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Palinspastic Reconstruction and Forward Modelling |
Husky Oil Operations Ltd, Box 6525, Station D, Calgary, Alberta T2P 3G7, Canada
Seismic data reveal the structure of a large normal fault that forms the western boundary of the Agedabia Trough in the central Sirte Basin, Libya. A significant monoclinal flexure in the sediments forming the hanging wall of this fault is interpreted to have been generated by their compaction. A computer forward model supports this interpretation. Characteristics of this kind of structure are a vertical synclincal axial plane above the hanging-wall cutoff of the basement and an inclined but less distinct anticlinal axial plane above the footwall cutoff of the basement. Dips increase with depth. The model also shows how compaction can cause sedimentary growth within the hanging wall rather than just at the fault plane. In some circumstances, compaction can produce anticlinal structures in normal fault hanging walls that could easily be confused with inversion structures. Structures can be produced by compaction in normal fault hanging walls even where no lithology contrast occurs across the fault. Compaction structures generally will be most obvious over large planar faults that involve basement. Nevertheless, compaction structures are also important in the case of detached listric faults: in this case the effects are often obscured by the superimposition of fault bend folds that will have similar or greater magnitudes but are typically anticlinal, whereas the compaction structures are usually synclinal. Compaction effects compound the difficulties of geometric inverse modelling.
