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Predicting The Internal Structure Of Fault Zones In Basalt Sequences And Their Effect On Along And Across Fault Fluid Flow
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Book Synopsis Predicting the Internal Structure of Fault Zones in Basalt Sequences, and Their Effect on Along- and Across-fault Fluid Flow by : Rachael Ellen
Download or read book Predicting the Internal Structure of Fault Zones in Basalt Sequences, and Their Effect on Along- and Across-fault Fluid Flow written by Rachael Ellen and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interest in the architecture and fluid flow potential of fault zones in basalt sequences has intensified over recent years, due to their applications in the hydrocarbon industry and CO2 storage. In this study, field mapping is combined with micro-structural analyses and flow modelling to evaluate fault growth, evolution, fluid-rock interactions, and permeability changes over time in faults in basalt sequences. Twelve brittle fault zones cutting basalt sequences in the North Atlantic Igneous Province were studied. This study finds that fault architecture is ultimately controlled by displacement and juxtaposition. Self-juxtaposed faults (i.e. basalt faulted against itself) are characterised by wide zones of brecciation, cataclasis, fracturing, mineralisation and alteration. Non self-juxtaposed faults (i.e. basalt faulted against an inter-lava unit) are characterised by relatively narrow principal slip zones, filled with clay smears or clay-rich gouge derived from inter-lava beds. This study also finds that brittle deformation of basalts at the grain scale is mineralogy dependent. Fe-Ti oxides and pyroxenes deform by intragranular fracturing and grain size reduction, whereas olivines and feldspars are susceptible to replacement by clay and zeolites. Fault rock bulk chemistries are likely to differ from their host rocks, and this is controlled by secondary mineral formation, with zeolite and clay minerals playing an important role. Flow modelling in this study shows that controls on along- and across-fault fluid flow can significantly change fault zone bulk permeability over time, as a result of mineralisation and alteration of the fault zone as it evolves. The results from this study are used to propose a model for how fault strength, fault-related alteration, and permeability change over time in fault zones in basalt sequences. Results highlight the impact that fault-related alteration could have on CO2 storage. A predictive model for fault structure at depth, developed from this study's findings, is presented for fault zones in basalt sequences, which has particular relevance to the hydrocarbon and CO2 industry.
Author :Christopher A. J. Wibberley Publisher :Geological Society of London ISBN 13 :9781862392533 Total Pages :384 pages Book Rating :4.3/5 (925 download)
Book Synopsis The Internal Structure of Fault Zones by : Christopher A. J. Wibberley
Download or read book The Internal Structure of Fault Zones written by Christopher A. J. Wibberley and published by Geological Society of London. This book was released on 2008 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Faults are primary focuses of both fluid migration and deformation in the upper crust. The recognition that faults are typically heterogeneous zones of deformed material, not simple discrete fractures, has fundamental implications for the way geoscientists predict fluid migration in fault zones, as well as leading to new concepts in understanding seismic/aseismic strain accommodation. This book captures current research into understanding the complexities of fault-zone internal structure, and their control on mechanical and fluid-flow properties of the upper crust. A wide variety of approaches are presented, from geological field studies and laboratory analyses of fault-zone and fault-rock properties to numerical fluid-flow modelling, and from seismological data analyses to coupled hydraulic and rheological modelling. The publication aims to illustrate the importance of understanding fault-zone complexity by integrating such diverse approaches, and its impact on the rheological and fluid-flow behaviour of fault zones in different contexts.
