--> ABSTRACT: Tectonics & Sedimentation in Extensional Basins: an Integrated Study, by Luis Otavio Aguiar Oliveira, Ken McClay, Dave Waltham, and Gary Nichols; #90906(2001)

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Luis Otavio Aguiar Oliveira1, Ken McClay2, Dave Waltham3, Gary Nichols2

(1) Petrobras S.A, Rio de Janeiro, Brazil
(2) Royal Holloway University of London, Egham, Surrey, England
(3) Royal Holloway University of London, Egham,Surrey, United Kingdom

ABSTRACT: Tectonics & Sedimentation in Extensional Basins: an Integrated Study

This work is an analysis of the interaction between segmented, extensional fault systems and clastic sedimentation. The research combined the development and application of a forward, three-dimensional, numerical model with reservoir-scale, field mapping of well-exposed, footwall-derived, fan systems from the central, eastern margin of the Gulf of Suez rift.

The numerical model incorporates spatially and temporally variable rates of sediment supply and fault-related subsidence as well as low and high frequency fluctuations in the regional base level.

Structural, sedimentological and sequence stratigraphic data obtained from the mapping of three coarse-grained fan bodies not only served as constraints for the mathematical modelling but enabled the assessment of a series of conceptual models. The Hommur, Baba and Sidri fan systems differ significantly in size and external form but show similarities with regard to large-scale stacking patterns and lithofacies distribution. Flooding surfaces are more common sequence boundaries than erosional unconformities within the syn-rift strata preserved in the active margin of the analysed half-grabens. Syn-depositional episodes of fold growth seem to occur after the propagating, associated extensional fault has breached the surface. Contrasting patterns of along-strike displacement variation were determined for the border fault segments.

The simulations demonstrated the major role played by the local subsidence rate, sediment supply rate and relative position of the sea level in controlling the 3-D sequence architectures. Non-unique solutions concerning individual effects upon the stratigraphy could be reached due to the large uncertainty associated with age determinations and values of the controlling factors.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado