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Littérature scientifique sur le sujet « Formation de caldeira »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 8 février 2022

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Articles de revues sur le sujet "Formation de caldeira"

Madeira, José, A. M. Monge Soares, António Brum Da Silveira et António Serralheiro. « Radiocarbon Dating Recent Volcanic Activity on Faial Island (Azores) ». Radiocarbon 37, n^o 2 (1995) : 139–47. http://dx.doi.org/10.1017/s0033822200030575.

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Recent fieldwork on the island of Faial (Azores) led to the establishment of a detailed volcanic stratigraphic sequence, which is composed of five main geological formations. One of them, the Caldeira Formation, comprising mainly pumice fall and flow deposits, was judged to be Holocene in age. Organic materials were found preserved in or below some of the pyroclastic deposits from this formation. Wood, charcoal, peat and soil samples were radiocarbon dated, permitting correlation of deposits from different sequences and the establishment of a chronological framework for the Caldeira volcanic activity. These materials yielded ages from ca. 10–1 ka bp. The average dormant interval in the Caldeira pyroclastic activity from 4–1 ka ago is ca. 400 yr, with eruptions approximately every 200–800 yr. This frequency of activity indicates that the Caldeira volcano is an active, dangerous structure that should be closely monitored.

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Ivlev, Boris I. « On formation of long-living states ». Canadian Journal of Physics 94, n^o 12 (décembre 2016) : 1253–58. http://dx.doi.org/10.1139/cjp-2016-0227.

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The motion of a particle in a potential well is studied when the particle is attached to an infinite elastic string. This is generic with the problem of dissipative quantum mechanics investigated by Caldeira and Leggett (Ann. Phys. 149, 374 (1983). doi: 10.1016/0003-4916(83)90202-6 ). Besides the dissipative motion there is another scenario of interaction of the string with the particle attached. Stationary particle–string states exist with string deformations accompanying the particle. This is like polaronic states in solids. Our polaronic states in the well are non-decaying and have a continuous energy spectrum. These states may have a link to quantum electrodynamics.

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Legendre*, Christelle, René C. Maury, Hervé Guillou, Joseph Cotten, Martial Caroff, Sylvain Blais et Gérard Guille. « Geological and petrologic evolution of Huahine island (Society archipelago, French Polynesia) : an unusual intraoceanic shield volcano ». Bulletin de la Société Géologique de France 174, n^o 2 (1 mars 2003) : 115–24. http://dx.doi.org/10.2113/174.2.115.

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Abstract Huahine (Leeward Islands, Society Archipelago) is composed of two islands, Huahine Nui and Huahine Iti, separated by the shallow Port Bourayne and Maroe bays and surrounded by a common lagoon. The two islands, however, belong to a single basaltic and trachybasaltic shield volcano, the emerged part of which was constructed during a very short period, between 2.65 and 2.52 Ma. The volcano is made of composite basaltic flows belonging to three distinct petrogenetic types, which derive from low degrees of partial melting of heterogeneous mantle sources. This building stage lead to the formation of a central caldeira. Then, a WSW-ENE trending graben formed separating Huahine Nui from Huahine Iti. As a consequence, Huahine differs from most of the other Polynesian islands which display large collapse structures opened toward the sea. After a period of inactivity of at least 0.25 m.y., magmatic activity resumed, leading to the emplacement of five trachyphonolitic intrusions along N-S trending deep regional fractures. These lavas, which do not result from the fractional crystallization of the shield basalts, are considered as derived from the melting of a deep intrusive network of dykes.

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Jeffery, A. J., R. Gertisser, R. A. Jackson, B. O'Driscoll et A. Kronz. « On the compositional variability of dalyite, K2ZrSi6O15 : a new occurrence from Terceira, Azores ». Mineralogical Magazine 80, n^o 4 (juin 2016) : 547–65. http://dx.doi.org/10.1180/minmag.2016.080.018.

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AbstractThe rare potassium zirconium silicate dalyite has been identified for the first time on Terceira, Azores, within syenitic ejecta of the Caldeira-Castelinho Ignimbrite Formation. New quantitative analyses of this dalyite were combined with the small number of published analyses from various locations worldwide to evaluate the mineral's compositional variability. Additionally, solid-state modelling has been applied to assess the site allocations of substituting elements. The new analyses yield the average formula (K1.84Na0.15)∑=1.99(Zr0.94Ti0.012Hf0.011Fe0.004)∑=0.967Si6.03O15. Model results predict the placement of substituting Hf and Ti in the octahedral site, and highlight the overall complexity in the incorporation of Fe, Mg and Ba. The combined dataset reveals that dalyite found within peralkaline granites and syenites is generally defined by higher Na↔K substitution and lower Ti↔Zr substitution relative to dalyite from highly potassic rocks. The Terceira dalyite exhibits a bimodal variation in the degree of Na↔K substitution which is attributed to a K-enrichment trend induced by late-stage pore wall crystallization and albitization, coupled with the control of pore size upon the degree of supersaturation required to initiate nucleation of dalyite in pores of varying size.

