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How does volcano internal structure and lithological contrasts control edifice erosion and morphologic evolution?

Daniel O'Hara 1, Simon Lambrecht2, Dávid Karátson3, Balázs Székely3, Benjamin Campforts4, Loraine Gourbet1, Matthieu Kervyn2

  • Affiliations: 1Earth Surface Process Modelling, GFZ Helmholtz Centre for Geosciences, 14473 Potsdam, Germany 2Department of Geography, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium 3Department of Physical Geography, Institute of Geography and Earth Sciences, Eötvös Loránd University, Budapest, Hungary 4Department of Earth Sciences, Vrije Universiteit Amsterdam, 1081HV Amsterdam, the Netherlands

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 172

  • Programme No: 3.5.31

  • Theme 3 > Session 5

Abstract

Volcanic edifices are heterogenic landforms that represent the long-term (thousands to millions of years) amalgamation of a variety of material. Shallow magmatic intrusions construct topography from below, while effusive and explosive material erupt from the volcano, mantling the surface with deposits that have time-dependent permeable and building topography from above. Furthermore, hydrologic alteration weathers rock, weakening layers and making them more susceptible to erosion. As these processes interact to generate an edifice with a complex internal structure, stochastic erosive processes associated with climate and mass wasting erode material, further degrading the edifice. Although most landscape evolution studies consider volcanoes as homogenous landforms, how these heterogeneities influence long-term erosion patterns and morphologic evolution remains unknown. Building on previous numerical studies, we analyze the effects of spatial and depth-dependent gradients in lithology on volcanic edifice drainage basin formation and evolution using landscape evolution models that incorporate fluvial and hillslope processes. Starting from a generalized stratovolcano shape, we construct an internal stratigraphic column that consists of 1) homogeneous material with surficial lobes of less erodible material, 2) homogenous internal material with an homogenous mantle of rock with time-varying erodibility, 3) heterogenous material with a less-erodible internal core, more-erodible lithologic shell, and less-erodible cap rock, 4) heterogenous material with alternating layers of erodibility, and 5) heterogenous material with lobes of time-varying erodibility. Analyzing the morphology of the edifice and encompassing drainages, we test how these spatial gradients in erodibility correspond to volcanic landform asymmetry, drainage basin geometric heterogeneity, and drainage divide migration and stability.