Characteristics for the recognition of Pliocene and early Pleistocene marker tephras in central Japan

AbstarctNumerous widespread tephra layers of late Pleistocene and Holocene age have been known since the early 1970s and greatly contribute to palaeoenvironmental reconstruction in the Japan islands and adjacent seas. However, the mapping of older tephra deposits has developed more slowly. Recent progress in describing many tephras occurring in the Pliocene and early Pleistocene uplifted marine and terrestrial deposits has resulted both from developments in the characterization of their component phases, their radiometric and geomagnetic dating and from an enhanced knowledge of their distribution. This study has constructed tephra correlations using the trace element composition of volcanic glass determined by ICP-AES analysis. Consequently, many widespread tephra layers of Pliocene and early Pleistocene age have been identified and can now be correlated extensively in central Japan. This paper catalogs these tephras, and provides the fundamental criteria for the establishment of a regional Pliocene–Pleistocene chronostratigraphy in central Japan.