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McCUTCHEON, S. R., H. E. ANDERSON et P. T. ROBINSON. « Stratigraphy and eruptive history of the Late Devonian Mount Pleasant Caldera Complex, Canadian Appalachians ». Geological Magazine 134, n^o 1 (janvier 1997) : 17–36. http://dx.doi.org/10.1017/s0016756897006213.

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Stratigraphic, petrographic and geochemical evidence indicate that the volcano-sedimentary rocks of the Late Devonian Piskahegan Group, located in the northern Appalachians of southwestern New Brunswick, represent the eroded remnants of a large epicontinental caldera complex. This complex – the Mount Pleasant Caldera – is one of few recognizable pre-Cenozoic calderas and is divisible into Exocaldera, Intracaldera and Late Caldera-Fill sequences. The Intracaldera Sequence comprises four formations that crop out in a triangular-shaped area and includes: thick ash flow tuffs, thick sedimentary breccias that dip inward, and stocks of intermediate to felsic composition that intrude the volcanic pile or are localized along caldera-margin faults. The Exocaldera Sequence contains ash flow tuffs, mafic lavas, alluvial redbeds and porphyritic felsic lavas that comprise five formations. The Late Caldera-Fill Sequence contains rocks that are similar to those of the outflow facies and comprises two formations and two minor intrusive units. Geochemical and mineralogical data support the stratigraphic subdivision and indicate that the basaltic rocks are mantle-derived and have intraplate chemical affinities. The andesites were probably derived from basaltic magma by fractional crystallization and assimilation of crustal material. The various felsic units are related by episodes of fractional crystallization in a high-level, zoned magma chamber. Fractionation was repeatedly interrupted by eruption of material from the roof zone such that seven stages of caldera development have been identified. The genesis of the caldera is related to a period of lithospheric thinning that followed the Acadian Orogeny in the northern Appalachians.

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Sanchez, L., et R. Shcherbakov. « Scaling properties of planetary calderas and terrestrial volcanic eruptions ». Nonlinear Processes in Geophysics 19, n^o 6 (6 novembre 2012) : 585–93. http://dx.doi.org/10.5194/npg-19-585-2012.

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Abstract. Volcanism plays an important role in transporting internal heat of planetary bodies to their surface. Therefore, volcanoes are a manifestation of the planet's past and present internal dynamics. Volcanic eruptions as well as caldera forming processes are the direct manifestation of complex interactions between the rising magma and the surrounding host rock in the crust of terrestrial planetary bodies. Attempts have been made to compare volcanic landforms throughout the solar system. Different stochastic models have been proposed to describe the temporal sequences of eruptions on individual or groups of volcanoes. However, comprehensive understanding of the physical mechanisms responsible for volcano formation and eruption and more specifically caldera formation remains elusive. In this work, we propose a scaling law to quantify the distribution of caldera sizes on Earth, Mars, Venus, and Io, as well as the distribution of calderas on Earth depending on their surrounding crustal properties. We also apply the same scaling analysis to the distribution of interevent times between eruptions for volcanoes that have the largest eruptive history as well as groups of volcanoes on Earth. We find that when rescaled with their respective sample averages, the distributions considered show a similar functional form. This result implies that similar processes are responsible for caldera formation throughout the solar system and for different crustal settings on Earth. This result emphasizes the importance of comparative planetology to understand planetary volcanism. Similarly, the processes responsible for volcanic eruptions are independent of the type of volcanism or geographical location.

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Martí, J., J. Mitjavila et V. Araña. « Stratigraphy, structure and geochronology of the Las Cañadas caldera (Tenerife, Canary Islands) ». Geological Magazine 131, n^o 6 (novembre 1994) : 715–27. http://dx.doi.org/10.1017/s0016756800012838.

