Redefinition of the Hida Gaien belt

Since the 1950s, rocks of the Hida Gaien belt have been subdivided into four units: (1) Middle to Upper Paleozoic shallow marine formations (including their metamorphosed facies of the Unazuki belt); (2) mafic to ultramafic igneous rocks including high P/T metamorphic rocks older than 300 Ma; (3) Upper Paleozoic limestone, chert and clastic rocks; and (4) Permian mafic igneous rocks and clastic formations. In this subdivision, the units are identified by their major lithology and their tectonic position. Over the last two decades, detailed knowledge of the lithology, age and stratigraphic relationships of these rocks has increased to such an extent that units (2), (3) and (4) are today correlated with rocks not of the Hida Gaien belt, but of the Sangun-Renge, Akiyoshi and Maizuru belts respectively. In this paper, the remaining unit (1) is correlated with the newly revised Hida Gaien belt. Unit (1) rocks are distributed in the Unazuki, Shiroumadake, Fukuji-Hongo-Furukawa, Naradani, Itoshiro and Asahi-Ise-Ohno areas. The type locality is designated as the Fukuji-Hongo-Furukawa area.