Association of hydrothermal venting with seafloor morphology from high-resolution bathymetry at the Polaris vent site, Gakkel Ridge

The Gakkel Ridge is the slowest-spreading axial ridge on Earth extending across the Arctic Ocean for ~1800 km. It was subdivided into a western and an eastern magmatically robust zone separated by a central sparsely magmatic zone, based on rock recovery during the AMORE expedition in 2001. During the same expedition, at least nine discrete hydrothermal sources were inferred from water-column plume detections. Due to the perennial ice cover limiting the deployment of underwater vehicles, only two of these plumes have ever been traced to their seafloor sources: the Aurora vent field, at the westernmost end of the Gakkel Ridge, and the Polaris vent field, in the Eastern Volcanic Zone.

In this study, we present an integrated high-resolution multibeam and optical dataset acquired onboard RV Polarstern at the axial volcanic high hosting the Polaris vent site (56°E) in 2016 using the towed camera system OFOBS. The combination of bathymetric data and photogrammetric reconstruction from optical imagery reveals pronounced morphological and geological heterogeneity across the study area. Based on these observations, we classify the seafloor into three main terrain types: (1) an axial volcanic summit dominated by pillow basalt, indicative of volcanic emplacement; (2) a faulted zone where tectonic structures focus hydrothermal activity, corresponding to the location of the Polaris vent field; and (3) a distal domain characterized by larger-scale tectonic structures with no clear evidence for recent volcanism or active hydrothermal venting.

By providing one of the few high-resolution bathymetric datasets of a hydrothermally hosted axial volcanic high, this dataset allows us to examine the relationship between hydrothermal venting and fine-scale seafloor morphology on the ultraslow-spreading Gakkel Ridge.