Are dykes just filled hydraulic fractures? - Inelastic deformation and emplacement mechanisms of igneous tabular intrusions

2021 ◽  
Author(s):  
Olivier Galland ◽  
Tobias Schmiedel ◽  
Håvard Bertelsen ◽  
Frank Guldstrand ◽  
Øystein Haug ◽  
...  
Keyword(s):  
Host Rock ◽  
Inelastic Deformation ◽  
Shear Failure ◽  
Volcanic Eruptions ◽  
Common Mechanism ◽  
Hydraulic Fractures ◽  
Field Observations ◽  
First Order ◽  
Magma Emplacement ◽  
Inelastic Damage

<p>Igneous tabular (sheet) intrusions such as dykes, sills and cone sheets, are fundamental elements of volcanic plumbing systems, as they represent the dominant pathways for magma transport and the main feeders of volcanic eruptions. When magma is intruded in the Earth’s crust, it makes its space by pushing and breaking the host rock, which can result in intense inelastic damage and fracturing. To understandand quantify the distribution of such intrusion-induced deformation patterns<em> in the host rock</em> is thus essential to resolve magma emplacement dynamics.</p><p>Sheet intrusions with their low thickness-to-length aspect ratios, resemble fractures. Based on this resemblance, tabular intrusions have been expected to form like (hydraulic) fractures propagating as tensile cracks with sharp and pointy tips, and assuming purely elastic deformation of the host rock. Even if some field observations support this theory, there is growing evidence that other mechanisms, involving significant inelastic deformation of the host rock, accommodate dyke and sill emplacement.</p><p>This contributionprovidesa summary review onthe role of inelastic deformation on the emplacement of tabular intrusions. (1) Field observations show that intrusion tips can be rounded, blunt, and the host deformation accommodating their propagation exhibits inelastic, compressional deformation, in drastic contradiction with theoretical predictions. (2) 3D and 2D laboratory experimentsof magma emplacement in a cohesive Mohr-Coulomb crusthighlightthat magma-induced inelastic deformation, in the form of shear damage and faulting, are first-order transient mechanical precursors for the propagating magma. In addition, these experiments show that the cohesion and friction properties of the model host rock are first-order parameters controlling the formation of intrusions of various shapes, including dykes, plugs, cone sheets, sills and laccoliths. (3) Elasto-plastic numerical models highlight that shear failure is the dominant mechanism to accommodate intrusion growth as soon as heterogeneities are introduced. We conclude that heterogeneities within the host-rock may locally "seed" shear faults ahead of the magmatic intrusion in the propagating direction, in good agreement with field observations. Given that rocks are naturally heterogeneous at multiple scale, these models suggest that shear failure is likely to be a common mechanism for accommodating magma propagation.</p><p>Overall, our field observations andmodelresultsshow that the brittle Coulomb properties of rocks, and their heterogeneities,must be accounted for revealing the nature and distribution of fractures and inelastic damage accommodating the emplacement of igneous tabular intrusions.</p>

Forecasting the propagation paths of fluid-driven fractures, particularly dikes and inclined sheets

2020 ◽  
Author(s):  
Agust Gudmundsson ◽  
Kyriaki Drymoni ◽  
Mohsen Bazargan ◽  
Kayode Adeoye-Akinde
Keyword(s):  
Numerical Models ◽  
Volcanic Eruptions ◽  
Pyroclastic Flows ◽  
Propagation Path ◽  
Normal Faults ◽  
Hydraulic Fractures ◽  
Pure Mode ◽  
Field Observations ◽  
Least Action ◽  
Propagation Paths

