Tectonic controls on volcanism and associated hydrothermal activity in a sediment-dominated mid-ocean ridge; Escanaba Trough

Chris Galley; John Jamieson; Amy Gartman; Isobel Yeo; Masako Tominaga; Maurice Tivey; Carlos Braga; Laura Moore; Sharon Walker

doi:10.1029/2025jb033347

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Tectonic controls on volcanism and associated hydrothermal activity in a sediment-dominated mid-ocean ridge; Escanaba Trough

Chris Galley·John Jamieson·Amy Gartman·Isobel Yeo·Masako Tominaga·Maurice Tivey·Carlos Braga·Laura Moore·Sharon Walker

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Abstract

Mid-ocean ridges, the Earth's most extensive volcanic system, exhibit unique characteristics in sediment-dominant environments. Thick sediment cover insulates the crust and channels fluid along pathways that can lead to the formation of distinct crustal alteration patterns, exceptionally large mineral deposits, and specialized chemosynthetic ecosystems. This study presents an interdisciplinary investigation into the tectonics of the Escanaba Trough, a heavily sedimented axial valley at the southern Gorda Ridge in the Northeast Pacific Ocean. A primary challenge in such environments is overcoming the masking effect of thick sediments on basement structures that control magmatic and hydrothermal activity. We address this by employing three-dimensional (3D) magnetic modeling of high-resolution near-seafloor magnetic data collected by an autonomous underwater vehicle (AUV). The 2022 surveys with AUV Sentry provided data for 3D magnetic susceptibility models, refining our understanding of the geometry of sub-sediment laccoliths/saucer-shaped sills and hydrothermal alteration. In conjunction with a new 1:100,000 scale lithostratigraphic map, we outline the tectonic controls on the emplacement of Escanaba Trough's three main volcanic centers, characterize the geometry of its spreading segments, and provide volumetric data on the distribution of sub-sediment volcanism in the southern Gorda Ridge.

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Source-reported bounding extent: 40.333° to 41.25° latitude; -128° to -127° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Chris Galley, John Jamieson, Amy Gartman, Isobel Yeo, Masako Tominaga, Maurice Tivey, Carlos Braga, Laura Moore, Sharon Walker. 2026-07-15. Tectonic controls on volcanism and associated hydrothermal activity in a sediment-dominated mid-ocean ridge; Escanaba Trough. https://doi.org/10.1029/2025jb033347

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