203 Old and the New, Long and the Short: Perspectives on Integration of Timescales of Magmatic Processes: Special Session Related to MGPV Awards to Madison Myers and Anita Grunder

We encourage papers that challenge and give insights into the interplay between timescales, methodologies, and processes to build a cohesive understanding of the lifespan, evolution, storage, and eruption of magma, from plutonic to volcanic systems.

Tuesday, 21 October 2025
1:30 PM - 5:30 PM
HBGCC, 216AB

Months between initiation and eruption observed for the four most recent lavas at a Cascade Volcano, Mount Baker (Kulshan), Washington, USA

Paper number: 203-1
Program: Technical Sessions
Time: 1:45 PM – 2:00 PM

Authors

Abstract

The timing between volcanic unrest and an eruption is difficult to forecast, requiring a thorough understanding of the magmatic plumbing system beneath a volcano. Mount Baker in Washington, USA is an active, very-high-threat, Cascade Arc volcano that consecutively erupts multiple co-crystallizing assemblages that suggest interaction between an ascending parent magma and distinct crystal mushes in a transcrustal magmatic plumbing system (Escobar-Burciaga, 2016; Garvey, 2022). What remains unknown is the timing of these interactions, the specific mechanisms that initiate eruptions, and how long magmas are stored eruptible (i.e., magma residence time). This study examines the crystal cargo of four effusive eruptions of Mount Baker’s most recent history, including the lavas of Dobbs Creek (~119 ka), Dobbs Cleaver (~105 ka), Swift Creek (~48 ka), and Sulphur Creek (~10 ka). Plagioclase and clinopyroxene populations reveal a similar sequence of magmatic processes prior to the four eruptions of interest, specifically recording mafic recharge and thermal underplating as important pre-eruptive processes not only for initiating eruptions, but also as a mechanism for magma mixing and the creation of intermediate magma compositions. Diffusion chronometry coupled with mineral thermometry using Mg- and Sr-diffusion in plagioclase and Fe-Mg interdiffusion in clinopyroxene rims suggest median eruption initiation times of 3 months (n=116). Plagioclase cores modeled at 850ºC (temperature near rheological lock-up for Sulphur Creek lava) suggests magma residence times on the order of years to decades for the youngest eruption (n=46). We aim to build a dataset of pre-eruptive timescales at Mount Baker to improve our understanding of future volcanic behavior.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413566

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