Book Synopsis Deriving Field-based Statistical Relationships to Characterize the Geometry, Heterogeneity and Permeability of Faults in Mixed Sand-shale Sequences by : Yannick Kremer
Download or read book Deriving Field-based Statistical Relationships to Characterize the Geometry, Heterogeneity and Permeability of Faults in Mixed Sand-shale Sequences written by Yannick Kremer and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fault zones can strongly affect fluid flow in the subsurface. Faults can act as (partial) barriers to flow, as conduits and as combined conduit-barrier systems. Understanding the relationship between faulting and fluid flow has many practical applications, including hydrocarbon exploration and production, mineral exploration, groundwater management, radioactive waste disposal, geothermal energy and carbon sequestration. This study is primarily focussed at the applications in the hydrocarbon industry. For hydrocarbon exploration, faults are important because they can act as long term barriers (fault sealing), in which case they can be part of structural traps. Faults acting as conduits also need to be considered, hydrocarbons moving vertically along a fault can either migrate into a reservoir, or the hydrocarbons can leak out of the reservoir along the fault. For hydrocarbon production also the short term effect of faults needs to be considered, as faults can block or baffle flow towards a well. For all these scenarios it is currently diffcult to reliably predict the behaviour of the fault deep underground. The research presented in this thesis aims to improve this prediction. Several studies have shown that fluid flow along and across fault zones is strongly affected by the heterogeneity of the fault zone and the presence of connected high permeability pathways. Both heterogeneity and high permeability pathways cannot be detected or predicted using currently available hydrocarbon industry tools. Therefore this study uses extensive field studies of faults exposed at the earth's surface, to characterize these features in detail. For this study 12 fault exposures have been studied in SE Utah and the western Sinai in Egypt. The faults are mapped with mm to cm-scale detail and samples are taken for petrophysical analysis. These data are further analyzed by numerical modelling of fluid flow through the fault zones. By combining fieldwork and flow modelling, the features that most strongly affect fluid flow (key flow controls) can be identified. Key flow controls provide a tool for efficient collection of data that allow the statistical characterization of fault zones. Statistical characterization of fault zone fluid flow properties can be used to improve hydrocarbon industry workflows.This study has revealed a wide variety in fault architectures for faults in sand-shale sequences. None of the faults studied here is dominated by a single homogenous gouge of mixed sand and shale, as is assumed by many current workflows for predicting (upscaled) fault permeability. With such a wide variety of fault architectures, it is impossible to define a simple rule for the fluid-flow characteristics of faults. For successful prediction of fault sealing and fault permeability it will be necessary to successfully predict fault architecture. Predicting fault architecture will require the detailed evaluation of host rock stratigraphy, fault structureand the deformation, fluid flow and thermal history.
Book Synopsis Integrated Fault Seal Analysis by : S. Ogilvie
Download or read book Integrated Fault Seal Analysis written by S. Ogilvie and published by Geological Society of London. This book was released on 2020-08-03 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Faults commonly trap fluids such as hydrocarbons and water and therefore are of economic significance. During hydrocarbon field development, smaller faults can provide baffles and/or conduits to flow. There are relatively simple, well established workflows to carry out a fault seal analysis for siliciclastic rocks based primarily on clay content. There are, however, outstanding challenges related to other rock types, to calibrating fault seal models (with static and dynamic data) and to handling uncertainty. The variety of studies presented here demonstrate the types of data required and workflows followed in today’s environment in order to understand the uncertainties, risks and upsides associated with fault-related fluid flow. These studies span all parts of the hydrocarbon value chain from exploration to production but are also of relevance for other industries such as radioactive waste and CO2 containment.
Book Synopsis The Nature and Tectonic Significance of Fault Zone Weakening by : Robert E. Holdsworth
Download or read book The Nature and Tectonic Significance of Fault Zone Weakening written by Robert E. Holdsworth and published by Geological Society of London. This book was released on 2001 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many faults appears to form persistent zones of weakness that fundamentally influence the distribution, arichitecture and movement patterns of crustal-scale deformation and associated processes in both continental and oceanic regions. They act as conduits for the focused migration of economically important fluids and also constitute one of the most important global geological hazards. This book brings together papers by an international group of Earth Scientists to discuss a broad range of topics centred upon the controls of fault weakening and the role of such faults during lithosphere deformation.
