scholarly journals The effects of base-salt relief on salt flow and suprasalt deformation patterns — Part 1: Flow across simple steps in the base of salt

2017 ◽  
Vol 5 (1) ◽  
pp. SD1-SD23 ◽  
Author(s):  
Tim P. Dooley ◽  
Michael R. Hudec ◽  
Dan Carruthers ◽  
Martin P. A. Jackson ◽  
G. Luo
Keyword(s):  
Early Stage ◽  
Physical Models ◽  
Structural Domains ◽  
Passive Margins ◽  
Campos Basin ◽  
Fold Belts ◽  
Base Salt ◽  
Deformation Patterns ◽  
Salt Flow ◽  
High Block

Passive margins underlain by a salt detachment are typically interpreted as kinematically linked zones of updip extension and downdip contraction separated by a zone of translation above a smoothly dipping base of salt. However, salt flow is affected by the base-of-salt geometry across which it flows, and early-stage gravity gliding induced by basin tilt may be complicated by the presence of salt-thickness changes caused by the pre-existing base-salt relief. We investigate these effects using physical models. Dip-parallel steps generate strike-slip fault zones separating domains of differential downslope translation and structural styles, provided the overburden is thin enough. If the overburden is thicker, it resists breakup, but a change in the structural trend occurs across the step. Steps with mild obliquity to the dip direction produce transtensional and transpressional faults in the cover separating structural domains. Deformation complexity in the overburden increases where base-salt steps strike at a high angle to salt flow, and it is especially dependent on the ratio between the thick ([Formula: see text]) and thin ([Formula: see text]) salt across the step at the base of salt. Where the salt-thickness ratio ([Formula: see text]) is high, basal drag generates major flux mismatches, resulting in a contractional thickening of the salt and associated overburden shortening in thin salt above a base-salt high block. Shortening is transient and superseded by extension as the salt thickening allows the flow velocity to increase. When transitioning off a base-salt high block into a low block, the greater flux within the thick salt results in a monocline with extensional and contractional hinges. Structures are further deformed as they translate through these hinge zones. Our physical models demonstrate that extensional diapirs and compressional fold belts can be initiated anywhere on a slope as the salt accelerates and decelerates across base-salt relief. A fold belt from the Campos Basin, offshore Brazil, is used to illustrate these processes.

scholarly journals The effects of base-salt relief on salt flow and suprasalt deformation patterns — Part 2: Application to the eastern Gulf of Mexico

2017 ◽  
Vol 5 (1) ◽  
pp. SD25-SD38 ◽  
Author(s):  
Tim P. Dooley ◽  
Michael R. Hudec
Keyword(s):  
Gulf Of Mexico ◽  
Early Stage ◽  
Flow Direction ◽  
Complex Salt ◽  
Complex Model ◽  
Physical Models ◽  
Eastern Gulf Of Mexico ◽  
Fold Belts ◽  
Base Salt ◽  
Salt Flow

In the eastern Gulf of Mexico, the pattern of early stage salt flow is complicated by basement topography consisting of a series of plunging arches that trend obliquely to the early flow direction. Seismic lines downdip of the Florida Middle Ground Arch reveal a puzzling array of structures. Sections trending roughly north–south (parallel to the regional dip) document predominantly extensional structures; however, east–west sections reveal shortening structures. Both sets of structures occur well updip of the downdip salt pinchout. We designed a physical-modeling study to investigate these puzzling relationships. Models presented in Part 1 of this paper indicate that localized shortening and extension can occur as salt passes over simple base-salt steps. Physical models were run with complex salt isopachs featuring plunging arches oblique to dip and salt flow. Models reveal the formation of shortening belts as the salt and its thin prekinematic overburden are translated across the arches. The complex salt isopachs deflect salt flow to produce convergent and divergent flow, which, along with flow-velocity gradients, results in the rotation of early formed thrust belts. Rotations of up to 70° were recorded in the most complex model, resulting in transported fold belts with trends that were close to dip parallel, similar to those observed on seismic data from the eastern Gulf of Mexico. Additional zones of shortening are found in and around complex salt pinchouts in the updip zones of the gravity-gliding system. The dynamic nature of these salt-related tectonic systems can result in the downdip translation of fold belts far from the basement topography over which they were created.

