Holocene lake development and glacial-isostatic uplift at Lake Skallen and Lake Oyako,Lützow-Holm Bay,East Antarctica: Based on biogeochemical facies and molecular signatures |
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| Authors: | Yoshinori Takano Jonathan James Tyler Hisaya Kojima Yusuke Yokoyama Yukiko Tanabe Takaharu Sato Nanako O Ogawa Naohiko Ohkouchi Manabu Fukui |
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| Institution: | 1. Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima, Yokosuka 237-0061, Japan;2. Department of Natural History Sciences, Hokkaido University, N10 W8, Kita-ku, Sapporo 060-0810, Japan;3. Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8564, Japan;4. Department of Earth and Planetary Sciences, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan;5. The Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo 060-0819, Japan;6. Department of Natural Environmental Studies, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8563, Japan;g Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8521, Japan;h National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan |
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| Abstract: | The paleolimnology of two lakes which were isolated as a result of the crustal uplift during the late Holocene along the Soya Coast, Lützow-Holm Bay, East Antarctica were studied. The focus was on temporal variations in the biogeochemical composition of sediment cores recovered from Lake Skallen at Skallen and Lake Oyako at Skarvsnes. Both sets of lake sediments record environmental changes associated with a transition from marine to lacustrine settings, as indicated by analyses of C and N contents, nitrogen isotopic compositions (δ15N), and major element concentrations. Changes in the dominant primary producers during the marine–lacustrine transition (marine diatom to cyanobacteria) at L. Skallen was clearly revealed by biogenic opal-A, diatom assemblages, and molecular signature from denaturing gradient gel electrophoresis (DGGE) with 16S ribosomal RNA (rRNA) gene analysis. Radiocarbon dating of acid-insoluble organic C suggested that the environmental transition from marine to fresh water occurred at 2940 ± 100 cal yr BP at L. Skallen and 1060 ± 90 cal yr BP at L. Oyako. Based on these data, a mean crustal uplift rate of 3.2 mm yr−1 is inferred for the history of marine–lacustrine transition via brackish conditions. The geological setting causing glacio-isostatic uplift was the primary factor in controlling the transition event in sedimentary and biological facies. |
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