Book Synopsis Rock Fractures and Fluid Flow by : National Research Council
Download or read book Rock Fractures and Fluid Flow written by National Research Council and published by National Academies Press. This book was released on 1996-08-27 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific understanding of fluid flow in rock fracturesâ€"a process underlying contemporary earth science problems from the search for petroleum to the controversy over nuclear waste storageâ€"has grown significantly in the past 20 years. This volume presents a comprehensive report on the state of the field, with an interdisciplinary viewpoint, case studies of fracture sites, illustrations, conclusions, and research recommendations. The book addresses these questions: How can fractures that are significant hydraulic conductors be identified, located, and characterized? How do flow and transport occur in fracture systems? How can changes in fracture systems be predicted and controlled? Among other topics, the committee provides a geomechanical understanding of fracture formation, reviews methods for detecting subsurface fractures, and looks at the use of hydraulic and tracer tests to investigate fluid flow. The volume examines the state of conceptual and mathematical modeling, and it provides a useful framework for understanding the complexity of fracture changes that occur during fluid pumping and other engineering practices. With a practical and multidisciplinary outlook, this volume will be welcomed by geologists, petroleum geologists, geoengineers, geophysicists, hydrologists, researchers, educators and students in these fields, and public officials involved in geological projects.
Book Synopsis Fault Zone Architecture and Deformation Mechanics of Normal Faults in Poorly Lithified Sediments, Miri - Malaysia by : Silvia Sosio de Rosa
Download or read book Fault Zone Architecture and Deformation Mechanics of Normal Faults in Poorly Lithified Sediments, Miri - Malaysia written by Silvia Sosio de Rosa and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fault zones are mechanical and hydrological heterogeneities in Earth's upper crust, however, the internal properties that cause heterogeneity, their three-dimensional variations, and the fundamental processes that lead to these variations are poorly understood. The hydraulic behaviour of faults at depth plays an important role in the exploration and production of hydrocarbons, as in several other subsurface engineering applications. Faults can act as conduits, barriers and combined conduit-barrier systems to fluid flow, depending on their petrophysical properties, on their internal structure and stress state. The degree to which a fault will impede fluid flow is only as great as its most permeable point. Producing reliable predictions of cross-fault and up-fault fluid flow requires an understanding of the processes that determine areas of the fault surface containing transmissible fault rocks. A field site in Miri, Jalan Mukag outcrop, was selected because it offers excellent 3D outcrops of normal faults in soft siliciclastic sediments, and gives the opportunity to investigate fault architecture both along-strike and down-dip. Weak-seal areas for cross-fault fluid flow along the fault zone exposures are identified combining detailed mapping of the fault zone architecture, analyses of the fault rock facies and geostatistical characterization (variograms) of variation in along-strike fault-core thickness. Processes that express the accumulation of of strain in the fault core (slip surfaces, boudinage and grain-scale mixing) are analysed because of their implications in terms of cross-fault fluid flow. The interaction between these processes in the fault core may or may not lead to complete mesoscale and grain-scale mixing, thus potentially induce changes in the capillary entry pressure of the fault rocks. Deformation mechanisms and geochemical processes that affect the fault zone are identified through petrographic, microstructural and mineralogical analysis,and they are used to infer along-fault fluid flow history and implications for cross-fault fluid flow.
