Geology Reference
In-Depth Information
belts surrounding the CS in the Mesoproterozoic, including
the Tanzanian Craton during the formation of Rodinia, and
Gondwana in the late Neoproterozoic-Early Cambrian, cre-
ated the still larger CAS that stabilized by ca. 540 Ma.
The Precambrian rock sequences were regionally
peneplained during and following formation and exhuma-
tion of the Pan-African orogenic Mountain systems that
lasted until at least 540 Ma, and possibly 490 Ma (e.g. de
Wit et al.
2001
); and the unconformities were covered by
marine carbonate-quartzite platform rocks as early as the
Cryogenian and, in turn unconformably overlain by Cam-
brian Redbeds. These fluvial-lacustrine and aeolian
Redbeds, which generally characterize hot and arid conti-
nental environments, form the basal units of the CB, record-
ing marked extreme climate changes across the CB (and the
CAS) during the Neoproterozoic-Cambrian transition.
In summary, the basement of the CB has a highly varied
geological history with a complex mantle lithosphere that
dates back to the Early Archean. Whilst detailed geophysics
and mantle petrology across the CAS are mostly lacking, the
variable ages of diamondiferous kimberlites, or the lack
thereof, from its varied cratonic blocks illustrates that a
simple
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´
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lithospheric mantle structure cannot be
used to model the evolution of the CB.
'
one-fits all
'
Acknowledgments
MdW would like to thank many colleagues from
De Beers for facilitating and participation during a decade of his many
long field escapes into Africa between 1995 and 2005; and BL into the
CB in 2008. Both of us are grateful to Tsodilo Resources for supporting
similar trips to Botswana. MdW acknowledges Sam Bowring (MIT) for
precise U/Pb zircon dates (most of which still remain unpublished, but
we are trying to do something about that) and Moctar Doucour
´
for his
calm and diplomatic Africa advice and wisdom during our African
adventures. We thank Bruce Eglington, Brendan Murphy and Mike
de Wit for critical reviews. Some of this work was funded through the
DST/NRF to AEON and Inkaba yeAfrica/!Khure Africa programs. This
is AEON contribution number 134 and Inkaba yeAfrica number 107.
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'
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