Base-salt Relief Controls Salt-related Contractional Styles in the Translational Domain of the Outer Kwanza Basin, offshore Angola

2020 ◽  
Author(s):  
Aurio Erdi ◽  
Christopher Jackson
Keyword(s):  
Three Dimensional ◽  
Passive Margin ◽  
Structure Evolution ◽  
Passive Margins ◽  
Kinematic Evolution ◽  
Local Contraction ◽  
Salt Structure ◽  
Flow Deceleration ◽  
Base Salt ◽  
Salt Flow

<p>Salt-bearing passive margins are typically characterized by thin-skinned, gravity-driven deformation above a salt detachment, resulting in kinematically-linked domains of updip extension and downdip contraction. These domains are commonly connected by a mid-slope translational domain in which salt-related structures accommodate local extensional and contractional strains associated with salt flow across base-salt relief. Despite a general understanding of these salt-tectonic processes and products, little is still known about the detailed geometric and kinematic evolution of mid-slope contractional structures.</p><p>We use a high-quality, depth-migrated three-dimensional seismic reflection dataset located in the mid-slope translational domain of the Outer Kwanza Basin, offshore Angola. We analysed the seismic-stratigraphic architecture of the Aptian salt and its immediate Albian overburden to reveal the distribution of local, salt-related contractional structures above varying geometries of base-salt relief.</p><p>Our analysis reveals two types of salt-related contractional structures, variably distributed in terms of their trend relative to underlying ramps that trend NW or N. The first type is represented by salt-cored anticlines, the limbs of which may be dissected by salt-detached thrusts. The folds trend parallel to the NW- or N-trending ramps, being located either updip or directly above the underlying ramp. These folds increase in amplitude and decrease in wavelength basinward, and are also locally polyharmonic; showing an upwards increase in wavelength, but a decrease in amplitude. The second type of structure is represented by two sub-types of salt walls: (i) reactive salt walls, and (ii) squeezed salt walls. These salt walls trend broadly parallel to, and are located above or downdip of NW-trending, basinward- and landward-facing ramps. The salt-cored anticlines are formed by local contraction associated with salt flow deceleration above ramp-updip. This process of local contraction also locally induces active rise and overburden piercement as salt walls translate over local base-salt structural highs. Still, other salt walls are locally contracted on the basinward-facing ramp during salt flow seaward, resulting in the squeezed salt wall.</p><p>We show that careful seismic-stratigraphic analysis of salt and overburden deformation, in the context of the underlying base-salt geometry, reveals complex patterns of salt structure evolution during seaward translation across the midslope translational domain. The results are applicable along salt-bearing passive margin worldwide and may provide an important insight in identifying potential plays along the midslope translational domain, where major deepwater oilfields reside.</p>

Salt thickness and heterogeneity control the degree of coupling between sub- and supra-salt structure during salt-detached translation: evidence from physical models

2021 ◽  
Author(s):  
Sian Evans ◽  
Christopher Jackson ◽  
Sylvie Schueller ◽  
Jean-Marie Mengus
Keyword(s):  
Structural Evolution ◽  
Structural Complexity ◽  
Vertical Movement ◽  
Sediment Supply ◽  
Physical Models ◽  
Structural Development ◽  
Salt Structure ◽  
Regional Tectonic ◽  
Base Salt ◽  
Strain Coupling

<p>Salt flows like a fluid over geological timescales and introduces significant structural complexity to the basins in which it is deposited. Salt typically flows seaward due to tilting of the basin margins, and is therefore influenced by the geometry of the surface that it flows across (e.g. fault scarps or folds on the base-salt surface). This can lead to coupling of sub- and supra-salt structures, with the orientation and distribution of base-salt structures reflected in the structure of the overburden. However, precisely what controls the degree of strain coupling during salt-detached translation is still poorly understood, in particular the role played by salt thickness and lithological heterogeneity. This partly reflects the fact that it can be difficult to deconvolve the relative contributions of natural variables such as the magnitude of relief, sediment supply, and regional tectonic regime. In addition, seismic data provide only the present structural configuration of salt basins, from which their formative kinematics must be inferred. If we can develop a better understanding of how sub-salt structure controls the types and patterns of supra-salt deformation, we can produce better kinematic (structural) restorations of salt basins and, therefore, have a better understanding of the related mechanics.</p><p>In order to isolate the influence of salt thickness and heterogeneity on sub- to supra-salt strain coupling during salt-detached horizontal translation, we present a series of physical analogue models with controlled boundary conditions. We use a simple base-salt geometry comprising three oblique base-salt steps, and vary the thickness and composition of the ductile salt analogue in each experiment. X-ray tomography allows us to image the internal structure during model evolution and therefore gain a 4D picture of its structural development.</p><p>Results show that thicker and more homogeneous salt units experience more vertical movement (i.e. minibasin subsidence and diapiric rise) and the overburden structure is less explicitly coupled with the underlying base-salt relief. Conversely, thinner and more heterogeneous salt units restrict vertical movement, and therefore the resulting overburden structure is dominated by lateral movement and more closely coupled to the geometry of the base-salt surface. These results highlight the important role of base-salt relief in the subsequent structural evolution of salt basins and why, despite broad similarities between different salt basins, there is significant variability in their structural styles.</p>

scholarly journals Testing the influence of a sand mica mixture on basin fill in extension and inversion experiments

