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Author: Michael Zackery McIntire Publisher: ISBN: Category : Languages : en Pages : 118
Book Description
Magmas are dynamic hydrogranular systems where the interactions between the melt and the residing crystals influences the eruptive behavior of volcanoes, the concentration of economic metals, and the stratification of the Earth's crust. Despite the importance of the interaction between these phases, little is known about the mechanics of these systems. The purpose of this dissertation is to investigate the interactions of the melt and crystals of magma from the formation of the crystal-rich mush to the expulsion of the melt from its interstitial spaces. I first examine the dilute case where suspended crystals are coupled to the fluid. I employed a combination of discrete element computational fluid dynamic (DEM-CFD) numerical simulations, field observations, and electron backscatter diffraction (EBSD) analyses to explore the mechanics of the interactions between the crystals and the melt of magmas. The formation of crystal clusters was explored using Voronoi tessellations in both a settling only model at a solid volume percent of 9 and an open system models (where a magma like fluid is injected into the accumulating mush) with solid volume percents of 1, 9, and 20. I find that there is statistically no difference in the distribution of clustering between the two systems and that clusters are just as likely as a random distribution. Indicating that abundant crystal clusters found in sampled magmatic systems are likely from a disaggregated magma mush. Next, I examined the crystal-rich state where the formation of granular flows transfer momentum to the resident fluid. I employed a DEM-CFD numerical dam break model of a polydisperse particle column to explore the kinematics of the collapse and runout of the particle column. The column develops two collapse regimes a toppling collapse, and a sliding collapse, which transition into three kinematic runout regimes, gravity current, heap flow, and a quasi-static region. Both a force and contact fabric develop in the heap flow where the particles have enduring contacts. The difference in anisotropy between the normal force and contact fabrics illustrates the non-affine nature of granular material and the issue with applying the concepts of continuum modelling to hydrogranular systems. The first two chapters were based on numerical models analyses to create an idealized framework of knowledge on hydrogranular systems. The final chapter builds on geological observations and fieldwork with a goal of determining the mechanisms of pore space reduction in a crystal-rich magma mush. I collected 12 samples from the mafic complex of Sierra Valle Fértil from which I conducted EBSD analyses to quantify the crystallographic preferred orientation (CPO) and the internal lattice distortions. I considered the evidence for tectonic filter pressing, mechanical compaction, and viscous compaction. The internal lattice distortions have a similar distribution across plagioclase, hornblende, and quartz. This suggests the crystal deformation happened subsolidus and was not caused by either viscous compaction or tectonic filter pressing, and that a mechanical compaction process was responsible for pore space reduction. Future work should focus on the physics of hydrogranular systems with non-spherical particles employing analogue and numerical models to better capture natural systems.
Author: Michael Zackery McIntire Publisher: ISBN: Category : Languages : en Pages : 118
Book Description
Magmas are dynamic hydrogranular systems where the interactions between the melt and the residing crystals influences the eruptive behavior of volcanoes, the concentration of economic metals, and the stratification of the Earth's crust. Despite the importance of the interaction between these phases, little is known about the mechanics of these systems. The purpose of this dissertation is to investigate the interactions of the melt and crystals of magma from the formation of the crystal-rich mush to the expulsion of the melt from its interstitial spaces. I first examine the dilute case where suspended crystals are coupled to the fluid. I employed a combination of discrete element computational fluid dynamic (DEM-CFD) numerical simulations, field observations, and electron backscatter diffraction (EBSD) analyses to explore the mechanics of the interactions between the crystals and the melt of magmas. The formation of