Geology Reference
In-Depth Information
Supergroup and the Rio Iva´-Paran´ Groups). Thus, dur-
ing this period, the general CWGB
Janeiro. This is AEON contribution number 131 and Inkaba yeAfrica
contribution number 101.
s surface was then
consistently inclined to the south toward the paleo-Pacific
(Fig.
13.8
).
During the following mid- to late Paleozoic glaciation
of Gondwana (ca. 300-350 Ma; Milani and de Wit
2008
)
significant erosion and widespread glaciogenic sequences
(the Dwyka, Itarar´ and Lower Lukuga Groups), depos-
ited with paleocurrents mainly to the southwest in the
CKB, to the north in the PB, and to the west in the CB,
indicate major highlands located near the center of
Gondwana (e.g. the Cargonian and Tanzanian Highlands;
Fig.
13.10
). Subsequent deglaciation and associated
extensive deposition of black shales at the end of the
Early Permian (ca. 270-280 Ma) were then followed by
Late Permian-Triassic sedimentation under increasingly
hot and arid conditions across the entire CWGB complex
(the Beaufort, Passa Dois, Santa Maria, Cassange and
Haute Lueki Groups). This regional regression can possi-
bly be linked to far-field processes related to the
Mauritanian-Variscan and Cape-de la Ventana orogens
along the northwestern and southern margins of
Gondwana, respectively (Daly et al.
1992
; Trouw and
de Wit
1999
; Dabo et al.
2008
;P
´
ngaro and Ramos
2012
). At about the same time, between 250-280 Ma
large volcanic activities within the proto-Andes produced
widespread air-fall tuffs in the sedimentary record of the
CWGB (Stollhofen et al.
2000
; Santos et al.
2006
; Fildani
et al.
2009
; Linol
2013
; see Chap.
8
, this Topic).
Triassic, and then Jurassic arid sedimentation across
the CWGB complex culminated in widespread deposition
of northerly-derived aeolian dunes (the Eliot, Etjo,
Piramboia, Botucatu and Dekese Formations), which
was episodically interrupted by voluminous extrusions
of continental flood basalt at 183 Ma (the Karoo LIP)
and at 132 Ma (the Paran´-Etendeka LIP), during initial
opening of the Indian and South Atlantic Oceans, respec-
tively. This main period of break-up of Gondwana is best
recorded in the CB (Fig.
13.15
), where it corresponds to
two distinct phases of subsidence associated with
shallowing lacustrine sequences. Following Late Creta-
ceous renewed fluvial sedimentation in the CB and PB,
epeirogeny both in south-central Africa and eastern South
America led to limited preservation of Cenozoic
sequences and widespread development of calcretes,
suggesting higher rates of evaporation during a more
humid climate.
'
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'
Acknowledgments
We acknowledge funding through the Inkaba
yeAfrica and !Khure Africa programs. We also acknowledge Petrobras
for providing support in Brazil. B. Linol particularly thanks Renata da
Silva Schmitt, convener of the Gondwana14 conference in Buzios and
leader of the Gondwana Map Project for welcoming him in the new
Gondwana mapping center at the Universidade Federal do Rio de
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