第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月26日（月） 国立国語研究所 ２階講

Ikehara M.

Khim B.K.

Nogi Y.

Shipboard Scientists KH10-07

National Institute of Polar Research Repository

  High-resolution CaCO3 variation of core COR-1bPC in the Conrad Rise in the Indian Sector of the East Antarctic  B.K. Khim1, M. Ikehara2, Y. Nogi3, and KH10-07 Shipboard Scientists 1Department of Oceanography, Pusan National University, Busan, Korea 2Center for Advanced Marine Core Research, Kochi University, Kochi, Japan 3National Institute of Polar Research, Tokyo, Japan  The Southern Ocean has played an important role in the global climate system. Ocean alkalinity change in the surface Southern Ocean is one of the crucial factors to explain glacial pCO2 reduction. Alkalinity increases in glacial periods are driven by reduction in North Atlantic Deep Water supply, which leads to increases in deep-water nutrients and dissolution of carbonate sediments and to increased Circumpolar Deep Water upwelling in the surface Southern Ocean. A core COR-1bPC (54o16.55’S, 39o46.24’E; water depth, 2835 m; core length 10.47 m) was collected from the south-west flank of the Conrad Rise during Cruise KH10-07 by R/V Hakuho-Maru in Dec. 2010. Age control for the core COR-1bPC was determined by AMS 14C dating and δ18O stratigraphy of planktonic foraminifers, showing the clear transition from the last glacial period into the Holocene. The sedimentation rate of core COR-1bPC is fairly high more than 2.5 cm/yr. High-resolution CaCO3 profile of core COR-1bPC shows the low and consistent CaCO3 contents during the glacial periods, which confirms the enhanced carbonate dissolution in the bottom water. During the deglacial periods, CaCO3 contents fluctuated in parallel with the climatic changes such as Bølling-Allerod, Younger Dryas, and Pre-Boreal events. Particularly, it is notable to note that a series of CaCO3 fluctuations can be observed distinctly during the Holocene, in contrast to no variation of ice-core δ18O records. Short-term variation of CaCO3 contents at the Conrad Rise during the Holocene will be discussed in more detail for the purpose of verifying that the Conrad Rise is the best site for revealing the evolution of Antarctic cryosphere such as the role of Antarctic Circumpolar Current and the migration of Antarctic Polar Front during the Quaternary.  

High-resolution CaCO3 variation of core COR-1bPC in the Conrad Rise in the Indian Sector of the East Antarctic

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High-resolution CaCO3 variation of core COR-1bPC in the Conrad Rise in the Indian Sector of the East Antarctic

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