Ruhuhu Fm
Type Locality and Naming
Ruhuhu Basin (Tanzania). Named for the Ruhuhu River and the broader Ruhuhu Basin in southwestern Tanzania. It was originally described and designated as the "K5" horizon or "Ruhuhu Beds" in the classic alphanumeric Karoo stratigraphic framework established by Stockley (1932). It was later formally elevated to the Ruhuhu Formation by Wopfner (2002). Lower formation in Beaufort Gr in Ruhuhu Basin (Tanzania).
Synonym: K5 Beds
Lithology and Thickness
Composed predominantly of a thick, fine-grained sequence of grey-green to dark grey, highly calcareous mudstones, shales, and siltstones, interbedded with fine-grained sandstones. A defining characteristic of the Ruhuhu Formation is the presence of prominent bands of dolomitic limestone and abundant calcareous nodules/concretions.
Relationships and Distribution
Lower contact
Conformably overlies the Mhukuru Fm/ Mbuyura Fm (K4 / Upper Coal Measures).
Upper contact
Conformably to transitionally overlain by the reddish, nodular, and highly fossiliferous mudstones of the Usili Fm (K6 / Lower Bone Bed).
Regional extent
Geographically restricted to the Ruhuhu Basin in southwestern Tanzania. Regionally, it correlates with the Lower/Middle Madumabisa Mudstone Fm in Zambia and Zimbabwe, and transitions into the equivalents of the lower Beaufort Gr in the Main Karoo Basin of South Africa.
GeoJSON
Fossils
Age
Depositional setting
Primarily a vast, low-energy lacustrine (lake) and shallow deltaic environment.
Additional Information