Abstract
The disturbance of the geomagnetic field by solar particles can help us see deep into the Earth’s interior. The way electrical current flows in geological layers often depends on the conductive properties of the fluid filling the empty spaces within the rock. When the Earth’s crust is stretched, seawater can move down to the viscous layer beneath, called the mantle. Here, we investigate the electrical properties of a hyperextended rift system in the Barents Sea and unveil possible fluid circulation between sediments and mantle. This is important because seawater reacts with mantle rocks to release natural hydrogen, a potential source of decarbonized energy.
The foundation of this doctoral thesis lies in the analysis of electromagnetic recordings collected on the seafloor of the Barents Sea. A model of the Earth electrical structures is obtained with an automated trial-and-error process called inversion. However, multiple models can equally explain the data. Therefore, we employed a probabilistic approach complemented by machine learning to generate thousands of best-fit models. We identify two likely conductors in deeply buried sediments and upper mantle. We interpret them as rocks filled with saline fluids, partially consumed through a chemical reaction with mantle rocks that releases natural hydrogen.