Black Shale and Coal Gr
Type Locality and Naming
Mid-Zambezi Basin (Zimbabwe and southern Zambia). Named after the Hwange (formerly Wankie) district in northwestern Zimbabwe. It is a historic, highly descriptive stratigraphic term coined by early 20th-century geologists (such as A.J.C. Molyneux and B. Lightfoot) during the initial mapping and exploitation of the region's vast coal resources. In modern regional stratigraphy, it is often formally designated as the Hwange (or Wankie) Coal Formation. Lower formation in Ecca Gr in Mid-Zambezi Basin
Synonym: Wankie Coal Formation, Hwange Coal Formation
Lithology and Thickness
It is characterized by thick beds of black, highly carbonaceous shales grading into massively thick, continuous coal seams. The most famous is the Wankie Main Seam, which can reach remarkable thicknesses of up to 10 to 14 meters of solid coal in some areas. Intercalated within the shales are thin, localized stringers of micaceous siltstone.
Relationships and Distribution
Lower contact
Conformably and transitionally overlies the finer-grained, micaceous upper layers of the Lower Wankie Sandstone Fm.
Upper contact
Unconformably overlain by the coarse-grained, high-energy Upper Wankie Sandstone Fm.
Regional extent
Extensively mapped and mined in the Hwange district of the Mid-Zambezi Basin in Zimbabwe, with correlative coal-bearing strata extending across the basin into southern Zambia. Lower to Middle Ecca Group Gr. It chronostratigraphically and environmentally correlates with the world-class coal-bearing units across southern Africa, such as the Vryheid Fm (Main Karoo Basin, South Africa) and the Boritse Fm or Tlapana Fm (Botswana).
GeoJSON
Fossils
Age
Depositional setting
Expansive paludal (peat swamp) and restricted, anoxic shallow lacustrine environments.
Additional Information
The Black Shale and Coal Gr is the economic heart of Zimbabwe's fossil fuel industry and has been extensively studied for over a century due to its massive, continuous coal reserves.