Tectonic controls on the timing of fjord incision at the Antarctic Peninsula

We report 534 detrital apatite (U-Th)/He thermochronometric ages collected along a >400 km latitudinal transect along the Antarctic Peninsula (AP). We use the dataset to evaluate the relative roles of climate change and tectonics on the timing of km-scale fjord incision. We find that the onset of km-scale topographic change occurred more than 15 million years after the initiation of glaciation in the region, and generally coincided with the arrival times of the spreading ridge at different latitudes. These results indicate that tectonically-initiated rock uplift accelerated rates of erosion during long glacial conditions at the AP. We infer that rock uplift primarily affected glacial erosion rates by increasing topographic relief, and thereby increasing ice motion and its capacity to erode. These are among the first empirical observations to reveal that a tectonic history, and its control on the regional topography of a landscape, has influenced glacial erosion rates over geologic timescales. •Detrital thermochronometry was used to determine the timing of fjord incision.•Topographic change began >15 million years after the onset of glaciation.•The timing of topographic change generally coincides with tectonic change.•Rock uplift likely increased glacial erosion rates by increasing topographic relief.•Empirical evidence that tectonics affect glacial erosion rates on geologic timescales.