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AbstractAfter a long period of subaerial fissure-fed extrusions of basaltic magmas (∼ 12 to > 3 Ma) volcanic activity was then concentrated in the central part of Tenerife. Phonolitic magma chambers formed and a central volcanic complex was constructed (the Las Canadas edifice). The formation of a large depression (the Las Canadas caldera) truncated the top of the edifice. The active twin strato-cones Teide—Pico Viejo are sited in this depression. The history of the Las Canadas caldera and edifice are established from stratigraphy, geochronology (K—Ar dates) and volcanological studies. Two different groups are recognized, separated by a major unconformity. The Lower Group is dated at 2 to 3 Ma and includes the products of several volcanic centres, which together represent several cycles. The Upper Group ranges from 1.56 to 0.17 Ma and includes three different formations representing three long-term (∼ 100 to 300 Ka) volcanic cycles. The periods of dormancy between each formation were of ∼ 120 to 250 Ka duration. The Las Canadas caldera is a multicyclic caldera which formed over the period 1.18–0.17 Ma. Each cycle of activity represented by a formation culminated in caldera collapse which affected different sectors of the Las Canadas edifice. Geological observation and geochronology support an origin by collapse into a magma chamber. The minimum volume of pyroclastic ejecta is substantially greater than the present caldera depression volume (45 km3), but approaches the inferred volume of the original caldera depression (> 140 km3). After the formation of the caldera, sector collapses could also occur at the northern flank of the volcano causing the disappearance of the northern side of the caldera wall.

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Smellie, J. L. « Lithostratigraphy and volcanic evolution of Deception Island, South Shetland Islands ». Antarctic Science 13, n^o 2 (juin 2001) : 188–209. http://dx.doi.org/10.1017/s0954102001000281.

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Deception Island is the most active volcano in the Antarctic Peninsula region. It is a large basalt–andesite shield volcano with a 10 km-wide restless caldera (Port Foster) and a complicated history of pre- and post-caldera eruptions. There has been no modern volcanological investigation of the entire island and it remains a largely unknown volcanic hazard. The pre-caldera period on the island began with the low-energy eruption of tephras from multiple centres (Fumarole Bay Formation), possibly by subaqueous fire fountaining during shoaling and likely initial emergence of the volcano. It was followed by subaerial effusive to weakly pyroclastic (Strombolian/Hawaiian) activity that constructed a small basaltic shield (Basaltic Shield Formation), and a large eruption that vented about 30 km3 of magma (Outer Coast Tuff Formation). The latter eruption may have been triggered by an influx of compositionally different magma into the main chamber feeding the volcano, and the evidence suggests that it was associated with a significant involvement with water (seawater?). The eruption was followed by caldera collapse, and there have been several small incremental caldera “collapses” subsequently. Post-caldera eruptions were all small-volume and predominantly phreatomagmatic (Baily Head and Pendulum Cove formations), but magmatic eruptions constructed several small lava deltas around the coast and also produced a local carapace of scoria and thin lavas, particularly around the caldera rim (Stonethrow Ridge Formation). Although the caldera is presently resurging, interpretation of the eruptive history of the island suggests that future eruptions are likely to be small in volume and will have only a limited regional impact.

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Sacchi, Marco, Giuseppe De Natale, Volkhard Spiess, Lena Steinmann, Valerio Acocella, Marta Corradino, Shanaka de Silva et al. « A roadmap for amphibious drilling at the Campi Flegrei caldera : insights from a MagellanPlus workshop ». Scientific Drilling 26 (2 décembre 2019) : 29–46. http://dx.doi.org/10.5194/sd-26-29-2019.

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Abstract. Large calderas are among the Earth's major volcanic features. They are associated with large magma reservoirs and elevated geothermal gradients. Caldera-forming eruptions result from the withdrawal and collapse of the magma chambers and produce large-volume pyroclastic deposits and later-stage deformation related to post-caldera resurgence and volcanism. Unrest episodes are not always followed by an eruption; however, every eruption is preceded by unrest. The Campi Flegrei caldera (CFc), located along the eastern Tyrrhenian coastline in southern Italy, is close to the densely populated area of Naples. It is one of the most dangerous volcanoes on Earth and represents a key example of an active, resurgent caldera. It has been traditionally interpreted as a nested caldera formed by collapses during the 100–200 km3 Campanian Ignimbrite (CI) eruption at ∼39 ka and the 40 km3 eruption of the Neapolitan Yellow Tuff (NYT) at ∼15 ka. Recent studies have suggested that the CI may instead have been fed by a fissure eruption from the Campanian Plain, north of Campi Flegrei. A MagellanPlus workshop was held in Naples, Italy, on 25–28 February 2017 to explore the potential of the CFc as target for an amphibious drilling project within the International Ocean Discovery Program (IODP) and the International Continental Drilling Program (ICDP). It was agreed that Campi Flegrei is an ideal site to investigate the mechanisms of caldera formation and associated post-caldera dynamics and to analyze the still poorly understood interplay between hydrothermal and magmatic processes. A coordinated onshore–offshore drilling strategy has been developed to reconstruct the structure and evolution of Campi Flegrei and to investigate volcanic precursors by examining (a) the succession of volcanic and hydrothermal products and related processes, (b) the inner structure of the caldera resurgence, (c) the physical, chemical, and biological characteristics of the hydrothermal system and offshore sediments, and (d) the geological expression of the phreatic and hydromagmatic eruptions, hydrothermal degassing, sedimentary structures, and other records of these phenomena. The deployment of a multiparametric in situ monitoring system at depth will enable near-real-time tracking of changes in the magma reservoir and hydrothermal system.

