Concentrations of methane (headspace gas) in gravity core GeoB21366-1 from Sartori Mud Volcano, Calabrian accretionary wedge (R/V POSEIDON cruise POS499)

Shallow sediment cores GeoB21366-1 and GeoB21367-1 were collected by gravity coring from the region of the Sartori Mud Volcano in the Calabrian accretionary prism during cruise POS499 with R/V POSEIDON. Both sites were positioned outside the mud volcano to the west or northwest of its rim. In order to determine ex-situ concentrations of methane dissolved in pore water, sediment samples were taken from the sediment cores with cut-off syringes and transferred into glass vials. Methane concentrations in the headspace gas were determined by gas chromatography and used to calculate concentrations of methane dissolved in pore water (uncorrected for sediment porosity and Bunsen coefficient).