Book Synopsis Mechanics, Structure and Evolution of Fault Zones by : Yehuda Ben-Zion
Download or read book Mechanics, Structure and Evolution of Fault Zones written by Yehuda Ben-Zion and published by Springer Science & Business Media. This book was released on 2009-12-30 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis The Role of Fluids in Faulting by : Yuyun Yang
Download or read book The Role of Fluids in Faulting written by Yuyun Yang and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid-rock interactions have long been recognized as crucial drivers in earthquakes and slow slip events. In the context of induced seismicity, the injection of high-pressure fluid underground during wastewater disposal, hydrothermal energy production or hydraulic fracturing operations have triggered earthquakes in geologically stable regions that previously had minimal detected seismicity. Many hypotheses about how these earthquakes were triggered have been proposed, including pore pressure diffusion, long-range poroelastic stressing, and fault loading and reactivation by aseismic slip. The injection of fluid into a fault not only alters pore pressure and triggers slip, but also changes properties of the fault zone that in turn impact fluid flow, pressure diffusion, and fault slip behavior. The most relevant properties here are porosity and permeability. Many experiments, in both the laboratory and in situ, show that dilatancy (the expansion of pores and the fluids within them) accompanies shear deformation of fault zone rocks. In the absence of fluid flow (i.e., undrained conditions), dilatancy reduces pore pressure, increasing the effective normal stress and strengthening the fault. Porosity changes also alter permeability. As pores dilate and more porous space becomes connected, permeability is enhanced. This facilitates fluid flow and enables pore pressure perturbations to reach greater distances along the fault in a shorter period of time. It is certainly evident that the evolution of porosity and permeability, while complex, can fundamentally influence fluid flow and fault slip behavior, and therefore needs to be taken into account in fault models with hydromechanical coupling. In the context of tectonic earthquakes and episodic slow slip events, rock porosity and permeability changes over the earthquake cycle also dictate the nature of the slip that occurs. During the coseismic period, rapid slip cracks open pore space and causes dilatancy, which strengthens the fault and prevents it from slipping further. Permeability is also enhanced as the porosity increases, which may act to weaken further parts of the fault as the fluid migrates. Over the interseismic period, the fault heals from mechanical compaction, and is also gradually sealed by ductile compaction mechanisms such as pressure solution, which involves dissolving minerals at stressed contact points and depositing them in pores. This closing of pores and permeability reduction increases the pore fluid pressure, which will weaken the fault and cause slip again, and this cycle continues. Understanding how the interplay of dilatancy, compaction produces and arrests fault slip is important in characterizing where and how slow slip events occur, and when that might give rise to earthquakes. In this thesis, I investigate the fault response to pore pressure changes coupled to porosity and permeability evolution using 2D numerical simulations of a strike-slip fault governed by rate-and-state friction. The first part of the thesis investigates aseismic slip triggered by fluid injection in the context of induced seismicity. The goal of this study is to evaluate the controlling factors for the initiation and propagation of aseismic slip, and to make testable predictions of potentially observable quantities like the migration rate of the aseismic slip front, as a function of prestress, permeability, injection rate, and frictional parameters. We showcase comparisons for different prestress conditions, permeability values, injection rates, initial state variables, and frictional properties, evaluating their relative importance in determining slip behavior. We also highlight how neglecting porosity and permeability evolution can drastically change the nature of fault slip, and connect our simulations with a limited set of observations to emphasize the important role of hydromechanical coupling in characterizing fault response to fluid injection. Furthermore, we calibrated our model and fit the results to InSAR observations of aseismic slip in the Delaware Basin that is caused by the injection of oilfield water. This shows the applicability of the numerical model to field data and potentially the monitoring of induced seismicity. The second part of the thesis focuses on earthquake cycle simulations in the tectonic context. We explore pore pressure, porosity and permeability evolution over the earthquake cycle and how they impact the occurrences of slow slip events and earthquake ruptures. The first model builds on the study of injection-induced aseismic slip and adds viscous compaction to porosity evolution to study slow slip events. We show that the slow slip events are driven by the interaction between pore compaction which raises fluid pressure and weakens the fault, as well as pore dilation which decreases fluid pressure and limits the slip instability. Cyclic behaviors of these events can range from long-term events lasting from a few months to years to very rapid short-term events lasting for only a few days. The accumulated slip for each event is on the order of centimeters, and the stress drop is generally less than 10 MPa. The second model ignores porosity evolution and only considers permeability evolution that is coupled to effective normal stress, fault slip and a characteristic healing time over which the fault heals interseismically. We demonstrate the viability of fault valving in an earthquake sequence model that accounts for permeability evolution and fault zone fluid transport. Predicted changes in fault strength from cyclic variations in pore pressure are substantial ($\sim$10-20 MPa) and perhaps even larger than those from changes in friction coefficient. We also show how fluids facilitate the propagation of aseismic slip fronts and transmission of pore pressure changes at relatively fast rates. The modeling framework we introduce here can be applied to a wide range of problems, including tectonic earthquake sequences, slow slip and creep transients, earthquake swarms, and induced seismicity.
