Seafloor images collected during the 'HACON expedition' with the RV Kronprins Haakon (cruise no. 2019708) (HK19) to the AURORA seamount, high Arctic, 19/09/2019 - 16/10/2019@en

The Aurora hydrothermal field sits in the westernmost segment of the Gakkel Ridge within the Western Volcanic Zone which extends for 220 km from 7°W to 3°E. The spreading rate here is 14.5-13.5mm/yr and the ridge axis floor at 4200m depth is bounded by steep normal fault rift valley walls and punctuated by a series of axial volcanic ridges and smaller volcanic mounds that rise up hundreds of meters above that axial floor depth. The Aurora field was first located associated with one such volcanic mound as part of the InterRidge two-icebreaker AMORE expedition in 2001. At 82°53'N, 6°15'W a small volcanic mound measuring ~1.5-2km in extent rises approximately 400m from the seafloor at a saddle-point where the rift- valley narrows from ~20km to ~15km wide. During a return cruise to the site aboard the FS Polarstern in 2014, CTD profiling coupled with water column sampling and CH4, TDMn and He-isotope anomalies revealed clear evidence for ongoing hydrothermal activity including strong evidence from CH4:TDMn ratios of ultramafic influence in the underlying vents. Buoyant plume signals intercepted with the CTD during that cruise suggested at least one source of venting was situated toward the south/southwest of the shallowest summit of the Aurora seamount and OFOS deep-tow camera tows from North to South across that summit revealed deep rifts through the thickly sediment seafloor surrounding the base of the volcanic mound. Those firsts were observed striking approximately E-W (across axis) immediately south of the summit of the mound on at least two OFOS tows. These paired observations (CTD, seafloor imaging) led to first imaging of an active vent at ~3900m depth at a Posidonia position of 82°53.83'N, 006°15.32'W. […]