TY - JOUR
AU - Heleen Vanneste
AU - Boris Kelly-Gerreyn
AU - Douglas Connelly
AU - Rachael James
AU - Matthias Haeckel
AU - Rebecca Fisher
AU - Katja Heeschen
AU - Rachel Mills
AB - Submarine mud volcanism is an important pathway for transfer of deep-sourced fluids enriched in hydrocarbons and other elements into the ocean. Numerous mud volcanoes (MVs) have been discovered along oceanic plate margins, and integrated elemental fluxes are potentially significant for oceanic chemical budgets. Here, we present the first detailed study of the spatial variation in fluid and chemical fluxes at the Carlos Ribeiro MV in the Gulf of Cadiz. To this end, we combine analyses of the chemical composition of pore fluids with a 1-D transport-reaction model to quantify fluid fluxes, and fluxes of boron, lithium and methane, across the sediment\textendashseawater interface. The pore fluids are significantly depleted in chloride, but enriched in lithium, boron and hydrocarbons, relative to seawater. Pore water profiles of sulphate, hydrogen sulphide and total alkalinity indicate that anaerobic oxidation of methane occurs at 34\textendash180 cm depth below seafloor. Clay mineral dehydration, and in particular the transformation of smectite to illite, produces pore fluids that are depleted in chloride and potassium. Profiles of boron, lithium and potassium are closely related, which suggests that lithium and boron are released from the sediments during this transformation. Pore fluids are expelled into the water column by advection; fluid flow velocities are 4 cm yr<sup>-1</sup> at the apex of the MV but they rapidly decrease to 0.4 cm yr<sup>-1</sup> at the periphery. The associated fluxes of boron, lithium and methane vary between 7\textendash301, 0.5\textendash6 and 0\textendash806 mmol m<sup>-2</sup> yr<sup>-1</sup>, respectively. We demonstrate that fluxes of Li and B due to mud volcanism may be important on a global scale, however, release of methane into the overlying water column is suppressed by microbial methanotrophy.
BT - Geochimica et Cosmochimica Acta
M1 - 4
N1 - doi: 10.1016/j.gca.2010.11.017
N2 - Submarine mud volcanism is an important pathway for transfer of deep-sourced fluids enriched in hydrocarbons and other elements into the ocean. Numerous mud volcanoes (MVs) have been discovered along oceanic plate margins, and integrated elemental fluxes are potentially significant for oceanic chemical budgets. Here, we present the first detailed study of the spatial variation in fluid and chemical fluxes at the Carlos Ribeiro MV in the Gulf of Cadiz. To this end, we combine analyses of the chemical composition of pore fluids with a 1-D transport-reaction model to quantify fluid fluxes, and fluxes of boron, lithium and methane, across the sediment\textendashseawater interface. The pore fluids are significantly depleted in chloride, but enriched in lithium, boron and hydrocarbons, relative to seawater. Pore water profiles of sulphate, hydrogen sulphide and total alkalinity indicate that anaerobic oxidation of methane occurs at 34\textendash180 cm depth below seafloor. Clay mineral dehydration, and in particular the transformation of smectite to illite, produces pore fluids that are depleted in chloride and potassium. Profiles of boron, lithium and potassium are closely related, which suggests that lithium and boron are released from the sediments during this transformation. Pore fluids are expelled into the water column by advection; fluid flow velocities are 4 cm yr<sup>-1</sup> at the apex of the MV but they rapidly decrease to 0.4 cm yr<sup>-1</sup> at the periphery. The associated fluxes of boron, lithium and methane vary between 7\textendash301, 0.5\textendash6 and 0\textendash806 mmol m<sup>-2</sup> yr<sup>-1</sup>, respectively. We demonstrate that fluxes of Li and B due to mud volcanism may be important on a global scale, however, release of methane into the overlying water column is suppressed by microbial methanotrophy.
PY - 2011
SN - 0016-7037
SP - 1124
EP - 1144
T2 - Geochimica et Cosmochimica Acta
TI - Spatial variation in fluid flow and geochemical fluxes across the sediment\quotesinglbaseÄ\ \iseawater interface at the Carlos Ribeiro mud volcano (Gulf of Cadiz)
UR - http://www.sciencedirect.com/science/article/pii/S0016703710006563
VL - 75
ER -