Bibliographies thématiques / Pyroclastite

Littérature scientifique sur le sujet « Pyroclastite »

Auteur : Grafiati
Publié le 4 mai 2024

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Articles de revues sur le sujet "Pyroclastite"

1

Picard, Christian, et Michel Piboule. « Pétrologie des roches volcaniques du sillon de roches vertes archéennes de Matagami – Chibougamau à l'ouest de Chapais (Abitibi est, Québec).1. Le groupe basal de Roy ». Canadian Journal of Earth Sciences 23, no 4 (1 avril 1986) : 561–78. http://dx.doi.org/10.1139/e86-056.

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In the northeastern part of the Abitibi orogenic belt, the Archean Matagami–Chibougamou greenstone belt (2700 Ma) includes a basal volcanic sequence named the Roy Group, unconformably overlain by a volcano-sedimentary series called the Opemisca Group.The Roy Group, to the west of the town of Chapais, consists of a thick, stratified, and polycyclic volcanic series (thickness = 11 000 m) resembling the large, western Abitibi submarine stratovolcanoes constructed by three mafic to felsic magmatic cycles. The first cycle (Chrissie Formation) shows lateral spreading and is composed only of a meta-andesite and felsic pyroclastite sequence of calc-alkaline affinity. The other two cycles (Obatogamau and Waconichi formations; then Gilman, Blondeau, and Scorpio formations) are characterized by a sequence of repeated MORB type basaltic lava flows of tholeiitic affinity and by intermediate to acid lava and pyroclastic sequences calc-alkaline affinity.The stratigraphic and petrographic data suggest emplacement of mafic lavas on an abyssal plain (Obatogamau Formation) or at a later time on the flanks of a large submarine volcanic shield (Gilman and Blondeau formations). The lava and felsic pyroclastite flows were formed by very explosive eruptions from central spreading type volcanoes above a pre-existing continental crust. In particular, the Scorpio volcanic rocks were emplaced on volcanic islands later dismantled by erosion.The contents and distribution of trace elements and rare earths show that basaltic lavas resulted from an equilibrium partial melting (F = 15–35%) of spinel lherzolite type mantle sources depleted to weakly enriched in Th, Ta, Nb, and light rare-earth elements (LREE), and from fractional crystallization at low pressure of feldspar, clinopyroxene, and olivine. The lavas and the felsic pyroclastites of the Waconichi and Scorpio formations appear to result from partial melting of a mantle source of lherzolite type enriched in LREE and involving some garnet. At a late stage, the melts were probably contaminated by some continental crust materials and then differentiated by fractional crystallization of plagioclase, amphibole, biotite, and magnetite. The lavas in the Chrissie Formation and the middle member of the Gilman Formation seem to result from partial melting of a mantle source enriched in LREE with a composition between the two described above. They were subsequently modified by fractional crystallization of the plagioclase, clinopyroxene, olivine, and titanomagnetite.In general, the mafic to felsic magmatic cycles observed are characterized by a thick sequence of repeated tholeiitic basalt flows similar to those of modern mid-oceanic ridges and by a lava and felsic pyroclastite sequence of calc-alkaline affinity comparable to those occurring in orogenic belts. The transition from one lava sequence to another is marked by a significant chemical discontinuity, and the mantle sources exhibit an increasing enrichment in LREE during a given magmatic cycle. A model is proposed to satisfactorily explain all the stratigraphic, petrographic, and geochemical data implying a hot spot type mechanism, which could be responsible for the cyclic, rising diapirs inside the stratified Archean mantle and for initiating the repeated mantle source meltings, depleted and enriched in LREE, respectively. [Journal Translation]
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Kazakov, A. I., O. V. Veselov et D. N. Kozlov. « Statistical analysis of the distribution of phreatic eruption products in the caldera of the Golovnin volcano (Kunashir Island, Kuril Islands) ». Geosystems of Transition Zones 5, no 1 (2021) : 14–26. http://dx.doi.org/10.30730/gtrz.2021.5.1.014-026.

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The paper presents the results of statistical processing of data on the thickness and size of the tephra fragments of andesidacite composition erupted as a result of a phreatic explosion in the caldera of Golovnin volcano about 1000 years ago. A petrochemical description of the products of volcanic activity of the crustal Golovnin volcano and its evolution process is presented based on geological and geophysical data. The relationship between the thickness of the tephra, the size of its fragments, and the distance to the eruption center was studied using the polynomial regressions of varying degrees and exponential distribution. The adequacy of the constructed models to the initial data is illustrated by determination coefficients. Tephra distribution models were constructed on the basis of a three-dimensional trend analysis. For the first time, a logarithmic model was used to describe the size of tephra fragments. The accuracy of the model used was estimated. A method for estimating the potential dispersion range of tephra fragments of a certain size was obtained. The work demonstrates the potential of mathematical statistics for describing the distribution of products of volcanic eruptions of a certain type. The results of this study are suitable for creating an information database of pyroclastite distribution across the Kuril-Kamchatka volcanic region.
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Huguet, David, Jean-Claude Thouret, Pierre Nehlig, Jeannine Raffy et Pierre Rochette. « Les lahars du strato-volcan du Cantal (Massif central, France) ; stratigraphie, modes de mise en place et implications paleo-geomorphologiques ». Bulletin de la Société Géologique de France 172, no 5 (1 septembre 2001) : 573–85. http://dx.doi.org/10.2113/172.5.573.

