C046-0004
Searching for very old ice with continuous stratigraphy at Larsen Blue Ice Area, East Antarctica

Monday, 14 December 2020
Poster
Giyoon Lee1, Jinho Ahn2, Hyeontae Joo3, Florian Ritterbusch4, Ikumi Oyabu5, Songyi Kim3, Kenji Kawamura6,7, Zheng-Tian Lu8, Sangyoung Han9, Sambit Ghosh10, Yeongcheol Han3, Sangbum Hong11, Changhee Han3, Soon Do Hur3, Wei Jiang8 and Guomin Yang12, (1)Seoul National University, Seoul, Korea, Republic of (South), (2)Seoul National University, School of Earth and Environmental Sciences, Seoul, Korea, Republic of (South), (3)Korea Polar Research Institute, Incheon, South Korea, (4)University of Science and Technology of China (USTC), Hefei, China, (5)National Institute of Polar Research, Tokyo, Japan, (6)Natl. Inst. of Polar Research, Tokyo, Japan, (7)Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (8)University of Science and Technology of China, Hefei, China, (9)Seoul National University, Seoul, South Korea, (10)Seoul National University, Earth Sciences, Seoul, South Korea, (11)KOPRI Korea Polar Research Institute, Incheon, Korea, Republic of (South), (12)University of Science and Technology of China, Hefei National Laboratory for Physical Sciences at Microscale, Hefei, China
Abstract:
Recent studies show that we may find ice with ages older than 1 Ma from blue ice areas (BIAs), where very old ice can outcrop on the glacier surface. In that regard, blue ice has a potential for deciphering the causes of Mid Pleistocene Transition (MPT). However, complicated stratigraphy at the oldest part of the blue ice hinders to accurately reconstruct full glacial-interglacial climate information including greenhouse gas concentrations. So far, the oldest blue ice was found at Allan Hills, Antarctica, but the ages with continuous stratigraphy cover only up to 250 ka, not sufficient for the study of MPT. Here, we present preliminary results from blue ice at Larsen Glacier, East Antarctica. The Ground Penetrating Radar (GPR) survey results show well-stratified ice layers with a dip of 1-5°. The δ18O of O2 indicates that Larsen BIA covers at least one of the glacial terminations. Greenhouse gas (CO2, CH4) concentrations are significantly altered at very shallow depths of 0-4 m, but some CO2 concentrations at depths of ~2 and 10 m indicate glacial levels of 200-210 ppm. Combining CO2 and δ18O-O2 may help us better constrain the ages by comparison with existing ice core records. To better constrain the ages, the stable isotopes of the ice (δ18Oice , δDice) have been analyzed and we are planning to conduct 81Kr age dating, which is expected to be very appropriate for blue ice chronology.
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