CONSTRAINING ROCK UPLIFT HISTORIES FROM IGNIMBRITE-ENGULFED LANDSCAPES (Invited Presentation)

Supervolcano eruptions are rare, but when they occur, large-volume, spatially-expansive ignimbrites can completely bury and preserve pre-existing landscapes, creating a low-angle upper surface that gives no hint of the former topography beneath. These ignimbrite surfaces, when combined with estimates of deposit thickness, provide a unique opportunity to constrain the geometries of paleo-landscapes buried beneath volcanic deposits and the tectonic histories they record. For example, buried landscapes can be used to constrain pre-eruption rock uplift rates and provide an independent constraint on tectonic histories that can be compared to estimates from other proxies, such as low-temperature thermochronometry.

In this study we provide a numerical framework for constraining the fluvial channel relief of landscapes buried by ignimbrites to estimate tectonic rock uplift rates from the time before ignimbrite emplacement. Our numerical landscape evolution model demonstrates how the geometries of river channels and overriding ignimbrites are linked. We then apply this model to a well mapped ignimbrite in the Central Andes in northern Chile to illustrate the potential of this approach.