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(Modified after Raucq 1957 , 1970 ). Note the 87 Sr/ 86 Sr ratios ranging
between 0.7069 and 0.7071 and the negative
Fig. 3.5 Southern margin of the Congo Shield. (A) Sketched geologi-
cal map of the Sankuru-Mbuji-Mayi-Lomami-Lovoy Basin (modified
after Raucq 1957 , 1970 ). (B) Synthetic stratigraphic log combined with
C and Sr isotopic curves of the Mbuji-Mayi Supergroup in the DRC
13 C shifts of 4.0
and
δ
6.1
in the BIIb and BIIc transition, which are reported with the
Bitter Springs anomaly around c. 810 Ma (Delpomdor et al. 2013 )
et al. 2001 ; Key et al. 2001 ; Barron et al. 2003 ) including
mafic volcaniclastic rocks (Lefebvre 1973 ; Cailteux 1983 ;
Cailteux et al. 2003 ; Kabengele et al. 2003 ) coeval with the
gabbroic bodies emplaced within rocks of the Dipeta Sub-
group (DRC) and Bancroft-Kanwangungu formations
(Mendelsohn 1961 ; Lefebvre 1975 ; Cailteux et al. 2007 ).
Cailteux et al. ( 2007 ) adopted a similar lithostratigraphic
scheme for the Upper Katanga Supergroup, i.e. the Nguba
and Kundelungu groups, between the DRC and Zambia.
The
2,000 m-thick Nguba Group comprises a shaly car-
bonate succession becoming siliciclastic at the top, and is
subdivided into (i) the Muombe Subgroup including the
diamictitic 765-735 Ma
Grand Conglom ´ rat
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
Subgroup. The Kundelungu Group is further subdivided
into: (i) the Gombela Subgroup including the glacigenic
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