A 14.5 million-year record of East Antarctic Ice Sheetfluctuations from the central Transantarctic Mountains,constrained with cosmogenic 3 He, 10 Be, 21 Ne, and 26 Al

Abstract. The distribution of moraines in the Transantarctic Mountains affords direct constraint of past ice-marginal positions of the East Antarctic Ice Sheet (EAIS). Here, we describe glacial-geologic observations and cosmogenic-nuclide exposure ages from Roberts Massif, an ice-free area in the central Transantarctic Mountains. We measured cosmogenic 3He, 10Be, 21Ne, and 26Al in 180 dolerite and sandstone boulders collected from 24 distinct deposits. Our data show that a cold-based EAIS was present, in a configuration similar to today, for many periods over the last ~ 14.5 Myr, including the mid-Miocene, Late Pliocene, and early-to-mid Pleistocene. Moraine ages at Roberts Massif increase with distance from, and elevation above the modern ice margin, which is consistent with a persistent EAIS extent during glacial maxima, and slow, isostatic uplift of the massif itself in response to trough incision by outlet glaciers. We also employ the exceptionally high cosmogenic-nuclide concentrations in several boulders, along with multi-isotope measurements in sandstone boulders, to infer extremely low erosion rates (