Origins of Antarctic Peninsula Topography: Constraints From Low Temperature Apatite Thermochronometry

Subduction along the western margin of the Antarctic Peninsula (AP) is largely responsible for its significant topography. To test a long-held view that Cenozoic uplift of a low-relief landscape was related to a series of northward migrating Antarctic–Phoenix plate ridge–trench collisions between ∼50 and 3 Ma this study used a compilation of new and published apatite thermochronological (fission track and (U-Th)/He) data sets to track exhumation histories. Measured ages and thermal history models of samples that span the entire length and width of the AP provide no evidence to support a south to north trend in exhumation predicted for successive ridge–trench collisions and/or diachronous unzipping of a slab window. Results record exhumation since the Late Cretaceous with marked increases between ∼60 and 30 Ma concomitant with development of a transpressive regime caused by changes in subduction obliquity and a drop in Phoenix Plate convergence rates. A phase of accelerated exhumation between 20–8 Ma, with a peak around 13 Ma, is recorded in samples along the length of western side of the AP and both post-date and pre-date cessation of subduction. This suggests rock uplift and exhumation was driven by a combination of dynamic topography and enhanced surface processes in response to global cooling following the middle Miocene Climate Transition at ∼14.7–13.8 Ma.