Publication Date
1-23-2026
Document Type
Article
Publication Title
Geochemistry Geophysics Geosystems
Volume
27
Issue
1
DOI
10.1029/2025GC012675
Abstract
Three voluminous inflated lobate lava flow complexes on the distal rifts of Axial Seamount are much larger than other known flows in the global spreading system. Each complex is 65–100 km2, is up to 130 m thick, and is ∼3.0–4.6 km3, almost 100 times the volumes of historical Axial flows. These extraordinary flows are 5–7 times thicker than typical drained ponds in sheet flows. They thickened as impounded lava accumulated under chilled crusts. As flows expanded, molten interiors partially drained and flow tops collapsed. Levees built around collapses when interiors are repressurized. This formation sequence was preserved when the levee around one deep pond breached and drained the interconnected ponds. The complexes formed during moderately high-rate eruptions. Lavas from the south rift complex are plagioclase phyric mid-ocean ridge basalt (MORB) and those from the north rift complex are nearly aphyric and slightly more evolved. Glass compositions are similar to those of the summit and most rift lavas, implying that they resided in the summit magma reservoir where depleted ridge-derived magma and more enriched hot-spot-derived magma mixed. The distal south rift complex formed ∼1259 ± 119 years BP (or ∼691 CE; based on 14C dating of planktic foraminifera from core bases), a date that is statistically indistinguishable from the dates of phreatomagmatic deposits at the summit and formation of the present-day caldera. The north rift voluminous flows erupted ∼12,870 ± 173 years BP. The southwest complex, although partly mapped, remains unsampled, and is still older. Eruptions of these earlier voluminous lava complexes may also have coincided with prior caldera collapses.
Funding Number
101034309
Funding Sponsor
U.S. Geological Survey
Keywords
AUV mapping, Axial Seamount, caldera formation, lava pond, mid-ocean ridge, voluminous inflated lobate flows
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Department
Geology
Recommended Citation
Jennifer B. Paduan, David A. Clague, David W. Caress, Ryan Portner, Morgane Le Saout, and Brian Dreyer. "Voluminous Inflated Lobate Flows on the Distal Rift Zones of Axial Seamount, Juan de Fuca Spreading Ridge" Geochemistry Geophysics Geosystems (2026). https://doi.org/10.1029/2025GC012675
