Paleogeography and Tectono-Stratigraphy of Carboniferous-Permian and Triassic ‘Karoo-Like’ Sequences of the Congo Basin - Geology and Resource Potential of the Congo Basin - page 107

7

Paleogeography and Tectono-Stratigraphy
of Carboniferous-Permian and Triassic
'Karoo-Like' Sequences of the Congo Basin

Bastien Linol, Maarten J. de Wit, Erika Barton, Francois Guillocheau,
Michiel C.J. de Wit, and Jean-Paul Colin

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7.1 Introduction

now the Democratic Republic of Congo (DRC). All research
materials from this exploration period are archived in the
Royal Museum for Central Africa (RMCA), in Tervuren,
Belgium.
Subsequently, during the 1970s, renewed petroleum
exploration led to the acquisition of additional geophysical
data and the drilling by

The Congo Basin (CB) of central Africa, also known as the
' , was first systematically explored geolog-

ically during the 1950s when this region was part of a
Belgian colony. This early exploration included extensive
field mapping, regional magnetic and seismic surveys
(e.g. Jones et al. 1959 ; Evrard 1960 ), and drilling of two
boreholes (Samba-1 and Dekese-1), each ca. 2 km deep
(Cahen et al. 1959 , 1960 ). This work defined the structural
setting and stratigraphy of the CB, culminating in the com-
pletion of the Geological Map of Zaire (Lepersonne 1974 ),

Cuvette centrale '

of two deeper wells
(Gilson-1 and Mbandaka-1), each ca. 4.5 km in depth (Esso-
Zaire 1981a , b ). This data has largely remained proprietary,
and only short summaries of this work were published
(Lawrence and Makazu 1988 ; Daly et al. 1991 , 1992 ).
Since then, very little new geologic or geophysical data has
been acquired across the CB (e.g. Kadima et al. 2011 ;
Sachse et al. 2012 ; Linol 2013 ). For that reason, the strati-
graphy of this unusually large (ca. 1.8 million km 2 ) sedi-
mentary basin remains very poorly characterized, preventing
a more modern basin analysis. Today, there is still contro-
versy about the basic definition of its major depositional
sequences

' Esso-Zaire '

(i.e. supersequences) and the age of their

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bounding unconformities.
Here, new field observations are integrated with
re-examination of the old literature (in French) and the
available seismic- and well-data to resolve some of these
major stratigraphic uncertainties, focusing on the ' Karoo-

like (Carboniferous-Permian and Triassic) sequences of the

CB. In addition, U-Pb dating of detrital zircons from core
samples of two of the deep boreholes characterizes the
source provenances for these sediments and helps to con-
strain the paleogeography of central Africa during the late
Paleozoic and early Mesozoic.

'

7.2 Geological Setting

The CB is surrounded by Precambrian basement and peri-
pheral Pan African fold-and-thrust belts of Neoproterozoic
carbonate and siliclastic platform sequences (Fig. 7.1 ; see