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

Abstract 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.