scholarly journals Petrologic Study of Explosive Pyroclastic Eruption Stage in Shirataka Volcano, NE Japan: Synchronized Eruption of Multiple Magma Chambers

10.5772/24926 ◽  
2012 ◽  
Author(s):  
Masao Ban ◽  
Shiho Hirotani ◽  
Osamu Ishizuka ◽  
Naoyoshi Iwat
Keyword(s):  
Magma Chambers ◽  
Pyroclastic Eruption ◽  
Petrologic Study ◽  
Ne Japan

Petrological investigation of long-term evolution of magma chambers and preparing processes of caldera-forming eruption, Numazawa volcano, NE Japan

2016 ◽  
Vol 122 (10) ◽  
pp. 533-550
Author(s):  
Yoshiko Masubuchi ◽  
Yasuo Ishizaki ◽  
Tomohito Shirai ◽  
Akiko Matsumoto ◽  
Mizuho Amma-Miyasaka ◽  
...  
Keyword(s):  
Long Term Evolution ◽  
Magma Chambers ◽  
Term Evolution ◽  
Ne Japan

scholarly journals The Temporal Variation of Magma Plumbing System of the Kattadake Pyroclastics in the Zao Volcano, Northeastern Japan

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 430
Author(s):  
Mirai Takebe ◽  
Masao Ban ◽  
Motohiro Sato ◽  
Yuki Nishi
Keyword(s):  
Basaltic Magma ◽  
Alkaline Rock ◽  
Plumbing System ◽  
Calc Alkaline ◽  
Magma Plumbing System ◽  
Shallow Magma Chamber ◽  
Northeastern Japan ◽  
Petrologic Study ◽  
Magma Plumbing ◽  
Ne Japan

The geologic and petrologic study of the Kattadake pyroclastics (around 10 ka) from the Zao volcano (NE Japan) revealed the structure of the magma plumbing system and the mixing behavior of the shallow chamber. The Kattadake pyroclastic succession is divided into lower and upper parts by a remarkable discontinuity. All rocks belong to medium-K, calc-alkaline rock series and correspond to ol-cpx-opx basaltic-andesite to andesite with 20–28 vol% phenocrystic modal percentage. All rocks were formed by mixing between andesitic magma and near aphyric basalt. The petrologic features of andesites of lower and upper parts are similar, 59–61 wt% SiO2, having low-An plagioclase and low-Mg pyroxenes, with pre-eruptive conditions corresponding to 960–980 °C, 1.9–3.5 kb, and 1.9–3.4 wt% H2O. However, the basalts were ca. 49.4 wt% SiO2 with Fo~84 olivine in the lower part and 51.8 wt% SiO2 with Fo~81 olivine and high-An plagioclase the in upper one. The percentage of basaltic magma in the mixing process was lower, but the temperature of the basalt was higher in the lower part than the upper one. This means that the shallow magma chamber was reactivated more efficiently by the hotter basalts and that the mixed magma with a 70–80% of melt fraction was formed by a smaller percentage of the basaltic magma.

scholarly journals Are plutons assembled over millions of years by amalgamation from small magma chambers?

GSA Today ◽  
2004 ◽  
Vol 14 (4) ◽  
pp. 4 ◽  
Author(s):  
Allen F. Glazner ◽  
John M. Bartley ◽  
Drew S. Coleman ◽  
Walt Gray ◽  
Ryan Z. Taylor
Keyword(s):  
Magma Chambers

scholarly journals Compositional Variation of Eudialyte-Group Minerals from the Lovozero and Ilímaussaq Complexes and on the Origin of Peralkaline Systems

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 548
Author(s):  
Lia N. Kogarko ◽  
Troels F. D. Nielsen
Keyword(s):  
Linear Trend ◽  
Major And Trace Elements ◽  
High Tech ◽  
Compositional Variation ◽  
Elemental Distribution ◽  
Magma Chambers ◽  
Eudialyte Group ◽  
System A ◽  
Distribution Of Elements ◽  
World Class

