HR: 15:30h
AN: PP53A-07    [Abstracts]
TI: Little ice age and global warming trends recorded in the late Holocene stalagmite from the Yongcheon lava tube cave in Jeju Island, Korea
AU: * Woo, K
EM: wooks@kangwon.ac.kr
AF: Kangwon National University, Department of Geology, Chuncheon, 200-701, Korea, Republic of
AU: Jo, K
EM: jokyoung95@hanmail.net
AF: Kangwon National University, Department of Geology, Chuncheon, 200-701, Korea, Republic of
AU: Li, H
EM: hli1960@mail.ncku.edu.tw
AF: National Cheong-Kung University, Department of Earth Sciences, Tainan, 70101, Taiwan
AU: Luo, S
EM: sluo@mail.ncku.edu.tw
AF: National Cheong-Kung University, Department of Earth Sciences, Tainan, 70101, Taiwan
AU: Wan, N
EM: L4893103@ccmail.ncku.edu.tw
AF: National Cheong-Kung University, Department of Earth Sciences, Tainan, 70101, Taiwan
AU: Suk, B
EM: bcsuk@kordi.re.kr
AF: Korea Ocean Research and Development Institute, Marine Environment Research Department, Ansan, 426-744, Korea, Republic of
AU: Park, B
EM: bkpark@kordi.re.kr
AF: Korea Ocean Research and Development Institute, Marine Environment Research Department, Ansan, 426-744, Korea, Republic of
AB: Yongcheon Cave is located on Jeju Island, the southernmost part of Korea. The island is under the strong influence of East Asian monsoon climate. The Yongcheon cave which contains numerous carbonate speleothems was the typical lava tube cave that probably formed between 0.2~0.4 Ma ago. A 11cm-long stalagmite, YC-1, was collected in its growth position in 2005. The 210Pb dating results show that the top 0.9cm of YC-1 is less than 100 years old with a growth rate of 0.033mm/yr. Assuming the constant growth rate of the stalagmite with this growth rate, it is estimated that the stalagmite is about 3,300 years old. Currently, about 100 samples were analyzed for 18O and 13C compositions in the upper 1.25cm part with a sampling interval of 0.125mm. The 18O ranges from -7.4 to -5.8 (PDB), and the 13C varies from -8.0 to -1.7 (PDB). Both 18O and 13C values have decreasing trends during the last 60 years, with the decreases of 1.2 and 4 for 18O and 13C, respectively. Carbon isotopic compositions are more enriched in SGL (Zone of spaced growth laminae; ca -2.5, PDB) than DGL (Zone of dense growth laminae; ca -7.5). This indicates that the carbon in SGL was mostly supplied from the overlying carbonate sediments. Also, more depleted carbon isotopic values in DGL should reflect more influence by organic carbon within the overlying vegetation cover and soil. Elemental results show that there are anti-phase correlations between Mg/Ca and Sr/Ca, and between Ba/Ca and P/Ca. The strong increase in Al/Ca ratio in the upper a few mm indicates that significant change occurred in the overlying sediments above the cave during the past 50 years. These preliminary results imply that the stalagmite of the Yongcheon Cave may have been affected by groundwater residence time related to variation of regional precipitation and carbonate dissolution rate. Oxygen isotopic variation of YC-1 in particular, clearly shows the period of the Little Ice Age and coincides with the instrumental records of Northern Hemisphere temperature variation during the last 1,300 years.
DE: 4958 Speleothems
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly