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oa Deposition Of Fourth-Order, Post-Rift Sequences And Sequence Sets, Lower Cretaceous (Lower Valanginian To Lower Aptian), Pletmos Basin, Southern Offshore, South Africa
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 3rd SAGA Biennial Conference and Exhibition, Apr 1993, cp-224-00043
Abstract
Post-rift Cretaceous siliclastic rocks of Early Valanginian<br>to Early Aptian age in the Pletmos Basin, southern<br>offshore, South Africa, display well-developed,<br>seismically resolvable, Type 1, fourth-order (simple)<br>depositional sequences arranged in progradational and<br>aggradational sequence sets. Each set is a depositional<br>systems tract within third-order composite sequences.<br>The fourth-order stacking patterns displayed by the<br>sequence sets primarily reflect the strong influence of<br>third-order eustatic cycles superimposed on tectonic<br>subsidence. Tectonic subsidence episodes and their<br>terminal uplift events are documented by the stacking<br>patterns of component sequence sets and the<br>tectonically enhanced erosional boundaries of respective<br>second-order supersequences. Conjunction of second-,<br>third-, and even fourth-order falling inflection points<br>produces maximum subaerial erosion and most favorable<br>lowstand reservoir sandstone poteritial.