Latest Early Miocene to earliest Middle Miocene Benthic Foraminifers and paleoenvironment of the Aratani Formation in Fukui Prefecture, Japan

• Main Authors: 中川, 登美雄, 中村, 洋喜, 野村, 律夫
• Format: Other/Unknown Material
• Language: Japanese
• Published: 福井大学地域環境研究教育センター 2020
• Subjects: 荒谷層; 福井県; 底生有孔虫; 前期中新世末〜中期中新世初頭; Planktonic foraminifera
• Online Access: http://hdl.handle.net/10098/00028610; https://u-fukui.repo.nii.ac.jp/record/28731/files/bd10125778.pdf; https://u-fukui.repo.nii.ac.jp/records/28731

The paleoenvironment of the Aratani Formation (Latest Early Miocene to earliest Middle Miocene) was reconstructed based on molluscan and foraminiferal fossils. The paleo-water depth of the Aratani Formation rapidly increased to the flood plain to upper shallow zone (water depth 0-30 m), the middle to upper shallow zone (water depth 50-100 m), the lower shallow zone to bathyal zone (water depth 100-200 m) in accending order, and became an oceanic environment containing a large amount of planktonic foraminifera. After the deposition of AT-2 pyroclastic rocks, it gradually changed to a bay-like environment in the middle-upper shallow sea area (water depth 30-100 m) that did not contain planktonic foraminifera. Foraminiferal assemblages of the Aratani Formation are mixed with various paleo-water depths from the upper shallow marine to bathyal. This is a characteristic feature observed during the expansion period of the Sea of Japan, where shallow sediments were scraped and transported to the deep sea area due to rapid subsidence (or transgression) at the time of deposition. departmental bulletin paper