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Amanda, Fajar F., Ryoichi Yamada, Masaoki Uno, Satoshi Okumura et Noriyoshi Tsuchiya. « Evaluation of Caldera Hosted Geothermal Potential during Volcanism and Magmatism in Subduction System, NE Japan ». Geofluids 2019 (21 janvier 2019) : 1–14. http://dx.doi.org/10.1155/2019/3031586.

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Deep-seated geothermal reservoirs beneath calderas have high potential as sources of renewable energy. In this study, we used an analysis of melt inclusions to estimate the amount of water input to the upper crust and quantify the properties of a deep-seated geothermal reservoir within a fossil caldera, the late Miocene Fukano Caldera (formation age 8–6 Ma), Sendai, NE Japan. Our research shows that Fukano Caldera consists of the southern part and northern part deposits which differ in the age and composition. The northern deposits are older and have higher potassium and silica contents than the southern deposits. Both the northern and southern deposits record plagioclase and plagioclase–quartz differentiation and are classified as dacite–rhyolite. The fossil magma chamber underlying the caldera is estimated to have a depth of ~2–10 km and a water content of 3.3–7.0 wt.%, and when the chamber was active it had an estimated temperature of 750°C–795°C. The water input into the fossil magma chamber is estimated at 2.3–7.6 t/yr/m arc length based on the magma chamber size the water content in the magma chamber and the length of volcanism periods of Fukano Caldera, NE Japan arc. The total amount of water that is stored in the chamber is ~1014 kg. The chamber is saturated in water and has potential as a deep-seated geothermal reservoir. Based on the shape of the chamber, the reservoir measures ~10 km × 5 km in the horizontal dimension and is 7–9 km in vertical extent. The 0th estimate shows that the reservoir can hold the electric energy equivalent of 33–45 GW over 30 years of power generation. Although the Fukano reservoir has great potential, commercial exploitation remains challenging owing to the corrosive nature of the magmatic fluids and the uncertain permeability network of the reservoir.

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Thèses sur le sujet "Formation de caldeira"

Morand, Alexandra. « Formation et instabilité de réservoirs de magma silicique dans la croûte continentale ». Thesis, Université de Paris (2019-....), 2019. https://theses.md.univ-paris-diderot.fr/MORAND_Alexandra_va2.pdf.

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Les grands systèmes magmatiques siliciques peuvent produire des éruptions dévastatrices avec des volumes émis supérieurs à 100 km3. La forme et l'organisation des zones de stockage du magma sont toujours source de débats. Or, la forme utilisée modifie les résultats des modélisations faites. Nous avons choisi de prendre le problème sous un angle nouveau, en réfléchissant aux raisons physiques qui expliquent la formation d'une zone de stockage pré-éruptive, ceci afin d'avoir une meilleure compréhension des contraintes exercées par la chambre magmatique sur son environnement. Notre hypothèse est que le magma silicique, sous l'effet de sa flottabilité positive, remonte dans la partie ductile de la croûte continentale sous forme de diapir. Il est ensuite stoppé par la transition fragile-ductile de la croûte continentale, provoquant la formation d'une zone de stockage. Ce travail de thèse suit trois axes. Dans le premier nous adaptons un modèle de déformation de plaque issu de la littérature, afin de pouvoir décrire les contraintes et les déplacements dus à un liquide de flottabilité positive stocké sous une plaque élastique. Le second axe est expérimental. Un montage expérimental a été créé afin de reproduire le stockage supposé en laboratoire. Nos résultats permettent de tester notre modèle. Troisièmement, afin de valider l'hypothèse de départ, les prédictions théoriques sont comparées à des données issues de cas naturels. Nous montrons d'abord que notre modèle permet de reproduire la répartition des grandes déformations observées au volcan Uturuncu en Bolivie. Plus généralement, nous montrons que les contraintes produites par la chambre magmatique dans la plaque, peuvent provoquer des failles circulaires au-dessus de la chambre magmatique. Ce résultat a des implications directes pour la compréhension de la formation des caldeiras lors des éruptions majeures des grands systèmes siliciques
Huge silicic magmatic systems can produce devastating eruptions with emitted volumes above 100 km³. The shape and the organisation of magmatic storage are still debated, despite their crucial influence on the results of theoretical predictions. We choose to look at the problem in a new light, by thinking about the physical reasons that explain the formation of a storage zone. This is in order to better understand stresses produced by the magma chamber in the host rocks. Our hypothesis is that silicic magma, due to its positive buoyancy, rises through the ductile continental crust as a diapir, and is then stopped by the brittle-ductile transition. This PhD follows three axes. The first presents the adaptation of a published theoretical plate-model which enables us to describe the stresses and displacements due to the storage of a buoyant liquid under an elastic plate. The second axis is an experimental one. An apparatus was built to reproduce experimentally the storage configuration assumed. Our results, allow us to test our model. Thirdly, in order to validate our starting hypothesis, numerical results are compared with data from natural systems. We show that our model can reproduce the large observed deformation at Uturuncu volcano in Bolivia. Then, more broadly, we show that stresses produced in the plate by the magma chamber can produce circular faults above the storage zone. This result has direct implications for the understanding of caldera formation during large silicic eruptions

