An investigation of salt tectonic structural styles in the Scotian Basin, offshore Atlantic Canada: 2. Comparison of observations with geometrically complex numerical models

Albertz, Markus; Beaumont, Christopher

doi:10.1029/2009tc002540

Cited by 26 publications

(18 citation statements)

References 10 publications

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“…All models initially had a horizontal, rectangular cross‐section 2 km thick salt basin constrained on either end by sedimentary rocks. This geometry was chosen for simplicity, but tapered salt basins could also be used [ Albertz and Beaumont , 2010; Albertz et al , 2010]. A smooth prograding deltaic sedimentary wedge was simulated by moving a half‐Gaussian curve seaward at a constant rate of 0.3 cm/yr, and filling all unoccupied space under the curve with sediment at each time step.…”

Section: Resultsmentioning

confidence: 99%

Impact of inconsistent density scaling on physical analogue models of continental margin scale salt tectonics

Allen¹,

Beaumont²

2012

J. Geophys. Res.

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[1] The influence of inaccuracies in density scaling on the structural evolution of physical analogue experiments of salt systems has been debated, and is here investigated considering a gravity spreading example. Plane strain finite element numerical analysis was used to systematically evaluate the impact of changes in density scaling on buoyancy force, sediment strength, and pressure gradient. A range of densities typical of natural systems (including compacting sediment) and physical analogue experiments was included. A fundamental shift in the structure of the salt-sediment system, from diapir-minibasin pairs to expulsion rollover, was observed when sediment and salt densities were altered from values typical of physical experiments (1600 and 990 kg/m 3 ) to those most often found in nature (1900-2300 and 2150 kg/m 3 ). Experiments equivalent to physical analogue models but with reduced sediment density showed diapir-minibasin pair geometry, persisting to sediment densities of $1300 kg/m 3 . Salt burial by pre-kinematic sediments was found to suppress diapir formation for thicknesses greater than $750 m (0.75 cm at the laboratory scale). The relative importance of disproportionately high buoyancy force, low sediment strength, and pressure gradient in physical experiments was investigated by isolating each of these scaling errors in turn. Buoyancy was found to be most influential in the development of diapir-minibasin pairs versus expulsion rollover geometry. Finally, we demonstrate that dry physical analogue experiments with sediment density reduced to $1140 kg/m 3 (achievable through mixing with hollow glass beads) would provide a reasonable approximation of submarine salt systems in nature (including water load and hydrostatic pore fluid pressure).Citation: Allen, J., and C. Beaumont (2012), Impact of inconsistent density scaling on physical analogue models of continental margin scale salt tectonics,

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Section: Resultsmentioning

confidence: 99%

Impact of inconsistent density scaling on physical analogue models of continental margin scale salt tectonics

Allen¹,

Beaumont²

2012

J. Geophys. Res.

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“…Additional salt structures in regions with SSA and SSB characteristics are not explained by the numerical models. In paper 2 [Albertz and Beaumont, 2010], we show that these features can be attributed to more complex initial basement geometries of the salt basins.…”

Section: Discussionmentioning

confidence: 99%

“…This salt may result from more complex geometries of these basins, processes not included in the models, or outof-plane salt flow and overburden deformation which cannot be reproduced by the two-dimensional models. The proposition that more complex initial salt basin geometry is the cause is tested in paper 2 [Albertz and Beaumont, 2010] and shown to provide a potential explanation. The more complex geometries lead to less efficient salt evacuation from the autochthonous basins.…”

Section: Failure Of the Simple Models To Account For The Amount And Dmentioning

confidence: 99%

“…We make this choice as a first approximation because the actual geometries are poorly constrained. We investigate more complex geometries in paper 2 [Albertz and Beaumont, 2010]. No attempt is made to include the actual effect of rift-related extension and associated faulting on the salt basin.…”

Section: Initial Configuration Of the Model Continental Margin And Samentioning

confidence: 99%

“…This study is designed to provide first-order insight into the underlying mechanics and is not an attempt to provide a simulation of the geological history of the Scotian Basin. It comprises two papers: paper 1 (this paper) focuses on the evolution of salt basins that have simple initial geometries and deformation that is driven by gravity and sedimentation; and paper 2 [Albertz and Beaumont, 2010] investigates the effect of more complex salt basin geometries.…”

Section: Introductionmentioning

confidence: 99%

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An investigation of salt tectonic structural styles in the Scotian Basin, offshore Atlantic Canada: 1. Comparison of observations with geometrically simple numerical models

Albertz¹,

Beaumont

Shimeld

et al. 2010

Tectonics

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[1] Three primary salt tectonic structural styles of the Scotian Basin are compared with plane strain finite element models in order to investigate their origin. Here, we focus on simplified model salt basins with initial rectangular cross-sectional geometries and follow their evolution in the context of tectonic and parametric thermal subsidence and under various sedimentation regimes. Structural style A, an open-ended roho system with a synkinematic wedge, is reproduced by models including deltaic progradation and seaward spreading/ gliding of sediments above a salt detachment. Structural style B, a linked salt tectonic system with landward regional normal faults and allochthonous salt sheets climbing seaward over Late Cretaceous and Paleogene strata, is shown to be a consequence of early aggradation followed by progradation. Structural style C is characterized by salt diapirs and intervening minibasins and is reproduced by models with Rayleigh-Taylor instabilities requiring compaction driven density inversions, weak sediments, and initial perturbations of the overburden-salt interface.

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Deformation, stress, and pore pressure in an evolving suprasalt basin

et al. 2017

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We develop a two‐dimensional plane strain large‐deformation coupled poroelastoplastic finite element model to simulate initiation and rise of a salt wall from a flat salt body during sedimentation. We run transient analyses with high‐permeability and low‐permeability sediments in the model to simulate drained conditions and overpressure (or pore fluid overpressure). We investigate deformation, stress, and overpressure in the evolving suprasalt basin. Model results show that horizontal stress increases even higher than vertical stress at the flank of the salt wall and in the minibasin due to horizontal pushing out of the rising salt wall and that orientations of principal stresses rotate in the minibasin relative to far‐field stress state. Model predicts that compared with far‐field overpressure, the overpressure near the salt wall and within the minibasin is largely perturbed by the salt body. We find that perturbations of pore pressure (or pore fluid pressure) near the salt wall and within the minibasin cannot be resolved by traditional pore pressure prediction methods such as normal compaction trend approach and mean stress model approach. In order to predict pore pressure more accurately, especially in the regions near salt bodies or where stresses are perturbed, we need to apply a method that includes both effects of mean effective stress and deviatoric stress on pore pressure and compaction, for example, the Modified Cam Clay model approach, to pore pressure prediction. Our results provide geoscientists insights into evolution of salt basins, near‐salt deformation, stress, overpressure, and overpressure prediction methods and have implications for near‐salt wellbore drilling programs.

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An investigation of salt tectonic structural styles in the Scotian Basin, offshore Atlantic Canada: 2. Comparison of observations with geometrically complex numerical models

Cited by 26 publications

References 10 publications

Impact of inconsistent density scaling on physical analogue models of continental margin scale salt tectonics

Impact of inconsistent density scaling on physical analogue models of continental margin scale salt tectonics

An investigation of salt tectonic structural styles in the Scotian Basin, offshore Atlantic Canada: 1. Comparison of observations with geometrically simple numerical models

Deformation, stress, and pore pressure in an evolving suprasalt basin

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