Bakouma Gr

Cenozoic

Mesozoic

Paleozoic

Neoproterozoic

Paleoproterozoic

Bakouma Gr

Period:

Cryogenian, Ediacaran, Cambrian

Age Interval:

late Cryogenian, Ediacaran, earliest Cambrian

Province:
Northern Congo Margin

Type Locality and Naming

The Fouroumbala-Bakouma Basin, which is located in the south central region of the CAR. The Neoproterozoic sedimentary rocks exposed on northern margin of CS, are recognized in the Ubangui and Fouroumbala-Bakouma basins of the south-western CAR, and in the Lindi Basin of the northeastern DRC, Trompette (1994) considered all these basins to be part of the Lindi Basin.

Synonym: Bakouma Subgroup

Reference: Trompette (1994)

[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, 1974) and the 1: 4Mmap Geology and Major Ore Deposits of Africa (Milesiet al., 2006)]

[Fig 3. Lithostratigraphic synthesis for the Neoproterozoic to Early Paleozoic period. Compiled after various authors. 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 LindiSupergoup in the DRC (modified after Verbeek 1970). (C and D) Stratigr aphic logs of the LindiSupergoup 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 dolomite, limestone and argillaceous limestone, sandstone-Quartzite/Conglomerate and having more than 100m thickness. Has Bondo Tillite at the base

Lithology Pattern:

Sandy Limestone

Relationships and Distribution

Lower contact

The basal Bondo Tillite overlies the Kembe-Nakando Fm

Upper contact

Not given

Regional extent

Extends in the northern margin of Congo Basin, the Fouroumbala-Bakouma basins extends the south-western CAR, and in the Lindi Basin of the northeastern DRC.

GeoJSON

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Fossils

Age

Indicated in correlation chart of de Wit et al (2015) to be coeval with the Upper Diamictite (its Bondo Tillite member), the Schisto-Calcaro carbonates and the Schisto-Greseaux siliciclastics of the West Congo Margin basins, hence latest Cryogenian (Marinoan) to early Cambrian?

Age Span:

Beginning stage:

Cryogenian

Fraction up in beginning stage:

0.9

Beginning date (Ma):

643.50

Ending stage:

Cambrian Stage 2

Fraction up in the ending stage:

1.0

Ending date (Ma):

521.00

Depositional setting

Post-glacial fluvial-marine depositional environment

Depositional pattern:

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