crystal clusters was explored using Voronoi tessellations in both a settling only model at a solid volume percent of 9 and an open system models (where a magma like fluid is injected into the accumulating mush) with solid volume percents of 1, 9, and 20. I find that there is statistically no difference in the distribution of clustering between the two systems and that clusters are just as likely as a random distribution. Indicating that abundant crystal clusters found in sampled magmatic systems are likely from a disaggregated magma mush. Next, I examined the crystal-rich state where the formation of granular flows transfer momentum to the resident fluid. I employed a DEM-CFD numerical dam break model of a polydisperse particle column to explore the kinematics of the collapse and runout of the particle column. The column develops two collapse regimes a toppling collapse, and a sliding collapse, which transition into three kinematic runout regimes, gravity current, heap flow, and a quasi-static region. Both a force and contact fabric develop in the heap flow where the particles have enduring contacts. The difference in anisotropy between the normal force and contact fabrics illustrates the non-affine nature of granular material and the issue with applying the concepts of continuum modelling to hydrogranular systems. The first two chapters were based on numerical models analyses to create an idealized framework of knowledge on hydrogranular systems. The final chapter builds on geological observations and fieldwork with a goal of determining the mechanisms of pore space reduction in a crystal-rich magma mush. I collected 12 samples from the mafic complex of Sierra Valle Fértil from which I conducted EBSD analyses to quantify the crystallographic preferred orientation (CPO) and the internal lattice distortions. I considered the evidence for tectonic filter pressing, mechanical compaction, and viscous compaction. The internal lattice distortions have a similar distribution across plagioclase, hornblende, and quartz. This suggests the crystal deformation happened subsolidus and was not caused by either viscous compaction or tectonic filter pressing, and that a mechanical compaction process was responsible for pore space reduction. Future work should focus on the physics of hydrogranular systems with non-spherical particles employing analogue and numerical models to better capture natural systems.
Author: Francesco Vetere Publisher: John Wiley & Sons ISBN: 1119521130 Category : Science Languages : en Pages : 224
Book Description
Explores the complex physico-chemical processes involved in active volcanism and dynamic magmatism Understanding the magmatic processes responsible for the chemical and textural signatures of volcanic products and igneous rocks is crucial for monitoring, forecasting, and mitigating the impacts of volcanic activity. Dynamic Magma Evolution is a compilation of recent geochemical, petrological, physical, and thermodynamic studies. It combines field research, experimental results, theoretical approaches, unconventional and novel techniques, and computational modeling to present the latest developments in the field. Volume highlights include: Crystallization and degassing processes in magmatic environments Bubble and mineral nucleation and growth induced by cooling and decompression Kinetic processes during magma ascent to the surface Magma mixing, mingling, and recharge dynamics Geo-speedometer measurement of volcanic events Changes in magma rheology induced by mineral and volatile content The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Author: Anastassia Borisova Publisher: Frontiers Media SA ISBN: 2832552994 Category : Science Languages : en Pages : 208
Book Description
During transport, a percolating melt or magma may contact rock or a magmatic mush, resulting in inevitable interactions that may be described as magma/melt-rock or magma/melt-mush interactions. Examples of these types of interactions include mantle metasomatism, mineral-melt reaction in the mantle, mineral dissolution in magma, crustal wallrock partial melting, and thermal remobilization of preexisting mushy magma (rejuvenation of mush) by intruding high specific enthalpy magma. This spectrum of processes plays a major role in the composition, thickness, and age of the mantle lithosphere and its associated crust. These interactions also impact the asthenosphere because melts that form in the deepest parts of the mantle may ascend and interact with shallower mantle during transport.