<p>It is of great importance in many fields to be able to forecast the likely propagation paths of fluid-driven factures. These include mineral veins, human-made hydraulic fractures, and dikes/inclined sheets. The physical principles that control the propagation of all fluid-driven fractures are the same. Here the focus is on dikes and inclined sheets where the selected path determines whether, where, and when a particular dike/sheet reaches the surface to erupt. Here we provide analytical and numerical models on dike/sheet paths in crustal segments (including volcanoes) that include layers of various types (lava flows, pyroclastic flows, tuff layers, soil layers, etc) as well as mechanically weak contacts and faults. The modelling results are then compared with, and tested on, actual data of two types. (a) Seismic data on the paths of dikes/sheets as well as human-made hydraulic fractures, and (b) field data on the actual propagation paths of dikes/sheets in layered and faulted rocks</p><p>The numerical results show that, particularly in stratovolcanoes, the paths are likely to be complex with common deflections along layer contacts, in agreement with field observations.  Also, some dikes/sheets may use existing faults as parts of their paths, primarily steeply dipping and recently active normal faults. The propagation path is thus not entirely in pure mode I but rather partly in a mixed mode. The energy required to propagate the dike/sheet is mainly the surface energy needed to rupture the rock, to form two new surfaces and move them apart as the fracture propagates. The energy available to drive the fracture is the stored elastic energy in the hosting crustal segment.</p><p>From its point of initiation in the magma-chamber roof, a dike/sheet can, theoretically, select any one of an infinite number of paths to follow to its point of arrest or eruption. It is shown that the eventual path selected is the one of least action, that is, the path along which the time integral of the difference between the kinetic and potential energies is an extremum (normally a minimum) relative to all other possible paths with the same endpoints. If the kinetic energy is omitted, and there are no constraints, then least action becomes the minimum potential energy, which was postulated as a basis for understanding dike propagation by Gudmundsson (1986). Here it is shown how this theoretical framework can help us make reliable forecasts of dike/sheet paths and associated volcanic eruptions.</p><p>Gudmundsson, A., 1986. Formation of dykes, feeder-dykes, and the intrusion of dykes from magma chambers. Bulletin of Volcanology, 47, 537-550.</p><p>Gudmundsson, A., 2020. Volcanotectonics: Understanding the Structure, Deformation, and Dynamics of Volcanoes. Cambridge University Press, Cambridge.</p><p>Drymoni, K., Browning, J. Gudmundsson, A., 2020. Dyke-arrest scenarios in extensional regimes: insights from field observations and numerical models, Santorini, Greece. Journal of Volcanology and Geothermal Research (in press).</p><p> </p>

scholarly journals Pressure-dependent flow behavior of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass

2003 ◽  
Vol 18 (9) ◽  
pp. 2039-2049 ◽  
Author(s):  
Jun Lu ◽  
Guruswami Ravichandran
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Inelastic Deformation ◽  
Shear Failure ◽  
Flow Behavior ◽  
Shear Bands ◽  
Ductile Deformation ◽  
Multiaxial Compression ◽  
Dependent Flow ◽  
Tresca Criterion

An experimental study of the inelastic deformation of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5 under multiaxial compression using a confining sleeve technique is presented. In contrast to the catastrophic shear failure (brittle) in uniaxial compression, the metallic glass exhibited large inelastic deformation of more than 10% under confinement, demonstrating the nature of ductile deformation under constrained conditions in spite of the long-range disordered characteristic of the material. It was found that the metallic glass followed a pressure (p) dependent Tresca criterion τ = τ0 + βp, and the coefficient of the pressure dependence β was 0.17. Multiple parallel shear bands oriented at 45° to the loading direction were observed on the surfaces of the deformed specimens and were responsible for the overall inelastic deformation.

scholarly journals Kinetic Evidence of a Common Mechanism in the Oxidation by Chromium(vi) Complexes: Oxidation of Benzyl Alcohol

2000 ◽  
Vol 2000 (3) ◽  
pp. 114-115 ◽  
Author(s):  
Chockalingam Karunakaran ◽  
Sadasivam Suresh
Keyword(s):  
Acetic Acid ◽  
Benzyl Alcohol ◽  
Perchloric Acid ◽  
Mineral Acid ◽  
Common Mechanism ◽  
Aqueous Acetic Acid ◽  
First Order ◽  
Chromium Vi ◽  
Oxidation Of Benzyl Alcohol

The oxidation of benzyl alcohol by dichromate and seven chromium(VI) complexes in aqueous acetic acid in the presence of perchloric acid is first order each in the oxidants, the alcohol and the mineral acid. The oxidation conforms to the isokinetic and Exner relationships and follows a common mechanism.

Evaluation of Induced Thermal Pressurization in Clearwater Shale Caprock in Electromagnetic Steam-Assisted Gravity-Drainage Projects

SPE Journal ◽  
2013 ◽  
Vol 19 (03) ◽  
pp. 443-462 ◽  
Author(s):  
Sahar Ghannadi ◽  
Mazda Irani ◽  
Rick Chalaturnyk
Keyword(s):  
Pore Pressure ◽  
Analytical Solutions ◽  
Oil Sands ◽  
Shear Failure ◽  
Gravity Drainage ◽  
Hydraulic Fractures ◽  
Low Permeability ◽  
Steam Assisted Gravity Drainage ◽  
Thermal Pressurization ◽  
Shale Formation

