South Africa - Inkaba.org

Comparing 1960’s Karoo basin seismic data with recent data
(Inkaba yeAfrica Line), to identify and correlate Karoo seismic
stratigraphy on a more regional basis
1 Lynise Esterhuizen, 2 George Smith
1 Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa
lynise04@hotmail.co.za,
2 Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa
george.smith@uct.ac.za
ABSTRACT
The project entails comparing 1960’s Karoo basin seismic data with recent data (Inkaba yeAfrica Line), to identify
and correlate Karoo seismic stratigraphy on a more regional basis.
Due to the recent interest in shale gas exploration in the Karoo basin of South Africa, there is an interest in reinterpreting
old 1960's seismic lines of SOEKOR (now archived by PASA). This project entails comparing these
lines with a recent Inkaba yeAfrica near vertical reflection line across the southern Karoo Basin (Lindeque, 2008),
and tying the reflections to the known litho-stratigraphy, based on outcrop mapping and borehole data. It forms
part of a shale gas project to identify the location and depths of the Whitehill and Prince Albert Formations. The
differences in appearance and quality between the old and new data are outlined.
The old Karoo seismic images are of poor quality, but were enhanced by two-dimensional convolutional filtering.
Thereafter, the sections were re-interpreted using the recent seismic data and existing well-data as a guide.
The Inkaba yeAfrica seismic line shows much deeper penetration, with depths of up to 50km through the crust and
across the Moho. The older data only shows the upper most crustal layers down to approximately 10km.
The comparison of the two sets of data shows the differences in processing and how seismic acquisition quality has
improved since the early 1960's. The data also indicate where the old data can still be of good use after significant
but time-consuming enhancement using modern filtering techniques.
Reference:
Lindeque, A.S, 2008, Deep Crustal profile across the southern Karoo Basin, South Africa, Unpublished Masters Thesis in the
Department of Geological Sciences, University of Cape Town
KEYWORDS: Karoo basin, seismic data, image enhancement
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