scholarly journals Chlorine heterogeneity in volcanic glass as a faithful record of silicic magma degassing

2021 ◽  
Author(s):  
Shumpei Yoshimura ◽  
Mitsuhiro Nakagawa
Keyword(s):  
Volcanic Glass ◽  
Silicic Magma ◽  
Magma Degassing

scholarly journals Fingerprint of silicic magma degassing visualised through chlorine microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shumpei Yoshimura ◽  
Takeshi Kuritani ◽  
Akiko Matsumoto ◽  
Mitsuhiro Nakagawa
Keyword(s):  
Silicic Magma ◽  
Magma Degassing

DIFFUSION CHRONOMETRY IN SANIDINE: HELPING UNRAVEL THERMAL HISTORIES OF LARGE SILICIC MAGMA RESERVOIRS

2019 ◽  
Author(s):  
Jordan Lubbers ◽  
◽  
Adam J.R. Kent ◽  
Frank Tepley ◽  
Dawid Szymanowski
Keyword(s):  
Silicic Magma ◽  
Diffusion Chronometry ◽  
Magma Reservoirs ◽  
Thermal Histories

scholarly journals Mineralogical and Geochemical Signatures of Metalliferous Sediments in Wocan-1 and Wocan-2 Hydrothermal Sites on the Carlsberg Ridge, Indian Ocean

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 26 ◽  
Author(s):  
Samuel Olatunde Popoola ◽  
Xiqiu Han ◽  
Yejian Wang ◽  
Zhongyan Qiu ◽  
Ying Ye ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Volcanic Glass ◽  
Mineral Chemistry ◽  
Hydrothermal Systems ◽  
Bulk Sediment ◽  
Sediment Samples ◽  
Metalliferous Sediments ◽  
Metalliferous Sediment ◽  
Carlsberg Ridge ◽  
Hydrothermal Environments

In this paper, we conduct a comparative study on the mineralogy and geochemistry of metalliferous sediment collected near the active hydrothermal site (Wocan-1) and inactive hydrothermal site (Wocan-2) from Wocan Hydrothermal Field, on the Carlsberg Ridge (CR), northwest Indian Ocean. We aim to understand the spatial variations in the primary and post-depositional conditions and the intensity of hydrothermal circulations in the Wocan hydrothermal systems. Sediment samples were collected from six stations which includes TVG-07, TVG-08 (Wocan-1), TVG-05, TVG-10 (Wocan-2), TVG-12 and TVG-13 (ridge flanks). The mineralogical investigations show that sediment samples from Wocan-1 and Wocan-2 are composed of chalcopyrite, pyrite, sphalerite, barite, gypsum, amorphous silica, altered volcanic glass, Fe-oxides, and hydroxides. The ridge flank sediments are dominated by biogenic calcite and foraminifera assemblages. The bulk sediment samples of Wocan-1 have an elevated Fe/Mn ratio (up to ~1545), with lower U contents (<7.4 ppm) and U/Fe ratio (<~1.8 × 10−5). The sulfide separates (chalcopyrite, pyrite, and sphalerite) are enriched in Se, Co, As, Sb, and Pb. The calculated sphalerite precipitation temperature (Sph.PT) yields ~278 °C. The sulfur isotope (δ34S) analysis returned a light value of 3.0–3.6‰. The bulk sediment samples of Wocan-2 have a lower Fe/Mn ratio (<~523), with high U contents (up to 19.6 ppm) and U/Fe ratio (up to ~6.2 × 10−5). The sulfide separates are enriched in Zn, Cu, Tl, and Sn. The calculated Sph.PT is ~233 °C. The δ34S returned significant values of 4.1–4.3‰ and 6.4–8.7‰ in stations TVG-10 and TVG-05, respectively. The geochemical signatures (e.g., Fe/Mn and U/Fe ratio, mineral chemistry of sulfides separates, and S-isotopes and Sph.PT) suggest that sediment samples from Wocan-1 are located near intermediate–high temperature hydrothermal discharge environments. Additionally, relatively low δ34S values exhibit a lower proportion (less than 20%) of seawater-derived components. The geochemical signatures suggest that sediment samples from Wocan-2 has undergone moderate–extensive oxidation and secondary alterations by seawater in a low–intermediate temperature hydrothermal environments. Additionally, the significant δ34S values of station TVG-05 exhibit a higher estimated proportion (up to 41%) of seawater-derived components. Our results showed pervasive hydrothermal contributions into station TVG-08 relative to TVG-07, it further showed the increased process of seafloor weathering at TVG-05 relative to TVG-10.

scholarly journals Obsidian and Obsidian-like Glass Tesserae: A Multidisciplinary Approach to Study the Dedication Wall Mosaic in the Church of St. Mary of the Admiral in Palermo (12th Century)