Summary Inductive methods, such as electromagnetic steam-assisted gravity drainage (EM-SAGD), have been identified as technically and economically feasible recovery methods for shallow oil-sands reservoirs with overburdens of more than 30 m (Koolman et al. 2008). However, in EM-SAGD projects, the caprock overlying oil-sands reservoirs is also electromagnetically heated along with the bitumen reservoir. Because permeability is low in Alberta thermal-project caprock formations (i.e., the Clearwater shale formation in the Athabasca deposit and the Colorado shale formation in the Cold Lake deposit), the pore pressure resulting from the thermal expansion of pore fluids may not be balanced with the fluid loss caused by flow and the fluid-volume changes resulting from pore dilation. In extreme cases, the water boils, and the pore pressure increases dramatically as a result of the phase change in the water, which causes profound effective-stress reduction. After this condition is established, pore pressure increases can lead to shear failure of the caprock, the creation of microcracks and hydraulic fractures, and subsequent caprock integrity failure. It is typically believed that low-permeability caprocks impede the transmission of pore pressure from the reservoir, making them more resistant to shear failure (Collins 2005, 2007). In cases of induced thermal pressurization, low-permeability caprocks are not always more resistant. In this study, analytical solutions are obtained for temperature and pore-pressure rises caused by the constant EM heating rate of the caprock. These analytical solutions show that pore-pressure increases from EM heating depend on the permeability and compressibility of the caprock formation. For stiff or low-compressibility media, thermal pressurization can cause fluid pressures to approach hydrostatic pressure, and shear strength to approach zero for low-cohesive-strength units of the caprock (units of the caprock with high silt and sand percentage) and sections of the caprock with pre-existing fractures with no cohesion.

Linking thermomechanical models with geodetic observations to evaluate the 2018 eruption of Sierra Negra Volcano, Galápagos

2020 ◽  
Author(s):  
Patricia Gregg ◽  
Yan Zhan ◽  
Falk Amelung ◽  
Jack Albright ◽  
Dennis Geist ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Host Rock ◽  
Volcanic Eruptions ◽  
Magma Reservoir ◽  
Tensile Failure ◽  
Model Calculations ◽  
Coulomb Failure ◽  
Magma System ◽  
Sierra Negra Volcano ◽  
Sierra Negra

<p>Ensemble based data assimilation approaches, such as the Ensemble Kalman Filter (EnKF), have been widely and successfully implemented to combine observations with dynamic models to investigate the evolution of a system’s state. Such inversions are powerful tools for providing forecasts as well as “hindcasting” events such as volcanic eruptions to investigate source parameters and triggering mechanisms. In this study, a high performance computing (HPC) adaptation of the EnKF is used to assimilate ground deformation observations from interferometric synthetic-aperture radar (InSAR) into high-fidelity, multiphysics finite element models to evaluate the prolonged unrest and June 26, 2018 eruption of Sierra Negra volcano, Galápagos. The stability of the Sierra Negra magma system is evaluated at each time step by estimating variations in reservoir overpressure, Mohr-Coulomb failure in the host rock, and tensile stress and failure along the reservoir boundary. The deformation of Sierra Negra is tracked over a decade, during which almost 5 meters of surface uplift has been recorded. The EnKF reveals that the evolution of the stress state in the host rock surrounding the Sierra Negra magma reservoir likely controlled the timing of the eruption. While increases in magma reservoir overpressure remained modest (< 10 MPa) throughout the data assimilation time period, significant Mohr-Coulomb failure is indicated in the lead up to the eruption coincident with increased seismicity along both trapdoor faults within Sierra Negra’s caldera and along the caldera’s ring faults. During the final stages of pre-eruptive unrest, the EnKF models indicate limited tensile failure, with no tensile failure along the northern portion of the magma system where the eruption commenced. Most strikingly, model calculations of significant through-going Mohr-Coulomb failure correspond in space and time with a Mw 5.4 earthquake recorded in the hours preceding the 2018 eruption. Subsequent stress modeling implicates the Mw 5.4 earthquake along the southern intra-caldera trapdoor fault as the potential catalyst for tensile failure and dike initiation along the reservoir to the north. In conclusion, the volcano EnKF approach successfully tracked the evolving stability of Sierra Negra, indicating great potential for future forecasting efforts.</p>

