Orogenesis: The Making of Mountains

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Orogenesis: The Making of Mountains
Title
Copyright
Contents
Preface
Acknowledgments
1: Major features of the Earth and plate tectonics
Plate tectonics
Mid Ocean Rises
Plate boundaries
Magnetic anomalies
Lithospheric plates
Orogens and plate tectonics
Rheological control over continental break-up
Dewey and Bird classification of orogens
Ancient plates and orogeny
Major features of orogens
Orogenic deformation
Mechanisms of lithospheric thickening
Orogenic metamorphism
Further reading
2: Driving mechanisms for plates, slab retreat and advance, and a cause of orogenesis
Retreat and advance of subduction zones
Gravity differences as driving forces in orogeny
Applications of the Platt and England model
3: Physical and chemical principles: rock deformation, isostasy, geochronology and heat production in the lithosphere
Rock deformation
Coulomb fracture theory
Stress and strain
S- and L-tectonites
Rotational and non-rotational strain
Three-dimensional strain
Rheology
Controls of deformation
Temperature
Confining pressure
Strain rate
Fluids in rock deformation
Permeability and non-permeability of rocks
Enhanced pore fluid pressure
Effective stress
Fluids in earthquakes and in pathways in the crust
Seismic pumping and valves
Mechanisms of rock deformation
Transformation and reaction-enhanced ductility
Crystal plasticity
Diffusive mass transfer
Isostasy
Geochronology and thermochronology
Geotherms and thermal structure
Heat transfer in the lithosphere
Heat sources
Heat advection
Further reading
4: Large-scale features of orogens: thrusts and folds
Arcuation of orogens and oroclines
Physical properties of thrust faults
Doubly vergent orogens
Classification of thrusts
(a) Gravity gliding or spreading/flow models
(b) Extrusion of orogen-scale tectonic wedges
(c) Dislocation model
(d) 'Push-from-behind' model
Detachment
Time spans of thrusts
Thrust systems
Imbricates and duplexes
Modelling
Relationship between folds and thrusts
Displacement on thrusts
Restored sections
Thrust terminations
Transport direction in thrusting
Thrust mechanics
Orogenic wedge theory
Ductile thrusts
Internal strain in thrust sheets
Folds in shear zones
Rotation of thrust sheets about a vertical axis
Further reading
5: Evolution of orogens
The transition from passive margin to active margin
Collision belts
Mountain uplift
Symmetry and asymmetry in orogens
Strike-slip orogens
Uplift and collapse of mountains
Stages of collision
Collision belts
The Himalayan Karakoram and Tibetan orogen
Mechanics of shortening in the Himalaya
Indentation
Thrusting
The South Tibetan Detachment (STD)
Underthrusting in the Himalaya
Oroclines
The metamorphic evolution of the Himalaya
Karakoram
The Tibetan Plateau
Pre-Cenozoic thickening in Tibet?
Deep crustal flow
Differences between North and South Tibet
N–S grabens
Timing of Tibetan uplift
The Alps
Culminations and depressions
Internal zone
External zone
The North Alpine Foreland Basin
Jura mountains
The Hinterland
Evolution of the Alps
Ultra-high-pressure metamorphism
The depth of subduction
Underplating and the orogenic wedge
The current view on evolution
Continent–continent convergence after final closure of the ocean:the late movements in the Alps
Dextral strike-slip tectonics
Indentation tectonics?
Comparisons between the Alps and the Himalaya
Cordilleran belts: the North and South American Cordillera
Subduction of the Nazca plate
Volcanism
Sectors of the Andes
Control over the upper slab deformation by the convergence direction of South America and Nazca
Structural units and shortening in the Andean belt
Thick-skinned or thin-skinned thrusts?
Timing of crustal thickening
Neotectonics
High plateau
Deep structure of the Andes
The North American Cordillera
Collision tectonics?
Extensional tectonics
The Canadian Cordillera
Timing in orogeny
Oblique collision belts
Caledonides of the North Atlantic
Caledonides in North America
The British Caledonides
The Grampian orogeny
Obducted ophiolites
The Scandian orogeny: closure of Iapetus
Sinistral transpression during the Scandian orogeny
Kinematic indicators of strike-slip movements
Switch to orogen-parallel motion
Sinistral transtensional regime
Oblique collision in the Zagros
Intraplate tectonics
Further reading
6: Lateral spreading of orogens: foreland propagation, channel flow and weak zones in the crust
Cause of orogenic spreading
Orogenic collapse
Metamorphic core complexes
Channel flow
Extrusion and channel flow
Couette and Poiseuille flow
Driving force for channel flow
Channel flow and erosion
Low-viscosity layers in the crust
Tests for the channel flow model
Deep crustal flow in Tibet
Is channel flow a special case confined to the Himalaya?
