Author: Simon Allen KattenhornPublisher:
ISBN:
Category : Faults (Geology)
Languages : en
Pages : 344
Book Description
A 3D Mechanical Analysis of Normal Fault Evolution and Joint Development in Perturbed Stress Fields Around Normal Faults
Author: Simon Allen KattenhornPublisher:
ISBN:
Category : Faults (Geology)
Languages : en
Pages : 344
Book Description
Fault-related Deformation Over Geologic Time
Author: Peter James LovelyPublisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 265
Book Description
A thorough understanding of the kinematic and mechanical evolution of fault-related structures is of great value, both academic (e.g. How do mountains form?) and practical (e.g. How are valuable hydrocarbons trapped in fault-related folds?). Precise knowledge of the present-day geometry is necessary to know where to drill for hydrocarbons. Understanding the evolution of a structure, including displacement fields, strain and stress history, may offer powerful insights to how and if hydrocarbons might have migrated, and the most efficient way to extract them. Small structures, including faults, fractures, pressure solution seams, and localized compaction, which may strongly influence subsurface fluid flow, may be predictable with a detailed mechanical understanding of a structure's evolution. The primary focus of this thesis is the integration of field observations, geospatial data including airborne LiDAR, and numerical modeling to investigate three dimensional deformational patterns associated with fault slip accumulated over geologic time scales. The work investigates contractional tectonics at Sheep Mountain anticline, Greybull, WY, and extensional tectonics at the Volcanic Tableland, Bishop, CA. A detailed geometric model is a necessary prerequisite for complete kinematic or mechanical analysis of any structure. High quality 3D seismic imaging data provides the means to characterize fold geometry for many subsurface industrial applications; however, such data is expensive, availability is limited, and data quality is often poor in regions of high topography where outcrop exposures are best. A new method for using high resolution topographic data, geologic field mapping and numerical interpolation is applied to model the 3D geometry of a reservoir-scale fold at Sheep Mountain anticline. The Volcanic Tableland is a classic field site for studies of fault slip scaling relationships and conceptual models for evolution of normal faults. Three dimensional elastic models are used to constrain subsurface fault geometry from detailed maps of fault scarps and topography, and to reconcile two potentially competing conceptual models for fault growth: by coalescence and by subsidiary faulting. The Tableland fault array likely initiated as a broad array of small faults, and as some have grown and coalesced, their strain shadows have inhibited the growth and initiation of nearby faults. The Volcanic Tableland also is used as a geologic example in a study of the capabilities and limitations of mechanics-based restoration, a relatively new approach to modeling in structural geology that provides distinct advantages over traditional kinematic methods, but that is significantly hampered by unphysical boundary conditions. The models do not accurately represent geological strain and stress distributions, as many have hoped. A new mechanics-based retrodeformational technique that is not subject to the same unphysical boundary conditions is suggested. However, the method, which is based on reversal of tectonic loads that may be optimized by paleostress analysis, restores only that topography which may be explained by an idealized elastic model. Elastic models are appealing for mechanical analysis of fault-related deformation because the linear nature of such models lends itself to retrodeformation and provides computationally efficient and stable numerical implementation for simulating slip distributions and associated deformation in complicated 3D fault systems. However, cumulative rock deformation is not elastic. Synthetic models are applied to investigate the implications of assuming elastic deformation and frictionless fault slip, as opposed to a more realistic elasto-plastic deformation with frictional fault slip. Results confirm that elastic models are limited in their ability to simulate geologic stress distributions, but that they may provide a reasonable, first-order approximation of strain tensor orientation and the distribution of relative strain perturbations, particularly distal from fault tips. The kinematics of elastic and elasto-plastic models diverge in the vicinity of fault tips. Results emphasize the importance of accurately and completely representing subsurface fault geometry in linear or nonlinear models.
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 636
Book Description
Coastal Engineering VII
Author: C. A. BrebbiaPublisher: Witpress
ISBN: 9781845640095
Category : Science
Languages : en
Pages : 376
Book Description
Bringing together contributions from researchers and professionals engaged in the development of modern computational and experimental tools, this book addresses many subjects relevant to the successful management of coastal areas.