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Pinel, Virginie. « Construction et destruction d'un édifice volcanique : conséquences pour le transport et le stockage du magma ». Paris, Institut de physique du globe, 2002. http://www.theses.fr/2002GLOB0007.

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Un édifice volcanique modifie de manière significative le champ de contrainte dans la croûte continentale sous-jacente. La perturbation induite dépend de la taille de l'édifice volcanique, elle évolue donc avec la construction ou la destruction du volcan. Le champ de contrainte présent sous l'édifice a des implications importantes sur l'aptitude du magma à atteindre la surface, la localisation des éruptions, les conditions de pression dans les réservoirs magmatiques superficiels et la formation des caldeiras. Nous montrons que le champ compressif créé sous l'édifice peut empêcher les magmas les plus denses d'atteindre la surface. Des zones de stockage superficielles sont créées et le transport latéral du magma sous l'édifice est favorisé. Nous évaluons comment l'édifice influe sur les volumes et les compositions des produits d'éruption en contrôlant la pression dans le réservoir magmatique. Les conséquences de la destruction partielle d'un volcan sont traitées

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Barde, Cabusson Stéphanie. « Formation de caldera par fluage d'un système hydrothermal volcanique ». Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2007. http://tel.archives-ouvertes.fr/tel-00718055.

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L'influence d'un système hydrothermal au sein d'un édifice volcanique est un concept encore peu étudiée au regard de son importance pour la stabilité d'un volcan. Ce travail s'intéresse à la relation entre système hydrothermal et tectonique à travers l'étude des déformations engendrées dans un cône volcanique par le fluage de roches affectées par l'altération hydrothermale. La présence de ces argiles, ductiles à l'échelle de temps considérée, modifie profondément le comportement d'un édifice volcanique au cours de son évolution, pouvant conduire à la formation de grandes structures d'effondrement de type caldera. La confrontation de modèles analogiques avec la géologie et les données géophysiques nous permet de contraindre dans ce sens l'interprétation des structures d'effondrement observées par exemple sur Nuku Hiva (Polynésie française) et sur le Piton de la Fournaise (Ile de la Réunion). La modélisation analogique montre également que la formation du plancher plat d'une caldera peut être le résultat d'un processus syneffondrement, ne nécessitant pas de resurfaçage postérieur par érosion ou mise en place de nouveaux produits éruptifs. Les expériences nous permettent d'identifier la pente du cône et la diminution des contraintes latérales sur l'édifice comme les paramètres prépondérants à l'origine de la déformation. Les variations de ces paramètres sont déterminantes pour la morphologie de la caldera.

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Barde-Cabusson, Stéphanie. « Formation de caldera par fluage d'un système hydrothermal volcanique ». Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2007. http://tel.archives-ouvertes.fr/tel-00268777.

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Radebaugh, Jani. « Formation and Evolution of Paterae on Jupiter's Moon Io ». Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1134%5F1%5Fm.pdf&type=application/pdf.

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Roche, Olivier. « Les mecanismes de formation des calderas : etude experimentale et modelisation ». Clermont-Ferrand 2, 2000. http://www.theses.fr/2000CLF22197.

