Prospectivity
au-v1.0
Orogenic gold, Tati and Vumba greenstone belts
All runs Does not rank
This run does not rank ground
- The blind-site hit rate is 29% against a threshold of 70%.
- The competent person rejected this run.
Nothing below is presented as a ranked target. The record stays visible so the next run can be built from what this one found.
Mineral system
Au Gold Definition 0.9
Orogenic gold, Tati and Vumba greenstone belts
Signed by K. Dlamini, FGSSA on 11 Aug 2026
Gradient-boosted trees, greenstone shear model · 250 m
Ran 27 Aug 2026, 161 min
Run by: Amini modelling team · Accepted by: K. Dlamini, FGSSA
Superseded by au-v1.1Capture efficiency
The top 10% of ranked ground holds 29% of the known deposits.
Search-space reduction 90.7%
The share of the modelled area a competent person can set aside for this commodity.
Validation
Blind-site hit rate 29%
Threshold agreed at MS1 70%
Block cross-validation 5 folds, 25 km blocks
AUC 0.64 ± 0.13
Physical constraints
- Prediction is confined to greenstone lithologies and their 5 km structural envelope.
- Granitoid interiors cannot score high without a mapped shear.
Features and importance
| Feature | Critical process | System role | Importance |
|---|---|---|---|
| Distance to second-order shear | Transport: shear zones focus auriferous fluid | Transport | |
| Banded iron formation contact | Trap: chemical trap at a reactive iron-rich host | Trap | |
| Occurrence density, 10 km | Source: historical workings mark a fertile corridor | Source | |
| Magnetic texture contrast | Transport: alteration destroys magnetite along the fluid path | Transport |
Inputs
| Dataset | Version | Confidence filter | Coverage |
|---|---|---|---|
| Geology 1:250k | 2023 | all, lineage recorded | 100% |
| Regional aeromagnetics, eastern tiles | 2004 levelled | B or better | 61% |
| Mineral occurrence register | 2026-07 | C or better | 55% |
Mineral occurrence register covers 55% of the modelled area and is the layer that governs the bounds.
Validation
| Withheld site | Withheld by | Class | In the high class |
|---|---|---|---|
| BS-AU-01 Map Nora | K. Dlamini, FGSSA | High | In the high class |
| BS-AU-02 Signal Hill | K. Dlamini, FGSSA | Medium | Missed |
| BS-AU-03 Golden Eagle | K. Dlamini, FGSSA | Low | Missed |
| BS-AU-04 Monarch south | K. Dlamini, FGSSA | Medium | Missed |
| BS-AU-05 Phoenix flanks | K. Dlamini, FGSSA | High | In the high class |
| BS-AU-06 Tekwane | K. Dlamini, FGSSA | Low | Missed |
| BS-AU-07 Bushman shear | K. Dlamini, FGSSA | Medium | Missed |
Outputs
- Prospectivity surface 1.0 · COG, 250 m
- Confidence surface 1.0 · COG, 250 m
Parameters
- learningRate
- 0.08
- maxDepth
- 6
- trees
- 600
- classCut
- high ≥ 0.76, medium ≥ 0.50
- negatives
- 1:1, granitoid interiors
Limitations and completeness
- Blind-site hit rate of 29% against a threshold of 70%: the run does not rank ground.
- Diagnosis: the occurrence register carries alluvial workings as hard rock labels, and magnetic coverage of the eastern tiles is 61%.
- Next step agreed with the competent person: re-label from the 1:50k mapping, re-fly the eastern gap, then re-run.
Against the previous edition
This is the first edition of this model.
Targets from this run
0 targets are attributed to this run and are held back from ranking.