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Abstract Introduction: The study of lahar (Lh) deposits (a) describes sedimentary facies associations in a volcano-sedimentary system, (b) establishes the identification of criteria to recognize epiclastic deposits in fossil volcanic successions [Thouret, 1999] and (c) reconstructs paleo-landforms (stratocones, paleovalleys, and volcaniclastic fans) in an old volcanic massif. Lh deposits form the "complexe conglomeratique superieur" ("upper conglomeratic complex") [Brousse et al., 1972, 1975, 1977, 1980, 1989] associated with pyroclastic deposits and streamflow deposits above the "breche inferieure" ("lower breccia"), reinterpreted as debris-avalanche (DAv) deposits. From 9.5 to 6.5 Ma, a trachyandesitic stratovolcano has been built up. Several sector collapses generated DAv and an explosive activity produced pyroclastic-flow deposits. Pyroclastic deposits and both Lh and DAv deposits built up volcaniclastic fans. The study aims (a) to determine Lh deposit generations associated with paleo-landforms and (2) to use Lh deposits as landmarks to recognize some geomorphologic stages in the history of Cantal volcano (45 degrees N-2.5 degrees E; 2500 km 2 , approximately 380 km 3 , 1 855 m). Lahar generations: Lh deposits (9 km 3 ) cover 280 km 2 (fig. 1). They show two facies, clast-supported and matrix-supported debris-flow deposits (fig. 2 and 3), located as far as 20 km from the geographic centre (Puy Griou). Firstly, field observations and geochronological data enable us to distinguish as much as five Lh deposit generations. Secondly, geometric and stratigraphic relations, between Lh deposits and both pyroclastic and DAv deposits, allow us to decipher the genetic relations between distinct volcaniclastic formations. The Cere valley shows three Lh generations. The "Faillitoux" generation is interbedded with the schistose basement and the lava and pyroclastic deposits of the Elanceze massif (1571 m) (fig. 4). An ankaramitic lava (9.53+ or -0,5 Ma, K/Ar) [Nehlig et al., 1999], fitting into Lh deposits of the Elanceze massif post-dates the apparition of the first lahar generation. The "Curebourse" generation was emplaced above DAv deposits (fig. 2A and 5). Both DAv and Lh deposits of the "Curebourse" generation filled the paleo-Cere valley about 7.1 Ma. The "Thiezac" generation (>6.7 Ma, K/Ar) [Nehlig et al., 1999] (fig. 2C) overlies a thick pyroclastic deposit (fig. 4) and is not related to the DAv and the "Curebourse" generation. The fourth generation (Impradine valley) is stratigraphically and genetically associated with pyroclastic deposits located in the upper Impradine valley (fig. 5). These pyroclastic deposits are older than 7.96 Ma (K/Ar age on a trachyandesitic lava overlying Lh deposits) and result from pyroclastic deposits removed as Lh deposits downvalley. The fifth identified lahar generation is located in the Petite-Rhue valley, to the north of the volcano, where a 5-m-thick pumiceous pyroclastite (7.6+ or -0.03 Ma; 40 Ar/ 39 Ar) [Platevoet, 2000] is interstratified with Lh deposits in Cheylade. Genetic relations with pyroclastic deposits: To determine the nature of the relationships between Lh deposits and DAv deposits, we observed geometric relationships between both formations. Some Lh deposits of "Curebourse" generation filled paleothalwegs (fig. 6) cut into DAv deposits suggesting a remission stage after emplacement of DAv deposits. We did not identify sedimentologic features such as dewatering structures indicating that lahars evolved from the top or the front of DAv deposits. Thus, no obvious genetic link was clearly determined between Lh and DAv deposits. In the Impradine valley, we observe the transformation of these pyroclastic deposits in Lh deposits. A proximal pyroclastic facies (upper Impradine) (fig. 5), intruded by numerous dykes and intercalated with trachyandesitic lava, shows the proximity of a stratocone located 1,5 km to the South-East. Field observations indicate a stratigraphic link between pyroclastic and Lh deposits. Debris flows have removed pyroclastic deposits over a 6 km distance. Lh deposits are ungraded or inversely graded and show matrix- or clast-supported facies. About 50% of dense subrounded to rounded clasts were incorporated during the flow. The remaining 50% are dense trachyandesitic juvenile clasts derived from primary pyroclastic-flow deposits. Geomorphological implications: Determinations of five Lh deposit generations and observations of geometrical relations with volcaniclastic deposits (DAv and pyroclastic deposits) enable us to reconstruct paleo-landforms and some stages of the geomorphic evolution of Cantal. In this way, the Impradine volcaniclastic unit is a fragment of a volcaniclastic fan facing north-east (fig. 7). In the Cere valley, the "Faillitoux" generation is the remnant of a proximal section of a volcaniclastic fan facing south-west. These lahars flowed from a trachyandesitic stratocone located close to the Elanceze massif about 9.5 Ma ago (fig. 7). These paleo-stratocones were eroded and are no longer visible in the present geomorphic landscape. Lh deposits allow us to determine geomorphic inheritances, contemporaneous with the activity of the stratovolcano from 9.5 to 6.5 Ma. About 7.1 Ma, the paleo-Cere valley was filled with DAv and Lh deposits of the "Curebourse" generation. The "Curebourse" generation formed a volcaniclastic fan on the top of DAv deposits. DAv and Lh deposits, that are less resistant than the trachyandesitic Elanceze massif and Plomb-du-Cantal range, have been eroded. Accordingly, the Cere valley is being exhumed. The present-day drainage pattern occupies the paleothalweg. However, in distal positions, paleo-landforms are not as well preserved. The current drainage pattern does not use any more paleothalwegs in contrast to what is seen in proximal position (fig. 8).
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Šimon, Ladislav, Viera Kollárová et Monika Kováčiková. « Neogene volcanics of the Burda mountain range nearby Štúrovo, Slovakia ». Mineralia Slovaca 55, no 2 (décembre 2023) : 117–32. http://dx.doi.org/10.56623/ms.2023.55.2.2.

