Abstract
A hitherto unreported dacite lava was found on Akusekijima Island, Tokara Islands, Japan. The lava, named Omune Lava, is 100 m thick. K-Ar dating of the lava by the sensitivity method considering mass fractionation of initially trapped atmospheric argon, shows it to be less than 0.08 Ma. The surface of the lava is much less dissected than surrounding areas, and is not covered by any tephra layer. It suggests an eruption even as recent as the Holocene. The range of SiO 2 wt.% of andesites (two pyroxene andesites) is between 56 and 63%. On the other hand, Omune Lava (hornblende dacite) contains 68-69% SiO 2 . Two trends are recognized with only a small difference among Akusekijima rocks. Our results show that dacite magma, instead of andesitic magma, concerned the latest volcanic activity in Akusekijima Island.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
