Understanding Faults: Detecting, Dating, and Modeling

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Understanding Faults: Detecting, Dating, and Modeling
Copyright
List of contributors
Preface
1 -
Introduction
	Definition of a fault surface, fault kinematics and displacement
	References
2 -
Fault mechanics and earthquakes
	2.1 Introduction
	2.2 Fractures
	2.3 From intact rocks to opening-mode fractures to faults
		2.3.1 Griffith cracks
		2.3.2 The Coulomb failure criterion and the Mohr circle
		2.3.3 Hydrofractures
		2.3.4 Stress state and dynamic fault classification of Anderson
		2.3.5 Wallace-Bott hypothesis
	2.4 Fault zone processes and structure
		2.4.1 The fault zone
		2.4.2 Principal slip surface
		2.4.3 Pseudotachylites
		2.4.4 Strain hardening/strain softening of the fault core
		2.4.5 Fault surface geometry and roughness
		2.4.6 The process zone
		2.4.7 Deformation bands
		2.4.8 Fault groups and their characterization
			2.4.8.1 Fault arrangement and fractal geometry
		2.4.9 Fault evolution with depth
		2.4.10 Fault-related folding
	2.5 Fault movement and seismicity
		2.5.1 Fault rupture
			2.5.1.1 The seismic cycle
			2.5.1.2 Barriers and asperities
		2.5.2 Fault creep
		2.5.3 Slow earthquakes
		2.5.4 The Cosserat theory as a concept to describe fault and deformation band behaviour
		2.5.5 Large overthrusts and the effect of fluid pressure
	2.6 Faults in soft-sediments
	References
3.-
Fault detection
	3.1 Introduction
	3.2 Active seismics
		3.2.1 Seismic method
		3.2.2 Resolution
		3.2.3 Seismic imaging of faults
		3.2.4 Imaging of faults – 2-D and 3-D
		3.2.5 Fracture detection
	3.3 Ground-penetrating radar (GPR)
		3.3.1 Principle
		3.3.2 Imaging of faults
		3.3.3 Examples
	3.4 Electrical resistivity tomography (ERT)
		3.4.1 Background
		3.4.2 Large-scale fault imaging with structural information
	3.5 Gravimetry and magnetics
		3.5.1 Gravity and magnetic anomalies – definition and instruments for measurement
		3.5.2 Gravity and magnetic anomalies - interpretation
	3.6 Seismology
		3.6.1 Detecting and illuminating faults by earthquake hypocentre distribution
			3.6.1.1 Localization of earthquakes
			3.6.1.2 What can be learnt from earthquakes?
				3.6.1.2.1 Spatial and temporal distribution of earthquakes
		3.6.2 Describing faults by interpretation of source mechanisms
			3.6.2.1 The mechanics of earthquakes
			3.6.2.2 The concept of the double couple
			3.6.2.3 Determination of focal mechanisms
			3.6.2.4 Styles of faulting
			3.6.2.5 The concept of the moment tensor
		3.6.3 Examples of detecting faults using hypocentre distributions and focal mechanisms
			3.6.3.1 Vogtland/NW-Bohemia swarm earthquake area
			3.6.3.2 Central Apennines, Italy
	3.7 Remote sensing
		3.7.1 History and background of remote sensing
		3.7.2 Instruments and data
			3.7.2.1 Active and passive sensor technologies
		3.7.3 Fault mapping and kinematics
			3.7.3.1 Fault mapping
			3.7.3.2 Topography
			3.7.3.3 Fault kinematics analysis
		3.7.4 Summary and outlook
	References
4 -
Numerical modelling of faults
	4.1 Introduction
	4.2 Numerical methods for hydromechanical fault zone modelling
	4.3 Material parameters of fault zone rocks required for modelling
	4.4 An example of numerical modelling
		4.4.1 Modelling concept and parameters
		4.4.2 Model geometry and discretization
		4.4.3 Hydromechanical rock properties
		4.4.4 Boundary and initial conditions
		4.4.5 Modelling results
	4.5 Conclusions
	References
5.-
Faulting in the laboratory
	5.1 Fault friction in the quasi-static regime
		5.1.1 Laboratory measurements of friction
		5.1.2 General observations of steady state friction
		5.1.3 Rate-and-state friction
		5.1.4 Observations of variations in velocity dependence of friction at room temperature
		5.1.5 Strength recovery (healing)
		5.1.6 Effect of hydrothermal conditions on velocity dependence of friction
	5.2 Fault friction in the dynamic regime
		5.2.1 Dynamic weakening mechanisms in gouges and solid rocks
		5.2.2 Melt lubrication
