Bangui Carbonate Fm

Period:

Ediacaran

Age Interval:

early Ediacaran

Province:
Northern Congo Margin

Type Locality and Naming

Ubangui Basin, southwest CAR. Located southwards to the Congo River. Neoproterozoic sedimentary rocks exposed in the SW of the CAR, around Bangui extend southwards to the Congo River. Lithostratigraphically, the Ubangui Basin has been described by Babet (1935), Legoux and Hourcq (1943), Ge´rard and Ge´rard (1952), Bessoles and Trompette (1980) and Poidevin (1976, 1985, 2007).

Synonym: Bangui carbonates

References: Alvarez 1995

[Fig 1. Simplified geological map of the Congo Basin, compiled from various published map. The stratigraphic units have been assembled into major sequences (Late Neoproterozoic, Paleozoic and Cenozoic)]

[Fig 2. Tectonic setting of the Neoproterozoic basins of present-day Central Africa, compiled from the 1: 2M geological map of the Zaire (Lepersonne, 1974a) and the 1: 4MmapGeology and Major Ore Deposits of Africa (Milesi et al., 2006)]

[Fig 3. Lithostratigraphic synthesis for the Neoproterozoic to Early Paleozoic period. Compiled after various authors (see text).Dotted lines between Banalia, Alolo and Galamboge formations: stratigraphic transition by recurrences]

[Fig 4. Lithostratigraphic columns for the Congo Basin established using data from the 4 wells in the central part of the basin and outcrops on its NE margin (Lindi-Ubangi and Kisangani-Kindu region), compared with the West-Congo and Katanga stratigraphy]

[Fig 5. Simplified geological map of Sub-Saharan Africa showing the Neoproterozoic basins on and around the Congo Shield (modified after De Waele et al. 2008). (LC) Lower Congo Basin, (Co) Comba Basin, (Sa) Sangha Basin, (Ny) Nyanga-Niari Basin, (An) Angola Basin, (SO) Semb-Ouesso Basin, (Ba) Ubangui Basin, (LiB) Likki-Bembe´ Basin, (Bk) Bakouma Basin, (Fou) Fouroumbala Basin, (Li) Lindi Basin, It Itombwe Basin, (Ma)Malagarazi-Bukoban Basin, (Mb) Sankuru-Mbuji-Mayi-Lomami-Lovoy Basin, (Lu) Luamba Group, (Kat) Katanga Basin, (RB) Ruwenzorian Belt, KaB) Karagwe-Ankole Belt, (RuB) Ruzisian Belt, (KiB) Kibaran Belt,(UB) Ubendian Belt, IB Irumide Belt]

[Fig 6. Northern margin of the Congo Shield. (A) Geological sketch map of the Lindi Basin (modified after Verbeek 1970; Poidevin 1985)]

[Fig 7. Stratigraphic logs of the Lindi Supergoup in the DRC (modified after Verbeek 1970). (C and D) Stratigraphic logs of the Lindi Supergoup in CAR (modified after Poidevin 1985). cc cap carbonates, SG Sturtian Glaciation, MG Marinoan Glaciation]

[Fig 8. Stratigraphic correlation between the Neoproterozoic sedimentary basins in Central Africa. Correlations based on Sr isotopic data, radiometric age constraints and revised lithological relationships]

Lithology and Thickness

Consists of carbonate series, rhythmites and microbial limestones

Lithology Pattern:

Limestone

Relationships and Distribution

Lower contact

Lies on the Bimbo Sandstone Fm

Upper contact

Not given; but assumed to be a regional hiatus at the Pan-African orogeny (collision).

Regional extent

Neoproterozoic sedimentary rocks exposed in the SW of the CAR, around Bangui extend southwards to the Congo River. Coeval (and similar lithology?) with the Schisto-Calcaire Subgroup of the West Congo Supergroup (Alvarez 1995).

GeoJSON

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Fossils

Age

Basal “cap carbonate” suggests base of Ediacaran. Coevel with the Schisto-Calcaire Gr of West Congo Margin basins; therefore assumed to also extend until Pan-African orogeny regional hiatus in mid-Ediacaran

Age Span:

Beginning stage:

Ediacaran

Fraction up in beginning stage:

0.0

Beginning date (Ma):

635.00

Ending stage:

Ediacaran

Fraction up in the ending stage:

0.45

Ending date (Ma):

591.71

Depositional setting

Depositional pattern:

Rhythmites and microbial carbonate environment

Additional Information

Compiler:

Enam O. Obiosio, Solomon Joshua Avong and Henry Nasir Suleiman (2024) - Stratigraphic Lexicon compiled from the following books:

Geology and Resource Potential of the Congo Basin by Maarten J. de Wit, François Guillocheau and Michiel C.J. de Wit, Published Springer-Verlag Berlin Heidelberg 2015; DOI 10.1007/978-3-642-29482-2