Further reading
7: Metamorphism in orogeny
Introduction
General characterisation of metamorphism
Mapping metamorphism: from isograds to facies
Facies series, progressive metamorphism and evaluation of regional P-T variations
Early perspectives on metamorphism in relation to tectonics
Metamorphism and thermal modelling
Quantification of metamorphism: from mineral assemblages to P–T diagrams
Composition-assemblage diagrams and projections
Petrogenetic grids and Schreinemakers´ nets
Divariant and multivariant equilibria – from Schreinemakers´ nets to pseudosections
Geothermobarometry
Crustal melting and orogeny
Melting processes and temperature conditions
Migmatites and migmatite terrains
Partial melting, migmatites and the strength and behaviour of orogens
The P–T realm of metamorphism: the current view
Pressure-temperature (P–T) paths and pressure-temperature-time (P–T–t) paths
Blueschist-eclogite and UHP metamorphism
Background and P–T domain
Timescales of HP/UHP metamorphism and rates of exhumation
Models for UHP rock exhumation
Collision and medium P/T metamorphism: Barrovian type metamorphism
Barrovian facies series and the Himalayan case study
Barrovian collisional metamorphism and inverted zones: models for orogen development
Channel flow and Himalayan metamorphic zones: timing and P–T paths
Problems with channel flow as a model for the Himalayan metamorphism
Collision and medium P/T metamorphism: eclogite–high-pressure granulite (E-HPG)
Background and P–T domain
Pressure–temperature–time paths
Formation and exhumation of E-HPG metamorphic rocks
Bohemian Massif – rapid buoyancy-driven vertical extrusion of HPG?
Caledonian E-HPG in Norway and Greenland
The Grenville Province: heterogeneous ductile flow and exhumation of E-HPG rocks and deep orogen interiors
Low P/T metamorphism: granulite and UHT metamorphism in orogeny
Background and P–T domain (low P/T and UHT)
Pressure–temperature–time paths in G-UHT
Timescales of G-UHT metamorphism: orogenic and other settings
Hot orogens and G-UHT metamorphism
Gravitational spreading, core complexes and extensional metamorphism
Concluding remarks
8: The erosion and exhumation of mountains
Mountains as barriers
Examples of the linkage between tectonics and erosion
Dating the rates of exhumation and uplift in mountain belts
The mass balance within an orogen
Terminology
The measurement of the rate of exhumation
Orogenic history
Exhumation of the Alps
Exhumation of the Himalaya
Further reading
9: Sedimentary history of the foredeep basins
Isostasy and Bouguer anomalies
Loading the lithosphere
A classification of foreland basins
Foredeeps and advancing thrust sheets
Basin evolution
Isostatic adjustments in foredeeps
Thermochronology using detrital minerals
Exhumation of orogens
The exhumation and uplift of the Alps
Unroofing the Himalaya
Sediment budgets in SE Asia
10: Deep structure, mountain support and phase changes
Rock densities and isostasy
Support for the load of orogens
Geophysical studies in the Himalaya–Tibet
Recent geophysical work on the deep structure of Tibet
Receiver function analysis and shear wave splitting detect the deep structure
Phase changes in the deep structure
Eclogitisation and the 'weighting of orogens'
The Cz/lz ratio
Eclogitisation and exhumation and collapse in other orogens
The rapid phase change from granulite to eclogite facies and vice versa
Basement control, reactivation and reworking
Further reading
11: Mountains and climate
Monsoons
The significance of the Tibetan Plateau
Climate change in the Cenozoic
Evidence for global climate change in the late Miocene and Pliocene
How does the Tibetan Plateau disrupt global circulation?
A possible threshold height for the plateau
A causal relation between plateau uplift and mantle dynamics
When did the plateau attain its present elevation?
Weakening of the monsoon at 8 Ma – a counter-argument
Monsoon precipitation as a tectonic forcer
Monsoon controls erosion in the Himalaya
Himalayan uplift and the chemical composition of the oceans
The 87Sr/86Sr plot
Transport of calcium
Drawdown of CO2
Oxygen isotopes
Proposed link between the Himalaya and chemical erosion
Erosion in channel flow
Further reading
12: Secular change in orogeny
Secular change in heat production and the Earth´s thermal budget
Modelling the onset of subduction and its consequences
Secular change in metamorphism in orogenic belts
Accretion, amalgamation and collision from the Palaeoproterozoic to NeoArchaean
The Trans-Hudson Orogeny of Canada
The Lewisian of northwest Scotland
The Archaean Gneiss Complex of southwest Greenland
Weak lithospheres and 'ultrahot' orogens
Further reading
References
Index