Open AccessHelium transport in sediment pore fluids of the Congo‐Angola margin
Author(s) -
Chaduteau Carine,
JeanBaptiste Philippe,
Fourré Elise,
Charlou JeanLuc,
Donval JeanPierre
Publication year - 2009
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2007gc001897
Subject(s) - geology , advection , radiogenic nuclide , flux (metallurgy) , helium , isotopes of helium , sedimentary rock , sediment , diffusion , geomorphology , geochemistry , mineralogy , thermodynamics , chemistry , physics , mantle (geology) , organic chemistry
During the ZaïRov2 cruise of the ZaïAngo project (1998–2000) on the passive Congo‐Angola margin, several gravity cores were analyzed for helium isotopic composition of sedimentary pore waters in two cold fluid seepage zones: the Astrid slide area and the Regab giant pockmark. Gas concentration and isotopic composition are presented along with thermal data in terms of the origin and circulation of fluids. Helium isotope data lie on a mixing line between bottom seawater and an almost pure radiogenic. Helium and temperature vertical profiles are well described by the classic diffusion‐advection equation. On the basis of He profiles, we estimate the advection rate on the rim of the pockmark between 1.2 and 2.3 mm/a. The He flux derived for a pure diffusive regime (2.4 × 10 −8 mol/m 2 /a) can favorably be compared to literature data and contrasts with the flux computed close to the pockmark center (1.9 × 10 −7 mol/m 2 /a). Helium depth profiles turned to be more sensitive to advection rate than temperature profiles are.