Gas hydrate pingoes: Deep seafloor evidence of focused fluid flow on continental margins

Fluid flow features in hydrocarbon plumbing systems: What do they tell us about the basin evolution?

“…Gas hydrates, bottom simulating reflections, free gas zones, chimneys and pipes are also frequently reported along the Angolan margin from the Lower Congo and Kwanza Basins ( Fig. 1) (Cunningham and Lindholm, 2000;Charlou et al, 2004;Serié et al, 2012).…”

Gas Seepage along the Edge of the Aquitaine Shelf (France): Origin and Local Fluxes

“…Any seep may be composed of a single gas stream or several ones very close to each other such that they clearly define its perimeter. Submarine seeps, at cold seeps, occur worldwide along the continental margins and are usually related to geological structures with either positive reliefs such as submarine pingoes [1][2][3][4][5][6][7], carbonate concretions and pavements [8][9][10][11], and mud volcanoes [9,[12][13][14][15][16][17][18] or negative reliefs like pockmarks [13,[19][20][21][22][23]. They also occur in seafloor-reaching fault areas at tectonically active regions without being associated with a specific relief [24][25][26][27][28].…”

Cold seeps at the salt front in the Lower Congo Basin II: The impact of spatial and temporal evolution of salt-tectonics on hydrocarbon seepage

“…Since then, seepage of fluids from the seafloor and the associated seafloor depressions as well as their sub-seafloor structure have been studied in various places on the West African continental margin (Fig. 1, Hovland et al, 1997;Spiess et al, 2003Spiess et al, , 2004Ondr eas et al, 2005;Gay et al, 2006Gay et al, , 2007Sahling et al, 2008;Spiess et al, 2008;Fekete et al, 2009;Løseth et al, 2011;Ho et al, 2012;Seri e et al, 2012). In the Lower Congo Basin (LCB) which comprises the continental margin seaward of the Congo River mouth down to the deep sea, seafloor expressions of fluid seepage were attributed to different geological features such as stacked Oligocene to Miocene channels (Gay et al, 2006) or sediment dewatering and seepage of microbial methane .…”