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The Neogene volcanic products of the Burda mountain range nearby Štúrovo belong to Burda Formation. At the base of the Burda Formation a succession of epiclastic volcanic rocks and pyroclastic rocks of andesites has developed. In the central part of the formation, the volcanic products associated with the activity of submarine volcanism of the Badenian age developed. Submarine extrusive volcanic domes of andesites are typical. In the upper part of the Burda Formation, pyroclastic and epiclastic facies of andesites were formed. Deposits of pyroclastic flows and redeposited pyroclastics are characterized by the presence of relics of petrified tree trunks, indicating transport from emergent forest-covered slopes from the higher levels of the volcanic edifice of the Börzsöny Mountains in todayʼs Hungary. This part of the Burda volcanics represents a transitional volcanic zone with the Börzsöny stratovolcano.
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Tommasi, Paolo, Luca Verrucci et Tatiana Rotonda. « Mechanical properties of a weak pyroclastic rock and their relationship with microstructure ». Canadian Geotechnical Journal 52, no 2 (février 2015) : 211–23. http://dx.doi.org/10.1139/cgj-2014-0149.

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The geotechnical behaviour of very weak pyroclastic rocks controls both the failure mechanisms at the margins of rock mesas, where historic hill towns are often sited, as well as the stability of old underground cavities in urban areas of Central Italy. The study focuses on the mechanical behaviour of one of the pyroclastic materials forming the Orvieto mesa (pozzolana), not unlike other pozzolanas in Central and Southern Italy and other pyroclastites from volcanic districts worldwide. The mechanical properties under static conditions of this weakly cemented rock are reported. A petrographic and physical characterization of the material was preliminary conducted, followed by a wide range of mechanical tests: oedometer, uniaxial, and isotropic compression tests and indirect tensile tests. The stress–strain and strength behaviours of the pozzolana are highlighted and compared with those of the rock materials of the pyroclastic formation (tuff). The mechanical behaviour of the pozzolana is related to its physical and textural characters, with special reference to continuity of the groundmass and porosity. Finally, the role of the material behaviour at the field scale is discussed.
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Nikashin, Konstantin I., et Svetlana O. Zorina. « Volcanogenic material in upper jurassic-lower cretaceous deposits of the Eastern Russian plate and its sources ». Izvestiya of Saratov University. New Series. Series : Earth Sciences 21, no 1 (25 mars 2021) : 49–57. http://dx.doi.org/10.18500/1819-7663-2021-21-1-49-57.

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. Widespread “camouflaged” pyroclastics including smectite, illite-smectite and heulandite are detected in the upper jurassic– lower cretaceous deposits of the Ulyanovsk-Saratov basin. Moreover, volcanic glasses are found in several stratigraphic units. The quantity of pyroclastic material in the study section (17–72%) is probably related to volcanic input in the basin. Concentrations of the trace and rare earth elements point to a predominantly acid source of ash material, except the Promzino and Ulyanovsk black shale formations linked to the mixed andesite-basaltic and felsic sources. Island arcs of the Northern Tethys basin and the High-Altitude Arctic Igneous Province are regarded as probable sources of the pyroclastic influx in the epeiric basin of the Russian Platform in the Jurassic-Early Cretaceous.
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Goldberd Harmuda Duva Sinaga, Winarto Silaban et Ady Frenly Simanullang. « Analysis of Coulomb Stress of Sumatera Earthquake Against Pyroclastic Flow of Mount Sinabung as Data Prone Volcano Disaster ». World Journal of Advanced Research and Reviews 13, no 1 (30 janvier 2022) : 793–803. http://dx.doi.org/10.30574/wjarr.2022.13.1.0086.

