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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of volcanology 60 (1999), S. 595-609 
    ISSN: 1432-0819
    Keywords: Key words Hawaiian basalt ; Pāhoehoe ; ‘a‘ā transition ; Textural characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Pāhoehoe and ‘a‘ā are the most common surface morphologies in basaltic lava flows, yet no predictive models exist to link physical parameters of flow emplacement to changes in their surface textures and rheological properties. We have characterized changes of vesicularity, vesicle deformation, and crystallinity across the pāhoehoe–‘a‘ā transition as preserved in two different eruptions, a brief, high-velocity effusion of lava from Kīlauea Volcano on 1 February 1996, and a small breakout from an ephemeral vent within a larger channel produced during the 1868 eruption of Mauna Loa. This allowed us to compare conditions leading to the pāhoehoe–‘a‘ā transition for both open channel flow (Kīlauea 1996) and reactivation of lava from an ephemeral vent (Mauna Loa 1868). Textural changes across the transition include (a) decrease in vesicularity and vesicle number density, (b) increase in microlite crystallinity and crystal number density, and (c) increase in vesicle deformation. The results support past qualitative descriptions of the transition and highlight the importance of plagioclase crystallinity in controlling lava rheology and surface morphology.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2021-01-27
    Description: X-ray computed microtomography is an excellent tool for the three-dimensional analysis of rock microstructure. Digital images are acquired, visualized, and processed to identify and measure several discrete features and constituents of rock samples, by means of mathematical algorithms and computational methods. In this paper, we present digital images of volcanic rocks collected with X-ray computed microtomography techniques and studied by means of a software library, called Pore3D, custom-implemented at the Elettra Synchrotron Light Laboratory of Trieste (Italy). Using the Pore3D software, we analyzed the fabrics and we quantified the characteristics of the main constituents (vesicles, crystals, and glassy matrix) of four different types of pyroclasts: frothy pumice, tube pumice, scoria, and “crystalline” scoria. We identified the distinctive features of these different types of volcanic rocks. The frothy pumices show vesicles that coalesce in isotropic aggregates, especially toward the sample interior, while the scoriae have a low porosity and an abundance of isolated vesicles. In the “crystalline” scoria sample most of the vesicle separation is due to the presence of crystals of different types, while the tube pumice shows an anisotropic distribution of vesicles and crystals at the microscale, as also observed at the scale of the hand sample. Quantitative analysis and textural information may supply an additional tool to investigate the eruptive processes and the origin of volcanic rocks.
    Description: Published
    Description: 793-804
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: X-ray tomography ; 3D imaging ; volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2017-04-04
    Description: No abstract
    Description: Published
    Description: 468-469
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Geomaterials ; 3D imaging ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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