Sigma coalfield, Vereeniging - Sasolburg coalfields, Fezile Dabi District Municipality, Free State, South Africai
| Regional Level Types | |
|---|---|
| Sigma coalfield | Coal Field |
| Vereeniging - Sasolburg coalfields | Coal Field |
| Fezile Dabi District Municipality | Municipality |
| Free State | Province |
| South Africa | Country |
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Latitude & Longitude (WGS84):
26° South , 27° East (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
~11km
Locality type:
Köppen climate type:
The Sigma basin is situated along a north-south line at the western edge of the Vereeniging-Sasolburg coalfield. Geologically the western margin of the basin is formed by a pre-Karoo outcrop of the Vredefort Dome and the eastern extremity by a ridge of Ongeluk Formation (Transvaal Supergroup) lava, which separates it from the Cornelia basin to the east.
Mining the basin started in the early 1950's at the Sigma colliery. Early bord-and pillar extraction mining methods left much of the resource un-mined and during the 1960's total extraction methods, such as long walling and pillar extraction, were introduced to improve extraction. These mining methods were found to have limited application at the Sigma Colliery and the rib-pillar method was introduced in 1980. Current exploration interest is in the south-eastern portion of the this basin.
The coal zone in the Sigma basin is between 30-40 m thick and contains three coal units, comprising four coal seams termed C1, C2A, C2B and C3. The coal seams extend over an area of approximately 300 km² and occur at depths below surface of between 20-250 metres. The wide variation in depth results from a general southward dip in the strata, coupled with a northward-sloping land surface, (Hancox and Gotz 2014).
Commodity List
This is a list of exploitable or exploited mineral commodities recorded from this region.List of minerals for each chemical element
References
Sort by
Year (asc) Year (desc) Author (A-Z) Author (Z-A)Hancox, P. John and Gotz, Annette E (2014) South Africa's Coalfields – A 2014 perspective. International Journal of Coal Geology 132: 170-254 doi:10.1016/j.coal.2014.06.019
External Links
Localities in this Region
- Free State
- Fezile Dabi District Municipality
- Vereeniging - Sasolburg coalfields
- Sigma coalfield
- Vereeniging - Sasolburg coalfields
- Fezile Dabi District Municipality
Other Regions, Features and Areas containing this locality
African Plate
- Karoo basinBasin
Somali PlateTectonic Plate
South Africa
- Witwatersrand goldfieldMining Region
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Sigma coalfield, Vereeniging - Sasolburg coalfields, Fezile Dabi District Municipality, Free State, South Africa