The Springbok Flats (SBF) Basin is one of the smaller basins associated with the
Karoo basins of the Late Carboniferous–Middle Jurassic age interval. The preserved SBF
basin is a topographically flat area with very few outcrops. It has a NE-SW orientation and is
approximately 205 km long and 30 km wide. This study is based on borehole log data
captured by the Council for Geoscience, which has been collected from various exploration
companies throughout the history of the investigation of the SBF Basin area.
The purpose of this study is to identify an evolutionary history of the basin by utilising
methods of basin analysis and literature search, and to establish how the basin relates to
other Karoo Supergroup basins in southern Africa. The postulated genetic model of a retroarc
fore-bulge rift basin was compared to the inferred depositional environments.
The geophysical interpretations and structural contour maps of the various strata
indicate the presence of the major Zebedelia Fault, which is part of the Thabazimbi
Murchison Lineament (TML) relay system. This fault runs along the northern boundary of the
basin and has caused the strata of the SBF Basin to be down-faulted by 800 to 1000 metres.
The isopachs of the identified Karoo successions do not indicate thickening towards this
lineament, which suggests that the faulting along this lineament post-dates the Karoo
The Thabazimbi Murchison Lineament played a significant role during the later
stages of the SBF sedimentation. Once the depocentre became more centrally located in the
depository, it began to migrate towards the TML. Although the major faulting was yet to
occur, the weakness in the craton was apparent. During the breakup of Gondwana, the
Zebedelia Fault shifted the strata down and allowed the extrusion of the Letaba Basalt, along
with the multi-intrusion of dykes throughout the strata.
The onset of the deposition of the Karoo Stratigraphy in the SBF was due to uplift
resulting from the mid-carboniferous assembly of Pangea. During the Lower Karoo
deposition, lithospheric subsidence was facilitated by crustal-scale faults, resulting in the
deposition of the glacial Dwyka and Lower Ecca sediments. Flexural subsidence was
occurring in the forebulge due to the relaxing of the initial compression of the Cape Fold Belt
(CFB). The later Ecca succession was characterized by large subsidence with little
accompanying brittle deformation. The lower Beaufort was a deltaic basin and was
terminated towards the end of the Permian period, identified by a significant loss of fauna
and flora. There was a ± 3km uplift, known as the Namaqua Uplift and erosion north of the
fold belt. This marked the structural inversion during deposition of the Beaufort Group and
Early Molteno Formation. These uplift events resulted in uplift in the foredeep which resulted
in the compression of the forebulge during the deposition of the Molteno Formation. Once
these events subsided, the forebulge relaxed and underwent subsidence and extension.
Elliot Formation formed during this unloading of structural relief and relaxation of basinforming
stresses. The upper Elliot and Clarens formations and Letaba Basalts exhibit the
transition from sinistral strain of the late Karoo Basin to the dextral tectonics of the
Gondwana breakup that terminated the basin deposition. The Karoo sediments in the SBF Basin clearly represent the broad spectrum of the
same set of palaeoenvironments that are recognised in the Main Karoo Basin rocks. These
reflect the progressive infilling of the Karoo Basins, the changing tectonic framework as well
as the migration of Gondwana from polar to tropical latitudes. However, due to the
development of the SBF basin on the forebulge, the compression of the CFB had the
opposite effect, where it resulted in uplift of the fore-bulge and subsidence of the foredeep.
This subsequently resulted in the SBF correlated Karoo sedimentary successions being
markedly thinner than those of the Main Karoo Basin, and in some cases, certain strata are
An extensional basin formed by reactivation of older structures, such as the TML, as
a result of displacement on the principle shear zones. This resulted in the preservation of the
SBF strata in the basin today.
This study is a baseline and preliminary investigation into the SBF Basin, and may
act as a canvas to which more in-depth investigations may be added. Various questions
have been identified that require further understanding and are listed under
recommendations. Many of the questions put forth may be answered with a thorough Quality
Assurance-Quality Control (QAQC) of the database.