Crustal Architecture And Magma Dynamics In A Large Continental Magmatic System
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Crustal Architecture And Magma Dynamics In A Large Continental Magmatic System
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Author : Dale H. Burns
language : en
Publisher:
Release Date : 2014
Crustal Architecture And Magma Dynamics In A Large Continental Magmatic System written by Dale H. Burns and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Ignimbrite categories.
The ~1 Myr history of the Purico-Chascon volcanic complex (PCVC) records significant changes in the production and storage of magmas in the crust. At ~1 Ma activity at the PCVC initiated with the eruption of a large 80-100 km3 crystal-rich dacite ignimbrite with restricted whole rock 87Sr/86Sr isotope ratios between 0.7085-0.7090. In-situ analyses of plagioclase from the Purico ignimbrite have 87Sr/86Sr=0.7087-0.7090. The dacite magma accumulated and evolved at relatively low temperatures around 800-850 °C in the upper crust at 4-8 km depth. Minor andesite and rhyolite pumice late in the sequence have similar restricted whole rock 87Sr/86Sr=0.7089-0.7091. The radiogenic isotopes of this 0.98 Ma activity are consistent with all these compositions resulting from 50 to 70% crustal assimilation by parental Central Andean "baseline" magmas at depths between 15-30 km. The final eruptions at the PCVC occurred 0.18 Ma producing three small 5 km3 crystal-rich dacite lava domes with whole rock 87Sr/86Sr ratios 0.7075 to 0.7081 containing abundant basaltic-andesite enclaves with whole rock 87Sr/86Sr ratios of 0.7057- 0.7061. Plagioclase and amphibole from samples from the largest of these domes, Cerro Chascon, record two distinct magmatic environments; an upper crustal environment identical to the Purico ignimbrite and a second deeper, ~15-20 km depth, higher temperature (~922-1001 °C) environment consistent with conditions recorded in the basaltic andesite enclaves. Accordingly, plagioclase cores in the host dacite lava and enclaves have enriched in-situ 87Sr/86Sr isotopic compositions of 0.7083 to 0.7095 while plagioclase rims and microphenocrysts in the enclaves have 87Sr/86Sr isotope ratios from 0.7057 to 0.7065 and 0.7062 to 0.7064 respectively. Lavas from Cerro Chascon also contain abundant Fo82 olivine with spinel and basaltic melt inclusions that crystallized in a deep crustal environment (1250 °C) consistent with a lower crustal MASH zone. The high baseline isotopic ratios observed in bulk rock and plagioclase crystals from Cerro Chascon (0.7057-0.7065) are consistent with MASH processes. The evolution of the PCVC is a microcosm of the Andean arc in this region where, from 10 - 1 Ma, dominantly dacitic upper crustal magmatism of the Altiplano-Puna Volcanic Complex ignimbrite flare-up persisted until ~1 Ma, when smaller volume, more heterogeneous and less isotopically enriched basaltic andesite to dacite composite volcanoes signal a return to steady state arc volcanism. I suggest that the PCVC captures the transition of the Andean arc from flare-up to steady state. The temporal trend at the PCVC is consistent with a waning thermal flux. High magmatic fluxes during the flare-up would have resulted in elevated geothermal gradients and efficient crustal processing leading to a dominantly dacitic upper crust (0 to 35 km) that fed the large volume Purico ignimbrite. As magmatic flux and thermal energy wanes, crustal isotherms relax resulting in greater thermal contrast between parental magmas, crust and remnant upper crustal dacite magma. This manifests in more heterogeneity and the survival of less isotopically enriched magmas in the upper crust. These arc scale magma dynamics are recorded even at the intra-crystalline scale. Individual crystals from Cerro Chascon also record vital information on the crystallization and evolution of mantle-derived magmas in continental magmatic arcs. Fo2 olivine, olivine hosted spinel, and basaltic melt inclusions record the crystallization of olivine at1250 °C in conditions consistent with a lower crustal (~70 km depth) MASH zone. Another significant crystallization event appears to have occurred at ~20 km depth, characterized by the crystallization of high An plagioclase (An--24) at ~1100-1050 °C followed by high-Al amphibole (~12-15 wt.% Al2O3) at ~1000-950 °C. The appearance of amphibole on the liquidus appears to have resulted from a nearly 2-fold increase in melt water content following ~45% crystallization of high An plagioclase. Following this extensive crystallization the highly crystalline mafic magma ascended into the upper crust and interacted with the remnant crystal mush from the Purico ignimbrite magma reservoir. Low An plagioclase (An3955), low Al amphibole (~6-9 wt.% Al2O3), sanidine, and biotite retain the chemical composition of the Purico ignimbrite magma, whereas, olivine, high An plagioclase, and high Al amphibole record the mafic recharge magma. The textures and compositions observed in Cerro Chascon are common in both continental and oceanic magmatic arcs worldwide and I propose that multiple crystallization events and upper crustal assimilation are fundamental processes intrinsic to arc magmatism. I have also used in situ 87Sr/86Sr isotope ratios in plagioclase from andesite, dacite, and rhyolite pumice from the ~1 Ma Purico ignimbrite to determine the cause for compositional zoning in the Purico ignimbrite magma reservoir. Andesite pumice contains two texturally, compositionally, and isotopically distinct types of plagioclase, small (500 [micro]m) subhedral to euhedral crystals with high MgO (130-490 ppm) and low 87Sr/86r crystals (0.7076-0.7084) record a hot (900 °C) andesite magma derived from an ~20 km deep magma reservoir. In contrast, the second type of plagioclase in the andesite appear to broken fragments of larger crystals and have significantly lower MgO (90-240 ppm), higher 87Sr/86Sr (0.7096-0.7114), and appears to be derived from the lower temperature (crystallized at ~800-900 °C), upper crustal (10 km) plutonic basement. Dacite pumice also contains two texturally and compositionally distinct types of plagioclase. However, both types have very restricted MgO (b.d.l.