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Les mecanismes de formation des calderas sont d'abord etudies en menant des experiences dimensionnees qui revelent que les styles de subsidence proposes dans la bibliographie pourraient etre obtenus a partir d'un seul mecanisme. Les differentes structures dependraient essentiellement du rapport de forme du toit (epaisseur/largeur). La subsidence dans une grande chambre magmatique superficielle serait coherente, asymetrique (trapdoor), et pourrait se produire par l'intermediaire d'un piston delimite par des failles inverses induisant la formation de failles normales externes delimitant des blocs bascules peripheriques. La subsidence dans une petite chambre profonde pourrait etre non-coherente (chaotique). Ce cas pourrait correspondre a certaines calderas en entonnoir. Les experiences permettent egalement de discuter les mecanismes de formation des pits-craters. Les comparaisons avec les mecanismes de subsidence dans les mines suggerent l'existence d'un mecanisme general de subsidence pour un toit dans un reservoir en sous-pression. Des calculs faits en utilisant un code base sur la methode des elements frontieres revelent que la sous-pression necessaire pour produire la rupture du toit de la chambre augmente avec le rapport de forme de celui-ci. Les mecanismes de la transition subsidence coherente/non-coherente sont ensuite discutes a l'aide d'un modele analytique valide par une serie d'experiences. Puis, les implications pour les processus eruptifs sont discutees a l'aide d'un second modele. Il indique que la fraction volumique de la chambre qui devrait etre evacuee pour produire une subsidence coherente de type piston augmenterait avec le rapport de forme de toit, jusqu'a ce que la chambre soit presque ou totalement videe pour un rapport de forme d'environ 1. 3-1. 4 qui pourrait etre celui auquel aurait lieu la transition subsidence coherente/non-coherente. Toutes les grandes eruptions ne meneraient ainsi pas necessairement a la formation d'une caldera.

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Kinvig, Helen Susan. « Spatial and temporal variations in the causative processes of caldera formation ; an example from Nisyros, Greece ». Thesis, University of Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629005.

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Collapse calderas are associated the most violent volcanic eruptions on Earth. Their destructive potential makes understanding their processes of formation crucial in assessing their vo1canic hazard. This thesis investigates the formation of a central caldera on Nisyros volcano,Greece. It reviews the volcanic stratigraphy of Nisyros; particularly addressing the deposits of its most recent explosive eruptions: the Lower Pumice and Upper Pumice. The eruption stratigraphy of the Lower Pumice and Upper Pumice is reconstructed and discussed, and their contribution to caldera formation is assessed. Lithic component analyses of xenoliths contained within the Lower and Upper Pumice pyroclastic deposits reveal important insights into their eruption chronologies, and vent locations . Circum-caldera lithic variations indicate the use of multiple vents during the caldera forming eruptions. Tephra distribution maps are used to estimate physical eruption parameters for the Pumice eruptions, and aid identification of vent-sites. It is concluded that the Nisyros caldera formed by incremental collapse, involving the cumulative magma withdrawal associated with the Lower pumice and Upper Pumice, and additionally the intercalated, high volume Nikia Rhyolite. A new model of Nisyros caldera formation is presented, in which regional tectonics are considered to have been an important influence on collapse and vent location. A new geological map implementing a revised volcanic stratigraphy is additionally presented. Finally, numerical models that implement an FEA method to investigate the effects of crustal layering on local stress field distribution during an eruption are presented and compared with existing criteria for ring fault initiation. Their results indicate that mechanical layering may be influential in facilitating or inhibiting caldera collapse. The results of the numerical study are discussed with reference to Nisyros volcano.

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Streffon, Jenna C. « Magma Mixing and Dome Formation : Dacite of East Pass Creek, Colorado ». Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1556705059361473.

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Pierre, Arnauld. « Mouvement et réalité dans l'oeuvre de Calder : des années de formation à la maturité ». Paris 4, 1995. http://www.theses.fr/1995PA040011.

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La méconnaissance de la période qui va des années de formation à la maturité d'Alexander Calder,c'est-à-dire du milieu des années vingt à la fin des années quarante,a oblitéré l'importance de ses découvertes et a coupé son art de ses racines historiques. Avant la guerre,Calder invente pourtant une des formes les plus neuves de la sculpture du XXe siècle,le mobile,et initie parallèlement un type de sculpture,le stabile,qui renouvellera l'art public et monumental. Artiste figuratif à ses débuts,il découvre un réalisme dont l'exigence essentielle est la transcription du mouvement. A partir de 1930,sous l'influence des avant-gardes constructives,son art intègre le mouvement comme composante réelle d'un art abstrait (non-figuratif)
The period of Calder's work going from his formative years to his maturity was generally unknown,consequently,the value of his achievements has not been recognized and his art has been cut from his historical coots. .