2015 ◽  
Vol 87 (1) ◽  
pp. 51-62 ◽  
Author(s):  
CAROLINE J.S. GOMES ◽  
TAYNARA D'ANGELO ◽  
GISELA M.S. ALMEIDA
Keyword(s):  
Shear Stress ◽  
Physical Models ◽  
Normal Faults ◽  
Striking Difference ◽  
Fault Propagation ◽  
Peak Shear Stress ◽  
Internal Deformation ◽  
Deformation Patterns ◽  
And Inversion ◽  
Basin Fill

We compare the deformation patterns produced by sand and a sand mica mixture (14:1 ratio of sand to mica by weight) while simulating basin fill in extension and inversion models to analyze the potential of the sand mica mixture for applications that require a strong elasto-frictional plastic analogue material in physical models. Sand and the sand mica mixture have nearly equal angles of internal friction, but the sand mica mixture deforms at a significantly lower level of peak shear stress. In extension, the sand mica mixture basin fill experiments show fewer normal faults. During inversion, the most striking difference between the sand and the sand mica mixture basin fill experiments is related to the internal deformation in fault-propagation folds, which increases with an increase in the basal friction. We conclude that our strongly elasto-frictional plastic sand mica mixture may be used to simulate folds in experiments that focus on mild inversion in the brittle crust.

scholarly journals Pre-salt rift morphology controls salt tectonics in the Campos Basin, offshore SE Brazil

2021 ◽  
Author(s):  
Francyne B. Amarante ◽  
Christopher A-L. Jackson ◽  
Leonardo M. Pichel ◽  
Claiton M. S. Scherer ◽  
Juliano Kuchle
Keyword(s):  
Hydrocarbon Exploration ◽  
Passive Margin ◽  
Salt Tectonics ◽  
Borehole Data ◽  
Temporal And Spatial Distribution ◽  
South Central ◽  
Campos Basin ◽  
Se Brazil ◽  
Gravity Driven ◽  
Base Salt

<p>Salt-bearing passive margin basins offshore SE Brazil have been and remain attractive for hydrocarbon exploration and production. In the Campos Basin, major reservoir types include post-salt turbidites, which are located in structural traps related to thin-skinned faulting above salt anticlines and rollers. Classic models of gravity-driven salt tectonics commonly depict kinematically linked zones of deformation, characterised by updip extension and downdip contraction, separated by a weakly deformed zone associated with downdip translation above a relatively smooth base-salt surface. We use 2D and 3D seismic reflection and borehole data from the south-central Campos Basin to show that this does not adequately capture the styles of salt-detached gravity-driven deformation above relict, rift-related relief. The base-salt surface is composed of elongated, broadly seaward-dipping ramps with structural relief reaching c. 2 km. These ramps define the boundary between the External High and the External Low, basement structures related to the rift tectonics. Local deformation associated with the base-salt ramps can overprint and/or influence regional, margin-scale patterns of deformation producing kinematically-variable and multiphase salt deformation. We define three domains of thin-skinned deformation: an updip extensional domain, subdivided into subdomains E1 and E2, an intermediate multiphase domain and a downdip contractional domain. The multiphase domain is composed of three types of salt structures with a hybrid extensional-contractional origin and evolution. These are: (i) contractional anticlines that were subjected to later extension and normal faulting; (ii) diapirs with passive and active growth later subjected to regional extension, developing landward-dipping normal faults on the landward flank; and, lastly, (iii) an extensional diapir that was subsequently squeezed. We argue that this multiphase style of deformation occurs as a consequence of base-salt geometry and relief creating local variations of salt flow that localize extension at the top and along the ramps, and contraction at the base. Translation and extension of salt and its overburden across major base-salt ramps resulted in three ramp syncline basins northeast of the study area, partially bounded by salt-detached listric faults. The temporal and spatial distribution and evolution of these and other key salt and overburden structures, and their relationship to base-salt relief, suggest 30 to 60 km of horizontal gravity-driven translation of salt and overburden.</p>

The sagittal curvature of the spine can be a leading cause of scoliosis in pediatric spine

2021 ◽  
Author(s):  
S Pasha
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Early Stage ◽  
Element Model ◽  
Sagittal Profile ◽  
Deformation Pattern ◽  
Element Simulation ◽  
Curve Deformation ◽  
Numerical Finite Element ◽  
Deformation Patterns

