Tectonic and Orbital Imprints in the Redox History of Japan Sea Since the Pliocene

• Published in: Paleoceanography and Paleoclimatology
• Main Authors: Zhao, Debo, Wan, Shiming, Zhai, Lina, Shi, Xuefa, Li, Anchun
• Format: Report
• Language: English
• Published: AMER GEOPHYSICAL UNION 2022
• Subjects: Geology; Oceanography; Paleontology; Geosciences; Multidisciplinary; PALEOENVIRONMENTAL CHANGES; WATER OXYGENATION; LATE PLEISTOCENE; SOUTHERN-OCEAN; CLIMATE; EVOLUTION; CIRCULATION; SEDIMENTS; NEOGENE; MECHANISMS; Southern Ocean; Pacific
• Online Access: http://ir.qdio.ac.cn/handle/337002/178250; https://doi.org/10.1029/2021PA004333

Oxygen content in the deep ocean plays a vital role in biogeochemical processes and has significant impacts on the global carbon cycle. The Japan Sea is a semiclosed basin with only shallow water connection to the Western North Pacific, and its redox history has been sensitively affected by tectonic and climatic changes in the past. Studies of paleo-redox changes in the Japan Sea focused on the tectonic and orbital scales since the Pliocene remain scarce to date. Here, we present two high-resolution paleo-redox records during the last 4 Ma at IODP Sites U1425 and U1430 drilled in the Japan Sea. Our authigenic U (uranium) and U/Al records suggest remarkable changes of Japan Sea redox history from relatively oxic to periodic oxic-anoxic conditions at similar to 1.7 Ma. This was mainly caused by the restricted input of North Pacific oxygen-rich water due to the uplift of northeastern Japan during late Pliocene and early Pleistocene, and opening of the Tsushima Strait and the periodic intrusion of Tsushima Warm Current following sea level change during glacial-interglacial cycles since similar to 1.7 Ma. Orbital changes of Japan Sea redox history suggest the existence of a long eccentricity cycle of 400 ka associated with East Asian summer monsoon rainfall evolution throughout the last 4 Ma. Changes of the amplitude of sea level and inflow of Tsushima Warm Current combined with the East Asian monsoon evolution produced eccentricity and obliquity cycles in Japan Sea redox environment after similar to 1.7 Ma, as well as a transition from relatively oxic to anoxic conditions during glacials before and after Middle Pleistocene Transition. Plain Language Summary Oxygen is a prerequisite for marine organisms' cellular respiration. Changes in the ocean oxygen levels can significantly impact the ocean ecosystem and even the global carbon cycle. During the geological time, shifts between ocean anoxia and oxygenation can be regulated by tectonic and climatic changes through water mass vertical mixing and current evolution. ...