Book Synopsis Effect of Faulting on Ground-water Movement in the Death Valley Region, Nevada and California by : Claudia C. Faunt
Download or read book Effect of Faulting on Ground-water Movement in the Death Valley Region, Nevada and California written by Claudia C. Faunt and published by . This book was released on 1997 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Effects of Fault Zones and Fluid Flow on the Structural, Hydrologic and Geomorphic Evolution of Accretionary Complexes by : Daniel Lewis Orange
Download or read book The Effects of Fault Zones and Fluid Flow on the Structural, Hydrologic and Geomorphic Evolution of Accretionary Complexes written by Daniel Lewis Orange and published by . This book was released on 1991 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Internal Structure of Fault Zones by : Chi-yuen Wang
Download or read book Internal Structure of Fault Zones written by Chi-yuen Wang and published by Birkhäuser. This book was released on 1986 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dead Sea Transform Fault System: Reviews by : Zvi Garfunkel
Download or read book Dead Sea Transform Fault System: Reviews written by Zvi Garfunkel and published by Springer. This book was released on 2014-07-03 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Dead Sea transform is an active plate boundary connecting the Red Sea seafloor spreading system to the Arabian-Eurasian continental collision zone. Its geology and geophysics provide a natural laboratory for investigation of the surficial, crustal and mantle processes occurring along transtensional and transpressional transform fault domains on a lithospheric scale and related to continental breakup. There have been many detailed and disciplinary studies of the Dead Sea transform fault zone during the last 20 years and this book brings them together. This book is an updated comprehensive coverage of the knowledge, based on recent studies of the tectonics, structure, geophysics, volcanism, active tectonics, sedimentology and paleo and modern climate of the Dead Sea transform fault zone. It puts together all this new information and knowledge in a coherent fashion.
Book Synopsis Characterisation of the 2D and 3D Density and Connectivity Attributes of Fracture Systems in Carbonate Reservoir Analogues by : David Adam Sagi
Download or read book Characterisation of the 2D and 3D Density and Connectivity Attributes of Fracture Systems in Carbonate Reservoir Analogues written by David Adam Sagi and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fault zones, hosted in fractured carbonate reservoirs, can behave as either high porosity and permeability conduits, favoring the migration of fluids; or, conversely, as low porosity and permeability barriers, retarding fluid flow, due to the presence of fine-grained fault gouges (Agosta and Aydin, 2006, Agosta and Kirschner, 2003). Due to these reasons, fault zones can have great economical importance for the hydrocarbon industry. Furthermore, within fault zones, the cyclic accumulation and sudden release of trapped, high pressure fluids can trigger earthquakes and aftershocks (Miller et al. 2004). In this project, we referred to the classical fault zone architecture models defined by Sibson (1977) and Chester et al. (1993), in which faults are built up of a fault core (where most of the displacement is localised), a damage zone (containing fractured host rocks) and the protolith (the unfractured host rock). Faults, with displacements ranging from cm- to km-scale have been studied within two study areas, Flamborough Head, UK and the Gubbio fault in the Northern Apennines, Italy. Flamborough Head is a peninsula in East Yorkshire, which represents analogues for hydrocarbon rich, fractured North Sea chalk reservoirs; whereas the Gubbio fault is a regional scale, seismically active normal fault, characterized by complex fault zone architectures, cutting through different types of carbonates. At both study areas, field-based, outcrop-scale structural observations were completed in order to explore the internal architecture and infer the fluid transmissibility of the fault zones. Additionally, microscale structural observations were made using representative thin sections, collected from the different fault zone domains of the studied fault zones. Qualitative structural observations were complemented with quantitative analyses to study the variation of fracture and vein density and connectivity patterns across the fault zones, which were later used as a proxy for fluid transmissibility. These analyses included established 1D (transects) and 2D (image analysis) methods and a newly developed workflow for the modelling of fracture networks in 3D, based on LiDAR data. 3D modelling of fracture networks was developed using different fracture height/length aspect ratios. The quantitative comparison of different aspect ratio 3D