Examining the Rates and Controls of Erosion and Landsliding in New Zealand with Cosmogenic Nuclides

The Southern Alps of New Zealand are known to be one of the fastest-eroding mountain ranges in the world, however the distribution of uplift and erosion, and the processes controlling them remain debated. To examine this, I will first present new ¹⁰Be catchment-averaged erosion rates from 20 catchments. Catchment-averaged erosion rates span an order of magnitude, between ~0.8 and >10 mm/yr. Tectonics can explain well the magnitude and general patterns of ¹⁰Be erosion rates along the range, but there is significant variability on the ¹⁰Be erosion rates that cannot be ascribed to the along-strike Alpine Fault throw patterns. We find that superimposed on the primary tectonic control, there is an elevation/temperature control on erosion rates, which is probably transient and related to frost-cracking and glacial retreat. While most work on tectonic-climate feedbacks has focused on orographic precipitation and glaciation, our results show that temperature-controlled erosion also plays an important role in the interplay of climate and tectonics. Second, I will present preliminary results on how we are using paired in-situ ¹⁴C-¹⁰Be measurements from recent landslides in New Zealand to infer long-term (10²-10³) landslide recurrence intervals and show how these measurements offer promise as a tool for tracing erosional depth-provenance, and potentially fingerprinting landslide-derived sediment.

Host: Claire Masteller

By joining department-hosted virtual colloquia, you agree to uphold our code of conduct for Zoom sessions.