[SGL31-P02] Origin of Marumori metamorphic rock
Keywords:Marumori metamorphic rock, orthoquartzite
This study focuses on garnet quartzite, garnet-biotite-quartz schist and amphibolite. Garnet quartzite consists garnet, biotite, sillimanite, quartz, plagioclase, and opaque minerals. Garnet-biotite-quartz schist consists garnet, biotite, quartz, plagioclase, and opaque minerals. Amphibolite consists amphibole(almost hornblend), plagioclase, quartz, and opaque minerals. All the rocks suggest schistosity plane(as for garnet quartzite, garnets line up). Quartz grains are observed roundness form and occupy 90% in garnet quartzite, but dust ring is not observed. And garnet-biotite-quartz schist(pelitic metamorphic rock) is a possibility of continental sediment from chemical composition. Nb/TiO2 > 10 indicates it. Trace elements of amphibolite isn’t same quantity of island arc basalts.
Garnet quartzite suggests its original rock is orthoquartzite. And garnet-biotite-quartz schist is metamorphosed from continental sediment. It is considered original rock of amphibolite is igneous mafic rock before Japan island arc formed(ca. 500Ma).