Abstract
The stratigraphy of Late Cenozoic Niigata sedimentary basin has been examined since 1900's for exploring of oil and gas. The basic stratigraphical division was established by these works. Recent stratigraphical methods, biostratigraphies of planktonic foraminifers, diatoms and calcareous nannoplanktons, tephra-stratigraphy and paleomagneto-stratigraphy are very useful for detailed correlation and age determination. A combined method of several stratigraphies is effective for the purposes. In Niigata sedimentary basin the technique is adopted for stratigraphical studies.
The history of the Sea of Japan has been discussed on the basis of field data taken from Niigata and Sado regions. The important events of geologic history are explained as following. 1) Early Miocene: the age of the eastern margin of continent, 2) Early/Middle Miocene: the age of great transgression, 3) early Middle Miocene: the age of deepening of a marginal sea I, 4) Middle and Late Miocene: the age of a deep sea, 5) Late Miocene/Early Pliocene: the age of uplifting and subsiding of a marginal sea, 6) Pliocene to Holocene: the age of climatic sea-level changes, subsiding of a sedimentary basin and uplifting of backbone ranges. The last age in Niigata region is divided into Pliocene marginal sea II, Early Pleistocene paleo-Uonuma plain, Middle-Late Pleistocene paleo-Echigo plain and Holocene Echigo plain.