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The islands of Sumatra and Sinabung are located southwest of the Sundaland Continent which is a convergence route between the Indian-Australian Plate that infiltrates to the west of the Eurasian/Sundaland Plate. The increase in activity of Mount Sinabung was preceded by large earthquakes to the west and south while the eruption of Mount Sinabung produced pyroclastics. The purpose of this study is to find out the analysis of coulomb stress from the Sumatra Island earthquake to the pyroclastic flow of Sinabung as data on volcanic disasters. This study used the coulomb stress method with coulomb 3.3. The earthquake data analyzed was Mw, depth, and focal mechanism. The results of the analysis in the form of the direction of the spread of stress and the value of increased coulomb stress in Sinabung in 2014-2016. Sinabung's positive stress coulomb value in 2014 was 0.113 bar with a positive coulomb stress spread angle of 90o against sinabung pyroclastic flow. Sinabung's positive stress coulomb value in 2015 was 0.235 bar with a positive coulomb stress spread angle of 90o against sinabung pyroclastic flow. Sinabung's positive stress coulomb value in 2016 was 0.118 bar with a positive coulomb stress spread angle of 90o against sinabung pyroclastic flow. Coulomb stress analysis affects the direction of prioclastic flow by as far as 180o although it is not the same as the results in the field. This is because the peak of Sinabung has landslides in the southeast-south, thus opening a pyroclastic flow road to the southeast-south.
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Petrik, Attila, Barbara Beke, László Fodor et Réka Lukács. « Cenozoic structural evolution of the southwestern Bükk Mts. and the southern part of the Darnó Deformation Belt (NE Hungary) ». Geologica Carpathica 67, no 1 (1 février 2016) : 83–104. http://dx.doi.org/10.1515/geoca-2016-0005.

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Abstract Extensive structural field observations and seismic interpretation allowed us to delineate 7 deformation phases in the study area for the Cenozoic period. Phase D1 indicates NW–SE compression and perpendicular extension in the Late Oligocene–early Eggenburgian and it was responsible for the development of a wedge-shaped Paleogene sequence in front of north-westward propagating blind reverse faults. D2 is represented by E–W compression and perpendicular extension in the middle Eggenburgian–early Ottnangian. The D1 and D2 phases resulted in the erosion of Paleogene suites on elevated highs. Phase D2 was followed by a counterclockwise rotation, described in earlier publications. When considering the age of sediments deformed by the syn-sedimentary D3 deformation and preliminary geochronological ages of deformed volcanites the time of the first CCW rotation can be shifted slightly younger (~17–16.5 Ma) than previously thought (18.5–17.5 Ma). Another consequence of our new timing is that the extrusional tectonics of the ALCAPA unit, the D2 local phase, could also terminate somewhat later by 1 Myr. D4 shows NE–SW extension in the late Karpatian–Early Badenian creating NW–SE trending normal faults which connected the major NNE–SSW trending sinistral faults. The D5 and D6 phases are late syn-rift deformations indicating E–W extension and NW–SE extension, respectively. D5 indicates syn-sedimentary deformation in the Middle Badenian–early Sarmatian and caused the synsedimentary thickening of mid-Miocene suites along NNE–SSW trending transtensional faults. D5 postdates the second CCW rotation which can be bracketed between ~16–15 Ma. This timing is somewhat older than previously considered and is based on new geochronological dates of pyroclastite rocks which were not deformed by this phase. D6 was responsible for further deepening of half-grabens during the Sarmatian. D7 is post-tilt NNW–SSE extension and induced the deposition of the 700 m thick Pannonian wedge between 11.6–8.92 Ma in the southern part of the study area.
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Byron, Benjamin D., Catherine M. Elder, Timothy D. Glotch, Paul O. Hayne, Lori M. Pigue et Joshua T. S. Cahill. « Evidence for Fine-grained Material at Lunar Red Spots : Insights from Thermal Infrared and Radar Data Sets ». Planetary Science Journal 4, no 9 (1 septembre 2023) : 182. http://dx.doi.org/10.3847/psj/acf134.

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Abstract Lunar red spots are small spectrally red features that have been proposed to be the result of non-mare volcanism. Studies have shown that a number of red spots are silicic, and are spectrally distinct from both highlands and mare compositions. In this work, we use data from LRO Diviner, Mini-RF, and Arecibo to investigate the material properties of 10 red spots. We create albedo maps using Diviner daytime solar reflectance data to use as an input to our improved thermophysical model, and calculate the rock abundance (RA) and H-parameter values that best fit Diviner nighttime thermal infrared radiance measurements. The H-parameter can be considered analogous to the thermal inertia of the regolith, with a high H-parameter corresponding to low thermal inertia. We find that the red spots generally have low RA, and do not have a uniform H-parameter but contain localized regions of high H-parameter. We additionally find that the red spots have a low circular polarization ratio (CPR) in many of the same locations that show a low RA and high H-parameter. Low RA, high H-parameter, and low CPR indicate a relative lack of rocks larger than ∼10 cm, which is consistent with previous findings of a mantling of fine-grained pyroclastic material for at least three red spots. Areas with high H-parameter but that do not show clear signs of pyroclastics in other data sets may be evidence of previously undiscovered pyroclastics, or could be due to the unique physical properties (e.g., porosity, rock strength/breakdown resistance) of the rocks that make up the red spots.
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Chékaraou, Mahamane M. S., et Moussa Konaté. « Permian Ages of “Younger Granites” from Mounio Province (Gouré area, Southeastern Niger) ». European Journal of Environment and Earth Sciences 2, no 6 (8 décembre 2021) : 27–35. http://dx.doi.org/10.24018/ejgeo.2021.2.6.220.

