- 1SINTEF AS, Applied Geoscience, Trondheim, Norway
- 2NTNU, Trondheim, Norway
- 3School of Ocean and Earth Science, University of Southampton, UK
- 4Equinor, Trondheim, Norway
- 5Sorbonne Université, CNRS-INSU, Institut des Sciences de la Terre de Paris, ISTeP, Lille, France
- 6Univ. Lille, CNRS, Univ. Littoral Côte d’Opale, UMR 8187 – LOG – Laboratoire d’Océanologie et de Géosciences, Lille,France
- 7Department of Earth and Environmental Sciences, Dalhousie University, Halifax, NS, Canada
Hydrothermal circulation is a fundamental Earth process that transfers elements and minerals from the crust and mantle to the oceans. This circulation commonly occurs along tectonic plate boundaries in the oceans, where heat sources are located at relatively shallow depths (~2–3 km). Cold seawater percolates downward, becomes heated, and is enriched with minerals from the host rock and magmatic volatiles. The resulting hot fluids (exceeding 300°C) rise buoyantly and are expelled into the ocean through chimney-like structures on the seafloor, commonly referred to as "Black Smokers." The ejected particles settle on the seafloor, forming rich mineral deposits known as "Seafloor Massive Sulfide" (SMS) deposits, making mid-ocean ridges highly attractive for meeting future mineral demands. Moreover, ridge settings hold significant potential for geothermal energy, white hydrogen production, and other valuable resources. However, harnessing these resources requires a thorough understanding of the complex hydrothermal systems to develop sustainable resource management strategies.
Hydrothermal venting sites are widespread along the mid-ocean ridge system, occurring at all spreading rates and across diverse geological settings. However, the mechanisms driving hydrothermal processes vary depending on factors such as the presence of magma bodies, permeable zones, tectonic activity, and temperature. At ultraslow spreading ridges, where spreading rates are less than 20 mm/yr—such as the Southwest Indian Ridge, Mohns Ridge, and Knipovich Ridge—tectonic processes dominate over magmatic activity, resulting in the exhumation of ultramafic material to the seafloor along large-scale detachment faults.
In this study, we developed two-dimensional, high-resolution velocity models through the crust and uppermost mantle of the Southwest Indian Ridge using wide-angle ocean-bottom seismic data. We present two ~150 km-long, high-resolution P-wave velocity models orthogonal to each other, running across and along the ridge axis at 64°30’E. We employed a state-of-the-art imaging technique known as full waveform inversion (FWI) using data from 32 ocean-bottom seismometers positioned along the two profiles. FWI is a data-fitting method in which the forward operator iteratively predicts the observed data by backpropagating the misfits to update the velocity model, thereby producing higher-resolution images of the subsurface.
Based on our high-resolution velocity models, we observe finer patterns of velocity anomalies compared to traveltime models, revealing more detailed variations in the degree of fluid-rock interaction. These interactions are influenced by the presence of faults and the extent of tectonic damage, aiding in the mapping of hydrothermal circulation. Additionally, our high-resolution images provide an improved understanding of the distribution of serpentinization and its correlation to mode of spreading. Overall, the high-resolution velocity models support the assessment of the feasibility of "Artificial Smoker," which replicates natural smokers, for the environmentally sustainable extraction of minerals, white hydrogen, and geothermal resources.
How to cite: Boddupalli, B., Arntsen, B., Minshull, T., Hokstad, K., Leroy, S., Johansen, S., Watremez, L., Corbalan, A., and Sørum, L.: Artificial Smoker: Geophysical characterization of an ultraslow ridge system for sustainable resource management, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11735, https://doi.org/10.5194/egusphere-egu25-11735, 2025.