Measuring host rock volume changes during magma emplacement: Reply

2000 ◽  
Vol 22 (4) ◽  
pp. 521-522
Author(s):  
Aaron S Yoshinobu ◽  
Gary H Girty
Keyword(s):  
Host Rock ◽  
Volume Changes ◽  
Magma Emplacement

scholarly journals Experimental multiblast craters and ejecta — seismo-acoustics, jet characteristics, craters, and ejecta deposits and implications for volcanic explosions

2022 ◽  
Author(s):  
Ingo Sonder ◽  
Alison Graettinger ◽  
Tracianne Neilsen ◽  
Robin Matoza ◽  
Jacopo Taddeucci ◽  
...  
Keyword(s):  
Seismic Energy ◽  
Volcanic Eruptions ◽  
Maximum Size ◽  
Seismic Signal ◽  
Energy Estimates ◽  
First Order ◽  
Blast Energy ◽  
Jet Characteristics ◽  
Volcanic Explosions ◽  
Explosion Depth

Blasting experiments were performed that investigate multiple explosions that occur in quick succession in the ground and their effects on host material and atmosphere. Such processes are known to occur during volcanic eruptions at various depths, lateral locations, and energies. The experiments follow a multi-instrument approach in order to observe phenomena in the atmosphere and in the ground, and measure the respective energy partitioning. The experiments show significant coupling of atmospheric (acoustic)- and ground (seismic) signal over a large range of (scaled)distances (30--330\m, 1--10\(\m\J^{-1/3}\)). The distribution of ejected material strongly depends on the sequence of how the explosions occur. The overall crater sizes are in the expected range of a maximum size for many explosions and a minimum for one explosion at a given lateral location. The experiments also show that peak atmospheric over-pressure decays exponentially with scaled depth at a rate of \bar{d}_0 = 6.47x10^{-4} mJ^{-1/3}; at a scaled explosion depth of \(4x10^{-3} mJ^{-1/3} ca. 1% of the blast energy is responsible for the formation of the atmospheric pressure pulse; at a more shallow scaled depth of 2.75x10^{-3 \mJ^{-1/3} this ratio lies at ca. 5.5–7.5%. A first order consideration of seismic energy estimates the sum of radiated airborne and seismic energy to be up to 20\% of blast energy.

Structural controls on the emplacement and evacuation of magma from a sub-volcanic laccolith: Reyðarártindur Laccolith, SE Iceland

2021 ◽  
Author(s):  
Vincent Twomey ◽  
William McCarthy ◽  
Craig Magee
Keyword(s):  
Host Rock ◽  
Surface Deformation ◽  
Flow Direction ◽  
Volcanic Eruptions ◽  
Magma Ascent ◽  
Magma Flow ◽  
Existing Structures ◽  
Forced Folding ◽  
Deformation Patterns ◽  
Echelon Fault

<p>Laccoliths play a significant role in the transport and storage of magma in sub-volcanic systems. The construction and geometry of laccoliths can influence host rock and surface deformation patterns that may precede and provide warning of active magmatism and impending eruptions. Yet how laccolith construction and internal magma dynamics controls the location and form of magma ascent conduits (e.g., dykes and inclined sheets), which facilitate magma evacuation and may feed volcanic eruptions, remains poorly documented in natural examples.</p><p>The excellently exposed silicic, sub-volcanic Miocene Reyðarártindur Laccolith in SE Iceland offers an opportunity to investigate how magma ascent within inclined sheets, which emanated from the laccolith, related to intrusion construction and deformation in the surrounding host rock. We combine detailed structural mapping with anisotropy of magnetic susceptibility (AMS) analyses, which allow us to map magnetic rock fabrics that reflect magma flow patterns, to show that the laccolith comprises of several distinct magma lobes that intruded laterally towards the south-west. Each lobe intruded, inflated, and coalesced along a NE-SW primary axis facilitated by doming (i.e., forced folding) of the host rock. We also shown that pre-existing NNE-striking, left-stepping, en-echelon fault/fractures, as well as those generated during intrusion-induced host rock uplift, host moderately to steeply inclined rhyolitic/granophyric sheets that emanate from the lateral terminations of some flow lobes.</p><p>Based on the observed geometrical relationships between AMS fabrics and the sheet margins where magnetic foliations subparallel sheet contacts, or characterize an imbrication fabric, we suggest that magma evacuated moderately to steeply upward via these fault/fracture-controlled sheets. As these inclined sheets dip towards the laccolith, any eruptions they may have fed would have been laterally offset from the laccolith and any overlying surface deformation driven by forced folding. Our study shows that magma evacuation and ascent from laccoliths can be facilitated by inclined sheets that form at the lateral terminations of magma lobes that are spatially controlled by laccolith construction (e.g., flow direction and doming of the host rock) and the presence of pre-existing structures.</p>

scholarly journals Mechanisms of overburden deformation associated with the emplacement of the Tulipan sill, mid-Norwegian margin