2020 ◽  
Vol 6 (1) ◽  
pp. 403-416
Author(s):  
Valentina Cantone ◽  
Rita Deiana ◽  
Alberta Silvestri ◽  
Ivana Angelini
Keyword(s):  
Multidisciplinary Approach ◽  
Multispectral Imaging ◽  
Volcanic Glass ◽  
Research Topic ◽  
Multidisciplinary Study ◽  
12Th Century ◽  
Challenging Research ◽  
Byzantine Period ◽  
Dark Glass ◽  
The Church

AbstractPliny the Elder testifies that roman workshops used volcanic glass (obsidian), but also produced and used a dark glass (obsidian-like glass) quite similar to the natural one. In the context of the study on medieval mosaics, the use of the obsidian and obsidian-like tesserae is a challenging research topic. In this paper, we present the results of a multidisciplinary study carried out on the Dedication wall mosaic, realized by a byzantine workshop in the 12th century in the Church of St. Mary of the Admiral in Palermo, and where numerous black-appearing tesserae, supposed to be composed of obsidian by naked-eyes observation, are present. Historical documents, multispectral imaging of the wall mosaic, and some analytical methods (SEM-EDS and XRPD) applied to a sample of black tesserae, concur in identifying here the presence of obsidian and different obsidian-like glass tesserae. This evidence, although related to the apparent tampering and restoration, could open a new scenario in the use of obsidian and obsidian-like glass tesserae during the Byzantine period in Sicily and in the reconstruction of multiple restoration phases carried out between 12th and 20th century AD on the mosaics of St. Mary of the Admiral.

scholarly journals New Deposit of Mordenite–Clinoptilolite in the Eastern Region of Cuba: Uses as Pozzolans

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4676
Author(s):  
Jorge Luis Costafreda ◽  
Domingo Alfonso Martín
Keyword(s):  
Effective Properties ◽  
Volcanic Glass ◽  
Heat Of Hydration ◽  
Quality Analysis ◽  
Insoluble Residue ◽  
Eastern Region ◽  
Secondary Phases ◽  
X Ray ◽  
Industrial Manufacturing ◽  
Hydration Resistance

This work describes the newly discovered zeolites in the eastern region of Cuba. In the researched area, there have been no previous studies of natural zeolite exploration. Therefore, the results shown here are new. The main object of this research is to analyse five samples of zeolites and demonstrate their pozzolanic capacity and the possibility of their usage in the industrial manufacturing of pozzolanic cements. The study of the samples was performed by X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM). A chemical analysis (CAQ) to determine the quality of the samples as pozzolans was performed, by determining the total SiO2, reactive SiO2, total CaO, reactive CaO, Al2O3, MgO and the insoluble residue (I.R.). Lastly, an eight-day pozzolanicity analysis (PA) was carried out to determine the pozzolanic reactivity of the samples. The results obtained by XRD, XRF and SEM established that the researched zeolite samples have two main zeolitic phases: mordenite and clinoptilolite. Altered volcanic glass, quartz and smectite (montmorillonite) are the secondary phases. The results of the chemical quality analysis (CAQ) showed that the samples contain a considerable amount of reactive SiO2 and reactive CaO, as well as a low content of insoluble residue, which reinforces their properties as pozzolans. The results of the pozzolanicity analysis (PA) concluded that the analysed samples actively react with Ca(OH)2 after eight days. Based on all the results mentioned above, it is established that both mordenite and clinoptilolite behave like pozzolans and can be recommended for the manufacture of pozzolanic cements, which have more effective properties than Portland cement, in terms of physical, chemical and mechanical strength, low heat of hydration, resistance to sulphates, low CO2 emissions to the atmosphere and negligible impacts on the environment.

Volcanic Glass as a Natural Analog for Borosilicate Waste Glass

1993 ◽  
Vol 333 ◽  
Author(s):  
Maury E. Morgenstein ◽  
Don L. Shettel
Keyword(s):  
Silica Glass ◽  
Glass Structure ◽  
Volcanic Glass ◽  
Waste Glass ◽  
Tensile Failure ◽  
Tensile Fracture ◽  
Failure Behavior ◽  
Basaltic Glass ◽  
Glass Waste ◽  
Natural Analog

ABSTRACTObsidian and basaltic glass are opposite end-members of natural volcanic glass compositions. Syngenetic and diagenetic tensile failure in basaltic glass (low silica glass) is pervasive and provides abundant alteration fronts deep into the glass structure. Perlitic fracturing in obsidian (high silica glass) limits the alteration zones to an “onion skin” geometry. Borosilicate waste glass behaves similarly to the natural analog of basaltic glass (sideromelane).During geologic time, established and tensile fracture networks form glass cells (a three-dimensional reticulated pattern) where the production of new fracture surfaces increases through time by geometric progression. This suggests that borosilicate glass monoliths will eventually become rubble. Rates of reaction appear to double for every 12C° of temperature increase. Published leach rates suggest that the entire inventory of certain radionuclides may be released during the 10,000 year regulatory time period. Steam alteration prior to liquid attack combined with pervasive deep tensile failure behavior may suggest that the glass waste form is not license defensible without a metallic- and/or ceramic-type composite barrier as an overpack.

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