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African formations intruded by the “Younger Granites” ring complex. In the study area, the “Younger Granites” are represented by volcanic to acid plutonic rocks with hyperalkaline trends (pyroclastic rocks, rhyolites, microgranites, granites, syenites), forming in the North, a circular structure called Gouré ring complex. Preliminary geochronological datings of the Mounio granites have yielded Carboniferous ages. However, recent investigations carried out in this province have identified structures similar to Pan-African deformation structures, such as folds and several generations of schistosity/foliation. Analysis of the relationship between deformation and magmatism has removed any ambiguity regarding the relative age of the deformation. This study focuses on the radiometric dating of the “Younger Granites” of Gouré area, in order to update the geochronological data. Thus, three samples (pyroclastitic rock, rhyolite, microgranite) were dated by the K-Ar method on total rock using a mass spectrometertype MI 1201 IG. Radiometric dating results assign a Lower Permian age (293-287 Ma) to the “Younger Granites” Ring Complex of the Mounio Province in Niger, classically considered to be Carboniferous in age.
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Thèses sur le sujet "Pyroclastite"

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Hughes, Simon. « Transport and deposition in pyroclastic surges ». Thesis, Cardiff University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340837.

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Tremblay, Élisabeth. « Sédimentologie des volcanoclastites de la formation de Beauceville, Appalaches du Québec / ». Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1997. http://theses.uqac.ca.

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Rowley, Pete. « Analogue modelling of pyroclastic density current deposition ». Thesis, Royal Holloway, University of London, 2010. http://repository.royalholloway.ac.uk/items/88a78dfe-a825-5663-2af7-835ddd9f4cb3/8/.

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A series of analogue flume experiments are used to investigate initiation, flow and deposition of static piles of polymict materials, the sorting during transport, and the three dimensional geometry of the resulting deposits. Sequential charges are used to investigate the effects and extent of reworking. The particle heterogeneity is designed to simulate typical PDC make-up, with analogues for juvenile pumice and lithic clasts, as well as the fine-grained pumiceous material which makes up the bulk of the flow. Analogue flume experiments are used to investigate the generation of complex facies variations typical of pyroclastic density current (PDC) deposits. Polymict charges are developed to behave as analogues for the particle size and density contrasts present in PDC (i.e. lithic and juvenile pumice clasts), and investigate the effect of granular sorting during flow on the geometry of deposit architectures. Multiple charges are used to simulate pulses or sequences of separate PDC in order to assess the extent and effects of reworking. 3D visualisation of the resulting deposits reveals stratigraphies analogous to those seen in PDC, including pumice ‘rafting' or over-passing and inverse grading of pumice, and normal grading of lithics by simple gravitational granular sorting. Reworking between differentially-coloured layers makes several complex shear-derived Kelvin-Helmholtz instability features apparent, from fully developed rotational eddies, to less developed recumbent flame structures. The implications for the formation of these in PDC are assessed, including the potential influences on temperature proxy data, radiogenic dating by included phenocrysts (40Ar/39Ar) or charcoals (14C), calculation of eruptive volumes, sedimentation rates and flow velocity.
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Douillet, Guilhem Amin. « Flow and sedimentation of pyroclastic density currents ». Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-182857.

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Calarge, Liane Maria. « Etude minéralogique et géochimique des bentonites du sud du bassin du Parana (Acegua, Brésil et Melo, Uruguay) ». Poitiers, 2001. http://www.theses.fr/2001POIT2320.

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Les séries Permiennes du bassin du Paraná contiennent des tonsteins et des bentonites dans la région sud du Rio Grande do Sul (Acegua, Brésil) et nord de l'Uruguay (Melo). Une bentonite massive de couleur rose est formée de montmorillonite calcique très bien cristallisée: ([Si3. 94 Al0. 06] O10 (Al1. 40 Fe3+0. 11 Ti0. 02 Mg0. 49 Mn0. 01) (OH)2 Na0. 01 K0. 08 Ca0. 18). La smectite est composées de 5 types différents de feuillets suivant leur degré d'expandibilité après saturation Ca, K puis K-Ca. Les élements imcompatibles représentés dans les "spider diagrams" indiquent que les cendres ont la composition d'un verre rhyolitique à Melo et d'une rhyo-dacite tholeitique à Aceguá. La bentonite de Melo est formée de deux dépôts volcaniques. La teneur en calcium des smectites montre que les cendres se sont déposées dans des eaux lagunaires sur-saturées vis-à-vis de la calcite
Some tonsteins and bentonite beds are interlaminated in the Permian sedimentary formations of the Parana Basin. Two bentonite beds have been studied in Acegua (Brazil, RS) and Melo (Uruguay. They form massive pink layers, the composition of which is nearly monomineralic: pure well crystallized montmorillonite ([Si3. 94 Al0. 06] O10 (Al1. 40 Fe3+0. 11 Ti0. 02 Mg0. 49 Mn0. 01) (OH)2 Na0. 01 K0. 08 Ca0. 18). According to expandability differences in the Ca-, K- and K-Ca-saturated states, the smectite appears to be composed of 5 types of layers. Spider diagrams show that the montmorillonite derives from rhylotic and rhyo-dacitic volcanic glass at Melo and Acegua respectively. The bentonite bed of Melo result from the alteration of two ash deposits. The high amounts of calcium in smectites is due to alteration in lagoon water oversaturated with respect to calcite
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Calder, Eliza Shona. « Dynamics of small to intermediate volume pyroclastic flows ». Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297925.