models with established 1D and 2D results, by using misfit graphs, enabled to validate the different 3D models and to estimate the mean aspect ratio of fractures within the fault zones. Qualitative and quantitative results were integrated in conceptual fault zone architecture and fluid flow models. At Flamborough Head small (cm-scale) and larger (up to 20 m) displacement normal faults were studied in two different types of chalks: one characterized by cm-scale interlayered marl horizons and another one, absent of it. Within the marl-free host rock, in the fault zones of both the small and the large displacement faults, fluid assisted deformation features, such as veins, are often observed. On the contrary, in marl-rich units, fluid assisted deformation features are absent, while fractures filled with intruded marl from the interlayered horizons are common. This suggests that the occurrence of fluid flow in this lithology is primarily controlled by the protolith. 1D quantitative analysis at Flamborough Head showed that, as also predicted by classical fault zone models, vein density progressively increases in the damage zones of faults moving from the protolith towards the fault core. 2D quantitative analysis showed that fracture connectivity remains as low as background values in the outer parts of the damage zones, whereas it increases rapidly in the inner parts. By comparing the fracture density and connectivity patterns measured from different aspect ratio 3D models with results measured from 1D and 2D analyses showed that the most realistic model is the 1/5 fracture aspect ratio one. The Gubbio fault cuts through a carbonatic multilayer containing carbonates with different marl content. In the Marne a Fucoidi formation marl is homogenously distributed, while in the overlying Scaglia Group marl is absent. Within the damage zone, hosted in the Marne a Fucoidi formation, fluid assisted deformation features are rare and are only present in the damage zones of subsidiary faults that entirely cut through the formation, linking the under and overlying marl free carbonates. On the contrary, within the damage zone, hosted in the Scaglia Group, fluid assisted deformation features are common, especially close to the fault core of the Gubbio fault and in the damage zone of subsidiary faults. Similarly to Flamborough Head, this suggests that the occurrence of fluid flow is primarily controlled by the nature of the protolith. As predicted by classical fault zone models, 1D quantitative analysis across the Gubbio fault showed that vein density increases in the damage zone moving from the protolith towards the fault core. Similarly to results from Flamborough Head, 2D quantitative analysis showed that fracture connectivity is low in the outer parts of the damage zones, but increases rapidly within the inner parts, and the comparison of 3D models with 1D and 2D results showed that the most realistic model is the 1/5 aspect ratio one. The conceptual fluid flow models, built for the study areas, highlights: a) the importance of different marl content host rocks controlling the initiation of fluid flow; b) the development of smaller and larger displacement normal faults and the effects of their displacements on fluid transmissibility; c) the effects of fault damage zones, positioned in an overlapping geometry, resulting in the development high and low fracture connectivity subdomains and fracture corridors; d) the differences in the relative variation of fracture/vein density and connectivity throughout the damage zone compared to background values; e) the fluid transmissibility of the different fault rocks, located within different subdomains of the fault core and f) the anisotropy of fluid transmissibility in the fault core.
Book Synopsis The Geometry and Growth of Normal Faults by : C. Childs
Download or read book The Geometry and Growth of Normal Faults written by C. Childs and published by Geological Society of London. This book was released on 2017-11-06 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: Normal faults are the primary structures that accommodate extension of the brittle crust. This volume provides an up-to-date overview of current research into the geometry and growth of normal faults. The 23 research papers present the findings of outcrop and subsurface studies of the geometrical evolution of faults from a number of basins worldwide, complemented by analogue and numerical modelling studies of fundamental aspects of fault kinematics. The topics addressed include how fault length changes with displacement, how faults interact with one another, the controls of previous structure on fault evolution and the nature and origin of fault-related folding. This volume will be of interest to those wishing to develop a better understanding of the structural geological aspects of faulting, from postgraduate students to those working in industry.
