). The permeabilities were calculated for the clastic zone as a whole, with no differentiation between shale and dolomite lithologies.
In general, the permeability increases with increasing effective porosity and decreases with increasing pressure. However, secondary porosity in the form of fracturing increases the bulk permeability of a geologic unit, as well as increasing its sensitivity to effective pressure.
The hydraulic conductivity for the Clastic Zone ranges from 0.02 to 0.07 m/d and the transmissivity ranges from 0.099 to 0.5 m2 /d. The high relative transmissivities shown by the shale lithologies, as well as the high permeability’s indicate that the flow system is complex with varying porosity of the dolomite and shale units, which are in turn dominated by secondary porosity related to fracturing.
This testing also indicates that lithological thickness vs. flow contribution for the shale unit has a higher transmissivity than the silty dolomite, which based on known textural differences, suggests significant secondary porosity (fracturing) within the shale.
Dimensions
• The brine bearing units are encountered at depth over the entire Anson claim area.
• Available data indicates that the units contains brine throughout its extent within the Anson claims.
• The Anson claims cover an area of about 10km x 10km and this entire area has been covered by the estimation.
• Within the claim area the brine unit (Clastic Zones 17, 19, 29, 31,33 and Mississippian) are found at vertical depths up to 1500m to 2500m below surface.
• The producing unit averages 6m in thickness.