Mayombe Gr

Cenozoic

Mesozoic

Paleozoic

Neoproterozoic

Paleoproterozoic

Mayombe Gr

Period:

Neoproterozoic

Age Interval:

Province:
West Congo Margin Basins

Type Locality and Naming

Named after the Mayombe Chain. The Mayombe Gr consists of the upward succession of the Mossouva Fm (Subgroup), Lower Tillite Fm (Subgroup), eastern Bouenza Fm and western Louila Fm (subgroups).

The Nyanga-Niari Basin in the northern part of the West Congo Belt on the western margin of the Congo Shield comprises two distinct geologic domains from west to east, i.e. the metasedimentary hinterland domain deposited on c. 1000–850 Ma magmatic Mabouine´ and Mayumba complexes, and the poorly constrained unmetamorphosed sedimentary foreland domain (Thie´blemont et al. 2009). The Mayumba basin is exposed on the Mabouine´ and Mayumba complexes.

Synonym: Mayumbe Gr (spelling)

References: Thie´blemont et al. 2009; de Wit et al., 2015; Fullgraf et al., 2024

[Fig 1. 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 2. 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 3. 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. 4. 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

The Mayombe Gr is comprised of the upward succession of the clayey sandstone of the Mossouva Fm, the glacial till of the Lower Diamictite Fm, and the inter-glacial Bouenza Fm of carbonates and clastics (Nairi Basin in the east) and the equivalent Loula Fm of mainly clastics (Mayombe Chain in the west) (de Wit et al., 2015; Fullgraf et al., 2024).

Lithology Pattern:

Sandstone

Relationships and Distribution

Lower contact

Rests on the Sounda Gr (Mvouti Fm)

Upper contact

Unconformably overlain by the fluvial-glacial till of the Niari Gr (Upper Diamictite).

Regional extent

Name applies to Nairi Basin (Gabon) and Mayombe Chain (Gabon, RC), plus Comba-Sangha Basin (RC); but equivalent are along entire West Congo belt.

GeoJSON

null

Fossils

Age

Middle Tonian (Mossouva begins ca. 870 Ma => 45% up in Tonian) to base of Marinoan glacial (the overlying Niari Tillite)

Age Span:

Beginning stage:

Tonian

Fraction up in beginning stage:

0.45

Beginning date (Ma):

874.00

Ending stage:

Cryogenian

Fraction up in the ending stage:

0.9

Ending date (Ma):

643.50

Depositional setting

Passive margin setting.

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

Fullgraf, T., Callec, Y., et al. (2024) Structural architecture and metamorphism of the Mayombe Chain and Niari Basin (West Congo Belt) in Congo Brazzaville. Jour. Afr. Earth Sci., 220: article 105369.