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Title: Structural and stratigraphic evolution of rift basins : the Hammam Faraun area, Suez rift, Egypt
Author: Jackson, Christopher Aiden-Lee
Awarding Body: University of Manchester : University of Manchester
Current Institution: University of Manchester
Date of Award: 2002
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Abstract:
This project aims to integrate structural and stratigraphic data from the Hammam Faraun area, Suez rift, Egypt, to investigate the temporal and spatial evolution of normal fault zones, fault arrays and fault-related folds in extensional settings, and the control the evolving structural style has on syn-rift depositional patterns and sequence stratigraphy. Structural and stratigraphic data from across the Hammam Faraun fault block suggests that during the early stages of rifting deformation was distributed across the fault block on numerous short (1-4 km), low displacement (<1 km) fault segments. These either grew and linked to form longer fault zones, or became inactive during the initial c. 6-7 Myr of rifting. During this phase, the majority of deformation was accommodated by the intrablock fault zones, which were surface-breaking and had greater displacement than those that became the rift border faults, which were blind at this time. Detailed analysis of the Hammam Faraun fault zone (HFFZ) suggests that at-surface monoclinal growth folding characterised the initial stages of fault growth, with secondary normal faulting and layerparallel slip accommodating distributed deformation in the cover. These observations are consistent with analogue and kinematic models based on trishear. Integration of structural (e. g. fault and fold relationships) and displacement-length (D-L) characteristics with detailed stratigraphic data (e. g. thickness and facies variations, onlap patterns) indicates that the during the initial c. 2.4 Myr of rifting, the intra-block East Tanka fault zone (ETFZ) was initially composed of two isolated segments c. 1-1.5 km long, separated by a transverse hangingwall high. Subsequent stratigraphic patterns indicate that > c. 2.4 Myr after the initiation of rifting, the two isolated fault segments hard-linked to form a longer fault zone, and the locus of maximum displacement and subsidence migrated into the region of linkage. The shift in the locus of activity is consistent with conceptual models of fault growth by segment linkage. Subsurface analysis of the shallow part of the October fault zone (OFZ), offshore central Suez rift, suggests both simple radial propagation, and growth and linkage of initially isolated segments were important in its evolution. Stratigraphic patterns in growth strata adjacent to the fault zone suggest that faulting initiated in the lower Pliocene, and overall the fault zone propagated southwards through time. The relationship between shallow fault zone, and the deepseated, basement-involved fault zone suggests that the underlying fault zone controlled the temporal and spatial evolution of the fault zone. Changes in basin geometry and subsidence patterns, linked to the evolution of fault zones, fault arrays and associated fault-related folds, had a marked control on syn-rift depositional patterns and sequence stratigraphy. For example, growth and hard-linkage of the ETFZ influenced syn-rift sediment supply pathways and facies distributions in early syn-rift continental deposits. Overlying tidal deposits are composed of recurring TST and HST deposits that are interpreted to reflect the continuous creation of accommodation in the hangingwall to the fault zone. Finally, shallow marine deposits show marked variations in stratal stacking patterns and key stratal surface development that can be related to the evolving basin-bounding fault zone. The key generic observations from the outcrop and subsurface studies are: i) rift basin structural style during the early stages of rifting is markedly different to that encountered in the latter stages of rifting, ii) the growth of normal fault zones by segment linkage is an important process in the evolution of basin-bounding fault zones in rifts, iii) the temporal evolution of normal fault zones can only be determined by integrating detailed stratigraphic data with structural observations, iv) folding is an important element in the evolution of normal fault zones in extensional settings, v) syn-rift depositional patterns and the sequence stratigraphic evolution of rifts is strongly influenced by the evolution of fault zones and fault arrays.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.488323  DOI: Not available
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