Regional Geology
Minas de Revuboè 4064C coal project lies within the Moatize Sub-basin, which similarly to other coal projects in sub-Saharan Africa is largely hosted in sedimentary rocks of the Karoo Supergroup.
The 4064C Project area is preserved in a half-graben. The initial accommodation space for the development of the Karoo Supergroup sequences is probably related to Late Carboniferous to Early Permian rift basin formation, which has subsequently been overprinted during two phases of extensional tectonics in the Middle Jurassic and Early Cretaceous.
The surface geology of the 4064C Project area is dominated by outcrops and subcrops of sedimentary rocks of the Vúzi, Moatize and Matinde formations, with basement exposures in the north.
A generalized (composite) stratigraphic succession and description for the 4064C concession area is provided below, along with the corresponding classic Tete sub-basin seam nomenclature.
The geometry of the economic coal units present in the concession is thought to be closely related to both depositional environment and active syn-depositional extensional faulting. The result is that the coal present in the west of the deposit is significantly different to the coal in the east in terms of geometry, although still very similar in coal quality. Figure 2 below shows the thickness of parting material within the Seam 3 (Chipanga Seam equivalent) group.
Coal Resource
The current in situ coal resource estimate is 1,580 Mt declared as of 31st July 2017. The Coal Resource consists of 605 Mt in the Measured Coal Resource category, 535 Mt in the Indicated category and the remaining 445Mt in the Inferred category. Table 1 below shows a summary of coal resources by seam group, with associated raw coal qualities.
| Tonnage (Million Tonnes) | Average Raw Coal Quality |
Mean Maximum Reflectance (RoMax) |
|||||||||
| Seam group | Measured | Indicated | Inferred | Total | Relative Density in situ (g/cc) | Ash % (Adb) | Inherent Moisture % (Adb) | Calorific value (Adb) kcal/kg | Volatile Matter (DAF) | Total Sulphur % (Adb) | |
| 13 | – | – | 47 | 47 | 1.75 | 48.18 | 0.89 | – | 28.08 | 0.00 | 1.15 |
| 10J | – | 6 | 15 | 21 | 1.78 | 50.37 | 1.24 | 3,869 | 31.45 | 1.53 | 1.21 |
| 9U | – | – | 5 | 5 | 1.66 | 41.62 | 0.86 | 4,383 | 31.63 | 1.76 | 1.50 |
| 9 | 9 | 58 | 47 | 114 | 1.66 | 39.99 | 0.86 | 4,291 | 30.02 | 1.12 | 1.10 |
| 8a | 1 | 0 | – | 1 | 1.77 | 48.82 | 0.65 | – | 32.37 | 0.00 | 1.13 |
| 7 | 18 | 81 | 50 | 148 | 1.68 | 41.20 | 0.86 | 4,299 | 30.70 | 1.05 | 1.28 |
| 5 | 99 | 38 | 46 | 182 | 1.61 | 34.97 | 0.90 | 4,976 | 28.20 | 1.05 | 1.32 |
| 3D | 10 | 4 | 7 | 21 | 1.67 | 39.25 | 0.67 | 5,048 | 27.90 | 1.24 | 1.08 |
| 3C | 77 | 85 | 40 | 202 | 1.76 | 44.83 | 0.93 | 3,968 | 29.25 | 1.31 | 1.41 |
| 3B | 221 | 130 | 93 | 444 | 1.70 | 41.41 | 0.86 | 4,218 | 28.07 | 1.02 | 1.45 |
| 3A | 170 | 133 | 97 | 399 | 1.71 | 41.84 | 0.84 | 4,505 | 27.64 | 0.88 | 1.50 |
| Total | 605 | 535 | 445 | 1,580 | |||||||
Table 1 Summary of the Coal Resources of the Revuboè deposit (Mining Concession 4064C)