[M-IS12] Paleoclimatology and paleoceanography

[MIS12-P14] Ventilation Changes in the Northwestern Pacific During the Glacial Period: Preliminary Results of the Core MR23-05 Leg 2 SMK3-PC

*Wei-Cheng Hsiung¹, Yusuke Okazaki¹, Kana Nagashima², Takuya Sagawa³, Takuto Kasuya^1,2, Atsuko Amano⁴, Takayuki Uchida³ (1.Department of Earth and Planetary Sciences, Kyushu University, 2.Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3. Institute of Science and Engineering, Kanazawa University, 4.Geological Survey of Japan, Research Institute of Geology and Geoinformation, AIST)

Keywords:Deep water circulation, Last Glacial Maximum, North Pacific

Global deep water circulation is important in regulating long-term carbon storage in the ocean and atmosphere. Downwelling deep water in high-latitude regions has been considered one of the major sources of sinking carbon dioxide. Although the modern North Pacific has no deep-water downwelling, previous studies revealed that during the Last Glacial Maximum (LGM), the North Pacific was better ventilated above around 2000 m. The watermass is called as the glacial North Pacific intermediate water (GNPIW). Besides, potential deep water might have formed and sunk to more than 3000 m during two deglacial cold periods, the Heinrich event 1 and the Younger Dryas. Thus, the deep-water circulation in the glacial and deglacial Pacific was quite different from that in the interglacial. In the 2023 summer, three piston cores, MR23-05 Leg2 SMK1-PC, SMK2-PC, and SMK3-PC were collected in the off-Shimokita during the R/V Mirai cruise MR23-05 Leg 2. Among them, the core MR23-05 Leg2 SMK3-PC with a water depth of 1356 m, located near the center of the GNPIW, has the potential to reveal the ventilation in the Northwestern Pacific. Here we report the MSCL and color reflection data that has been completed on board, water content, coarse fraction, and XRF data processed by Itrax of the core MR23-05 Leg2 SMK3-PC. Most data indicate higher variability in the upper three sections. This period may be related to the last deglaciation while an age model is needed to check this interpretation.