Search Results

You are looking at 1 - 10 of 315 items :

  • "ignimbrite" x
Clear All

SPECIAL COLLECTION: GLASSES, MELTS, AND FLUIDS, AS TOOLS FOR UNDERSTANDING VOLCANIC PROCESSES AND HAZARDS Volatiles in magmas related to the Campanian Ignimbrite eruption: Experiments vs. natural findings† Sara Fanara1,*, roman E. Botcharnikov1, Danilo m. PallaDino2, FranziSka aDamS1, Julia BuDDEnSiEck1, anDrEaS mulch3,4 anD haralD BEhrEnS1 1Institut für Mineralogie, Leibniz Universität Hannover, Callinstrasse 3, D-30167, Hannover, Germany 2Dipartimento di Scienze della Terra, Sapienza-Universitá di Roma, Piazzale Aldo Moro 5, 00185, Roma, Italy 3Biodiversität

Range. This granite batholith, here named the Wyoming batholith, is exposed in Laramide basement-involved uplifts that extend 200 km from east to west. It is everywhere composed of undeformed biotite granite, even though outcrops expose varying structural levels. We investigate its petrogenesis and its potential similarity to the granitic batholiths that are inferred to underlie large silicic ignimbrite provinces. Geologic setting The Neoarchean magmatic rocks of central Wyoming compose part of the Wyoming province, an Archean craton that extends across most of

geochemical trends of volcanic rocks from Campania, southern Italy. Ecolgae Geologicae Helvetie 63: 57–68. [9] Civetta L and Gasparini P, 1973. U and Th distributions in recent volcanics from southern Italy: magmatological and geophysical implications. Rivista Italiana di Geofisica XXII (3/4): 127–139. [10] Civetta L, Orsi G, Pappalardo L, Fisher RV, Heiken G and Ort M, 1997. Geochemical zoning, mingling, eruptive dynamics and depositional processes e the Campanian Ignimbrite, Campi Flegrei caldera, Italy. Journal of Volcanology and Geothermal Research 75(3–4): 183

at temperatures higher than 700 °C ( Kats 1962 ; Kronenberg et al. 1986 ), thus hydroxyl defects are supposed to be sensitive to changes in pre-eruptive P , T , or chemical activities. In spite of this, there are only sporadic data on the hydroxyl defect concentration in quartz crystals from volcanic systems. The first measurements of hydroxyl defect concentrations in ignimbrite-hosted quartz phenocryst fragments reported hydroxyl defect concentrations ranging from ~2.0 to ~4.1 ppm ( Biró et al. 2016 ), which is much lower than those in experimental quartz: 40

American Mineralogist, Volume 97, pages 1998–2006, 2012 0003-004X/12/1112–1998$05.00/DOI: http://dx.doi.org/10.2138/am.2012.4161 1998 Edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2, a new series of calcium humite-group minerals from altered xenoliths in the ignimbrite of Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia EvgEny v. galuskin,1,* Biljana lazic,2 Thomas armBrusTEr,2 irina o. galuskina,1 nikolai n. PErTsEv,3 vikTor m. gazEEv,3 Roman Włodyka,1 mateusz dulski,4 PiotR dzieRżanoWski,5 aleksandR e. zadov,6 and leonid s

pyroclastic deposit characteristics: Kos Plateau Tuff, eastern Aegean Sea, J. Volcanol. Geoth. Res., 2001, 105, 141–162 http://dx.doi.org/10.1016/S0377-0273(00)00222-5 [35] Yokoyama, S., Rapid formation of river terraces in non-welded ignimbrite along the Hishida River, Kyushu, Japan. Geomorphology, 1999, 30, 291–304 http://dx.doi.org/10.1016/S0169-555X(99)00037-9 [36] Allen S.R., Stadlbauer E., Keller J., Stratigraphy of the Kos Plateau Tuff: product of a major Quaternary explosive rhyolitic eruption in the eastern Aegean, Greece, int. J. Earth Sci., 1999, 88, 132–156 http

equations with improved accuracy for SiO 2 , TiO 2 , FeO, CaO, and K 2 O, compared with Ridolfi and Renzulli (2012) . The accuracy of our chemometric equations is tested using a second, independent experimental data set. Importantly, our formulations are independent of pressure and we propose models both with and without temperature terms. This brings significant advantages in application of the equations to natural systems. We apply the new equations to infer melt compositions coexisting with amphiboles erupted in the Ongatiti ignimbrite, Taupo Volcanic Zone, New

disequilibria of olivine crystals in large volume Holocene basalts from Iceland: Evidence for magmatic digestion and erosion of Pleistocene hyaloclastites, Geochimica et Cosmochimica Acta 72, 2008, 4397–4420 or][31] Stadlbauer E., Vulkanologishe-geochemische Analyse eines jungen Ignimbrites: Der Kos-Plateau-Tuff (Südost-Ägäis), PhD, Freiburg, 1988 [30] Smith P.E., Evensen N.M., York D., Under the volcano; a new dimension in Ar-Ar dating of volcanic ash, Geophysical Research Letters 27, 2000, 585–588 [31] Smith P.E., York D., Chen Y., Evensen N.M., Single crystal 40Ar/39Ar

caldera to investigate the nature of the mafic lineages in this area and consider their likely origins. The Huckleberry Ridge Tuff The ~2.08 Ma, ~2500 km 3 Huckleberry Ridge Tuff (HRT) is the product of the climactic eruption of the first of three volcanic cycles in the YPVF ( Christiansen 2001 ; Rivera et al. 2014 ; Singer et al. 2014 ; Wotzlaw et al. 2015 ). The HRT consists of initial fall deposits, which are overlain by three ignimbrite packages (members A, B, and C), with additional fall deposits beneath member C ( Christiansen 2001 ). The HRT eruption was

Quaternary silica-undersaturated lavas from Campi Flegrei (Naples, Italy). Samples studied comprise the pre- and post Campanian Ignimbrite (ca. 40 ka) lava domes of Cuma and Punta Marmolite, and Astroni and Accademia, respectively. The in situ sample preparation required initial identification of baddeleyite crystals from sawed and polished rock billets using scanning electron microscope (SEM) backscatter imaging and energy-dispersive X-ray analysis. U-Th baddeleyite isochron ages for intra-caldera Astroni and Accademia lava domes are 5.01+2.61–2.55 ka (MSWD = 2.0; n