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State shifts in the deep Critical Zone drive landscape evolution in volcanic terrains

Leif Karlstrom·Nathaniel Klema·Gordon E. Grant·Carol A. Finn·Pamela L. Sullivan·Sarah Cooley·Alex Simpson·Becky Fasth·Katherine Cashman·Ken Ferrier·Lyndsay B. Ball·Daniele McKay
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Abstract

Understanding the near-surface environment where atmospheric and solid earth processes interact, often termed the “Critical Zone,” is important for assessing resources and building resilient societies. Here, we examine a volcanic landscape in the Oregon Cascade Range, an understudied Critical Zone setting that is host to major regional water resources, pervasive silicate weathering, and significant geohazards. We leverage a bedrock age chronosequence to show that the volcanic Critical Zone undergoes a structural shift, from depth extents of >1 km to meters, over timescales of ~1 My. We map an active groundwater volume comparable to major continental lakes, stored at the Cascade Range crest. This state shift makes volcanic landscape evolution a unique probe of deep coupling between Earth systems.

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Leif Karlstrom, Nathaniel Klema, Gordon E. Grant, Carol A. Finn, Pamela L. Sullivan, Sarah Cooley, Alex Simpson, Becky Fasth, Katherine Cashman, Ken Ferrier, Lyndsay B. Ball, Daniele McKay. 2025-01-13. State shifts in the deep Critical Zone drive landscape evolution in volcanic terrains. https://doi.org/10.1073/pnas.2415155122

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