箱根火山幕山溶岩円頂丘に産出する白色球果についての一考察
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概要
- 論文の詳細を見る
White globules of highly silicic composition occur in the alternating bands of dacite and rhyolite making up of the Makuyama lava dome, one of the parasitic volcanoes of the Quaternary Hakone volcanic complex. The white globules show a sharp outline and consist dominantly of fine grained feldspar and tridymite. The globules show a fairly constant composition which is similar to Si-rich immiscible glass compositions previously described in many andesites. The petrographic features suggest that the white globules crystallized from a silica-rich immiscible liquid droplet suspended in the dacitic magma. The white globule shows various textures indicative of agglomeration processes such as the coalescene of liquid droplets and liquid-wetting on phenocrysts. The light coloured rhyolite bands and streaks in the dome are composed dominantly of white globules. Bulk rock chemistry of the globules, the rhyolite bands, and the dacite bands suggest that the rhyolite was probably formed by the agglomeration of the silica-rich immiscible liquid prior to or during the protrusion of the dome.
- 横浜国立大学の論文
- 1988-10-31