The Lovozero complex, Kola peninsula, Russia and the Ilímaussaq complex in Southwest Greenland are the largest known layered peralkaline intrusive complexes. Both host world-class deposits rich in REE and other high-tech elements. Both complexes expose spectacular layering with horizons rich in eudialyte group minerals (EGM). We present a detailed study of the composition and cryptic variations in cumulus EGM from Lovozero and a comparison with EGM from Ilímaussaq to further our understanding of peralkaline magma chambers processes. The geochemical signatures of Lovozero and Ilímaussaq EGM are distinct. In Lovozero EGMs are clearly enriched in Na + K, Mn, Ti, Sr and poorer Fe compared to EGM from Ilímaussaq, whereas the contents of ΣREE + Y and Cl are comparable. Ilímaussaq EGMs are depleted in Sr and Eu, which points to plagioclase fractionation and an olivine basaltic parent. The absence of negative Sr and Eu anomalies suggest a melanephelinitic parent for Lovozero. In Lovozero the cumulus EGMs shows decrease in Fe/Mn, Ti, Nb, Sr, Ba and all HREE up the magmatic layering, while REE + Y and Cl contents increase. In Lovozero EGM spectra show only a weak enrichment in LREE relative to HREE. The data demonstrates a systematic stratigraphic variation in major and trace elements compositions of liquidus EGM in the Eudialyte Complex, the latest and uppermost part of Lovozero. The distribution of elements follows a broadly linear trend. Despite intersample variations, the absence of abrupt changes in the trends suggests continuous crystallization and accumulation in the magma chamber. The crystallization was controlled by elemental distribution between EGM and coexisting melt during gravitational accumulation of crystals and/or mushes in a closed system. A different pattern is noted in the Ilimaussaq Complex. The elemental trends have variable steepness up the magmatic succession especially in the uppermost zones of the Complex. The differences between the two complexes are suggested to be related dynamics of the crystallization and accumulation processes in the magma chambers, such as arrival of new liquidus phases and redistributions by mush melts.

scholarly journals New insights on Br speciation in volcanic glasses and structural controls on halogen degassing

2020 ◽  
Vol 105 (6) ◽  
pp. 795-802 ◽  
Author(s):  
Marion Louvel ◽  
Anita Cadoux ◽  
Richard A. Brooker ◽  
Olivier Proux ◽  
Jean-Louis Hazemann
Keyword(s):  
Atmospheric Chemistry ◽  
Divalent Cations ◽  
Stratospheric Ozone ◽  
High Energy ◽  
Aluminosilicate Glass ◽  
High Energy Resolution ◽  
Magma Chambers ◽  
Structural Controls ◽  
Volcanic Glasses ◽  
Melt Composition

Abstract The volcanic degassing of halogens, and especially of the heavier Br and I, received increased attention over the last 20 years due to their significant effect on atmospheric chemistry, notably the depletion of stratospheric ozone. While the effect of melt composition on halogen diffusion, solubility, or fluid-melt partitioning in crustal magma chambers has been thoroughly studied, structural controls on halogen incorporation in silicate melts remain poorly known, with only few studies available in simplified borosilicate or haplogranite compositions. Here, we demonstrate that high-energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD-XAS) with a crystal analyzer spectrometer (CAS) is well-suited for the study of Br speciation in natural volcanic glasses which can contain lower Br concentrations than their laboratory analogs. Especially, HERFD-XAS results in sharper and better-resolved XANES and EXAFS features than previously reported and enables detection limits for EXAFS analysis down to 100 ppm when previous studies required Br concentrations above the 1000 ppm level. XANES and EXAFS analyses suggest important structural differences between synthetic haplogranitic glass, where Br is surrounded by Na and next-nearest oxygen neighbors, and natural volcanic glasses of basaltic to rhyodacitic compositions, where Br is incorporated in at least three distinct sites, surrounded by Na, K, or Ca. Similar environments, involving both alkali and alkaline earth metals have already been reported for Cl in Ca-bearing aluminosilicate glass and our study thus underlines that the association of Br with divalent cations (Ca2+) has been underestimated in the past due to the use of simplified laboratory analogs. Overall, similarities in Cl and Br structural environments over a large array of compositions (46–67 wt% SiO2) suggest that melt composition alone may not have a significant effect on halogen degassing and further support the coupled degassing of Cl and Br in volcanic systems.

scholarly journals Replenished magma chambers: effects of compositional zonation and input rates

1982 ◽  
Vol 57 (2) ◽  
pp. 345-357 ◽  
Author(s):  
Herbert E. Huppert ◽  
J. Stewart Turner ◽  
R. Stephen ◽  
J. Sparks
Keyword(s):  
Magma Chambers ◽  
Compositional Zonation
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