Geochemistry of hydrothermal fluids at the Lucky Strike Hydrothermal Field data from the EMSO-Azores observatory, 2025

High temperature hydrothermal fluids are collected by gas-tight fluid sampler manipulated and triggered by the hydraulic arm of the submarine vehicle (HOV Nautile). Several hydrothermal vents are sampled, namely : Aisics, Eiffel tower, Montsegur, Isabel, Sintra, Y3, White Castle, Cypress, South Crystal, Crystal, Capelinhos, Roldan. Several chemical analyses are performed aboard the research vessel: such as salinity and d20/20 by refractometer, Conductivity, salinity and total dissolved solid (TDS) by electrode (standard solution at 1413 µS/cm), pH and Eh by electrode (pH standard 4.01 and 7; Eh standard solution at 220mV), iron concentration by photometer (up to 5 ppm), H2S and total S concentrations measured by electrode (AquaMS, amperometric method) at measured pH value.