A permeability estimate in 56 Ma crust at ODP Hole 642E, Vّring Plateau Norwegian Sea

Temperature measurements made in Ocean Drilling Program (ODP) Hole 642E are used to estimate bulk crustal permeability. Hole 642E is located on the Vøring Plateau near the transition between oceanic and continental crust on a volcanically rifted margin. A temperature–depth profile measured 20 yr after the hole was drilled indicates fluid flowing from the basement, up the Hole and into the ocean. This flow regime suggests that the basement is naturally over pressured with respect to hydrostatic. We estimate the up-hole flow rate to be approximately 6–11 m h− 1. This flow rate, coupled with an estimated minimum differential overpressure of 13–20 kPa, and an estimated aquifer thickness of 100 m, yields a bulk permeability of 10− 13 m2. This result suggests that fluid flow through basement may be an important component of passive margin hydrology.