Distribution of Venting Along the Mid-Atlantic Ridge (29–38°N) and Implications for Hydrothermal Exchange and Vent Ecosystems
Research cruise:
M190 with RV Meteor to the Atlantic Ocean
08.06. – 10.07.2023
Find a Blog (in German) from Prof. Harald Strauß here:
https://strauss2023.uni-muenster.blog/
Participating institutions:
- UHB University of Bremen
- CUB Constructor University, Bremen
- MPIMM Max Planck Institute for Marine Microbiology
- ULy University of Lyon
- UGö University of Göttingen
- UMs University of Münster
- DWD Deutscher Wetterdienst, Geschäftsfeld Seeschifffahrt
Project description:
The major aims of cruise M190 with the research vessel Meteor were to coordinate the sampling of their fluids, rocks, and biota, as part of the joint geo-bio interface studies in the Research Area ‘Ocean Floor as a Reactor’ of the MARUM Cluster of Excellence “The Ocean Floor – Earth’s Uncharted Interface” (https://www.marum.de/Ozeanboden.html). The hydrothermal vents at the Mid-Atlantic Ridge (MAR) between 29°10’N and 37°50’N occur in different geological settings (axial volcano vs. detachment fault vs. axial volcanic ridge) and are therefore geochemically highly diverse. To understand the high diversity of these systems we tried to sample the fluids which are dispersing from the chimney structures for chemistry, the rocks to understand the geology of these systems and bacterial mats and mussels with an ROV (Remotely Operated Vehicle). Apart from sampling hot fluids with the ROV, we sampled the non-buoyant plume which is dispersing from the hydrothermal vent systems and can spread over several kilometres in the water column with a CTD (Conductivity, Temperature, Depth) water sampler. The team from the Constructor University focussed on the dissolved trace metal chemistry from the vent structures, the rising plume and the non-buoyant plume to show how metals transform between different size fractions (0.8 µm and 0.2µm) and what kind of metal-organic complexes along the mixing gradient between vent fluid and ambient seawater. This information is important for estimating the hydrothermal flux of trace metals into the ocean. Our sampling areas were the Broken Spur Hydrothermal Field (BSHF), the Main Lucky Strike Hydrothermal Field (MLSHF), the Rainbow Hydrothermal Field (RHF) and the Menez Gwen Hydrothermal Field (MGHF), where we sampled high temperature and pressure hydrothermal vent fields with over 300°C and diffuse outflows with temperatures between 20°C and 200°C.
Main research questions:
- How diverse are the hydrothermal fluids between those km-spaced vents and what are the volcanic and faulting controls of this diversity?
- How are metals transformed within the rising and neutrally buoyant parts of hydrothermal plumes and how is the fate of metals controlled by primary differences in metal:sulfide and metal:carbon ratios?
- What can we learn from comprehensive analyses of diffuse fluids about subseafloor microbial activity?
