Cretaceous and Cenozoic episodic denudation of the Transantarctic Mountains, Antarctica: New constraints from apatite fission track thermochronology in the Scott Glacier region

Apatite fission track thermochronology utilizing vertical sampling profiles, with results interpreted using the concept of exhumed partial annealing zones, is applied in the Scott Glaciet area (86°S) of the Transantarctic Mountains (TAM). Patterns in age profiles indicate that episodes of denudation in the Early Cretaceous, Late Cretaceous, and Cenozoic were separated by periods of relative tectonic stability. Thermal modeling of time-temperature histories compared to observed data indicates that denudation episodes commenced at ̃125 Ma, ̃95 Ma, and 50-45 Ma. Magnitude of denudation is constrained only as ̃700 m for the Early Cretaceous and from barely detectable to 1.5 km for the Late Cretaceous. Since the early Cenozoic, denudation within the TAM Front was similar in magnitude to other localities along the TAM (-4-6 km), decreasing inland. Rock uplift was also a maximum at the coast, decreasing inland. Patterns of rock uplift and denudation are complicated by Cenozoic faulting, mostly by faults oriented ∼45° to the TAM Front. Along the length of the TAM there is an apparent systematic variation in the angle of these Cenozoic faults to the TAM Front, possibly reflecting greater components of dextral transtension southward along the TAM. The three denudation episodes correspond to regional tectonic events: Early Cretaceous southward translation of the Ellsworth-Whitmore Mountains block of West Antarctica relative to East Antarctica; Late Cretaceous extension in the Ross Embayment between East and West Antarctica; and Cenozoic rejuvenated faulting, magmatism, and deformation within the Victoria Land Basin and its presumed southward extension under the Ross Ice Sheet.