Geology Reference
In-Depth Information
Fig. 3.4
Eastern margin of the Congo Shield. (A) Geological sketch map of the Itombwe and Malagarazi-Bukoban basins. (B) Synthetic
stratigraphic log of the Itombwe Supergroup in the DRC (modified after Walemba and Masters
2005
).
SG
Sturtian Glaciation
basins in the DRC and Burundi-Tanzania successively
(Fig.
3.4A
). The Itombwe Supergroup is affected by meta-
morphism from greenschist facies to weakly wrinkled
metamorphosed (Villeneuve
1976a
,
b
,
1977
,
1979
;
Walemba
2001
), while the Malagarazi-Bukoban Supergroup
are unmetamorphosed (Tack
1995
). Deformation in the
Itombwe and Malagarazi-Bukoban basins may be kinemati-
cally linked with strike-slip reactivation of the Kibaran and
Karangwe-Ankole belts and/or Ubendian Belt during Pan-
African orogen (Theunissen et al.
1992
; Fernandez-Alonso
and Theunissen
1998
).
consists of approximately 3,700 m-thick siliciclastic rocks
subdivided into three formations, i.e. Kigogo, Kalama and
Mudubwe. The Upper Kadubu Group has two formations, i.
e. Nya-Kasiba and Tsibangu. This Group comprises approx-
imately 8,000 m-thick siliciclastic rocks including at the top
>
800 m-thick diamictitic sequences of the Diamictite Mem-
ber (Walemba and Masters
2005
). The age of the Itombwe
Supergroup is estimated between 1310
12
Ma (Villeneuve
1976a
,
b
,
1979
; Cahen et al.
1979
; Waleffe
1988
), and between 1020
40 and 648
83 Ma (Walemba
and Master
2005
). Fernandez-Alonso et al. (
2012
) proposed
a maximum age of approximately 750 Ma for the base of the
Itombwe Supergroup.
50 and 575
3.3.3.1 Itombwe Basin, DRC
The Itombwe Supergroup is lithostratigraphically divided
into (Fig.
3.4B
; Villeneuve
1976a
,
b
,
1977
,
1979
; Cahen
et al.
1979
): the Lower Kadubu and Upper Kadubu groups.
The Lower Kadubu Group rests unconformably on a meta-
morphic and crystalline Burundian-Ruzizian basement, and
3.3.3.2 The Malagarazi-Bukoban Basin, Burundi,
Tanzania
The Malagarazi-Bukoban Basin (Fig.
3.4A
) is located along
the boundary between the Archean Tanzania Craton to the
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