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The utility of topography in disentangling volcano construction, erosion, and magmatic histories

Daniel O'Hara1

Abstract

Volcanic edifices represent a long-term convolution of magmatism, volcanism, erosion, and climate. Edifices grow through both subsurface intrusions that uplift the surface from below, and lava flows and ash deposits that mantle the surface from above. Meanwhile, these periods of growth are temporally-juxtaposed against the longer-term backdrop of climate- and gravity-driven erosive processes that degrade the edifice. Deconvolving these signals is challenging, yet presents new insight into understanding volcanic terrain as an interface between crustal and surficial systems. Here, I demonstrate the utility of incorporating geomorphology-based analyses into volcanology to resolve construction histories, volcano-climate interactions, and connection to underlying crustal magma structure. Beginning with La Réunion, I show that erosion patterns correlate with volcano unit age, and that drainage basin morphologies are indicative of rainfall gradients across the island. Expanding to sets of stratovolcanoes, I demonstrate that morphometrics of edifices and their drainage basins are strong temporal indicators for volcanic activity ages. Finally, in the U.S. Cascades, I show how arc-scale distributions of edifice erosion volumes relate to both precipitation gradients and volcano locations, suggesting potential feedbacks between climate, erosion, topography, and shallow-crustal magmatism. I end with a discussion on future challenges and research idea for bridging volcanology and geomorphology.