[M-IS24] Biogeosciences of cold seeps, mud volcanoes, and hydrothermal vents

[MIS24-02] Noble-gas geochemistry in the pore fluids of unconsolidated sediments: potential and challenges

★Invited Papers

*Yama Tomonaga¹, Matthias S Brennwald¹, Edith Engelhardt¹, Stefanie B Wirth², Jin-Oh Park³, Juichiro Ashi³, Naoto Takahata³, Yuji Sano⁴, Rolf Kipfer¹ (1.Swiss Federal Institute of Aquatic Science and Technology, 2.University of Neuchâtel, 3.Atmosphere and Ocean Research Institute, The University of Tokyo, 4.Center for Advanced Marine Core Research, Kochi University)

Keywords:noble gases, pore water, terrigenic fluids, gas partitioning, fluid transport, isotope geochemistry

Noble gases are powerful tracers to study physical and biogeochemical processes in aquatic systems. The development over the last two decades of methods for the sampling and determination of noble gases in sediment pore water [1,2] allowed the concepts of noble-gas geochemistry to be applied to unconsolidated sediments in a robust and experimentally feasible manner [3].
With this contribution we aim to review the potential and the challenges related to the determination and interpretation of noble gas isotope concentrations in pore fluids. The available analytical methods will be screened in terms of advantages and limitations. Case studies related (for instance) to deep drilling, cold seeps, pockmarks, mud volcanoes, and hydrothermal vents will be discussed.
We will also provide lookout on new methods that, based on a recently developed portable mass spectrometer system [4], enable the simple determination of trace gases in porous media. Such methods, originally conceived to address the dating of Quaternary sediments or characterize gas-clay interactions in deep geological repositories [5], have the potential to support further research focusing on noble gases in pore fluids as geochemical tracers.


[1] Brennwald, M. S., Hofer, M., Peeters, F., Aeschbach-Hertig, W., Strassmann, K., Kipfer, R., & Imboden, D. (2003). Analysis of dissolved noble gases in the porewater of lacustrine sediments. Limmnol. Oceanogr. Methods, 1, 51–62.
[2] Tomonaga, Y., Brennwald, M. S., & Kipfer, R. (2011). An improved method for the analysis of dissolved noble gases in the pore water of unconsolidated sediments. Limnol. Oceanogr.: Methods, 9, 42–49, doi:10:4319/lom.2011.9.42.
[3] Brennwald, M. S., Vogel, N., Scheidegger, Y., Tomonaga, Y., Livingstone, D. M., & Kipfer, R. (2013). Noble gases as environmental tracers in sediment porewaters and in stalagmite fluid inclusions. In P. Burnard (Ed.), The Noble Gases as Geochemical Tracers (pp. 123–153). Advances in Isotope Geochemistry. Berlin, Heidelberg: Springer, doi:10.1007/978-3-642-28836-4_6.
[4] Brennwald, M. S., Schmidt, M., Oser, J., & Kipfer, R. (2016). A portable and autonomous mass spectrometric system for on-site environmental gas analysis. Environ. Sci. Technol., 50, 13455–13463, doi:10.1021/acs.est.6b03669.
[5] Tomonaga, Y., Wersin, P., Rufer, D., Pastina, B., Koho, P., Ville, H., & Kipfer, R. (2022). Gas-bentonite interactions: Towards a better understanding of gas dynamics in Engineered Barrier Systems. Appl. Geochem., 138, 105205, doi:10.1016/j.apgeochem.2022.105205.