A record of deformation within submarine landslides and role of salt diapirism in controlling the sedimentology and distribution of deep-water deposits
File(s)
Author(s)
Abu, Clara
Type
Thesis
Abstract
Seabed relief created by mass-transport complexes (MTCs) and salt diapirs profoundly influences the evolution and development of sediment gravity flows. The general kinematics of MTCs and their internal structure are relatively well understood. However, the multiphase, non-coaxial nature of deformation, and the dynamics of basal shear zone growth in the contractional region, both spatially and temporally, need to be better understood.
I describe this thesis in two main sections; the first part uses three-dimensional seismic reflection datasets from two large passive margins (salt-influenced Kwanza Basin, offshore Angola, and the Angoche Basin, offshore Mozambique) to analyze the external and internal morphology of the MTCs, and their emplacement kinematics (section 1.2). On the Angolan margin, I conclude that the interaction between the decametre-scale rugose topography of the MTC controlled the deposition of reservoirs and channels on the slope. On the Mozambique margin, there is a minimal contractional strain within the slide body, and this may explain some of the observed structural styles in the toe region of the submarine slide.
The second part of the thesis investigates the influence of passively rising diapirs on flank deformation and the resultant stratigraphic architecture of syn-kinematic units (section 1.3). Halokinetic sequences associated with flank deformation have been previously studied. However, these studies use outcrop data, needing more detailed information on sub-seismic depositional and deformational processes. Here, I identify, characterize, and deduce the controls on host rock deformation during salt diapirism by utilizing an integrated seismic, petrophysical well data, and core analysis. In the East Central Graben, North Sea, offshore UK, I conclude that core-scale evidence for large-scale fracturing is associated with drape folding in the Ekofisk Formation resulting from the diapiric salt movement. Bedding parallel slip zones and slump folds observed in the Forties Sandstone Member signifies a rotational relationship with the growing salt diapirs.
I describe this thesis in two main sections; the first part uses three-dimensional seismic reflection datasets from two large passive margins (salt-influenced Kwanza Basin, offshore Angola, and the Angoche Basin, offshore Mozambique) to analyze the external and internal morphology of the MTCs, and their emplacement kinematics (section 1.2). On the Angolan margin, I conclude that the interaction between the decametre-scale rugose topography of the MTC controlled the deposition of reservoirs and channels on the slope. On the Mozambique margin, there is a minimal contractional strain within the slide body, and this may explain some of the observed structural styles in the toe region of the submarine slide.
The second part of the thesis investigates the influence of passively rising diapirs on flank deformation and the resultant stratigraphic architecture of syn-kinematic units (section 1.3). Halokinetic sequences associated with flank deformation have been previously studied. However, these studies use outcrop data, needing more detailed information on sub-seismic depositional and deformational processes. Here, I identify, characterize, and deduce the controls on host rock deformation during salt diapirism by utilizing an integrated seismic, petrophysical well data, and core analysis. In the East Central Graben, North Sea, offshore UK, I conclude that core-scale evidence for large-scale fracturing is associated with drape folding in the Ekofisk Formation resulting from the diapiric salt movement. Bedding parallel slip zones and slump folds observed in the Forties Sandstone Member signifies a rotational relationship with the growing salt diapirs.
Version
Open Access
Date Issued
2023-08
Date Awarded
2024-02
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Jackson, Christopher
Publisher Department
Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)