Abstract:In the Seba area of the Sambagawa belt it was previously proposed that eclogitic basic schists found in the area adjacent to a metagabbro body formed by solid-state contact metamorphism as a result of tectonic emplacement of the metagabbro. This explanation has been reexamined through later studies, which include discovery of a number of eclogitic basic schists (or their constituting mineral, omphacite) distant from the metagabbro and recognition of relationship between multiple deformation stages and growth of omphacite. The results indicate formation of all the eclogitic basic schists in the Seba area can be attributed to a single regional eclogite-facies metamorphism. This research history gives the following implications to field studies for high-grade metamorphic regions: 1) recognition of key metamorphic minerals and of its map distribution should be done with great care; and 2) multiple deformation stages and their associated structures should be classified in relationship to growth timing of metamorphic minerals.
Abstract:The Sambagawa and Chichibu pelitic rocks are in direct contact in Kohtaki outcrop, which has been found out in field studies carried out in the Odai area, eastern Kii Peninsula. In the Kohtaki outcrop, it is suggested that difference in degree of metamorphic recrystallization between the two lithologies can be recognized by naked eyes, i.e. the Sambagawa pelitic phyllite is more highly recrystallized than the Chichibu pelitic mixed rock. In addition to this observation, overall difference in their constituent protolith was used to determine the boundary between the Sambagawa and Chichibu belts. The result suggests that the pelitic mixed rock in the Chichibu belt overlies pelitic phyllite in the Sambagawa belt with a moderately south dipping tectonic boundary, in contradiction with a previous study. It is also discussed that the juxtaposition of the two belts already completed by the end of the Sambagawa main deformation stage, Ds, which is associated with regional-scale E-W stretching. The Kohtaki outcrop likely preserves original structural relationships between the Sambagawa and Chichibu belts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.