Aruwimi Gr

The type section is exposed near Yambuya on the Aruwimi river (Mathieu 1922)

Synonym: Known as the Sequence 3 of the Gilson, Mbandaka, and Dekese wells (de Wit et al., 2015), and is referred to by Daly et al. (1992).

Reference: Cahen 1954; Mathieu 1922; Poidevin 2007; Verbeek 1970; Sechse et al., 2011

[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: 4M map Geology 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. 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]

Aruwimi Group is predominantly clastic (Verbeek 1970; Poidevin 2007). The Aruwimi Group is characterized by basal transgressive sandstones, overlain by shales, and capped by progradational sandstones. It subdivided successively from base to top into: the Galamboge Fm massive arkoses and quartzites (100–150 m); Alolo Fm red to dark carbonaceous shales with limestone intercalations (350–400 m); and the relatively thick up to 1,200 m) red arkoses of the Banalia Fm (Banalia Arkose – separated as a distinct formation here, following de Wit et al., 2015), with ca.100 m thick transitional units between them (Verbeek 1970), bringing its total thickness to an estimated 1760m (Sechse et al., 2011).

Considered coeval with the Mpioka Gr of West Congo Margin basins, so given the same late Ediacaran through earliest Cambrian age span

Foreland Basin-platform deposits