Hydrothermal vents at 5000m on the Mid-Cayman Rise: Where basement lithology and depth of venting controls sulphide deposit composition

Abstract

This contribution describes the geological setting of hydrothermal activity within the Mid-Cayman Rise (MCR) using data acquired during RRS James Cook cruise JC44 (MAR-APR 2010) from the deep-towed sidescan sonar TOBI, 6000m-diving AUV Autosub6000 and the Robotic Underwater Vehicle (RUV) HyBIS. The 110 km-long Mid-Cayman Rise (MCR), located within the Cayman Trough, Caribbean Sea, is the deepest seafloor-spreading centre in the world reaching to ∼7000m. Its morphology is consistent with ultra-slow-spreading and magnetic anomalies confirm its divergence rate of only ∼15 mm yr−1, with active spreading since ∼49 Ma. Hence the MCR poses an end-member of extreme depth for oceanic accretion and hydrothermal circulation.