Rob L. Gawthorpe¹, Ian Sharp², Christopher A. Jackson¹, Mike Young¹

(1) University of Manchester, Manchester, United Kingdom
(2) Norsk Hydro Research Center ASA, Bergen, Norway

ABSTRACT: Integrated Structural and Sequence Stratigraphic Analysis Reveals the Spatial and Temporal Evolution of Normal Fault Arrays; Suez Rift, Egypt

Pseudo-3D exposure of Miocene syn-rift sequences and normal fault zones from the Suez rift provide exceptional outcrop analogues for structural styles and stratigraphic responses in evolving normal fault populations. Surface deformation associated with growth and linkage of fault segments is reflected by characteristic changes in the three-dimensional form of depositional sequences, their internal stratal geometry and bounding stratal terminations. Here we use these parameters, within key stratigraphic intervals, to reconstruct the early stages of fault array evolution from the southern portion of the Hammam Faraun fault block. The present-day structural style of this area comprises a 10-15 km wide half graben bounded by 25-50 km long fault zones with kilometres of displacement. Results indicate that the early syn-rift structural style was markedly different to that suggested by the present-day structural geometry.

Early stages in the evolution are characterised by numerous, small isolated depocentres. These depocentres were typically <4 km long and 1-2 km wide, reflecting the size of the early normal fault segments. Stratal geometries and thickness distributions indicate that many of these early depocentres were controlled by growth folds above blind normal faults. Within the first few million years of rifting, some of these faults propagated upward to break surface, and linked to form fault zones up to 10 km long. During this time interval, other fault zones died and were overstepped by syn-rift deposits. Deformation did not localise onto the major half graben bounding fault zones until some 5-7 million years after the onset of rifting.

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