Diachronous Evolution of a Multi-crater Hydrothermal Vent Complex in the Vøring Basin, offshore Norway

Hydrothermal vent complexes (HTVCs) form when water, carbon dioxide (CO₂), methane (CH₄), and other fluids, along with sediment, are rapidly ejected into the ocean and atmosphere, driven by the expansion and boiling of pore fluids surrounding intrusive magma in sedimentary basins. HTVCs are a common feature of Large Igneous Provinces (LIPs), which host the largest known magmatic intrusions on Earth. Given their nature and chronology, LIPs have historically been linked to major mass extinctions and global climate change, owing to their role in carbon degassing. The North Atlantic Igneous Province (NAIP, 61–58Ma and 56–53Ma) is the youngest large LIP emplacement and hosts hundreds of hydrothermal vents within the Vøring and Møre basins. Due to their timing and potential to emit a large volume of greenhouse gases, the HTVCs within the NAIP have been proposed to play a role in the onset and long duration of the Paleocene-Eocene Thermal Maximum (PETM, ca. 56 Ma). However, several aspects of the formation, timing, and impact of these particular HTVCs formation on the carbon cycle remain poorly understood. Here, we present a detailed stratigraphic and morphological reconstruction of the Modgunn Vent in the Vøring Basin, offshore Norway. High-resolution 3D P-Cable seismic data and borehole observations from the International Ocean Discovery Program (IODP) Expedition 396 reveal a multi-crater architecture, with four sub-craters formed through individual eruptive events, each associated with discrete sill intrusions and sediment infill phases. The four mapped craters present distinct subsidence, infill stratigraphy, and uplift signatures, indicating that, although currently clustered in a single HTVC, they formed independently and later amalgamated. Crater-specific uplift patterns and internal vent deformation features suggest a late-stage reactivation of vent conduits driven by renewed sill emplacement or fluid and mud migration. Biostratigraphic data tie the formation of the youngest crater in the Modgunn vent to the period immediately preceding the PETM. However, our seismic interpretation shows that the other three craters formed earlier. Our findings emphasise isochronous vent activity across the North Atlantic Igneous Province and reinforce a prolonged, dynamic scenario of greenhouse gas release. Further detailed subsurface imaging and stratigraphic analysis are crucial for refining models of vent evolution and, consequently, carbon degassing and its role in rapid climate perturbations.