PMEL Publications Abstract
FY 2026
Tectonic controls on volcanism and associated hydrothermal activity in a sediment-dominated mid-ocean ridge; Escanaba Trough
Galley, C.G., J. Jamieson, A. Gartman, I. Yeo, M. Tominaga, M. Tivey, C. Braga, L. Moore, and S.L. Walker
J. Geophys. Res., 131(7), e2025JB033347, doi: 10.1029/2025JB033347, View open access article at Wiley/AGU (external link) (2026)
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.
Plain Language Summary. Mid-ocean ridges are extensive submarine volcanic systems that encircle the globe. In rare cases these ridges are located near continents whose erosion blankets them in thick layers of sediment, masking much of their structure and creating unique types of volcanos and deep-sea vents. This study presents a new geologic map of the Escanaba Trough, a sediment-dominant mid-ocean ridge segment off the coast of Oregon and California, USA, created from remote-sensing data sets. The map allowed for the quantification of the volume of volcanic material erupted below the sediment and helped explain the positioning of the region's three discrete volcanic centers. A closer inspection of Escanaba's deep-sea venting and volcanic processes was accomplished through the three-dimensional modeling of magnetic data collected during an expedition to the Escanaba Trough in 2022. These six magnetic models, created by modeling magnetic data collected near the seafloor by an autonomous underwater vehicle, refined our understanding on the emplacement and geometry of intrusions, deep-sea vents, and volcanoes in heavily sedimented portions of the seafloor where marine exploration continues to be challenging.