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Elle Marie Schollnberger1
(1) Rice University, Houston, TX

Abstract: Sedimentation and salt tectonics - Lower Congo and Kwanza Basins, Angola

Large discoveries offshore Angola in recent years highlight the significance of the Lower Congo and Kwanza basins of Angola. To continue successful exploration and development in these two basins, the impact of sedimentation and salt tectonics on the petroleum system must be understood.

Using regional 2D seismic lines, the sedimentary and tectonic history of the Lower Congo and Kwanza basins is interpreted. Using sequence stratigraphic principles, unconformities are used to define sequences. The sequences are mapped within and between the basins. Regional uncomformities are separated from local unconformities. The relative timing of sedimentation and the creation and movement of salt structures is investigated.

Both the amount of sediment input and the style of salt tectonics varies between and within the Lower Congo and Kwanza basins. The Lower Congo basin has a significantly thicker Tertiary sediment package than the Kwanza Basin. Due to the different thickness of overlying sediment and initial salt layer, the type of salt structures varies between the basins. Within each of the basins, the tectonic setting changes along a dip profile. the general styles moving from east to west are an extensional platform, salt withdrawal mini-basins, compressional folds and thrusts.

The variations of sedimentation and salt tectonics between and within the Lower Congo and Kwanza basins impact the petroleum system. The distribution of reservoirs, the migration pathways available to hydrocarbons through time, and the trapping of those hydrocarbons are dependent on the interaction of sedimentation and salt tectonics.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana