Leppard, Chris1, Rob Gawthorpe1
(1) University of Manchester, Manchester, United Kingdom
ABSTRACT: Variability of Rift-Climax Stratigraphy in the Hangingwall to a Rift Border Fault: The Thal Fault, Hammam Faraun Fault Block, Suez Rift, Egypt
The evolution and linkage of fault segments to form basin bounding normal fault zones is an important control on the stratigraphic evolution of rift-basins. However, little quantitative data exists regarding the controls on along-strike variation in stratigraphic architecture and facies distribution in the hangingwall to a rift border fault. We document the factors that are important in developing subtle syn-rift exploration plays in the Rudeis Formation deep water ‘rift climax’ sequences in the hangingwall of the Thal fault zone, and discuss the factors controlling the distribution, geometry and stratigraphic evolution of coarse clastics.
The Rudeis Formation is characterised by basinal, mudstone-dominated facies, with locally restricted coarse-grained units. Antecedent sediment transport pathways controlled the location of coarse-grained submarine fan complexes, which are comprised of channelised, lobate mass flows that pass rapidly basinwards into sheet-like interbedded basinal mudstones and turbiditic sandstones within <800 m of the fault zone. Laterally these submarine fan complexes pinch-out into a coarse-grained base of slope apron and mass transport deposits sourced directly from the immediate footwall, again these pass rapidly basinwards into basinal mudstones within <250 m of the footwall. The unroofing history of the footwall influenced the temporal evolution of these deposits, in particular the erosion of mudstone dominated pre-rift units led to the switching off of major fan bodies. Several major stratal surfaces can however be identified basin-wide that are approximately contemporaneous (within biostratigraphic resolution) and are believed to be the result of relative base-level changes operating at a larger scale than the individual fault segments.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.