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Wilcock, Jack. « Magmatic recharge during formation and resurgence of the Valles caldera, New Mexico, USA : evidence from quartz compositional zoning and geothermometry ». Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95220.

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The Valles caldera complex in north-central New Mexico, USA, represents the type example of resurgent caldera system, characterised by eruption of two voluminous high-silica rhyolite ignimbrites (the Otowi and Tshirege Members of the Bandelier Tuff) at 1.608 ± 0.010 Ma and 1.256 ± 0.010 Ma, respectively. Refined dating has shown that resurgence occurred shortly after eruption of the Tshirege, or Upper Bandelier Tuff (UBT). Central resurgence of ~1000 m was accompanied by small-volume eruptions of the Deer Canyon Rhyolite, followed closely by the Redondo Creek Rhyodacite. The Cerro del Medio Rhyolite lava dome complex is a product of ring fracture volcanism following resurgence, erupting at 1.229 ± 0.017 Ma. A central aim of this study was to find evidence for magmatic recharge during this geologically short (~ 27 ka) time period. We have combined cathodoluminescence (CL) imaging and titanium-in-quartz geothermometry techniques to individual quartz crystals from 1) different stratigraphic horizons of the UBT ignimbrite, 2) samples of the Deer Canyon Rhyolite and 3) the Cerro del Medio Rhyolite lavas. CL imaging reveals that ~80% of the erupted volume UBT ignimbrite contains unzoned quartz crystals (average concentration = 28 ± 2 ppm Ti), recording relatively isothermal temperatures of 647-696 °C. An abrupt occurrence of compositionally zoned quartz crystals ) within the mid-to-late erupted UBT ignimbrite units 3-5 reveals evidence for interaction with hotter magma. Corresponding titanium-in-quartz measurements of outer, bright CL rims (71 ± 9 ppm Ti) reveal temperature increases of ~100 °C relative to the start of the UBT eruption. We have discovered an interesting heterogeneity within the Deer Canyon Rhyolite lavas, with strong spatial control on eruption of porphyritic lavas containing complexly zoned quartz crystals onto the western regions of the resurgent dome. Conversely, crystal-poor to aphyric lavas containing small, unzoned quartz crystals are conf
Le complexe de caldeiras de Valles au centre-nord du Nouveau-Mexique, Etats-Unis, constitue l'exemple type d'un système de caldeira résurgente, caractérisé par l'éruption de deux volumineuses ignimbrites rhyolitiques riche en silice (les Membres Otowi et Tshirege de la Bandelier Tuff) à 1.608 ± 0.010 Ma et 1.256 ± 0.010 Ma, respectivement. Des techniques de datation de haute precision ont montré que la résurgence s'est produite rapidement après l'éruption de la Tshirege ou Upper Bandelier Tuff (UBT). La résurgence du centre de la caldeira d'environ 1000 m s'est accompagnée des éruptions mineures des rhyolites de Deer Canyon, puis de la rhyodacite de Redondo Creek. Le complexe de dômes de lave rhyolitiques de Cerro del Medio est le produit de volcanisme de fracture annulaire post-résurgence à 1.229 ± 0.017 Ma. Un point clé de cette étude était de trouver des évidences de recharge magmatique durant ce court episode ~ 27 ka. Nous avons analysé des cristaux de quartz par imagerie de cathodoluminescence (CL) et géothermométrie du titane dans 1) plusieurs niveaux stratigraphiques de l'ignimbrite d'UBT, 2) des échantillons des rhyolites de Deer Canyon et 3) des laves des rhyolites de Cerro del Medio. L'imagerie CL révèle que ~80% du volume d'UBT contient des cristaux de quartz non zonés (concentration moyenne = 28 ± 2 ppm Ti), représentant des températures relativement homogènes de 647-696 °C. Une transition abrupte vers des quartz optiquement zonés dans les unités 3-5 des phases intermediaires et tardives de l'éruption d'UBT suggère une interaction avec un magma plus chaud. Les mesures correspondantes de titane dans les bordures externes lumineuses des cristaux (70 ± 9 ppm Ti) indiquent une augmentation de température d'environ 100 °C depuis le début de l'éruption d'UBT. Nous avons découvert une hétérogénéité intéressante dans les laves rhyolitiques de Deer Canyon: les laves porphyriques contenant des cristaux avec zo

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Livres sur le sujet "Formation de caldeira"

Kokelaar, B. P. Classical areas of British geolopgy : Glencoe caldera volcano, Scotland. Nottingham : British Geological Survey, 2006.

