272-1 Glaciovolcanism and Geothermal Resources of Mount Baker, Washington

Abstract:

Mount Baker (Kweq' Smánit) is a 3,286 m, andesitic stratovolcano in the North Cascades of Washington State. The edifice is mantled by glaciers, including a glacial plug in Sherman Crater. The volcano has a long Quaternary eruption history, experienced thermal unrest in 1975, and has two very active fumarole fields. The edifice is the most recent expression of arc-based volcanism in this part of the North Cascades, with edifices as old as 3.7 mya to the northeast; the result of clockwise rotation of the crust.

Play fairway studies of geothermal favorability identified the Mount Baker region as an area of high geothermal potential. To the east of the edifice is Baker Hot Spring and wells with elevated geothermal gradient. Geochemical and geophysical studies correlate these heat signatures with faulting. Standard geothermometers at Baker Hot Spring are at equilibrium with calcedony and a reservoir temperature of 120-140 ^oC. Thermal imaging and spring chemistry surrounding the volcano reveal no other expression of heat in the near surface. Non-thermal springs in surrounding volcanics, metasediments, and ultramafics have very low TDS. Carbonate springs actively precipitate travertine.

A 2025 expedition in Sherman Crater mapped 1.5 km of glaciovolcanic cave, conducted drone-based photogrammetry, collected thermal imaging scans, and sampled fumaroles and thermal springs for geochemistry. Fumaroles exceed 90°C, are high in hydrogen sulfide, and have an isotopic profile consistent with a volcanic source. Geochemical syntheses, including standard geothermometers, reveal that volcanogenic waters in Sherman Crater are separately sourced from Baker Hot Spring and have a reservoir temperature of 250-380 ^oC.

This work responds to Washington Senate Bill 6039 directing Washington Geological Survey to prepare studies for geothermal focus areas. Work in Sherman Crater was funded by Mazamas, the National Cave and Karst Research Institute, and the National Speleological Society.

Geological Society of America Abstracts with Programs. Vol. 58, No. 5, 2026

doi: 10.1130/abs/2026AM-21288

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.