-200 ppm) and 87Sr/86Sr (0.7085-0.7095) ratios and appear to have grown at ~850°C. These crystals are also significantly larger (1000 [micro]m) than plagioclase from the andesite pumice and have clear euhedral rims. Rhyolite pumice from the Purico ignimbrite also contains distinct types of plagioclase. Both types of plagioclase are similar in size (
Crustal Magmatic System Evolution
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Author : Matteo Masotta
language : en
Publisher: John Wiley & Sons
Release Date : 2021-07-07
Crustal Magmatic System Evolution written by Matteo Masotta and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-07-07 with Science categories.
A comprehensive picture of the architecture of crustal magmatic systems The composition of igneous rocks – their minerals, melts, and fluids – reveals the physical and chemical conditions under which magmas form, evolve, interact, and move from the Earth’s mantle through the crust. These magma dynamics affect processes on the surface including crustal growth and eruptive behaviour of volcanoes. Crustal Magmatic System Evolution: Anatomy, Architecture, and Physico-Chemical Processes uses analytical, experimental, and numerical approaches to explore the diversity of crustal processes from magma differentiation and assimilation to eruption at the surface. Volume highlights include: Physical and chemical parameterization of crustal magmatic systems Experimental, theoretical and modelling approaches targeting crustal magmatic processes Timescales of crustal magmatic processes, including storage, recharge, and ascent through volcanic conduits 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. Find out more about this book in a Q&A with the Editors.
Magma Dynamics And Evolution In Continental Arcs
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Author : Stephanie B. Grocke
language : en
Publisher:
Release Date : 2014
Magma Dynamics And Evolution In Continental Arcs written by Stephanie B. Grocke and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Magmas categories.
Constraining the magma evolution and dynamics that lead to the eruption of large volume continental arc systems is fundamental to our understanding of continental crust formation. An investigation into the magmagenesis that results in the formation of the Central Volcanic Zone (CVZ) in the Andes of South America, situated atop overthickened continental crust (80 km thick), provides insights into large volume silicic magma reservoirs and how they evolve prior to their potentially catastrophic explosive eruption on the Earth's surface. A focused case study of the Cerro Guacha Caldera Complex (CGCC), a nested volcanic system in the Altiplano-Puna Volcanic Complex of SW Bolivia, puts constraints on the progressive stages of development of the magmatic underpinnings of the caldera complex. Whole rock data, in conjunction with matrix glass, mineral compositions and melt inclusions, are used to infer processes that gave rise to the formation of the Guacha II Caldera, the younger of two main collapse features, formed from the supereruption of the Tara Ignimbrite (800 km3 DRE) at 3.49 ± 0.01 Ma. The eruptive history of the Guacha II Caldera from pre-caldera to post-caldera is fully represented, allowing magma dynamics associated with a complete caldera cycle, from pre-climactic (catastrophic caldera-forming) magma accumulation through to post-climactic effusions that are part of the resurgent history of the caldera, to be examined. Analysis of the high-K, calcalkaline suite of andesite to high Si-rhyolite Tara pyroclastic deposits provides insights into the storage conditions and magma dynamics leading up to a supervolcanic eruption. The Tara eruptive products define a liquid line of descent from the basal andesite lava (62 wt % SiO2) to the high-silica rhyolite post-collapse Chajnantor Dome lava (78 wt.% SiO2), with major and trace element trends consistent with fractionation of quartz, plagioclase, orthopyroxene, hornblende, sanidine, biotite, and Fe-Ti oxides. Isotope ratios span a significant range in 87Sr/86Sr (0.709 to 0.713) and a relatively narrow range in 143Nd/144Nd (0.512179 to 0.512297) and [delta]18O[subscript (qtz)] (+8.68 to +8.43[per mil]). These data require AFC processes to explain both the isotope and trace element compositions in the Tara magmas. Geothermobarometry reveals pre-eruptive temperatures (~800 - 950 °C), pressures (~200 MPa), and H2O contents (~5 wt%) that suggest storage of a large-volume rhyodacite magma reservoir between 5 and 9 km depth in the upper crust. Analyses of quartz-hosted melt inclusions from pumices in the climactic plinian and ignimbrite phase of eruption reveal that pre-eruptive H2O contents in the plinian pumice overlap with those in the ignimbrite pumice (2.2 to 6.0 and 2.1 to 5.4 wt.% H2O, respectively). The ignimbrite magma, however, contains higher CO2 (630 versus
Magmatic Systems
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Author : Michael P. Ryan
language : en
Publisher: Academic Press
Release Date : 1994-08-26
Magmatic Systems written by Michael P. Ryan and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994-08-26 with Science categories.
