Provenance of LGM glacial till (sand fraction) across the Ross embayment,Antarctica |
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| Institution: | 1. Korea Polar Research Institute, Incheon, South Korea;2. University of Science and Technology-Korea, Daejeon, South Korea;3. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale-OGS, Trieste, Italy;4. University of Trieste, Trieste, Italy;5. Research Institute of Oceanography, Seoul National University, Seoul, South Korea;6. Institute of Marine Sciences-National Research Council (ISMAR-CNR), Venice, Italy;7. Victoria University of Wellington, Wellington, New Zealand;1. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;2. First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China;3. Department of Earth Sciences, Utrecht University, Budapestlaan 17, 3584 CD Utrecht, The Netherlands;1. Korea Polar Research Institute, Incheon 21990, South Korea;2. Department of Polar Sciences, University of Science and Technology (UST), Incheon 21990, South Korea;3. Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing, China;4. Department of Surface Geosciences, GNS Science, Lower Hutt, New Zealand |
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| Abstract: | The provenance of Late Quaternary Ross Embayment till was investigated by comparing the coarse sand composition of East and West Antarctic source area tills with till samples from across the Ross Sea. The West Antarctic samples from beneath the Whillans (B) and Kamb (C) ice streams are petrologically distinct from samples of lateral moraines flanking several East Antarctic outlet glaciers. The characteristic assemblage of four West Antarctic samples includes felsic intrusive and detrital sedimentary lithic fragments, plagioclase and abundant quartz. In contrast, most of the ten East Antarctic till samples contains abundant mafic intrusive and detrital sedimentary lithic fragments as well as less abundant quartz. The distinctive composition of these source areas can be linked to 33 samples from 20 cores of Last Glacial Maximum (LGM) age till distributed across the Ross Sea. Western Ross Sea till samples exhibit mineralogic and lithological similarities to East Antarctic till samples, although these western Ross Sea tills contain higher percentages of felsic intrusive and extrusive lithic fragments. Eastern Ross Sea till samples are compositionally similar to West Antarctic till, particularly in their abundance of quartz and dearth of mafic and extrusive lithic components. Central Ross Sea till exhibits compositional similarities to both East and West Antarctic source terranes including a mafic lithic component, and marks the confluence of ice draining from East and West Antarctica during the LGM, thus West Antarctic-derived ice streams did not advance into the western Ross Sea. This indicates that even if pre-LGM equivalents of the present Siple Coast ice streams existed, they did not simply expand allowing West Antarctic-derived ice to dominate the LGM Ross Ice Sheet. |
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