Title: The Role of Strike-Slip Faulting on Deep ‘Basement’ Faults in Cretaceous Depositional History and Fiqa Channel Location, as Determined from Analysis of 3D Seismic Over an Offshore Field, Abu Dhabi
Abstract:Abstract From structural analysis of 3D seismic data over a giant field, offshore Abu Dhabi, a complex pattern of intersecting, broadly conjugate, strike-slip dominated en-echelon fault systems are ob...Abstract From structural analysis of 3D seismic data over a giant field, offshore Abu Dhabi, a complex pattern of intersecting, broadly conjugate, strike-slip dominated en-echelon fault systems are observed from ‘basement’ levels up to latest Cretaceous horizons. Over geologic time these fault systems exerted fundamental controls on depositional patterns within the study area. Use of new attribute techniques, isochron mapping, flattening on key intra-Cretaceous horizons, cinematic time-slice ‘movies’ and a review of the available vertical seismic sections has indicated that many apparent velocity anomaly zones are controlled by deep-seated fault systems developed as strike-slip dominated ‘flower structures’. Spatial continuity of these fault zones, the most prominent of which trend ~NE-SW, exhibit a linear nature on a scale of several kilometers to tens of kilometers; have flower-zone geometry in cross-section but with increasingly en-echelon nature at Upper Cretaceous levels; low apparent normal offsets on long fault segments; anastomosing, convergent and divergent, patterns at different stratigraphic levels; wrench offset with respect to other deep fault systems; throw terminations with rapidly decreasing displacement gradients along en-echelon zones into the crossover zones with other fault systems. There are four prominent fault systems that exert control on the depositional systems: (1) NE to NNE trending ‘Fiqa’ direction, also delineating local depositional highs/lows and Mishrif ‘reef’ margin; (2) NW-SE zones defining depositional areas of step-wise thickening/thinning; (3) Conjugate WNW-ESE and WSW-ENE en-echelon strike-slip zones, and (4) NNW-SSE fault zones displaying local control on thinning or thickening. Temporal fault activity on these zones is linked to sedimentary thickening and thinning patterns, though deeper level faults provided only ‘soft’ links to the sedimentary sequences of early Cretaceous age. By late Cretaceous times the transtensional / transpressional fault systems provided ‘hard’ links to the deposition systems (e.g. Fiqa channel system).Read More
Publication Year: 2005
Publication Date: 2005-03-12
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 5
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