Stress pinch points from glacial loading modulate magma ascent and storage in continental arcs

Stress pinch points from glacial loading modulate magma ascent and storage in continental arcs | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Stress pinch points from glacial loading modulate magma ascent and storage in continental arcs Meredith Townsend, Pablo Moreno-Yaeger, Andrew Harp, Christian Huber, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7437527/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 20 Feb, 2026 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Growing evidence indicates that glacial cycles influence volcanic activity, yet the physical mechanisms linking glaciation to magmatic processes in continental arcs remain poorly understood. Here, we integrate realistic ice and topographic loads with a mechanical model of dike propagation to evaluate how glaciation modulated magma ascent and storage beneath Mocho-Choshuenco, Chile, a continental arc volcano impacted by the growth of the Patagonian Ice Sheet during the Last Glacial Maximum (LGM) 35-18 ka, followed by rapid ice loss between 18 and 16 ka. We find that during peak ice thickness, dikes ascending from lower crustal reservoirs and initiated below an ice load-induced stress “pinch point” stall several kilometers deeper than in ice-free conditions, effectively cutting off recharge to shallow reservoirs. This mechanism offers a straightforward explanation for the ~2-3 km increase in magma storage depths and the marked reduction in eruption rates observed during the LGM, without requiring changes in mantle melt supply or reservoir strength. By shutting off shallow recharge, glacial loading also favors prolonged magma differentiation, setting the stage for potentially explosive silicic eruptions once deglaciation again permits dikes to reach upper crustal levels. Our results thus identify a robust mechanism by which modest glacially driven stress changes regulate dike arrest depths, offering a unified framework to explain observed shifts in magma composition, storage depth, and eruption rate at Mocho-Choshuenco and potentially other arc volcanoes worldwide. Earth and environmental sciences/Solid Earth sciences/Volcanology Earth and environmental sciences/Climate sciences/Palaeoclimate Earth and environmental sciences/Natural hazards Earth and environmental sciences/Solid Earth sciences/Tectonics Full Text Additional Declarations There is NO Competing Interest. Supplementary Files FigS1.pdf Fig S1 FigS2.pdf Fig S2 FigS3.pdf Fig S3 FigS4.pdf Fig S4 FigS5.pdf Fig S5 FigS6.pdf Fig S6 Cite Share Download PDF Status: Published Journal Publication published 20 Feb, 2026 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7437527","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":529891135,"identity":"a725aae8-34cd-4d99-9116-fcf9baa960bf","order_by":0,"name":"Meredith 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