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Title: 4D evolution deepwater fold-and-thrust belt, western Niger Delta
Author: Constantino, Diego
Awarding Body: University of London
Current Institution: University of London
Date of Award: 2012
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This thesis presents a detailed 40 evolutionary model of the deepwater fold-and-thrust belt of the western Niger Delta using a 3D seismic reflection dataset. The geometries and kinematics of the fault-related folds interpreted in the study area have been compared to two series of 20 sandbox analogue models of a doubly-vergent wedge to understand the evolution of these structures. The regional interpretation of the 3D seismic dataset revealed the occurrence of four thrust domains separated by dextral tear faults. Each domain is characterised by differing deformational styles. Distinct structural styles have been interpreted in e~ch thrust domain. Section restoration of regional cross sections revealed different amounts of shortening, from 0.7 km to 2.7 km, within each domain, an overall break-forward propagation sequence, and a complex thrust interaction with reactivations and synchronous activity commonly observed. The detailed 3D interpretation and structural analysis of individual fault-related folds demonstrated ~hat these structures evolved initially as detachment folds which were subsequently faulted by break thrusts in their limbs, resulting in faulted detachment folds. At the Present Day, the structures show geometric similarities to shear fault bend folds but clearly have evolved in a non self similar way. Detailed analyses have revealed that folds are partitioned vertically with brittle duplex systems at the detachment level, , overlain by a region of pure shear homogeneous strain which itself is overlain by a pre-kinematic sequence representing the flexural lid of the folds. Fold growth is recorded by growth strata and shows an initial rapid rate of crestal uplift followed by a decrease in uplift with continued shortening. This is interpreted to be a result of fold growth by limb rotation. The above-described structural aspects are included in the new evolutionary models of fault-related folds proposed in this thesis. The 20 scaled analogue modelling of doubly-vergent wedge using high- resolution digital photography and Die analyses have clearly shown that the laboratory models also evolve in a similar fashion and develop in some way similar geometries to those in the deepwater fold belts.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available