Book Synopsis Spatio-temporal History of Fluid-rock Interaction in the Hurricane Fault Zone by : Jace Koger
Download or read book Spatio-temporal History of Fluid-rock Interaction in the Hurricane Fault Zone written by Jace Koger and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Hurricane Fault is a 250-km long, west dipping, Basin and Range-bounding normal fault in SW Utah and NW Arizona that initiated in the mid-Miocene to Pliocene. It has been primarily active in the Quaternary, with slip rates of 0.2 - 0.6 mm/yr. There are multiple hot springs along its 250-km length and multiple late Tertiary-Quaternary basaltic centers broadly parallel the fault. Possible sources of hot spring fluids include deeply-circulated meteoric water that experienced water-rock exchange at high temperatures (>100 ℗ʻC) and deep-seated crustal fluids. Aside from the source of modern hot spring fluids and heat, questions about the spatio-temporal history of fluid flow along the Hurricane Fault remain unaddressed. Abundant damage zone veins, cements, and host rock alteration are present, indicative of past fluid flow. Carbonate veining and cementation is a key feature of the Hurricane Fault zone, and is the primary feature exploited to characterize the thermochemical history of fault-related paleofluids. A combination of macroscopic and microscopic carbonate observations, chemical composition, and precipitation temperature of calcite veins was used to determine past water-rock diagenetic interaction and vein evolution in the Hurricane Fault zone. Calcite iv in concretions and veins from the damage zone of the fault shows a wide range of carbon and oxygen stable isotope ratios, with Îþ13CPDB from -4.5 to 3.8 0́ʻ and Îþ18OPDB from -17.7 to -1.10́ʻ. Fluid inclusion microthermometry homogenization temperatures range from 45 to 160 ℗ʻC, with fluid salinities of 0 to 15 wt% NaCl calculated from melting temperatures. Combining the two datasets, two main fluids that interacted with the fault zone are inferred: (1) basin brines with a Îþ 18OSMOW of 9.2 0́ʻ and (2) altered meteoric fluids with a Îþ 18OSMOW of -11.9 to -8.3 0́ʻ. Calculated dissolved CO2 Îþ 13CPDB (-8.5 to -1.3 0́ʻ) indicates mixed marine carbonate and organic or magmatic sources. Fault zone diagenesis was caused by meteoric water infiltration and interaction with carbonate-rich rocks, mixed with upwelling basin brines. Fluid-rock interaction is concentrated in the damage zone, where fracture-related permeability was utilized for fluid flow. A distinct mineralization event punctuated this history, associated with basin brines that were chemically influenced by nearby basaltic magmatism. This implies a hydrologic connection between the fault and regional magmatism.
Book Synopsis Flow Processes in Faults and Shear Zones by : G. Ian Alsop
Download or read book Flow Processes in Faults and Shear Zones written by G. Ian Alsop and published by Geological Society of London. This book was released on 2004 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Faults and their deeper level equivalents, shear zones, are localized regions of intense deformation within the Earth. They are recognized at all scales from micro to plate boundary, and are important examples of the nature of heterogeneous deformation in natural rocks. Faults and shear zones are significant as they profoundly influence the location, architecture and evolution of a broad range of geological phenomenao The topography and bathymetry of the Earth's surface is marked by mountain belts and sedimentary basins that are controlled by faults and shear zoneso In addition, faults and shear zones control fluid migration and transport including hydrothermal and hydrocarbon systems. Once faults and shear zones are established, they are often long-lived features prone to multiple reactivation over very large time-scales. This collection of papers addresses lithospheric deformation and the rheology of shear zones, together with processes of partitioning and the unravelling of fault and shear zone histories.
