10:45 AM - 12:15 PM
[ACC26-P05] Considerations on the drilling site for "Oldest Ice Core" around Dome Fuji, East Antarctica, based on combined interpretations of ground-based radar data and ice sheet simulations
Keywords:Antarctica, Dome Fuji, Ice core, Ice sheet model, Ice radar
The past environmental changes such as temperature, atmospheric composition, dust and aerosols can be reconstructed at various spatio-temporal scales from ice cores from the Antarctic ice sheet. At Dome Fuji in East Antarctica, a deep ice core covering the past 720,000 years was drilled, which is the second longest ice-core record after the EPICA Dome C core (800,000 year old)(the third is the 420,000-year Vostok core). At these sites, the ice sheet is melting at the bottom by geothermal heat, thus there are no older ice at the current coring sites.
About 1 million years ago, the periodicity of glacial-interglacial cycle shifted from 40,000 to 100,000 years (Mid Pleistocene Transition), but the cause and mechanism of this transition remain unclear. Since the early 2000s, IPICS (International Partnership in Ice Core Sciences) has proposed the "Oldest Ice Core" project to collect Antarctic ice cores that will be essential for such studies. As IPICS emphasizes, a single ice core is not sufficient to ensure the reliability of the oldest ice core data. This is because very old ice exist only within 100-200 m of the bedrock, where the ice is relatively warm and annual layers are extremely thin. Therefore, it is very important to collect multiple ice cores from different areas and compare the results, which can only be done through international efforts. The EU and Australian projects have determined the drilling sites near Dome C, and other countries are aiming to drill ice cores at different sites at different locations.
The Japanese Antarctic Research Expedition (JARE) has conducted three inland surveys including an international survey (e.g., ice sheet radar observations and shallow ice coring), to locate candidate sites for collecting an oldest ice core in the Dome Fuji area. Also, new ice sheet models were developed and used for numerous simulations for reliable estimation of ice-sheet age and temperature profiles. After six years of observation, modeling, analyses, and discussion, the new ice core drilling site was selected at a site (77°21'40" S, 39°38'38" E) about 5 km south-southwest of the previous drilling site of the Dome Fuji ice core. In this presentation, we will introduce the characteristics of the selected site for the coming JARE deep drilling as well as other potential areas for future studies.
About 1 million years ago, the periodicity of glacial-interglacial cycle shifted from 40,000 to 100,000 years (Mid Pleistocene Transition), but the cause and mechanism of this transition remain unclear. Since the early 2000s, IPICS (International Partnership in Ice Core Sciences) has proposed the "Oldest Ice Core" project to collect Antarctic ice cores that will be essential for such studies. As IPICS emphasizes, a single ice core is not sufficient to ensure the reliability of the oldest ice core data. This is because very old ice exist only within 100-200 m of the bedrock, where the ice is relatively warm and annual layers are extremely thin. Therefore, it is very important to collect multiple ice cores from different areas and compare the results, which can only be done through international efforts. The EU and Australian projects have determined the drilling sites near Dome C, and other countries are aiming to drill ice cores at different sites at different locations.
The Japanese Antarctic Research Expedition (JARE) has conducted three inland surveys including an international survey (e.g., ice sheet radar observations and shallow ice coring), to locate candidate sites for collecting an oldest ice core in the Dome Fuji area. Also, new ice sheet models were developed and used for numerous simulations for reliable estimation of ice-sheet age and temperature profiles. After six years of observation, modeling, analyses, and discussion, the new ice core drilling site was selected at a site (77°21'40" S, 39°38'38" E) about 5 km south-southwest of the previous drilling site of the Dome Fuji ice core. In this presentation, we will introduce the characteristics of the selected site for the coming JARE deep drilling as well as other potential areas for future studies.