Behavior of iron isotopes in hydrothermal systems: Beebe and Von Damm vent fields on the Mid-Cayman ultraslow-spreading ridge

It is now clear that, in some parts of the ocean, inputs of hydrothermal iron (Fe) can make a more significant contribution to the Fe inventory than previously thought. While the Fe isotopic signature of seawater has proved useful for distinguishing between inputs of Fe from atmospheric deposition and seafloor sediments, the Fe isotope signature of hydrothermal vent fluids may change during mixing of vent fluids and seawater. To better constrain the processes leading to these changes, the Fe isotopic compositions (δ56Fe) of dissolved and total dissolvable Fe have been determined in high temperature vent fluids and the buoyant hydrothermal plumes at the Beebe and the Von Damm vent fields, which are located along the ultraslow Mid-Cayman spreading center in the Caribbean Sea.