Abstract
Many andesitic lava flows of the calc-alkaline rock series erupted during the middle to late Miocene time are distributed in the western part of the Setouchi Inland Sea volcanic province. They cna be divided into the following three stages: 1) glassy andesitic and biotite dacitic, dykes 2) hornblende bearing andesitic laves and their pyroclastics, and 3) andesites forming domes or lavas and their pyroclastics. Porphyritic andesites are characterized by high MgO content, though calculated groundmass compositions as well as aphyric andesites reveal the nature of the common Japanese calc-alkaine series. MgO-FeO+Fe2O3-Na2O+K2O diagram shows that these andesitic rocks are chemically divided into MgO-poor and MgO-poor and MgO-rich groups. The former group carries granitic xenolith, indicating the effect of contamination.
Sign-in/Register to access full text options 
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 callMore From: The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Disclaimer: 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.
