TY  - JOUR
T1  - An Integrated Geophysical Approach to Mapping and Modelling the Karoo
Dolerite Intrusions in the South-Eastern Karoo Basin of South Africa
AU - Baiyegunhi, Christopher AU - Gwavava, Oswald AU - Liu, Kuiwu AU - Baiyegunhi, Temitope L. 
JO  - Journal of Engineering and Applied Sciences
VL  - 14
IS  - 6
SP  - 1885
EP  - 1911
PY  - 2019
DA  - 2001/08/19
SN  - 1816-949x
DO  - jeasci.2019.1885.1911
UR  - https://makhillpublications.co/view-article.php?doi=jeasci.2019.1885.1911
KW  - Dolerite intrusions
KW  -magnetic
KW  -depth slicing
KW  -gravity
KW  -modelling
KW  -Karoo Basin
AB  - The South-Eastern Karoo Basin has several dolerite intrusions that possibly introduced heat into the
basin and resulted in the large scale conversion of oil to gas. To date, the geometry of these dolerites and
variations in electrical resistivity of the purported shale gas hosting Ecca Group is poorly documented despite
over 30 years of research in the area. In this study, we investigate the variations in resistivity of the Ecca Group,
estimate the average depths to magnetic signatures and produce gravity models that unravel the basin
architecture and how dolerite intrusions are interconnected at depth. The magnetic map shows some ring-like
or circular structures which coincide with dolerites that were mapped in the field. Depth slicing revealed that
the dolerites are pervasive in the study area, extending up to 5400 m. The Bouguer anomaly map shows gravity
values increasing from inland to coastal areas. The gravity models revealed that the dolerites form a network
of interconnected sills, dykes and inclined sheets at depth. The subsurface apparent resistivity of the Ecca
Group varies between 2 Ωm and 557000 Ωm. The pseudosections show that the lower Ecca Group rocks are
generally characterised by low resistivity compared to the upper Ecca Group rocks
ER  -