Ultra-slow spreading and hydrogen-based deep biosphere: A site survey proposal for zero-age drilling of the Knipovich Ridge

We propose to study geodynamic and hydrothermal processes along one of the most slow-spreading segments of the global ridge system. This will lay the ground for a European lead proposal to the Integrated Ocean Drilling Program (IODP) aimed to test hypothe sis on the geodynamics and the extent and nature of hydrothermal activity, water-rock interactions and the deep biosphere at the ultraslow end of the spreading rate spectrum. The Knipovich Ridge, which is one of the Arctic spreading ridges in the Norw egian-Greenland Sea, represents the target area for the project. With an effective spreading rate of only ~ 6 mm/y, the southernmost part of this ridge is one of the slowest spreading ridge segments on Earth. Water column analyses show that hydrothermal v enting currently takes place along this ridge segment, and an up to several hundred meters thick sedimentary sequence that cover large parts of the rift valley floor probably provide a record of the extent and nature of the hydrothermal activity. This sed imentary cover further provides a unique opportunity for zero-age drilling, which potentially may provide groundbreaking new insight as to the existence of a hydrogen-based deep biosphere sustained by the formation and alteration of oceanic crust and mant le by ultraslow spreading.