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Kaminski, Édouard. « Deux aspects de la dynamique des fluides géologiques : (1) : le volcanisme explosif (2) : les panaches thermiques laminaires et leur interaction avec la lithosphère ». Paris 7, 1997. http://www.theses.fr/1997PA077237.

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Cette thèse comporte deux parties, une de volcanologie, l'autre de géodynamique mantellique. Le chapitre 1 débute la partie volcanologie. Il développe un modèle de dynamique des fluides pour la dilatation et le figeage des ponces lors d'une éruption plinienne, en fonction de la viscosité du magma. Ce modèle permet d'utiliser les mesures de vésicularité pour contraindre les taux de décompression et de refroidissement atteints pendant l'éruption. Le chapitre 2 étudie la dispersion des éjecta éruptifs et montre que cette dispersion suit une loi puissance. Des expériences de fragmentation illustrent l'origine possible de cette distribution. Le chapitre 3 utilise cette distribution pour étudier la transition plinien/pyroclastique pendant une éruption. On montre que la distribution contrôle la teneur en cendres qui elle même contrôle la teneur en gaz dans l'écoulement et l'évolution thermique de la mixture. Un critère réaliste est établi pour la transition. Le chapitre 4 débute la partie géodynamique. Il étudie la subsidence de quatre bassins intracratoniques d'Amérique du nord. Un modèle thermomécanique axisymétrique permet de décrire la perturbation thermique à l’ origine de ces bassins. Le chapitre 5 propose des lois d'échelle théoriques pour la dynamique des panaches thermiques laminaires. Ces lois sont expérimentalement et numériquement testées en fonction du nombre de prandtl du fluide. Dans le dernier chapitre, ces lois sont utilisées pour l'interprétation d'expériences analogiques d'amincissement d'un solide par un panache. Les résultats sont alors testes sur les 4 bassins du chapitre 4.
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Metrich, Nicole. « Mécanismes d'évolution à l'origine des magmas potassiques d'Italie centrale et méridionale : exemples du Mont Somma-Vésuve, des Champs Phlégréens et de l'île de Ventotène / ». Saclay : Centre d'études nucléaires, Laboratoire Pierre Süe, 1985. http://catalogue.bnf.fr/ark:/12148/cb348682408.

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Whitham, A. G. « Transport and deposition of pyroclastic materials in subaqueous environments ». Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355512.

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Lagmay, Alfredo Mahar Francisco Amante. « Studies on explosive eruptions and emplacement of pyroclastic flows ». Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.622006.

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Livres sur le sujet "Pyroclastite"

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Schneider, Jean-Luc. Obispo Formation, California : Remobilized pyroclastic material. [Washington : U.S. G.P.O., 1996.

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Shimron, Aryeh E. Early Cretaceous pyroclastic volcanism on the Hermon Range. Jerusalem : Geological Survey of Israel, 1993.

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Branney, M. J. Pyroclastic density currents and the sedimentation of ignimbrites. London : Geological Society, 2002.

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Crandell, Dwight Raymond. Deposits of pre-1980 pyroclastic flows and lahars from Mount St. Helens volcano, Washington. [Reston, Va.?] : Dept. of the Interior, U.S. Geological Survey, 1988.

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Daag, Arturo Santos. Modelling the erosion of pyroclastic flow deposits and the occurrences of lahars at Mt. Pinatubo, Philippines. Enschede : International Institute for Geoinformation Science and Earth Observation, 2003.

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D, Ayres L., et Geological Association of Canada, dir. Pyroclastic volcanism and deposits of cenozoic intermediate to felsicvolcanic islands : With implications for precambrian greenstone-belt volcanoes. Ann Arbor : U.M.I., 1987.

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Conkin, James Elvin. Disconformities and weathered pyroclastics : Tools for determining age relationships of the Devonian oil shales of eastern North America. Louisville, Ky : Dept. of Geology, University of Louisville, 1987.

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Crandell, Dwight Raymond. Deposits of pre-1980 pyroclastic flows and lahars from Mount St. Helens volcano, Washington : Lithology and stratigraphy of unconsolidated deposits, other than air-fall tephra, formed by eruptions during the past 40,000 years. Washington, DC : U.S. Dept. of Interior, 1987.

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Crandell, Dwight Raymond. Deposits of pre-1980 pyroclastic flows and lahars from Mount St. Helens volcano, Washington : Lithology and stratigraphy of unconsolidated deposits, other than air-fall tephra, formed by eruptions during the past 40,000 years. Washington : U.S. G.P.O., 1987.

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Pyroclastic Rocks. Springer, 2011.

