Table1_The arc-scale spatial distribution of volcano erosion implies coupled magmatism and regional climate in the Cascades arc, United States.XLSX

The morphology and distribution of volcanic edifices in volcanic terrains encodes the structure and evolution of underlying magma transport as well as surface processes that shape landforms. How magmatic construction and erosion interact on long timescales to sculpt these landscapes, however, remains poorly resolved. In the Cascades arc, distributed volcanic edifices mirror long-wavelength topography associated with underlying crustal magmatism and define the regional drainage divide. The resulting strong along- and across-arc modern precipitation gradients and extensive glaciation provide a natural laboratory for climate-volcano interactions. Here, we use 1,658 volcanic edifice boundaries to quantify volcano morphology at the arc-scale, and reconstruct primary edifice volumes to create first-order estimations of Cascades erosion throughout the Quaternary. Across-arc asymmetry in eroded volumes, mirroring similarly asymmetric spatial distribution of volcanism, suggests a coupling between magmatism and climate in which construction of topography enhances erosion by orographic precipitation and glaciers on million-year timescales. We demonstrate with a coupled landscape evolution and crustal stress model that mountain building associated with magmatism and subsequent orographically-induced erosion can redistribute surface loads and direct subsequent time-averaged magma ascent. This two-way coupling can thus contribute to Myr-scale spatial migration of volcanism observed in the Cascades and other arcs globally.

火山地貌中的火山锥（volcanic edifices）的形态与分布，蕴含了下伏岩浆运移的结构与演化过程，以及塑造地表形态的表层作用机制。然而，岩浆建造与侵蚀作用如何在长期时间尺度上相互作用以塑造这类地貌，目前仍未得到充分厘清。在喀斯喀特弧（Cascades arc）中，分布的火山锥与下伏地壳岩浆作用相关的长波长地形相呼应，并构成了区域分水岭。由此形成的沿弧与跨弧方向显著的现代降水梯度，以及广泛的冰川作用，为气候-火山相互作用研究提供了天然实验场。本研究利用1658处火山锥边界，实现弧尺度下的火山形态量化，并通过重建火山锥原始体积，首次估算了第四纪（Quaternary）以来喀斯喀特弧的侵蚀总量。侵蚀体积的跨弧不对称性，与火山活动的空间分布不对称性相呼应，表明岩浆作用与气候之间存在耦合关系：在百万年时间尺度上，地形建造通过地形降水与冰川作用加剧侵蚀。本研究通过耦合地貌演化与地壳应力模型证明，与岩浆作用相关的造山过程，以及随后由地形诱导的侵蚀作用，能够重新分配地表负荷，并控制后续时间平均的岩浆上升路径。这种双向耦合作用，可解释喀斯喀特弧及全球其他弧系中观测到的百万年尺度火山活动空间迁移现象。