Yama Tomonaga

The following co-authored article has been published in Marine Geology:

• Nuzzo, M., Tomonaga, Y., Schmidt, M., Valadares, V., Faber, E., Piñero, E., Reitz, A., Haeckel, M., Tyroller, L., Godinho, E., Kipfer, R., Terrinha, P.G., & Hensen, C. (2019). Formation and migration of hydrocarbons in deeply buried sediments of the Gulf of Cadiz convergent plate boundary – Insights from the hydrocarbon and helium isotope geochemistry of mud volcano fluids. Mar. Geol.,410, 56–69 doi:10.1016/j.margeo.2019.01.005.

Highlights:

• Clay dehydration water expelled from buried sediments drives mud volcanism.
• Rise of fluids mediated by crustal-scale strike-slip faults cross-cutting wedge.
• On active accretionary wedge, petroleum accumulations were dismantled in Neogene.
• ⁴He enrichment and δ¹³C-CH₄ ~−50‰ in fluids reflect an open hydrocarbon system.
• Petroleum pools remain on shallow margin. Microbial gas vented out of active wedge.

Here you can download the manuscript for free until March 13th, 2019.

The following co-authored manuscript has been accepted for publication in Applied Geochemistry:

• Sciarra, A., Cantucci, B., Ricci, T., Tomonaga, Y., & Mazzini, A. (2019). Geochemical characterization of the Nirano mud volcano, Italy. Appl. Geochem., doi:10.1016/j.apgeochem.2019.01.006.

In this work soil gas geochemistry and exhalation fluxes were determined in the Nirano mud volcano field. Soil degassing shows two high emission zones controlled by a buried tectonic system of caldera collapse structures. Gas discharged from active gryphons is methane-dominated with a thermogenic signature suggesting a deep source. The dissolved noble-gas signature in the discharged mud highlights secondary exchange at depth of few kilometers supporting deep origin. Soil gas monitoring allowed to detect the areas with the major potential for the formation of new gryphons.

Here you can download the manuscript for free until March 20th, 2019.