DFG Priority Program 1144 "From Mantle to the Ocean: Energy,  Material and Life Cycles on Spreading Axes" - Release and Transport of Methane and Helium at the Mid Atlantic Ridge", DFG SCHM 2530/1

The Logatchev hydrothermal field at 14°45’N on the MAR is characterized by gas plumes that are enriched in methane and helium compared to the oceanic background. We investigated CH₄ concentration and δ¹³C together with δ³He in the water column of that region. These data and turbidity measurements indicate that apart from the known vent fields, another vent site exists northeast of the vent field Logatchev 1. The distribution of methane and ³He concentrations along two sections were used in combination with current measurements from lowered acoustic Doppler current profilers (LADCP) to calculate the horizontal plume fluxes of these gases. According to these examinations 0.02 mmol s^-1 of ³He and 0.21 mol s^-1 of methane are transported in a plume that flows into a southward direction in the central part of the valley. Based on ³He measurements of vent fluid (22 ± 6 pM), we estimate a total vent flux in this region of about 900 L s^-1 and a total flux of CH₄ of 3.2 mol s^-1.

 

References

Schmale O., Walter M., Schneider v. Deimling J., Sültenfuß J., Walker S., Rehder G., and Keir R. (2012). Fluid and gas fluxes from the Logatchev hydrothermal vent area, Geochem. Geophys. Geosyst., 13, Q07007, 2012.

Keir R., Schmale O., Seifert R., and Sültenfuß, J.: Isotope fractionation and mixing in methane plumes from the Logatchev hydrothermal field, Geochem. Geophys. Geosyst., 10, Q05005, 2009.