The Petroleum Potential of South Africa's Onshore Karoo Basins
Lindiwe Raseroka and Ian R. McLachlan
Frontier Geology, Petroleum Agency SA, Cape Town, South Africa
The Late Carboniferous to Mid-Jurassic Karoo basins hold an important place in South African geology and economics as they occupy more than half of the nation's land area and host the coal deposits that provide most of the country's energy. Together with the gold in the underlying Archaean Witwatersrand deposits they have provided the focus for the development of South Africa's industrial heartland. As yet very little systematic modern exploration for petroleum has been done - the opportunity exists for a new generation of explorers to test the potential of these huge basins.
The Great Karoo basin covers an area of over 700 000 sq kms and constitutes a retro-arc foreland basin. Maximum down-warping occurred in the south where cummulative sediment thickness reached 12 kms. South Africa's main coal deposits occur in an arc across the northern flank of the basin but major reserves are also contained in the smaller fault controlled basins that lie to the north.
Promising petroleum exploration plays include:
Unconventional, possibly biogenic gas (associated with high concentrations of helium - up to 26%) that occurs in the Witwatersrand Group and other ancient basement rocks in the Welkom and Evander gold field areas.
Deep tight shale gas
The present energy shortfall in South Africa provides a new impetus for the development of an expanded natural gas industry.
AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery