Mapping stagnant ice and age in the Dome Fuji region, Antarctica, by combining radar internal layer stratigraphy and flow modeling

The Dome Fuji (DF) region in Antarctica is a potential site for holding an ice record older than one million years. Here, we combine the internal airborne radar stratigraphy with a 1-D inverse model to reconstruct the age field of ice in the DF region. As part of the Beyond EPICA - Oldest Ice reconnaissance (OIR), the region around DF was surveyed with a total of 19000 km of radar lines in the 2016/17 Antarctic summer. Internal stratigraphy in this region has now been traced. Through these tracked radar isochrones, we transfer the age-depth scale from DF ice core to the adjacent 500 km² region. A 1-D inverse model has been applied at each point of the survey to extend the age estimates to deeper regions of the ice sheet where no direct or continuous link of internal stratigraphy to the ice cores is possible, and to construct basal thermal state and accumulation rates. Through the reliability index of each model, we can evaluate the reliability of the 1-D assumption. Mapped age of basal ice and age density imply there might exist promising sites with ice older than 1.5 million years in the DF region. Moreover, the deduced basal state, i.e., melting rates and stagnant ice provide constraints for finding old-ice sites with a cold base. The accumulation rate ranges from 0.014 to 0.038 m a^-1 (in ice equivalent) in the DF region, which is also an important criterion for potential old ice.