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11
Multiphase Phanerozoic Subsidence and Uplift
History Recorded in the Congo Basin: A Complex
Successor Basin
Bastien Linol, Maarten J. de Wit, Francois Guillocheau, Cecile Robin,
and Olivier Dauteuil
11.1
Introduction
information of the basin fill and rely on the stratigraphy
from the 1950s and 1970s that, as will be shown here, is
frequently inadequate and often inaccurate (Linol
2013
; see
In this contribution, we use revised stratigraphic and
sedimentological data of the four historic deep boreholes
(each ca. 2 to 4.5 km in depth) drilled near the center of
the basin to calculate a new first-order model for the subsi-
dence and uplift history across this vast region of central
Africa (Fig.
11.1
for location). To achieve this, the four
borehole-sections are backstripped using a procedure espe-
cially adapted to this terrestrial (non-marine) basin, as
described below. The results reveal a more complex (multi-
phase) geodynamic evolution of the CB during the Phanero-
zoic, including distinctive phases of rapid subsidence
separated by episodic uplifts. We then propose a complex
successor basin model for the CB during and following the
period between the final amalgamation of Gondwana (and
Pangea) supercontinent and its subsequent break-up
resulting in the successive openings of the Indian and
South Atlantic Oceans.
The stratigraphic record of the Congo Basin (CB) represents
a long (ca. 550 million years) history of sedimentation,
erosion and preservation in the heartland of Gondwana
and, following Gondwana break-up, in central Africa. This
long-lived Phanerozoic basin features large in many tectonic
models of Africa, yet paradoxically it remains very poorly
understood because of limited recent field and geophysical
data acquired in this politically unstable region, especially
the war-torn Democratic Republic of Congo (DRC), host to
the greater part of the basin. In particular, there is consider-
able controversy about the origin and influence of its
associated long wavelength (ca. 1,500 km) negative gravity
anomaly (Fig.
11.1
). This anomaly is commonly linked to a
long-lived dynamic
in the underlying mantle and
related to convective down-welling, resulting in a long his-
tory of slow and continuous subsidence of the CB since the
late Precambrian (Hartley and Allen
1994
; Downey and
Gurnis
2009
; Crosby et al.
2010
; Kadima et al.
2011
; Buiter
et al.
2012
). But,
cold spot
'
'
these studies are based on meagre
11.2
Stratigraphic Record and Subsidence
Analysis
Based on stratigraphic data, the evolution of the CB is
analyzed by modeling its subsidence and uplift history.
The vertical displacements of the basin basement are defined
as subsidence, which increases when the basin sinks or
decreases when it uplifts, resulting from different processes
that can generate vertical movement: thermal cooling, sedi-
ment (and water) loading and tectonics (e.g. McKenzie
1978
; Cochran
1983
; Allen and Allen
1990
; Vail et al.
1991
).
The total subsidence of the basin is reflected in its sedi-
mentary infill (sequences) that becomes progressively more
compacted as it is buried, and interrupted by phases of
erosion during uplift that create regional unconformities.
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