2017 ◽  
Vol 5 (3) ◽  
pp. SK23-SK38 ◽  
Author(s):  
Tobias Schmiedel ◽  
Sigurd Kjoberg ◽  
Sverre Planke ◽  
Craig Magee ◽  
Olivier Galland ◽  
...  
Keyword(s):  
Host Rock ◽  
Shear Failure ◽  
Sedimentary Basins ◽  
Rock Deformation ◽  
3D Seismic ◽  
Elastic Bending ◽  
Hydrocarbon Maturation ◽  
Dome Structure ◽  
Well Data ◽  
Host Rocks

The emplacement of igneous intrusions into sedimentary basins mechanically deforms the host rocks and causes hydrocarbon maturation. Existing models of host-rock deformation are investigated using high-quality 3D seismic and industry well data in the western Møre Basin offshore mid-Norway. The models include synemplacement (e.g., elastic bending-related active uplift and volume reduction of metamorphic aureoles) and postemplacement (e.g., differential compaction) mechanisms. We use the seismic interpretations of five horizons in the Cretaceous-Paleogene sequence (Springar, Tang, and Tare Formations) to analyze the host rock deformation induced by the emplacement of the underlying saucer-shaped Tulipan sill. The results show that the sill, emplaced between 55.8 and 54.9 Ma, is responsible for the overlying dome structure observed in the seismic data. Isochron maps of the deformed sediments, as well as deformation of the younger postemplacement sediments, document a good match between the spatial distribution of the dome and the periphery of the sill. The thickness [Formula: see text] of the Tulipan is less than 100 m, whereas the amplitude [Formula: see text] of the overlying dome ranges between 30 and 70 m. Spectral decomposition maps highlight the distribution of fractures in the upper part of the dome. These fractures are observed in between hydrothermal vent complexes in the outer parts of the dome structure. The 3D seismic horizon interpretation and volume rendering visualization of the Tulipan sill reveal fingers and an overall saucer-shaped geometry. We conclude that a combination of different mechanisms of overburden deformation, including (1) elastic bending, (2) shear failure, and (3) differential compaction, is responsible for the synemplacement formation and the postemplacement modification of the observed dome structure in the Tulipan area.

Satellite and ground-based magnetic field observations related to volcanic eruptions

2020 ◽  
Author(s):  
Konrad Schwingenschuh ◽  
Werner Magnes ◽  
Xuhui Shen ◽  
Jindong Wang ◽  
Bingjun Cheng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Volcanic Eruptions ◽  
Low Earth Orbit ◽  
Propagation Path ◽  
Satellite Orbits ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Coupling Mechanism ◽  
Field Observations ◽  
Total Electron

<p>In this study we investigate volcanic eruption phenomena related to ionospheric disturbances, e.g. Heki (2006) used total electron content (TEC) measurements for this task. In particular, a model is developed how discharge phenomena (e.g. Houghton etal, 2013) can produce magnetic field variations at SWARM and CSES satellite orbits, i.e. altitudes of ~500 km in the F-region. Several coupling mechanism between lithosphere, atmosphere, and ionosphere are discussed by Simões etal (2012).<br>Experimental evidence is based on magnetic field observations aboard CSES mission in the time frame July 2018 to January 2019. The theoretical considerations include the source mechanism, propagation path, and the signal strength at low earth orbit satellite altitude.</p><p>Ref:<br>(1) Heki, K., Explosion energy of the 2004 eruption of the Asama Volcano, central Japan, inferred from ionospheric disturbances, GRL, 33, L14303, 2006. doi:10.1029/2006GL026249<br>(2) Houghton, I. M. P., K. L. Aplin, and K. A. Nicoll, Triboelectric Charging of Volcanic Ash from the 2011 Grı́msvötn Eruption, PRL, 111, 118501, 2013. doi:10.1103/PhysRevLett.111.118501 arXiv:1304.1784<br>(3) Simões F., R. Pfaff, J.-J. Berthelier, J. Klenzing, A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms, SSR, 168:551–593, 2012. doi:10.1007/s11214-011-9854-0</p>

Sign in / Sign up

Export Citation Format

Share Document