Overview of the Neoproterozoic Sedimentary Series Exposed Along Margins of the Congo Basin - Geology and Resource Potential of the Congo Basin - page 47

13 C
enrichments, attributed to the Bitter Spring negative excursion and a
second negative

Fig. 3.6 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
Cailteux et al. 2005 ). Note the declines in

the Lower Roan Group, followed by intervals with strong

δ

13 C shift at the top of the Mwashia Group, reported to
the Sturtian glacial events (Bull et al. 2011 )

δ

13 C estimated at 6.7

in

δ ‰

'

Petit Conglom ´ rat

'

diamictites of the or Kyandamu Forma-

tion and the cap carbonates of the Lusele Formation; (ii) the
carbonate, then siliciclastic Ngule Subgroup; and (iii) the
siliciclastic

deformed by short-lived phases of compression during the
Neoproterozoic (e.g. Fernandez-Alonso et al. 2012 ).
The Itombwe and Malagarazi-Bukoban supergroups
accumulated in passive intraplate or cratonic sag-type basins
(Mbede 1991 ), and the Mbuji-Mayi Supergroup in a failed-
rift intracratonic basin (Kadima et al. 2011 ; Delpomdor et al.
2013 ). These successions are interpreted as molasse deposits
related to a tectonic reactivation of the Kibaran and/or
Karangwe-Ankole mountains (Fernandez-Alonso et al.
2012 ), or as rift deposits during the first phases of Rodinia
break-up. Along the western margin of the CS, the Zadinian
and Mayumbian groups, and the time-equivalent Mabouin ´
and Mayumba complexes,

573 Ma Biano Subgroup (Master et al. 2005 ).

3.4 Discussion and Conclusion

3.4.1 Depositional settings

Since the Mesoproterozoic Eon, the CS region was subjected
to intermittent episodes of extensional activity resulting in
long-lived shallow cratonic basins, which were subsequently

represent a continental rift