Solid sulfur spherules near fumaroles of Hakone volcano, Japan
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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.
KeywordsSulfur spherule Molten sulfur Fumarole Hakone volcano
We wish to thank Mr. Naoki Honma (Japan Meteorological Agency) for help in field observations. Dr. Felipe Aguilera and an anonymous reviewer are thanked for their constructive comments that helped improve the manuscript. We thank Dr. Wolf-Christian Dullo for editorial help. This research was supported by a Grant-in-Aid for Young Scientists (B) (no. 16K16372) from Japan Society for the Promotion of Science (JSPS). This work was also partially supported by Cross-ministerial Strategic Innovation Promotion Program (SIP), “Next-generation technology for ocean resources exploration (Zipangu in the Ocean)”.
- Hamasaki S, Itoh J, Mannen K, Kikukawa J, Ishizuka Y, Furukawa R, Yamasaki S, Kusano Y (2015) Constituent minerals of volcanic ash and mud flow erupted from the Owakudani Valley in Hakone volcano on June 29–30, 2015 (abstract). In: Volcanological Society of Japan 2015 Fall Meeting, Abstract number A3-15, p 43 (in Japanese) Google Scholar
- Kobayashi M, Mannen K, Okuno M, Nakamura T, Hakamata K (2006) The Owakidani Tephra Group: a newly discovered post-magmatic eruption product of Hakone volcano, Japan. Bull Volcanol Soc Jpn 51:245–256 (in Japanese) Google Scholar
- Mannen K, Yukutake Y, Kikugawa G, Harada M, Itadera K, Takenaka J (2018) Chronology of the 2015 eruption of Hakone volcano, Japan: geological background, mechanism of volcanic unrest and disaster mitigation measures during the crisis. Earth Planets Space 70:68. https://doi.org/10.1186/s40623-018-0844-2 CrossRefGoogle Scholar
- Meeker GP, Hinkley TK (1993) The structure and composition of microspheres from the Kilauea Volcano, Hawaii. Am Mineral 78:873–876Google Scholar
- Ohashi R (1919) On the peculiar sulphur spherules produced in a crater lake of the volcano Shirane, in the province of Kozuke, Central Japan. J Akita Min Coll 1:1–10Google Scholar
- Ossaka J (1982) Activity of volcanos and clay minerals. J Clay Sci Soc Jpn 22:127–137 (in Japanese) Google Scholar
- Theilig E (1982) A primer on sulfur for the planetary geologist. NASA Contract Rep 3594:1–34Google Scholar
- Watanabe T (1940) Eruptions of molten sulphur from the Siretoko-Iosan Volcano, Hokkaido, Japan. Jpn J Geol Geogr 17:289–310Google Scholar
- Watanuki K (1966) Chemical composition of Owakidani hot spring water, Hakone. J Hot Spring Sci 17(1):22–27 (in Japanese) Google Scholar
- White DE, Hutchinson RA, Keith TEC (1988) The geology and remarkable thermal activity of Norris Geyser Basin, Yellowstone National Park, Wyoming. USGS Prof Pap 1456:1–84Google Scholar