Mbuyura Fm
Type Locality and Naming
Ruhuhu Basin (Tanzania). Named for the Mbuyura area in the Ruhuhu Basin of southwestern Tanzania. Originally described by Stockley (1932) as the "K3" horizon or the "Intermediate Marls and Sandstones," it was later formally established as the Mbuyura Formation by Wopfner (2002) within the revised Songea Group stratigraphy. Middle formation in Ecca Gr in Ruhuhu Basin (Tanzania)
Synonym: K3 Beds,
Lithology and Thickness
Composed of a massive and highly variable terrestrial clastic sequence. It is characterized by thick, coarse-grained, cross-bedded feldspathic (arkosic) sandstones and conglomerates, heavily intercalated with distinctive red, purplish, and green mudstones and marls.
Relationships and Distribution
Lower contact
Conformably to disconformably overlies the coal-bearing carbonaceous shales and sandstones of the Mchuchuma Fm (K2 / Lower Coal Measures). In some marginal graben areas, it may overstep directly onto the pre-Karoo basement.
Upper contact
Conformably overlain by the carbonaceous and coal-bearing Mhukuru Fm (K4 / Upper Coal Measures), or directly by the Ruhuhu Fm (K5) where the K4 is locally absent.
Regional extent
Widespread throughout the Ruhuhu Basin and extending into adjacent Karoo-aged rift structures in southwestern Tanzania. Regionally, it correlates with early-to-middle Ecca Gr equivalents in the Main Karoo Basin of South Africa and other coarse, red-bed terrestrial sequences in eastern African rifts
GeoJSON
Fossils
Age
Depositional setting
High-energy continental braided fluvial systems transitioning into broad alluvial plains and playas.
Additional Information