10월 26일(목)
․고기후․고해양학/IODP178 • • 2006 대한지질학회 추계학술발표회 초록집
Reconstruction of marine paleoenvironmental change recorded in a sediment core of the Southern Drake Passage, Antarctica
Suk Hee Yoon1,*․Kyung Hoon Shin1․Ho Il Yoon2․Kyu-Cheul Yoo2
1Dept. of Environmental Marine sciences, Hanyang university, [email protected]
2Korea Ocean Polar Research Institute
In order to reconstruct paleoproductivity related to paleoclimate change of Southern Ocean, the biogeochemical indicators such as organic carbon and total nitrogen contents, their stable isotopes ratios (δ
13
C, δ15
N), biogenic opal and biogenic barium contents were determined with the sediment core (GC98-06 core length 251cm), which was collected in the deep basin of the Drake Passage, Antarctic. TOC, TN, biogenic opal and biogenic barium contents were higher in the interglacial periods (i.e., MIS 1, MIS 3, MIS 5 stage) than in the glacial periods (i.e., MIS 2, MIS 4, MIS 6 stage) reflecting that marine productivity increased during the interglacial periods when the sea ice covered area was retreated. In general, when TOC contents were the lower, the corresponding TN contents were much lower, showing the high C/N ratio. These results exhibit that marine primary productivity might be controled by the limited nitrogen utilization at each period. Biogenic opal contents ranged from 12% to 24%, which were almost corresponding to the changes of organic carbon and total nitrogen contents.But in some periods (i.e, 180~190cm in MIS 5), biogenic opal contents was low, even though organic carbon contents was high, suggesting that other phytoplanktons were dominant species rather than diatom in the Drake Passage, in Southern Ocean. On the other hand, biogenic opal contents were high despite low organic carbon contents during the MIS 4. These might be caused by iron limitation related to the expansion of sea ice cover.
The large variations of carbon and nitrogen stable isotopes ratios were found in the middles of MIS 5, and this period should be regarded MIS 5.5 as a warmer interglacial period than the Holocene. It seems to be occurred by severe stratification under maximal warming conditions in the interglacial period, showing abrupt changes of marine biogeochemical proxies.
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