Université de Fribourg

Downslope-shifting pockmarks: interplay between hydrocarbon leakage, sedimentations, currents and slope’s topography

Ho, Sutieng ; Imbert, Patrice ; Hovland, Martin ; Wetzel, Andreas ; Blouet, Jean-Philippe ; Carruthers, Daniel

In: International Journal of Earth Sciences, 2018, vol. 107, no. 8, p. 2907–2929

Pockmarks in Pliocene-Quaternary continental slope deposits offshore Angola show features related to: (1) fluid leakage craters that formed repeatedly, (2) authigenic methane-derived carbonates that indicate the (former) presence of hydrocarbons and (3) erosional–depositional structures that are clearly related to current activity. Depending on topography, the pockmarks show differing...

Université de Fribourg

Mechanisms of biogenic gas migration revealed by seep carbonate paragenesis, Panoche Hills, California

Blouet, Jean-Philippe ; Imbert, Patrice ; Foubert, Anneleen

In: AAPG Bulletin, 2017, vol. 101, no. 8, p. 1309–1340

A comprehensive study of seep carbonates at the top of the organic-rich Maastrichtian to Danian Moreno Formation in the Panoche Hills (California) reveals the mechanisms of generation, expulsion, and migration of biogenic methane that fed the seeps. Two selected outcrops show that seep carbonates developed at the tip of sand dykes intrude up into the Moreno Formation from deeper sandbodies....