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Chapitres de livres sur le sujet "Formation de caldeira"

Aramaki, Shigeo. « Formation of the Aira Caldera, Southern Kyushu, ∼22,000 Years Ago ». Dans Collected Reprint Series, 8485–501. Washington, DC : American Geophysical Union., 2014. http://dx.doi.org/10.1002/9781118782095.ch19.

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Afanasiev, V. V., N. N. Dunaev, A. O. Gorbunov et A. V. Uba. « The Manifestation of Caldera-Forming Volcanism in the Formation of the Coast (On Example of Iturup Island of the Great Kuril Ridge) ». Dans Processes in GeoMedia—Volume I, 51–61. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-38177-6_7.

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Gudmundsson, Agust. « Chapter 8 Magma-Chamber Geometry, Fluid Transport, Local Stresses and Rock Behaviour During Collapse Caldera Formation ». Dans Caldera Volcanism : Analysis, Modelling and Response, 313–49. Elsevier, 2008. http://dx.doi.org/10.1016/s1871-644x(07)00008-3.

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Ocampo-Díaz, Yam Zul Ernesto, Sonia Alejandra Torres-Sánchez, Carita Augustsson, José Luis Macías, Giovanni Sosa-Ceballos, Guillermo Cisneros-Máximo, Laura García-Sánchez et al. « Provenance of the El Salto Formation (early Oligocene to early Miocene), southern part of La Reforma caldera, Baja California Sur, Mexico ». Dans Southern and Central Mexico : Basement Framework, Tectonic Evolution, and Provenance of Mesozoic–Cenozoic Basins. Geological Society of America, 2020. http://dx.doi.org/10.1130/2021.2546(11).

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McClaughry, Jason D., Mark L. Ferns, Martin J. Streck, Karyn A. Patridge et Caroline L. Gordon. « Paleogene calderas of central and eastern Oregon : Eruptive sources of widespread tuffs in the John Day and Clarno Formations ». Dans Volcanoes to Vineyards : Geologic Field Trips through the Dynamic Landscape of the Pacific Northwest, 407–34. Geological Society of America, 2009. http://dx.doi.org/10.1130/2009.fld015(20).

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Martí, Joan, Carlos Soriano, Inés Galindo et Raymond A. F. Cas. « Resolving problems with the origin of Las Cañadas caldera (Tenerife, Canary Islands) : Los Roques de García Formation—Part of a major debris avalanche or an in situ, stratified, edifice-building succession ? » Dans Stratigraphy and Geology of Volcanic Areas. Geological Society of America, 2010. http://dx.doi.org/10.1130/2010.2464(06).

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Actes de conférences sur le sujet "Formation de caldeira"

Wolff, John A., William A. Starkel, Christopher D. Henry, Ben Ellis et Frank C. Ramos. « MAFIC AND INTERMEDIATE MAGMATISM AT MCDERMITT CALDERA, NEVADA–OREGON : ICELANDITE TRIGGER FOR CALDERA FORMATION ». Dans GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-302049.

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Faust, Megan Thackeray Scott. « IMPLEMENTING A CALDERA FORMATION ACTIVITY IN INTRODUCTORY GEOSCIENCE COURSES TO IMPROVE STUDENT UNDERSTANDING OF CALDERA LANDFORMS AND ASSOCIATED VOLCANIC PROCESSES ». Dans 115th Annual GSA Cordilleran Section Meeting - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019cd-329869.

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Grosfils, Eric B. « COMPARING RING FAULT AND CALDERA FORMATION CONDITIONS ON EARTH AND MARS USING FINITE ELEMENT MODELS ». Dans 113th Annual GSA Cordilleran Section Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017cd-292428.

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Mahan, Shannon A., David Sammeth, Craig Rasmussen et Harrison Gray. « VALLES CALDERA, NEW MEXICO, USA : DATING AND DEFINING THE RATE OF FORMATION OF SOILS AND WILDFIRE ACTIVITY USING LUMINESCENCE ». Dans GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-301348.

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Rapports d'organisations sur le sujet "Formation de caldeira"

Papike, J. J., M. S. Servilla et K. H. Wohletz. Simulating silicic eruptions at Long Valley, California as a method to understand processes that influence eruption phenomena associated with caldera formation. IGPP progress report, October 1, 1993--August 31, 1994. Office of Scientific and Technical Information (OSTI), décembre 1994. http://dx.doi.org/10.2172/10118358.

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