日本海深海掘削の成果とその層序学的意義
1992 年 57 巻 1 号 p. 103-111
詳細
1992 年 57 巻 1 号 p. 103-111
Japan Sea Legs 127 and 128 of Ocean Drilling Program were conducted in the summer of 1989. The drilling results at 6 sites during the cruises gained our understanding on the history of the Japan Sea. Based on the new chrono-stratigraphic informations, opening of the Japan Sea started at least before 18 to 20Ma, which is much older than the age of 15Ma estimated from paleomagnetic evidence by OTOFUJI and MATSUDA (1983).
Lithostratigraphy of the sediments above the acoustic basement was established, which was proved to be correlatable throughout the Japan Sea. The lithostratigraphy is also correlatable with that in oilfield areas in the Tohoku region. The change in lithology through time is probably influenced by global changes in sea level as well as climate.
Seismic stratigraphy is correlated with lithostratigraphy at 3 sites drilled during Leg 127. The result suggests remarkable coincidence of opal-A/CT diagenetic boundary with the Bottom Simulating Reflector [BSR].
These results will have profound influences on stratigraphic studies in the Japan Sea and its environs.
