Abstract
Occurrence of sulfur spherules near subaerial fumaroles is relatively uncommon and their mineralogical characteristics and formation mechanisms are still incompletely understood. Yellow to greenish-gray solid sulfur spherules were observed near a fumarole that was formed in the fumarolic area (Owakudani) during the 2015 eruption of Hakone volcano, Japan. The yellow sulfur spherules (up to 1 mm in diameter) are composed entirely of α-sulfur, and the greenish-gray spherules (up to 2 mm in diameter) consist mainly of matrix-forming α-sulfur with lesser amounts of pyrite, amorphous silica, pyrophyllite, and rare marcasite. Based on the results of the field observations and the micro-analyses of the samples, these sulfur spherules were formed by rapid cooling of molten sulfur blobs ejected from a low-viscosity molten sulfur pool (124.7–128.7 °C) in the bottom of the fumarole during vigorous fumarolic activity. Color difference between yellow and greenish-gray sulfur spherules is explained by the presence of xenolithic altered mineral fragments in the greenish-gray sulfur spherules. Our observations indicate significant fluctuations of the level of the molten sulfur forming inside the fumarolic vent, and these fluctuations may imply the existence of other molten sulfur reservoirs beneath the fumarolic area. Presence of solid sulfur spherules in the fumarolic area may be an indicator of a molten sulfur pool within fumaroles or volcanic vents that are often difficult to directly observe.
| Original language | English |
|---|---|
| Pages (from-to) | 347-356 |
| Number of pages | 10 |
| Journal | International Journal of Earth Sciences |
| Volume | 108 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Feb 8 2019 |
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All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)
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Solid sulfur spherules near fumaroles of Hakone volcano, Japan. / Ikehata, Kei; Date, Minori; Ishibashi, Junichiro; Kikugawa, George; Mannen, Kazutaka.
In: International Journal of Earth Sciences, Vol. 108, No. 1, 08.02.2019, p. 347-356.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Solid sulfur spherules near fumaroles of Hakone volcano, Japan
AU - Ikehata, Kei
AU - Date, Minori
AU - Ishibashi, Junichiro
AU - Kikugawa, George
AU - Mannen, Kazutaka
PY - 2019/2/8
Y1 - 2019/2/8
N2 - Occurrence of sulfur spherules near subaerial fumaroles is relatively uncommon and their mineralogical characteristics and formation mechanisms are still incompletely understood. Yellow to greenish-gray solid sulfur spherules were observed near a fumarole that was formed in the fumarolic area (Owakudani) during the 2015 eruption of Hakone volcano, Japan. The yellow sulfur spherules (up to 1 mm in diameter) are composed entirely of α-sulfur, and the greenish-gray spherules (up to 2 mm in diameter) consist mainly of matrix-forming α-sulfur with lesser amounts of pyrite, amorphous silica, pyrophyllite, and rare marcasite. Based on the results of the field observations and the micro-analyses of the samples, these sulfur spherules were formed by rapid cooling of molten sulfur blobs ejected from a low-viscosity molten sulfur pool (124.7–128.7 °C) in the bottom of the fumarole during vigorous fumarolic activity. Color difference between yellow and greenish-gray sulfur spherules is explained by the presence of xenolithic altered mineral fragments in the greenish-gray sulfur spherules. Our observations indicate significant fluctuations of the level of the molten sulfur forming inside the fumarolic vent, and these fluctuations may imply the existence of other molten sulfur reservoirs beneath the fumarolic area. Presence of solid sulfur spherules in the fumarolic area may be an indicator of a molten sulfur pool within fumaroles or volcanic vents that are often difficult to directly observe.
AB - Occurrence of sulfur spherules near subaerial fumaroles is relatively uncommon and their mineralogical characteristics and formation mechanisms are still incompletely understood. Yellow to greenish-gray solid sulfur spherules were observed near a fumarole that was formed in the fumarolic area (Owakudani) during the 2015 eruption of Hakone volcano, Japan. The yellow sulfur spherules (up to 1 mm in diameter) are composed entirely of α-sulfur, and the greenish-gray spherules (up to 2 mm in diameter) consist mainly of matrix-forming α-sulfur with lesser amounts of pyrite, amorphous silica, pyrophyllite, and rare marcasite. Based on the results of the field observations and the micro-analyses of the samples, these sulfur spherules were formed by rapid cooling of molten sulfur blobs ejected from a low-viscosity molten sulfur pool (124.7–128.7 °C) in the bottom of the fumarole during vigorous fumarolic activity. Color difference between yellow and greenish-gray sulfur spherules is explained by the presence of xenolithic altered mineral fragments in the greenish-gray sulfur spherules. Our observations indicate significant fluctuations of the level of the molten sulfur forming inside the fumarolic vent, and these fluctuations may imply the existence of other molten sulfur reservoirs beneath the fumarolic area. Presence of solid sulfur spherules in the fumarolic area may be an indicator of a molten sulfur pool within fumaroles or volcanic vents that are often difficult to directly observe.
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U2 - 10.1007/s00531-018-1657-z
DO - 10.1007/s00531-018-1657-z
M3 - Article
VL - 108
SP - 347
EP - 356
JO - International Journal of Earth Sciences
JF - International Journal of Earth Sciences
SN - 1437-3254
IS - 1
ER -