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Chapitres de livres sur le sujet "Pyroclastite"

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Buchwaldt, Robert. « Pyroclastic Flow ». Dans Encyclopedia of Natural Hazards, 791–96. Dordrecht : Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-1-4020-4399-4_281.

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Dobran, Flavio. « Pyroclastic Dispersions ». Dans Volcanic Processes, 487–536. Boston, MA : Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0647-8_7.

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Brož, Petr. « Pyroclastic Cone ». Dans Encyclopedia of Planetary Landforms, 1–6. New York, NY : Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4614-9213-9_283-1.

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Filiberto, Justin. « Pyroclastic Deposits ». Dans Encyclopedia of Planetary Landforms, 1–11. New York, NY : Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4614-9213-9_284-1.

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Brož, Petr. « Pyroclastic Cone ». Dans Encyclopedia of Planetary Landforms, 1660–64. New York, NY : Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4614-3134-3_283.

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Filiberto, Justin. « Pyroclastic Deposits ». Dans Encyclopedia of Planetary Landforms, 1665–73. New York, NY : Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4614-3134-3_284.

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Bennett, Kristen, et James F. Bell. « Pyroclastic Deposits, Remote Sensing of ». Dans Encyclopedia of Lunar Science, 1–7. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-05546-6_117-1.

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Bevilacqua, Andrea. « Pyroclastic density current invasion maps ». Dans Doubly Stochastic Models for Volcanic Hazard Assessment at Campi Flegrei Caldera, 61–94. Pisa : Scuola Normale Superiore, 2016. http://dx.doi.org/10.1007/978-88-7642-577-6_3.

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Bennett, Kristen, et James F. Bell. « Pyroclastic Deposits, Remote Sensing of ». Dans Encyclopedia of Lunar Science, 989–95. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-319-14541-9_117.

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Cas, R. A. F., et J. V. Wright. « Crystal-rich volcaniclastics—pyroclastic or epiclastic ? » Dans Volcanic Successions Modern and Ancient, 332–47. Dordrecht : Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-3167-1_11.

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Actes de conférences sur le sujet "Pyroclastite"

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Pellegrino, A. M., A. Scotto di Santolo, A. Evangelista et P. Coussot. « Rheological behaviour of pyroclastic debris flow ». Dans DEBRIS FLOW 2010. Southampton, UK : WIT Press, 2010. http://dx.doi.org/10.2495/deb100051.

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Allen, Carlton. « Oxygen Production from Lunar Pyroclastic Deposits ». Dans ASCEND 2021. Reston, Virginia : American Institute of Aeronautics and Astronautics, 2021. http://dx.doi.org/10.2514/6.2021-4236.

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Moura, Rui, Ana Cristina Pires, Marina Cabral Pinto et Joao Carlos Nunes. « GENERAL CHARACTERISTICS OF THE CAPELINHOS VOLCANO (AZORES ISLANDS, PORTUGAL) AS A NEW PLANETARY ANALOG SITE AIMED AT SPACE EXPLORATION RESEARCH ». Dans 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/1.1/s05.68.

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Volcanic sites on Earth provide valuable insights into the geological processes that shape our planet and can also serve as effective analogs for studying similar volcanic activity on other celestial bodies, such as the Moon. This work aims to discuss the general characterization of the Capelinhos volcanic site, in the archipelago of Azores in Portugal, showing the potential as a planetary analog. It�s barren landscape, covered with pyroclastic rocks can lend itself the purpose of becoming a lunar planetary analog site, possibly even a Martian site. This geological site was formed during an eruption that occurred in 1957-58, thus the vegetation is practically absent. By examining the physical and chemical properties of its pyroclastic rocks, as well as the associated volcanic landforms, researchers of different fields can better understand lunar volcanic activity and its implications for many aspects of future lunar exploration. Although its origin is different from most of the locations on the lunar surface, since it doesn�t contemplate the impactism originated regolith characteristics and associated geomorphology, it does resemble this setting for a broad range of research objectives.
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Hadiyanto, Imam Fikri, Dina Hanifah et Wildan Nur Hamzah. « Distribution of Volcanic Rocks Porosity of Dissected Kromong Paleovolcano : Analogue of Volcanic Reservoir ». Dans International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21240-ms.