Fault-related Deformation Over Geologic Time
Author: Peter James LovelyPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A thorough understanding of the kinematic and mechanical evolution of fault-related structures is of great value, both academic (e.g. How do mountains form?) and practical (e.g. How are valuable hydrocarbons trapped in fault-related folds?). Precise knowledge of the present-day geometry is necessary to know where to drill for hydrocarbons. Understanding the evolution of a structure, including displacement fields, strain and stress history, may offer powerful insights to how and if hydrocarbons might have migrated, and the most efficient way to extract them. Small structures, including faults, fractures, pressure solution seams, and localized compaction, which may strongly influence subsurface fluid flow, may be predictable with a detailed mechanical understanding of a structure's evolution. The primary focus of this thesis is the integration of field observations, geospatial data including airborne LiDAR, and numerical modeling to investigate three dimensional deformational patterns associated with fault slip accumulated over geologic time scales. The work investigates contractional tectonics at Sheep Mountain anticline, Greybull, WY, and extensional tectonics at the Volcanic Tableland, Bishop, CA. A detailed geometric model is a necessary prerequisite for complete kinematic or mechanical analysis of any structure. High quality 3D seismic imaging data provides the means to characterize fold geometry for many subsurface industrial applications; however, such data is expensive, availability is limited, and data quality is often poor in regions of high topography where outcrop exposures are best. A new method for using high resolution topographic data, geologic field mapping and numerical interpolation is applied to model the 3D geometry of a reservoir-scale fold at Sheep Mountain anticline. The Volcanic Tableland is a classic field site for studies of fault slip scaling relationships and conceptual models for evolution of normal faults. Three dimensional elastic models are used to constrain subsurface fault geometry from detailed maps of fault scarps and topography, and to reconcile two potentially competing conceptual models for fault growth: by coalescence and by subsidiary faulting. The Tableland fault array likely initiated as a broad array of small faults, and as some have grown and coalesced, their strain shadows have inhibited the growth and initiation of nearby faults. The Volcanic Tableland also is used as a geologic example in a study of the capabilities and limitations of mechanics-based restoration, a relatively new approach to modeling in structural geology that provides distinct advantages over traditional kinematic methods, but that is significantly hampered by unphysical boundary conditions. The models do not accurately represent geological strain and stress distributions, as many have hoped. A new mechanics-based retrodeformational technique that is not subject to the same unphysical boundary conditions is suggested. However, the method, which is based on reversal of tectonic loads that may be optimized by paleostress analysis, restores only that topography which may be explained by an idealized elastic model. Elastic models are appealing for mechanical analysis of fault-related deformation because the linear nature of such models lends itself to retrodeformation and provides computationally efficient and stable numerical implementation for simulating slip distributions and associated deformation in complicated 3D fault systems. However, cumulative rock deformation is not elastic. Synthetic models are applied to investigate the implications of assuming elastic deformation and frictionless fault slip, as opposed to a more realistic elasto-plastic deformation with frictional fault slip. Results confirm that elastic models are limited in their ability to simulate geologic stress distributions, but that they may provide a reasonable, first-order approximation of strain tensor orientation and the distribution of relative strain perturbations, particularly distal from fault tips. The kinematics of elastic and elasto-plastic models diverge in the vicinity of fault tips. Results emphasize the importance of accurately and completely representing subsurface fault geometry in linear or nonlinear models.
