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Download Low viscosity structures of the rhyolite lava robe like basaltic pillow
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34th International Geological Congress Unearthing our Past and Future — Resourcing Tomorrow Low viscosity structures of the rhyolite lava robe like basaltic pillow lobes on the Yahiko seaside in the central Japan Koichi TERASAKI Independent Researcher, 6379-72 Ichino-Tyou Ikarashi Niigata 950-2101, Japan [email protected] The wide area of the Yahiko-Kakuda mountain situated in the Central Japan is underlain by volcanic rocks of the late miocene Teradomari formation, such as basalt, andesite and rhyolite. These are aqueous volcanic rocks including pillow lava and hyaloclastite. On the Gakematsu seashore, there are many lava lobes in the aqueous rhyolite lava dome which are accompanied by hyaloclastite. The lava lobes present ropy wrinkle, corrugation (B) and similar structure to intraflow folding as in the case of basaltic pillow lava; suggesting low viscosity. Commonly it has been understood that these structures are not formed from high viscosity lava flow like andesite or rhyolite but from low viscosity basaltic lava. I conjectured a high temperature environment in the rhyolite subaqueous lava dome to maintain low viscosity. In my poster session I’ll report unique structures of the Gakematsu rhyolite lava loves and my idea. 497
