New constraints on the pre-glacial and glacial uplift and incision history of the central Transantarctic Mountains using multiple low-temperature thermochronometers

The Transantarctic Mountains (TAM) form one the longest and highest relief mountain belts on Earth. They are characterized by extensional tectonics related to development of the West Antarctic Rift System (WARS) since ~100 Ma, and later were deeply incised by major glacial troughs since formation of the East Antarctic ice sheet at ~34 Ma. However, the tectonic and geomorphic processes that led to their uplift, and the timing and magnitude of this uplift, remain poorly known owing to their remoteness, ice cover, and the lack of any post-Jurassic onshore stratigraphic record. Much of what we currently understand about post-Jurassic TAM uplift history has been informed by thermal histories documented by limited apatite fission track (AFT) thermochronology studies. Traditionally these results have been used to propose that the TAM formed through episodic rift flank uplift in the Early and Late Cretaceous, and Paleogene. However, more recent alternative explanations for TAM evolution and uplift include a vast Mesozoic sedimentary basin that buried the TAM until Paleogene rift-related inversion; Cretaceous extensional collapse of a high elevation "Altiplano-like" plateau; Uplift associated with lithospheric foundering beneath the central and southern TAM, and that up to half of the elevation of the high peaks of the central TAM can be explained by isostatic rebound in response to localized glacial incision. A crucial aspect for testing these various models is a more complete understanding of the thermal and erosion history of the TAM. To help resolve this, instead of relying on just AFT, we present new results from multiple thermochronometers (apatite and zircon FT and (U-Th)/He dating) from ~100 samples distributed across a 200x300 km region of the central TAM between the Beardmore and Shackleton Glaciers, including several vertical transects. Our initial results favor slow cooling since Ferrar magmatism at ~180 Ma, a cooling event at ~100-80 Ma associated with elevated heat flow and/or erosion during inception of the WARS, a further period of slow cooling, and accelerated cooling at ~34 Ma reflecting onset of glacial incision. Our results reveal more flexural isostatic rock uplift due to glacial incision than previously proposed for the central TAM, as significant post-34 Ma erosion of peaks was not accounted for.