Annual Commencement
Author: Stanford UniversityGeometry, Evolution and Scaling of Fault Relay Zones in 3D Using Detailed Observations from Outcrops and 3D Seismic Data
Author: Jonathan James LongPublisher:
ISBN:
Category : Fault zones
Languages : en
Pages :
Book Description
A new surface attribute was developed during the course of the thesis, which enables fault-related deformation? specifically, the apparent dip of mapped horizons measured in a direction perpendicular to the average strike of a fault array (here termed?fault-normal rotation?, or?FNR?)? to be quantitatively analysed around imaged faults. The new utility can be applied to any 3D surface and was used to analyse centimetre-scale to kilometre-scale fault-arrays, interpreted from laser scan point clouds, digital elevation models, and 3D seismic datasets. In all studied examples, faults are surrounded by volumes of fault-related deformation that have variable widths, and which can consist of faults, fractures and continuous bed rotations (i.e. monoclines). The vertical component of displacement calculated from the areas of fault-related deformation on each horizon act to?fill-in? apparently missing displacements observed in fault throw profiles at fault overlaps. This result shows that complex 3D patterns of fault-related strain commonly develop during the geometrically coherent growth of a single fault-array. However, if the component of continuous deformation was not added to the throw profile, the fault-array could have been misinterpreted as a series of isolated fault segments with coincidental overlaps. The FNR attribute allows the detailed, quantitative analysis of fault linkage geometries. It is shown that overlapping fault tip lines in relay zones can link simultaneously at multiple points, which results in a segmented branch line. Fault linkage in relay zones is shown to control the amount of rotation accommodated by relay ramps on individual horizons, with open relay ramps having accommodated by larger rotations than breached relay ramps in the same relay zone. Displacements are therefore communicated between horizons in order to maintain strain compatibility within the relay zone. This result is used to predict fault linkage in the subsurface, along slip-aligned branch lines, from the along-strike displacement distributions at the earth?s surface. Relay zone aspect ratios (AR; overlap/separation) are documented to follow power-law scaling relationships over nine orders of magnitude with a mean AR of 4.2. Approximately one order of magnitude scatter in both separation and overlap exists at all scales. Up to half of this scatter can be attributed to the spread of measurements recorded from individual relay zones, which relates to the evolution of relay zone geometries as the displacements on the bounding faults increase. Mean relay AR is primarily controlled by the interactions between the stress field, of a nearby fault, and overlapping fault tips, rather than by the host rock lithology. At the Kilve and Lamberton study areas, mean ARs are 8.60 and 8.64 respectively, which are much higher than the global mean, 4.2. Scale-dependent factors, such as mechanical layering and heterogeneities at the fault tips are present at these locations, which modify how faults interact and produce relatively large overlap lengths for a given separation distance. Despite the modification to standard fault interaction models, these high AR relay zones are all geometrically coherent.
Mechanical and Geological Controls on the Long-term Evolution of Normal Faults
Author: Jean-Arthur Louis OlivePublisher:
ISBN:
Category : Fault zones
Languages : en
Pages : 186
Book Description
This thesis investigates the long-term evolution of rift-bounding normal faults in extensional environments. My main objective is to develop a theoretical framework that explains the controls on maximum fault offset in terms of a few key mechanical and geological controls. In Chapter 2, I propose that flexural rotation of the active fault plane enables faults to evolve along a path of minimal energy, thereby enhancing their life span. In Chapter 3, I show that surface processes can increase the life span of continental faults by reducing the energy cost of topography build-up. In Chapter 4, I focus on lithospheric bending induced by fault growth. I demonstrate that numerical models that treat the lithosphere as a visco-plastic solid properly predict fault evolution only when the rate-dependent viscous flexural wavelength of the lithosphere is accommodated within the numerical domain. In Chapter 5, I investigate the growth of normal faults in relation to a depth-variable rate of magma emplacement. These models predict both faulting styles and crustal architecture at slow mid-ocean ridges. Finally, in Chapter 6 I use a newly developed 3-D numerical model to establish a relation between along-axis fault continuity and spatial heterogeneities in lithospheric thickness at a ridge segment.
Mechanics, Structure and Evolution of Fault Zones
Author: Yehuda Ben-ZionPublisher: Springer Science & Business Media
ISBN: 3034601387
Category : Science
Languages : en
Pages : 375
Book Description
Considerable progress has been made recently in quantifying geometrical and physical properties of fault surfaces and adjacent fractured and granulated damage zones in active faulting environments. There has also been significant progress in developing rheologies and computational frameworks that can model the dynamics of fault zone processes. This volume provides state-of-the-art theoretical and observational results on the mechanics, structure and evolution of fault zones. Subjects discussed include damage rheologies, development of instabilities, fracture and friction, dynamic rupture experiments, and analyses of earthquake and fault zone data.
Author: