Abstract
The Omma, Zukawa, Junicho and Yabuta Formations are typical of Plio-Pleistocene marine sediments in Hokuriku Province. The Omma and Junicho Formations have been previously dated to be early Pleistocene and late Pliocene to early Pleistocene respectively. The Takakubo Formation underlies the Omma Formation, and is dated from middle Miocene to early Pliocene.In order to establish tephrostratigraphy of the three formations (Omma, Zukawa and Junicho F.), and to make clear the stratigraphical relationship between Omma and Takakubo Formations, petrographical method, and analysis of the chemical components by energy dispersive X-ray spectrometry (EDS) were applied for the comparison of volcanic glass.As a result of this study, the following conclusions were obtained. (1) The uppermost part of the Takakubo Formation, and the lower parts of the Zukawa and Junicho Formations are in a relationship of contemporaneous heterotopic facies based on correlation of volcanic ash beds (TR 2-HK 2-SZp-T 3). (2) Based on tephrostratigraphy and biostratigraphy, the uppermost part of the Takakubo Formation is dated late Pliocene at eastern part of Kanazawa city and western part of Toyama Prefecture. (3) Between the type locality of the Omma Formation and that of the western part of Toyama Prefecture, correlation of horizons by previous biostratigraphy is inconsistent with the correlation by volcanic ash bed.
