Sarradin Pierre-Marie

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Sarradin
First Name
Pierre-Marie
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  • Preprint
    Hydrothermal activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge) : distribution, heatflux, and geological controls
    ( 2015-09) Escartin, Javier E. ; Barreyre, Thibaut ; Cannat, Mathilde ; Garcia, Rafael ; Gracias, Nuno ; Deschamps, Anne ; Salocchi, Aura ; Sarradin, Pierre-Marie ; Ballu, Valerie
    We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment, to evaluate the distribution of hydrothermal activity. We have identified a new on-axis site with diffuse flow, Ewan, and anactive vent structure ~1.2 km from the axis, Capelinhos. These sites are minor relative to the Main field, and our total heatflux estimate for all active sites (200-1200 MW) is only slightly higher than previously published estimates. We also identify fossil sites W of the main Lucky Strike field. A circular feature ~200 m in diameter located on the flanks of a rifted off-axis central volcano, is likely a large and inactive hydrothermal edifice, named Grunnus. We find no indicator of focused hydrothermal activity elsewhere along the segment, suggesting that the enhanced melt supply and the associated melt lenses, required to form central volcanoes, also sustain hydrothermal circulation to form and maintain large and long-lived hydrothermal fields. Hydrothermal discharge to the seafloor occurs along fault traces, suggesting focusing of hydrothermal circulation in the shallow crust along permeable fault zones.
  • Preprint
    A dual sensor device to estimate fluid flow velocity at diffuse hydrothermal vents
    ( 2009-06-12) Sarrazin, Jozée ; Rodier, P. ; Tivey, Margaret K. ; Singh, Hanumant ; Schultz, A. ; Sarradin, Pierre-Marie
    Numerous attempts have been made over the last thirty years to estimate fluid flow rates at hydrothermal vents, either at the exit of black smoker chimneys or within diffuse flow areas. In this study, we combine two methods to accurately estimate fluid flow velocities at diffuse flow areas. While the first method uses a hot film anemometer that performs high frequency measurements, the second allows a relatively rapid assessment of fluid flow velocity through video imagery and provides in situ data to calibrate the sensor. Measurements of flow velocities on hydrothermal diffuse flow areas were obtained on the Mid-Atlantic Ridge (MAR). They range from 1.1 to 4.9 mm/sec., at the substratum level, in low temperature (4.5 to 16.4°C) diffuse flow areas from the Tour Eiffel sulfide edifice. A strong correlation was observed between fluid flow velocities and temperature, supporting the possible use of temperature as a proxy to estimate flow rates in diffuse flow areas where such a simple linear flow/temperature relation is shown to dominate.