Evolution of the glacial landscape of the Southern Alps of New Zealand: Insights from a glacial erosion model

A new version of a landscape evolution model that includes the evolution of an ice cap at a 10³ to 10⁵ year timescale and its associated erosion patterns is presented and applied to the Southern Alps of New Zealand. Modeling of the ice cap evolution is performed on a higher-resolution grid (i.e., ∼100 m) than previously (Braun et al., 1998). It predicts which parts of the landscape are, and have been, affected by glacial erosion. The model results highlight the complexity of the erosion patterns induced by ice caps and glaciers. Glacial erosion in a tectonically active area is, as suggested by the model, not uniform across the mountain range. Furthermore, high rock uplift rates, heavy precipitation, and climatic oscillations constantly interact. The feedback mechanisms are such that they render the landform very dynamic and transient. However, under conditions of reduced rock uplift rate and precipitation, the landform becomes more stable at the timescale of the glacial cycle. Finally, the modeling results favor a tectonic model in the Southern Alps in which the maximum rock uplift is offset from the Alpine Fault.