Prospectivity
li-v1.3
Continental brine lithium, Makgadikgadi
All runs Ranks ground
Mineral system
Li Lithium Definition 1.2
Continental brine lithium, Makgadikgadi
Signed by M. Mokgatlhe, MAusIMM CP on 15 Jul 2026
Physics-constrained ensemble, brine residence model · 500 m
Ran 06 Aug 2026, 145 min
Run by: Amini modelling team · Accepted by: M. Mokgatlhe, MAusIMM CP
Superseded by li-v1.4Capture efficiency
The top 10% of ranked ground holds 55% of the known deposits.
Search-space reduction 92.9%
The share of the modelled area a competent person can set aside for this commodity.
Validation
Blind-site hit rate 50%
Threshold agreed at MS1 50%
Block cross-validation 5 folds, 60 km blocks
AUC 0.76 ± 0.09
Physical constraints
- Prediction is confined to closed sub-basins with a modelled evaporite sequence.
- Graben-bounding structures set the lateral extent.
Features and importance
| Feature | Critical process | System role | Importance |
|---|---|---|---|
| Modelled evaporite thickness | Trap: evaporative concentration of brine in a closed basin | Trap | |
| Gravity-derived basin depth | Trap: accommodation space holding the brine column | Trap | |
| Distance to graben-bounding fault | Transport: structural control on inflow and residence | Transport | |
| Playa persistence, multi-year | Preservation: a surface that has not been flushed | Preservation |
Inputs
| Dataset | Version | Confidence filter | Coverage |
|---|---|---|---|
| Makgadikgadi borehole hydrochemistry | 2024 compilation | B or better, screened intervals | 29% |
| National gravity | 2021 | A and B only | 83% |
| Sentinel-2 evaporite and playa indices | 2026-05 | cloud < 5% | 98% |
Makgadikgadi borehole hydrochemistry covers 29% of the modelled area and is the layer that governs the bounds.
Validation
| Withheld site | Withheld by | Class | In the high class |
|---|---|---|---|
| BS-LI-01 Sua Pan east | M. Mokgatlhe, MAusIMM CP | High | In the high class |
| BS-LI-02 Ntwetwe centre | M. Mokgatlhe, MAusIMM CP | Medium | Missed |
| BS-LI-03 Nata delta margin | M. Mokgatlhe, MAusIMM CP | Medium | Missed |
| BS-LI-04 Mosu escarpment | M. Mokgatlhe, MAusIMM CP | High | In the high class |
Outputs
- Prospectivity surface 1.3 · COG, 500 m
- Confidence surface 1.3 · COG, 500 m
Parameters
- ensemble
- 3 members, physics-weighted
- classCut
- high ≥ 0.74, medium ≥ 0.50
- residenceYears
- 12000
- negatives
- basin margin, outside closed drainage
Limitations and completeness
- Borehole coverage of 29% leaves the centre of the basin inferred from geophysics alone.
- No felsic catchment term: the source side of the system was unproxied.
Against the previous edition
This is the first edition of this model.
Targets from this run
0 targets are ranked from this run.