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Abstract The potentiality of unconventional play on the volcanic reservoir was evaluated for the purpose to deliver an integrated evaluation of shallow reservoir target associated with the Northwest Java Basin (NWJB). This study provides basis discovery for further exploration and dissemination of volcanic reservoir by presenting an overview of geometric and porosity type analysis of Kromong paleo-volcano complex deposits associated with the NWJB comprehensively. Furthermore, reservoir lithofacies and pore space deployment of Kromong volcanic deposits were studied. The detailed lithofacies analysis was carried out based on field observations from several dissected- and obscure dipping-outcrops in Kromong area associated with NWJB. Following this, a set of outcrop samples were processed for megascopic description integrated with thin-section analysis by using the polarized light microscope and XRF, respectively to assess different types of reservoir pore spaces and structure. Subsequently, the physical properties-porosity measurement was conducted using ImageJ software tools to understand the potentiality of high-quality reservoir formation. The results of this study show that rocks in Kromong area associated with NWJB can be comprehensively classified into reefal limestone for carbonate deposit and into 4 categories, including volcaniclastic lava, sheeting joint lava, pyroclastic breccia, volcanic intrusion, for volcanic deposits. The proposed volcanic reservoirs of volcanic play in this study are lithologically composed of autobreccia lava, sheeting joint lava, pyroclastic breccia to andesitic- and andescitic-dikes, which comprises explosive facies and intrusive facies. Pyroclastic breccia reservoirs are primary pore-type reservoirs with devitrified micropores as main reservoir space. Whilst volcanic dikes reservoirs are mainly porous-fractured-type reservoirs with cooling fracture porosity. In conclusion, following factors that control the presence of a volcanic reservoir are lithology, lithofacies, tectonism and vulcanism. Despite worldwide discoveries of volcanic reservoirs, neither the detailed potentiality evaluation nor the postulated assumption of volcanic reservoir development in NWJB field has been examined sufficiently. This contribution offers knowledge benefits by discussing the potentiality of the Cenozoic-Quarternary volcanic reservoir of the NWJB field and providing a reference for future exploration in the petroleum industry.
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Houghton, B. F., T. R. Orr, J. Taddeucci et R. J. Carey. « STYLES OF PYROCLASTIC ACTIVITY AT KīLAUEA, 2011-2017 ». Dans 113th Annual GSA Cordilleran Section Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017cd-292652.

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Houghton, B. F., Donald A. Swanson, Tim R. Orr, Matthew Patrick et Rebecca Carey. « EXPLAINING DIVERSITY IN RECENT PYROCLASTIC ERUPTIONS AT KĪLAUEA, HAWAII ». Dans GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-284171.

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ONGARO, T. ESPOSTI, C. CAVAZZONI, G. ERBACCI, A. NERI et G. MACEDONIO. « PARALLEL NUMERICAL SIMULATION OF PYROCLASTIC FLOW DYNAMICS AT VESUVIUS ». Dans Proceedings of the International Conference ParCo2001. PUBLISHED BY IMPERIAL COLLEGE PRESS AND DISTRIBUTED BY WORLD SCIENTIFIC PUBLISHING CO., 2002. http://dx.doi.org/10.1142/9781860949630_0016.

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Itakura, Yasumasa. « Observation system of pyroclastic flow with digital video-image processing ». Dans 17th Congress of the International Commission for Optics : Optics for Science and New Technology. SPIE, 1996. http://dx.doi.org/10.1117/12.2316247.

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Kyle, Philip R., Ted L. Eggleston, William C. McIntosh, Nelia Dunbar, Charles M. Hammond, W. David Johnson, Michael Knoper et Judith Moore. « Pyroclastic rocks associated with the Taylor Creek Rhyolite, Scales Canyon ». Dans 37th Annual Fall Field Conference. New Mexico Geological Society, 1986. http://dx.doi.org/10.56577/ffc-37.197.

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Whalen, Patrick James, et Frank R. Ettensohn. « EVALUATING PYROCLASTIC SEDIMENTARY ROCKS : EXAMPLES FROM THE OLIGOCENE OF CENTRAL COLORADO ». Dans 65th Annual Southeastern GSA Section Meeting. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016se-271967.

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Rapports d'organisations sur le sujet "Pyroclastite"

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G.A. Valentine et C.D. Harrington. DESERT PAVEMENTS AND SOILS ON BASALTIC PYROCLASTIC DEPOSITS AT LATHROP WELLS AND RED CONE VOLCANOES, SOUTHERN NEVADA. Office of Scientific and Technical Information (OSTI), août 2005. http://dx.doi.org/10.2172/859265.

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Corriveau, L., et A. L. Bonnet. Volcanisme pyroclastique protérozoïque dans le Groupe de Wakeham, région des lacs Musquaro et d'Auteuil, Province de Grenville, Québec. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2001. http://dx.doi.org/10.4095/212172.

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G.A. Valentine et C.D. Harrington. DESERT PAVEMENTS AND SOILS ON BASALTIC PYROCLASTIC DEPOSITS AT LATHROP WELLS AND RED CONE VOLCANOES, SOUTHERN NEVADA ABSTRACT. Office of Scientific and Technical Information (OSTI), août 2005. http://dx.doi.org/10.2172/884942.

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Woldegabriel, Giday, Elizabeth D. Miller, Richard E. Kelley et Emily S. Schultz-Fellenz. Geochemistry, extent, signatures, and chronology of basaltic and young silicic pyroclastic eruptions : Refining existing data to support a future volcanic hazards assessment of LANL. Office of Scientific and Technical Information (OSTI), mai 2013. http://dx.doi.org/10.2172/1079548.

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Geologic maps of pyroclastic-flow and related deposits of the 1980 eruptions of Mount St. Helens, Washington. US Geological Survey, 1990. http://dx.doi.org/10.3133/i1950.

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Age of the Lospe Formation (early Miocene) and origin of the Santa Maria Basin, California. Petroleum source potential and thermal maturity of the Lospe Formation (lower Miocene) near Point Sal, onshore Santa Maria Basin, California. Obispo Formation, California ; remobilized pyroclastic material. US Geological Survey, 1996. http://dx.doi.org/10.3133/b1995mno.

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