Cette recherche s'applique uniquement aux ressources en bibliothèque.
26 résultats
Trier par:
Ajouter à la liste:
    • Plusieurs versions

    Earth's dynamic systems

    Hamblin, William Kenneth
    • Plusieurs versions

    Petrogenesis of the Darvazeh mafic-intermediate intrusive bodies, Qorveh, Sanandaj-Sirjanzone, Iran

    Yeganeh, Tahereh Molaei, Torkian, Ashraf, Christiansen, Eric H., Sepahi, Ali A.
    Arabian Journal of Geosciences, 5/2018, Vol.11(9) [Revue évaluée par les pairs]

    • Plusieurs versions

    Petrogenesis of Sierra Nevada plutons inferred from the Sr, Nd, and O isotopic signatures of mafic igneous complexes in Yosemite Valley, California

    Nelson, Wendy, Dorais, Michael, Christiansen, Eric, Hart, Garret
    Contributions to Mineralogy and Petrology, 2013, Vol.165(2), pp.397-417 [Revue évaluée par les pairs]

    • Plusieurs versions

    Implications of dune pattern analysis for Titan’s surface history

    Savage, Christopher J, Radebaugh, Jani, Christiansen, Eric H, Lorenz, Ralph D
    Icarus, 15 February 2014, Vol.230, pp.180-190 [Revue évaluée par les pairs]

    • Article

    Contrasting processes in silicic magma chambers: evidence from very large volume ignimbrites

    Christiansen, Eric H.
    Geological Magazine, 2005, Vol.142(6), pp.669-681 [Revue évaluée par les pairs]
    Cambridge University Press
    Titre: Contrasting processes in silicic magma chambers: evidence from very large volume ignimbrites
    Auteur: Christiansen, Eric H.
    Sujet: Magma -- Environmental Aspects ; Igneous Rocks -- Environmental Aspects ; Crystallization -- Environmental Aspects;
    Description: Very large volume (1000 km of magma) crystal-rich dacitic ignimbrites that lack pronounced evidence of fractional crystallization or vertical zonation erupt in some continental magmatic arcs (e.g. the Lund Tuff of the Great Basin and the Fish Canyon Tuff of Colorado in western USA). Apparently, their magma chambers were only modestly heterogeneous and not systematically zoned from top to bottom. These ignimbrites have 40 to 50% phenocrysts set in a high-silica rhyolite glass. Mineral assemblages and mineral compositions suggest pre-eruption temperatures were 730 to 820C and water and oxygen fugacities were relatively high. We have speculated that these very large volume ignimbrites are unzoned because crystallization and convection in slab-shaped magma chambers inhibited separation of crystals from liquids and resulted in a chamber filled with compositionally heterogeneous magma that lacked systematic chemical zonation or strong fractionation. However, many other very large volume silicic ignimbrites are strongly fractionated and may be vertically zoned (e.g. tuffs related to the Yellowstone hotspot). These rhyolitic tuffs typically have few phenocrysts, anhydrous mineral assemblages, low oxygen fugacities, crystallization temperatures of 830 to 1050C, and a strong imprint of fractional crystallization. Yet these Yellowstone-type rhyolites are derived from chambers 40 to 70 km across which have sill-like shapes (depthdiameter ratios much less than 1). Thus, factors other than chamber shape must be important for establishing the degree of evolution and nature of zonation in silicic magma chambers. Here, the role of crystallinity-dependent viscosity on the evolution of these two types of contrasting magmas is explored. Calculated magma viscosities for the hot, dry, crystal-poor rhyolites are significantly lower than for the cooler, wetter, crystal-rich dacites. Perhaps these hot rhyolites had low enough crystal contents and viscosities to allow efficient crystalliquid separation, probably by a combination of unhindered crystal-settling, floor crystallization (including compaction), and crystallization on the walls of large chambers. Clean separation of melt from residual solids at their sources may have been promoted by their high temperatures and low viscosities (10 Pa s). In contrast, monotonous dacitic magmas may never have been crystal-free near-liquidus magmas. Their large magma chambers may have developed by progressive growth at a shallow level with repeated input of intermediate to silicic magma. Crystallization of the water-enriched dacitic magmas occurred at lower temperatures (800 C) where crystallinity and hence magma viscosity (10 Pa s) were significantly higher. These characteristics inhibited all forms of crystalliquid separation, hindered development of systematic vertical zonation, and promoted quasi-equilibrium crystallization in small domains within large heterogeneous magma chambers. Eruptions of these crystal-rich dacites may only occur if the roof fails over a growing magma chamber that is becoming increasingly molten.
    Fait partie de: Geological Magazine, 2005, Vol.142(6), pp.669-681
    Identifiant: 0016-7568 (ISSN); 1469-5081 (E-ISSN); 10.1017/S0016756805001445 (DOI)

    • Plusieurs versions

    Role of fluids in the tectonic evolution of Titan

    Liu, Zac Yung-Chun, Radebaugh, Jani, Harris, Ron A, Christiansen, Eric H, Rupper, Summer
    Icarus, 15 May 2016, Vol.270, pp.2-13 [Revue évaluée par les pairs]

    • Plusieurs versions

    Origins and evolution of rhyolitic magmas in the central Snake River Plain: insights from coupled high-precision geochronology, oxygen isotope, and hafnium isotope analyses of zircon

    Colón, Dylan P., Bindeman, Ilya N., Wotzlaw, Jörn-Frederik, Christiansen, Eric H., Stern, Richard A.
    Contributions to Mineralogy and Petrology, 2/2018, Vol.173(2) [Revue évaluée par les pairs]

    • Plusieurs versions

    Lineations and structural mapping of Io's paterae and mountains: Implications for internal stresses

    Ahern, Alexandra A, Radebaugh, Jani, Christiansen, Eric H, Harris, Ronald A, Tass, E. Shannon
    Icarus, 15 November 2017, Vol.297, pp.14-32 [Revue évaluée par les pairs]

    • Plusieurs versions

    Evidence for Cyclical Fractional Crystallization, Recharge, and Assimilation in Basalts of the Kimama Drill Core, Central Snake River Plain, Idaho: 5.5-Million-Years of Petrogenesis in a Mid-crustal Sill Complex

    Potter, Katherine E, Shervais, John W, Christiansen, Eric H, Vetter, Scott K
    Frontiers in Earth Science, 16 February 2018, Vol.6 [Revue évaluée par les pairs]

    • Plusieurs versions

    Drilling Into the Track of the Yellowstone Hot Spot

    Shervais, John W., Evans, James P., Schmitt, Douglas R., Christiansen, Eric H., Prokopenko, Alexander
    Eos, Transactions American Geophysical Union, 11 March 2014, Vol.95(10), pp.85-86