The etiology of the adolescent idiopathic scoliosis (AIS) remains unknown. Variations in the sagittal profile of the spine between the early stage scoliotic and non-scoliotic pediatric patients have been shown. However, no quantitative study has shown the link between the sagittal profile and 3D deformity of the spine. 126 right thoracic scoliosis with spinal and 3D reconstructions were included. A 2D finite element model was developed for each of the sagittal curve types without any deformity in the frontal or axial planes. Physiological loadings were determined from the literature and were applied in the finite element model. The 3D deformation patterns of the models were compared to the 3D spinal patterns of the AIS with the same sagittal type. A significant correlation was found between the 3D deformity of the scoliotic curves and the numerical finite element simulation of the corresponding sagittal profile as determined by pattern correlation, p<0.001. The sagittal curve deformation patterns corresponded to the spinal deformities in the patients with the same sagittal curvature. Finite element models of the spines, representing different sagittal types in 126 AIS patients showed that deformation pattern of the sagittal types changes as a function of the spine curvature and associates with the patterns of 3D spinal deformity in AIS patients with the same sagittal curves. This finding provided evidence that the sagittal curve of the spine can determine the deformity patterns in AIS.

scholarly journals Early Stage Digital Twins for Early Stage Engineering Design

2019 ◽  
Vol 1 (1) ◽  
pp. 2557-2566 ◽  
Author(s):  
David Edward Jones ◽  
Chris Snider ◽  
Lee Kent ◽  
Ben Hicks
Keyword(s):  
Life Cycle ◽  
Product Life Cycle ◽  
Early Stage ◽  
Physical Models ◽  
The Other ◽  
Digital Twin ◽  
Digital Twins ◽  
Design Cycle ◽  
Revision Control ◽  
First Time

ABSTRACTWhile extensive modelling - both physical and virtual - is imperative to develop right-first-time products, the parallel use of virtual and physical models gives rise to two interrelated issues: the lack of revision control for physical prototypes; and the need for designers to manually inspect, measure, and interpret modifications to either virtual or physical models, for subsequent update of the other. The Digital Twin paradigm addresses similar problems later in the product life-cycle, and while these digital twins, or the “twinning” process, have shown significant value, there is little work to date on their implementation in the earlier design stages. With large prospective benefits in increased product understanding, performance, and reduced design cycle time and cost, this paper explores the concept of using the Digital Twin in early design, including an introduction to digital twinning, examination of opportunities for and challenges of their implementation, a presentation of the structure of Early Stage Twins, and evaluation via two implementation cases.

scholarly journals Parameter subset reduction for patient-specific modelling of arrhythmogenic cardiomyopathy-related mutation carriers in the CircAdapt model

2020 ◽  
Vol 378 (2173) ◽  
pp. 20190347 ◽  
Author(s):  
Nick van Osta ◽  
Aurore Lyon ◽  
Feddo Kirkels ◽  
Tijmen Koopsen ◽  
Tim van Loon ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Computational Models ◽  
Clinical Decision Making ◽  
Early Stage ◽  
Patient Specific ◽  
Model Parameters ◽  
Arrhythmogenic Cardiomyopathy ◽  
Tissue Properties ◽  
Myocardial Disease ◽  
Deformation Patterns

Arrhythmogenic cardiomyopathy (AC) is an inherited cardiac disease, clinically characterized by life-threatening ventricular arrhythmias and progressive cardiac dysfunction. Patient-specific computational models could help understand the disease progression and may help in clinical decision-making. We propose an inverse modelling approach using the CircAdapt model to estimate patient-specific regional abnormalities in tissue properties in AC subjects. However, the number of parameters ( n  = 110) and their complex interactions make personalized parameter estimation challenging. The goal of this study is to develop a framework for parameter reduction and estimation combining Morris screening, quasi-Monte Carlo (qMC) simulations and particle swarm optimization (PSO). This framework identifies the best subset of tissue properties based on clinical measurements allowing patient-specific identification of right ventricular tissue abnormalities. We applied this framework on 15 AC genotype-positive subjects with varying degrees of myocardial disease. Cohort studies have shown that atypical regional right ventricular (RV) deformation patterns reveal an early-stage AC disease. The CircAdapt model of cardiovascular mechanics and haemodynamics has already demonstrated its ability to capture typical deformation patterns of AC subjects. We, therefore, use clinically measured cardiac deformation patterns to estimate model parameters describing myocardial disease substrates underlying these AC-related RV deformation abnormalities. Morris screening reduced the subset to 48 parameters. qMC and PSO further reduced the subset to a final selection of 16 parameters, including regional tissue contractility, passive stiffness, activation delay and wall reference area. This article is part of the theme issue ‘Uncertainty quantification in cardiac and cardiovascular modelling and simulation’.

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