Nguba Gr

Cenozoic

Mesozoic

Paleozoic

Neoproterozoic

Paleoproterozoic

Nguba Gr

Period:

Cryogenian

Age Interval:

Cryogenian

Province:
Southern Congo Margin

Type Locality and Naming

Katanga Basin, Southern Congo margin in DRC and Zambia. This group subdivided into (i) the Muombe Subgroup including the diamictitic 765–735 Ma ‘Grand Conglomerate’ or Mwale Formation correlated with the global Sturtian glacial event; and (ii) the carbonate and siliciclastic Bunkeya SubGroup.

Synonym:

References: Cailteux et al. 2007; Key et al. 2001; Wendorff and Key 2009; Frimmel et al. 2006; Cailteux et al. 2007; Heijlen et al. 2008

[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, Aloloand 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: Southern margin of the Congo Shield. (A) Geological sketch map of the Katanga Basin (modified after Heijlen et al. 2008). (B) Synthetic stratigraphic log combined with C and Sr isotopic curves of the Katanga Supergroup in the DRC and Zambia (modified after d ‰13, Cailteux et al. 2005). Note the declines in C estimated at 6.7 in d 1 the Lower Roan Group, followed by intervals with strong 3C enrichments, attributed to the Bitter Spring negative excursion and a d1 second negative 3C shift at the top of the Mwashia Group, reported to the Sturtian glacial events (Bull et al. 2011)]

[Fig 7: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 shaly carbonate succession becoming siliciclastic at the top, about 2,000 m- thickness. This group subdivided into (i) the Muombe Subgroup including the diamictitic 765–735 Ma ‘Grand Conglomerate’ or Mwale Formation (Key et al. 2001; Wendorff and Key 2009) correlated with the global Sturtian glacial event (Cailteux et al. 2007); and (ii) the carbonate and siliciclastic Bunkeya SubGr

Lithology Pattern:

Clayey limestone

Relationships and Distribution

Lower contact

Lies conformably on the Roan Gr

Upper contact

Overlain conformably by the Petit Conglomerate Fm at base of the Kundelungu Gr

Regional extent

Katanga Basin, Southern Congo margin in DRC and Zambia.

GeoJSON

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Fossils

Age

The basal Grand Conglomerate assumed to span Sturtian glacial (lower 70% of Cryogenian); and the overlying upper Nguba Gr units spanning interglacial, overlain by the Petit Conglomerate Fm of the Marinoan glacial (90% up in Cryogenian)

Age Span:

Beginning stage:

Cryogenian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

720.00

Ending stage:

Cryogenian

Fraction up in the ending stage:

0.9

Ending date (Ma):

643.50

Depositional setting

Sediments accumulate in continental, lacustrine to fluvio-deltaic semi-arid environments, and all are interpreted as Pan African-related late-orogenic molasses deposits (Frimmel et al. 2006; Cailteux et al. 2007; Heijlen et al. 2008).

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