		5.2.3 Flash heating and flash weakening
		5.2.4 Thermal pressurization
		5.2.5 Thermal decomposition and pressurization
		5.2.6 Fluid phase changes
		5.2.7 Powder lubrication
		5.2.8 Activation of crystal-plastic (viscous) mechanisms
		5.2.9 Dynamic rupture in laboratory experiments
			5.2.9.1 High confinement, small rock sample experiments
			5.2.9.2 Low confinement, large rock sample experiments
			5.2.9.3 Low confinement, analogue material experiments
		5.2.10 Frontiers
	5.3 Faults in scaled physical analogue models
		5.3.1 Introduction
		5.3.2 Scaling tectonic faulting to the laboratory
		5.3.3 Rock analogue materials and their bulk properties
		5.3.4 Quantifying stress and strain in analogue models
		5.3.5 Fault formation in analogue models
		5.3.6 Faulting in single and multi-layer systems
		5.3.7 Frontiers
	5.4 Microstructures of laboratory faults
		5.4.1 Introduction of localization features
		5.4.2 Development of gouge microstructure with strain/displacement
		5.4.3 Distribution of slip on structural elements
		5.4.4 Role of Y or B shears in generation of unstable slip
		5.4.5 Clay-bearing versus non-clay bearing
		5.4.6 Frontiers
	References
6 -
The growth of faults
	6.1 Introduction
	6.2 Geometric indicators of fault growth
		6.2.1 Conceptual ‘ideal isolated fault’ model
		6.2.2 Mechanical layering and displacement variations
		6.2.3 ‘Isolated’ fault lateral displacement profiles
		6.2.4 Interaction and lateral displacement profiles
		6.2.5 Relay zones and lateral interactions
		6.2.6 Damage zones and lateral growth
	6.3 Direct kinematic indicators of fault growth
		6.3.1 Displacement through time
		6.3.2 Fault lateral propagation
		6.3.3 Fault upward propagation and reactivation
	6.4 Displacement-length relations and fault growth
	6.5 End-member fault growth models
	6.6 Earthquakes and incremental growth
	6.7 Concluding remarks
	References
7- Direct dating of fault movement
	7.1 Dating of authigenic clay minerals in brittle faults
		7.1.1 Outline of the concept and the analytical method
		7.1.2 K-Ar and 40Ar/39Ar clay dating principles
		7.1.3 Fault gouge dating constraints
		7.1.4 Authigenic clay gouge age interpretation
		7.1.5 Case studies
	7.2 Dating methods based on thermal reset
		7.2.1 Outline of the method
		7.2.2 Fission track dating
		7.2.3 (U-Th)/He dating
		7.2.4 Trapped charge dating
		7.2.5 Case studies
	References
8. Fault sealing
	8.1 Introduction
	8.2 How does a fault seal?
	8.3 General tools for fault seal analysis
		8.3.1 2D juxtaposition and Allan maps
		8.3.2 Juxtaposition diagrams
	8.4 Fault sealing in siliciclastic rocks
		8.4.1 Clay smear
		8.4.2 Deformation bands
		8.4.3 Fault seal predicting algorithms
		8.4.4 Fault permeability from fault seal algorithms
		8.4.5 Clay injection and mechanical clay injection potential (MCIP)
		8.4.6 Assessing fault reactivation and seal breach risk
		8.4.7 Analogue and numerical experiments of fault clay smear
			8.4.7.1 Ring shear experiments
			8.4.7.2 Direct shear experiments
			8.4.7.3 Triaxial experiments
			8.4.7.4 Sandbox experiments
			8.4.7.5 Numerical simulations
	8.5 Fault sealing in carbonates
		8.5.1 Introduction
		8.5.2 Fault processes in low-porosity carbonates
			8.5.2.1 Outcrop observations
			8.5.2.2 Microstructures
		8.5.3 Faulting processes in high-porosity carbonates
			8.5.3.1 Outcrop observations
			8.5.3.2 Microstructures
		8.5.4 Carbonate faults cutting through heterogeneous stratigraphy
		8.5.5 Normal, thrust, and strike-slip fault architectures in carbonates
		8.5.6 Fault permeability, fluid circulation, and seal in carbonate hydrocarbon reservoirs
	8.6 Evaporites and fault seals
	8.7 Case studies of fault seal
		8.7.1 The Molasse Basin in Germany and the Rhenish Massif
		8.7.2 Inboard area of the Baram Delta Province, NW Borneo
		8.7.3 Clay smears in aquifers of the Lower Rhine Embayment
	References
Conclusions
	References
Index
	A
	B
	C
	D
	E
	F
	G
	H
	I
	J
	K
	L
	M
	N
	O
	P
	Q
	R
	S
	T
	U
	V
	W
	X
	Y
	Z
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