Karlstrom Leif, Klema Nathaniel, Grant Gordon E, Finn Carol, Sullivan Pamela L, Cooley Sarah, Simpson Alex, Fasth Becky, Cashman Katharine, Ferrier Ken, Ball Lyndsay, McKay Daniele
Department of Earth Sciences, University of Oregon, Eugene, OR 97403.
Department of Physics and Engineering, Fort Lewis College, Durango, CO 81301.
Proc Natl Acad Sci U S A. 2025 Jan 21;122(3):e2415155122. doi: 10.1073/pnas.2415155122. Epub 2025 Jan 13.
Volcanic provinces are among the most active but least well understood landscapes on Earth. Here, we show that the central Cascade arc, USA, exhibits systematic spatial covariation of topography and hydrology that are linked to aging volcanic bedrock, suggesting systematic controls on landscape evolution. At the Cascade crest, a locus of Quaternary volcanism, water circulates deeply through the upper [Formula: see text]1 km of crust but transitions to shallow and dominantly horizontal flow as rocks age away from the arc front. We argue that this spatial pattern reflects a temporal state shift in the deep Critical Zone. Chemical weathering at depth, surface particulate deposition, and tectonic forcing drive landscapes away from an initial state with minimal topographic dissection, large vertical hydraulic conductivity, abundant lakes, and muted hydrographs toward a state of deep fluvial dissection, small vertical hydraulic conductivity, few lakes, and flashy hydrographs. This state shift has major implications for regional water resources. Drill hole temperature profiles imply at least [Formula: see text] km[Formula: see text] of active groundwater currently stored at the Cascade Range crest, with discharge variability a strong function of bedrock age. Deeply circulating groundwater also impacts volcanism, and Holocene High Cascades eruptions reflect explosive magma-water interactions that increase regional volcanic hazard potential. We propose that a Critical Zone state shift drives volcanic landscape evolution in wet climates and represents a framework for understanding interconnected solid earth dynamics and climate in these terrains.
火山地区是地球上最活跃但了解最少的地貌之一。在这里，我们表明美国喀斯喀特山脉中部呈现出地形与水文的系统空间协变，这与古老的火山基岩有关，表明对地貌演化存在系统控制。在第四纪火山活动的中心——喀斯喀特山脉山顶，水在地表以下1千米的地壳中深度循环，但随着岩石远离弧前而变老，水流转变为浅层且主要是水平流动。我们认为这种空间模式反映了深部关键带的时间状态转变。深部的化学风化、地表颗粒沉积和构造作用力使地貌从初始状态转变，初始状态具有最小的地形切割、大的垂直水力传导率、丰富的湖泊和平缓的水文曲线，转变为深部河流切割、小的垂直水力传导率、少量湖泊和快速变化的水文曲线的状态。这种状态转变对区域水资源有重大影响。钻孔温度剖面表明，目前喀斯喀特山脉山顶至少储存了[公式：见原文]千米[公式：见原文]的活跃地下水，其流量变化是基岩年龄的强函数。深部循环的地下水也影响火山活动，全新世喀斯喀特山脉的火山喷发反映了爆炸性的岩浆 - 水相互作用，增加了区域火山灾害潜力。我们提出，关键带状态转变驱动了湿润气候下的火山地貌演化，并代表了一个理解这些地区固体地球动力学与气候相互联系的框架。
