Characterizing the Unique Chemical Imprint of On-Axis, Lower-Temperature Hydrothermal Flow to the Deep Ocean (Southern East Pacific Rise, 16.5°-18.0°S)

Authors

• Laura E. Moore, Oregon State University
• Randelle M. Bundy, University of Washington - Seattle Campus
• Joseph A. Resing, University of Washington - Seattle Campus
• Scott White, University of South Carolina - Columbia
• Tamara Baumberger, Oregon State University
• Peter N. Sedwick, Old Dominion UniversityFollow
• Nathaniel J. Buck, University of Washington
• Anson M. Antriasian, Oregon State University and NOAA Pacific Marine Environmental Laboratory
• Isaac Keohane, University of South Carolina - Columbia
• Bettina M. Sohst, Old Dominion UniversityFollow
• Sharon L. Walker, NOAA Pacific Marine Environmental Laboratory
• Christopher R. German, Woods Hole Oceanographic Institution

ORCID

0000-0003-0663-8323 (Sedwick), 0000-0002-4983-5223 (Sohst)

Document Type

Article

Publication Date

2026

DOI

10.1029/2025GL120412

Publication Title

Geophysical Research Letters

Volume

53

Issue

7

Pages

e2025GL120412

Abstract

In addition to high-temperature vents, lower-temperature flow (LTF) (< 300°C) is abundant along mid-ocean ridges and contributes globally-important fluxes of heat and water along with largely-unconstrained geochemical influences on the ocean. We examined the impact of on-axis LTF on the chemical composition of the overlying water column (< 40 m above seafloor) along the 16.5°-18.0°S sector of the ultrafast-spreading southern East Pacific Rise using autonomous underwater vehicle Sentry surveys and conductivity-temperature-depth rosette casts. LTF sites were typically spatially isolated from high-temperature systems and imparted unique chemical signatures to the overlying ocean. Water column samples impacted by LTF exhibited low particulate iron:sulfur ratios and high methane: total-dissolvable manganese ratios, whereas samples influenced by high-temperature venting exhibited opposite trends. We confirmed that LTF imparts a distinct and measurable chemical signature to the water column, independent from high-temperature vents. Isolated, on-axis LTF will be important to consider when assessing hydrothermal circulation impacts upon ocean biogeochemistry.

Rights

© 2026. The Authors.

This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Data Availability

The tdMn and tdFe used for characterizing water column samples in this study are available at the biological and chemical oceanography data management office via 10.26008/1912/bco-dmo.944890.1 with Creative Commons Attribution 4.0 International License. (Moore et al., 2024). The ORP, backscatter, and temperature anomaly cast data are available through the Marine Geoscience Data System (MGDS) via 10.60521/331701 with Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. (Walker et al., 2024). The ORP, backscatter, and temperature anomaly data from AUV Sentry dives S597, S598, S601, S602, S604, S605 and S606 used to generate distributions of along axis flow are available through MGDS via 10.60521/332479 with Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License (German, White, & Resing, 2025). The photographs from AUV Sentry are available through MGDS for dives S598 (10.26022/IEDA/331049), S600 (10.26022/IEDA/331051), S602 (10.26022/IEDA/331053), and S603 (10.26022/IEDA/331054) are available through MGDS (White et al., 2022a, 2022b, 2022c, 2022d). The particulate sulfur, particulate iron, dissolved hydrogen and dissolved methane data are available through Zenodo via 10.5281/zenodo.17428310 with Creative Commons 0 license (Baumberger et al., 2025). Version 0.6.2 of ggbiplot used for principal component analysis is preserved at 10.32614/CRAN.package.ggbiplot, available via General Public License 2, and developed openly at https://CRAN.R-project.org/package=ggbiplot (Vu & Friendly, 2024).

This package was used in RStudio (version 2025.05.0+496), available at http://www.posit.co/via the GNU Affero General Public license (Posit Team, 2025). Bathymetry data for Figure 1 was processed using MB-System, available at https://www.mbari.org/technology/mb-system and developed openly at https://github.com/dwcaress/MB-System via the GNU Affero General Public license, version 3 (Caress & Chayes, 2024). Map in Figure 1 was created using ESRI ArcGIS (esri.com) using a combination of the GMRT database via 10.1594/IEDA.100,001 (Ryan et al., 2009) and bathymetry data from the RR2106 expedition available through the MGDS via 10.26022/IEDA/331076 (White et al., 2022e).

Original Publication Citation

Moore, L. E., Bundy, R. M., Resing, J. A., White, S., Baumberger, T., Sedwick, P. N., Buck, N. J., Antriasian, A. M., Keohane, I., Sohst, B. M., Walker, S. L., & German, C. R. (2026). Characterizing the unique chemical imprint of on-axis, lower-temperature hydrothermal flow to the deep ocean (southern East Pacific Rise, 16.5°–18.0°s). Geophysical Research Letters, 53(7), Article e2025GL120412. https://doi.org/10.1029/2025GL120412

Repository Citation

Moore, Laura E.; Bundy, Randelle M.; Resing, Joseph A.; White, Scott; Baumberger, Tamara; Sedwick, Peter N.; Buck, Nathaniel J.; Antriasian, Anson M.; Keohane, Isaac; Sohst, Bettina M.; Walker, Sharon L.; and German, Christopher R., "Characterizing the Unique Chemical Imprint of On-Axis, Lower-Temperature Hydrothermal Flow to the Deep Ocean (Southern East Pacific Rise, 16.5°-18.0°S)" (2026). OES Faculty Publications. 572.
https://digitalcommons.odu.edu/oeas_fac_pubs/572