Author: Bernard Charlier Publisher: Springer ISBN: 9401796521 Category : Science Languages : en Pages : 749
Book Description
This edited work contains the most recent advances related to the study of layered intrusions and cumulate rocks formation. The first part of this book presents reviews and new views of processes producing the textural, mineralogical and geochemical characteristics of layered igneous rocks. The second part summarizes progress in the study of selected layered intrusions and their ore deposits from different parts of the world including Canada, Southwest China, Greenland and South Africa. Thirty experts have contributed to this update on recent research on Layered Intrusions. This highly informative book will provide insight for researchers with an interest in geology, igneous petrology, geochemistry and mineral resources.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A number of recent papers by Bachmann and co-authors investigate a hypothesis that the catastrophic eruption of large-volume, crystal-rich silicic magmas is a consequence of reheating (so-called rejuvenation) and overturn of partially molten, buoyant silicic material by repeated injection of dense, hot mafic magma. In support of this model, we analyse an extensive suite of kinematic indicators for the buoyant overturn of silicic crystal mush layers of the Coastal Maine Magmatic Province, apparently in response to the injection and cooling of hot, dense mafic magmas. We use spectral analysis, microtextural analysis and scaling theory to identify, characterise and understand the length-scales of deformation along sharp interfaces separating mafic and silicic intrusive layers, from the scale of individual crystals (~1 cm) to in excess of the mafic layer thickness (>100 m). Deformations at the largest scale lengths are comparable to the silicic layer thickness, consistent with Rayleigh-Taylor theory, and support a conjecture that mafic recharge can cause large-scale overturning of silicic magma chambers. By contrast, deformations at the scale of crystals probably record buoyancy effects related to melt percolation and intermediate scales are explained by compaction. The evolution of rejuvenation is investigated and a condition for large-scale overturn of the chamber is proposed. This work provides the first field-based confirmation of the rejuvenation-overturn hypothesis. Additional laboratory experiments addressing the overturn of a particle-rich buoyant fluid layer overlain by a denser fluid layer are outlined in Appendix C.
Author: D.E. James Publisher: Springer Science & Business Media ISBN: 0442243669 Category : Science Languages : en Pages : 1299
Book Description
Consisting of more than 150 articles written by leading experts, this authoritative reference encompasses the entire field of solid-earth geophysics. It describes in detail the state of current knowledge, including advanced instrumentation and techniques, and focuses on important areas of exploration geophysics. It also offers clear and complete coverage of seismology, geodesy, gravimetry, magnetotellurics and related areas in the adjacent disciplines of physics, geology, oceanography and space science.
Author: Michael P. Ryan Publisher: Academic Press ISBN: 0080959911 Category : Science Languages : en Pages : 427
Book Description
With its integrated and cohesive coverage of the current research, Magmatic Systems skillfully explores the physical processes, mechanics, and dynamics of volcanism. The text utilizes a synthesized perspective--theoretical, experimental, and observational--to address the powerful regulatory mechanisms controlling the movement of melts and cooling, with emphasis on mantle plumes, mid-ocean ridges, and intraplate magmatism. Further coverage of subduction zone magmatism includes:Fluid mechanics of mixed magma migrationInternal structure of active systemsGrain-scale melt flowRheology of partial meltsNumerical simulation of porous media melt migrationNonlinear (chaotic and fractal) processes in magma transportIn all, Magmatic Systems will prove invaluable reading to those in search of an interdisciplinary perspective on this active topic. Key Features* Fluid mechanics of magma migration from surface region to eruption site* Internal structure of active magmatic systems* Grain-scale melt flow in mantle plumes and beneath mid-ocean ridges* Physics of magmatic systems and magma dynamics
Author: Joachim Gottsmann Publisher: Springer ISBN: 331958412X Category : Nature Languages : en Pages : 313
Book Description
This open access book summarizes the findings of the VUELCO project, a multi-disciplinary and cross-boundary research funded by the European Commission's 7th framework program. It comprises four broad topics: 1. The global significance of volcanic unrest 2. Geophysical and geochemical fingerprints of unrest and precursory activity 3. Magma dynamics leading to unrest phenomena 4. Bridging the gap between science and decision-making Volcanic unrest is a complex multi-hazard phenomenon. The fact that unrest may, or may not lead to an imminent eruption contributes significant uncertainty to short-term volcanic hazard and risk assessment. Although it is reasonable to assume that all eruptions are associated with precursory activity of some sort, the understanding of the causative links between subsurface processes, resulting unrest signals and imminent eruption is incomplete. When a volcano evolves from dormancy into a phase of unrest, important scientific, political and social questions need to be addressed. This book is aimed at graduate students, researchers of volcanic phenomena, professionals in volcanic hazard and risk assessment, observatory personnel, as well as emergency managers who wish to learn about the complex nature of volcanic unrest and how to utilize new findings to deal with unrest phenomena at scientific and emergency managing levels. This book is open access under a CC BY license.