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 migration Internal structure of active systems Grain-scale melt flow Rheology of partial melts Numerical simulation of porous media melt migration Nonlinear (chaotic and fractal) processes in magma transport In 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
Dynamics Of Crustal Magma Transfer Storage And Differentiation
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Author : Catherine Annen
language : en
Publisher: Geological Society of London
Release Date : 2008
Dynamics Of Crustal Magma Transfer Storage And Differentiation written by Catherine Annen and has been published by Geological Society of London this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Science categories.
Magmas are subject to a series of processes that lead to their differentiation during transfer through and storage within the Earth's crust. The depths and mechanisms of differentiation, the crustal contribution to magma generation through wall-rock assimilation, the rates and timescales of magma generation, transfer and storage, and how these link to the thermal state of the crust are subject to vivid debate and controversy. This volume presents a collection of research articles that provide a balanced overview of the diverse approaches available to elucidate these topics, and includes both theoretical models and case studies. By integrating petrological, geochemical and geophysical approaches, it provides new insights to the subject of magmatic processes operating within the Earth's crust, and reveals important links between subsurface processes and volcanism.
Dynamic Magma Evolution
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Author : Francesco Vetere
language : en
Publisher: John Wiley & Sons
Release Date : 2021-01-07
Dynamic Magma Evolution written by Francesco Vetere and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-01-07 with Science categories.
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.
Himalaya Dynamics Of A Giant Tectonic Units And Structure Of The Himalaya
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Author : Rodolphe Cattin
language : en
Publisher: John Wiley & Sons
Release Date : 2023-08-29
Himalaya Dynamics Of A Giant Tectonic Units And Structure Of The Himalaya written by Rodolphe Cattin and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-08-29 with Science categories.
Physical Geology Of High Level Magmatic Systems
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Author : Christoph Breitkreuz
language : en
Publisher: Geological Society of London
Release Date : 2004
Physical Geology Of High Level Magmatic Systems written by Christoph Breitkreuz and has been published by Geological Society of London this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Science categories.
European geologists, many from former Soviet bloc countries, present 14 studies they delivered at an October 2002 workshop in Freiberg, Germany on the physical geology of sub-volcanic systems. The subject has not been so thoroughly examined since 1970, they say, and could be of interest to igneous petrologists, volcanologists, structural geologists
Structure And Emplacement Of High Level Magmatic Systems
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Author : Kenneth Thomson
language : en
Publisher: Geological Society of London
Release Date : 2008
Structure And Emplacement Of High Level Magmatic Systems written by Kenneth Thomson and has been published by Geological Society of London this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Science categories.
There are continual rounds of annual conferences, special sessions and other symposia that provide ample opportunity for researchers to convene and discuss igneous processes. However, the origin of laccoliths and sills continue to inspire and confound geologists. In one sense, this is surprising. After all, don't we know all we need to know about these rocks by now? As testified by the diverse range of topics covered in this volume, the answer is clearly 'no'. This book contains contributions on physical geology, igneous petrology, volcanology, structural geology, crustal mechanics and geophysics that cover the entire gambit of geological processes associated with the shallow emplacement of magma. High-level intrusions in sedimentary basins can also act as hydrocarbon reservoirs and as sources for thermal maturation. In drawing together a diversity of perspectives on the emplacement of sills, laccoliths and dykes we hope to advance further our understanding of their behaviour.
Chemical Physical And Temporal Evolution Of Magmatic Systems
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Author : L. Caricchi
language : en
Publisher: Geological Society of London
Release Date : 2015-11-06
Chemical Physical And Temporal Evolution Of Magmatic Systems written by L. Caricchi and has been published by Geological Society of London this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-11-06 with Science categories.
Our understanding of the physical and chemical processes that regulate the evolution of magmatic systems has improved tremendously since the foundations were laid down 100 years ago by Bowen. The concept of crustal magma chambers has progressively evolved from molten-rock vats to thermally, chemically and physically heterogeneous reservoirs that are kept active by the periodic injection of magma. This new model, while more complex, provides a better framework to interpret volcanic activity and decipher the information contained in intrusive and extrusive rocks. Igneous and metamorphic petrology, geochemistry, geochronology, and numerical modelling, all contributed towards this new picture of crustal magmatic systems. This book provides an overview of the wide range of approaches that can nowadays be used to understand the chemical, physical and temporal evolution of magmatic and volcanic systems.