後期新生代における東北本州弧南部の構造発達史  [in Japanese] On the late Cenozoic tectonic history in the southern part of northeast Honshu in Japan  [in Japanese]

The Neogene and Pleistocene stratigraphy along the traverses of the southern part of Northeast Honshu Arc was synthesized using the available age data for microbiostratigraphy, botanical biostratigraphy, magnetostratigraphy and isotopic geochronology. Five tectonic stages were distinguished by the characters of sedimentary facies, thickness, stratigraphic relations, geologic structure and volcanism. Neogenic tectonics began with the subaerial andestic volcanism. It was succeeded by the origination of graben-like narrow basins in some restricted areas. They were rapidly filled by thick and coarse clastic sediments. The regional marine transgression began at about 16 Ma, and the marine sediments onlapped not only the Lower Miocene strata but also basement rocks. It resulted in a archipelago which was associated with the middle to upper bathyal environment. At the initial stage of the marine transgression, rhyo-dacitic volcanism was quite intense. It declined toward the Middle Miocene. The regional uplifting and marine regression became distinctive at about 10 Ma in the region from Ohu Back-bone Range to Echigo Range, where the sedimentary basins were divided into smaller and shallower ones. Main sedimentary basin was shifted to the Japan Sea side, and the shallower but somewhat wide basin was left on the eastern side of Ohu Back-bone Range. The marine condition disappeared in the central region by about 6 Ma. The volcano-tectonic depressions were formed on Ohu Back-bone Range during the period from 8 Ma to 6 Ma. The regional uplifting was continued during Pliocene, and it was intensified in Early Pleistocene, associating faulting. It renewed the residual sedimentary basins as intermontane basins. Pumice flows, which are precursor of the Quaternary andesite volcanism, were wide spread on the both the mountaneous region and the intermontane basines. The Neogene formations, including Lower Pleistocene sediments, are folded and faulted under the E-W-trending compression in the recent.