[M-IS06] Evolution and variability of the Tropical Monsoon and Indo-Pacific climate during the Cenozoic Era

[MIS06-07] Changes in the Tsushima Warm Current System in the Japan Sea Throughout the Holocene

*松崎 賢史¹、板木 拓也²、佐川 拓也³、鈴木 克明²、入野 智久⁴、池原 研² (1.東京大学 大気海洋研究所、2.産業技術総合研究所　地質情報研究部門、3.金沢大学 理工研究域 地球社会基盤学系、4.北海道大学 大学院地球環境科学研究院 )

キーワード：日本海、完新世、対馬暖流、北極振動モード

The Japan Sea, connected to adjacent seas through four shallow straits (Tsushima, Tsugaru, Soya, and Mamiya), is characterized by limited water exchange restricted to surface waters, leading to the formation of unique Japan Sea Proper Water. The Tsushima Warm Current (TWC), originating from the East China Sea, is the primary current system transporting heat and nutrients in this semi-enclosed basin. During the Holocene (last 11,700 years), global climate experienced distinct phases: Early Holocene warming (11,700-8,200 BP), Mid-Holocene maximum warmth (8,200-4,200 BP), and Late Holocene cooling (4,200 BP-present). The Arctic Oscillation (AO), a significant climate pattern affecting the Northern Hemisphere, influences winter weather patterns and potentially impacts Japan Sea oceanography and TWC dynamics. Previous studies have demonstrated strong relationships between radiolarian species distribution and water mass properties, particularly nutrients and sea surface temperature (SST). This study aims to reconstruct TWC evolution throughout the Holocene and investigate possible connections with AO phases through analysis of radiolarian assemblages from 7 sediment cores collected along a south-north transect in the Japan Sea by the Geological Survey of Japan (Exp. DGC6; GH93-82; GH95-1202; GH96-1217; GH772-P103; GH872-308) and JAMSTEC (Exp. KR15-10). We will reconstruct paleo-SSTs based on radiolarian assemblages and compare them with TWC-related species fluxes and nutrient-indicator species to evaluate TWC variability during different Holocene climate phases and AO conditions.