The Mineralogy of Hydrothermal Plume Particles at the Endeavour Mid-Ocean Ridge




Beaupre-Olsen, Isabelle

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Hydrothermal vents (aka black smokers) exist along mid-ocean ridges where volcanoes continuously create ocean crust. These have recently been recognized as an important source of biologically important elements, such as Fe, to seawater. However, most dissolved constituents of hydrothermal plumes are precipitated into minerals near vents and these settle to the seafloor forming sediments. This study examines the mineralogy and geochemistry of those sediment-hosted particles to better understand the hydrothermal contribution of elements to biogeochemical cycles in the ocean. A sediment core taken near the hydrothermal vents at the Endeavour ridge segment of the Juan de Fuca ridge (300 km west of Vancouver Island) was used to examine post depositional changes in the mineralogy and chemistry of plume particles in this sediment. A six-step dissolution was applied to extract carbonates, biogenic silicates, Fe- and Mn-oxyhydroxides and Fe-oxide phases with the major and trace element compositions of each extraction analysed by ICP-MS. This data is being used to test the hypothesis that labile poorly crystalline Fe-oxyhydroxides redissolve over 100-1000’s of years, providing a mechanism by which Fe is releasing into the water column from the seafloor. This may provide a hitherto unrecognized source of biologically available Fe to the ocean.



sequential extraction, hydrothermal sediments, Fe-oxyhydroxides, Endeavour, Iron, Fe, Hydrothermal