Geological characterization of the Aurora hydrothermal vent field, Gakkel Ridge

Abstract

The Aurora hydrothermal vent field is located on Gakkel Ridge, an ultraslow-spreading mid-ocean ridge in the Arctic Ocean, in a region of perennial sea-ice cover. Previous expeditions to Aurora revealed high-temperature black smoker chimneys on pillow basalts near an axial volcano summit, but challenges operating in drifting sea ice prevented detailed exploration and sampling of the site. The hydrothermal vents were imaged in detail for the first time during the 2021 HACON expedition, and rock sampling of three active vents and adjacent hydrothermal talus by remotely operated vehicle marked the first successful geological exploration of a hydrothermal field under ice. This study provides a geological characterization of Aurora using video footage and mineralogical and geochemical analyses of hydrothermal rock samples. While situated on mafic substrate, the hydrothermal precipitates contain Ni-Co sulfide minerals and low Si, Pb, and Ba concentrations, characteristics of ultramafic rock-influenced vent fields on slow-spreading ridges. Chimney structures are unusually thin and friable, lacking many of the lowtemperature minerals commonly found in other deposits. The results are discussed in the context of the poorly explored Gakkel Ridge, with implications for future interdisciplinary exploration of hydrothermal systems and for seafloor massive sulfide mineral potential in the Arctic.