The Pre-Cruise Thought Process

My name is Alexandra and I completed BSc with a major in Environmental Science this year. For my undergraduate thesis I analyzed a set of hydrothermal fluid samples taken from the East Scotia Ridge and my results allowed me infer conditions of sub-surface fluid flow and processes. Having gained some experience in data analysis I am really looking forward to completing the picture with sample acquisition and data collection on the R/V Thompson. So far we have had a few introductory workshops on some of the mapping and modeling software that we will be using (HIPS made by Caris and COVE, a modeling program developed for the regional scale nodes data) but the action starts tomorrow as we board the Thompson! Coming from London, Canada where I’ve been separated from all the preparation activity, it’s been a long wait for me!

Over the next two weeks I am going to build on my knowledge of ocean chemistry. Specifically, I would like to examine pre- and post eruption differences in water chemistry surrounding hydrothermal vents. The Mid-Ocean Ridge (MOR) is an underwater mountain chain, over 60,000 km long that defines the edges of tectonic plates. Upwelling magma beneath the ridge pushes the tectonic plates apart, generating new ocean crust as magma erupts and solidifies in the process. The new ocean crust is very porous, allowing seawater to penetrate into the seafloor. As the water sinks deeper it heats up and reacts with the surrounding rocks, becoming altered hydrothermal fluid. Eventually the sinking fluid nears the magma source where it becomes extremely hot and buoyant and forces its way back up to the surface. When an eruption occurs on the bottom of the ocean, the subsurface network of veins that allow fluid transport to occur can become altered, changing hydrothermal activity at the surface. Additionally, the influx of heat influences reactions between hydrothermal fluid and the solidifying ocean crust. These processes alter the influx of chemicals in the ocean with consequences for the surrounding biological activity. By measuring the chemical composition of hydrothermal fluids and the surrounding seawater, we can gain a better understanding of processes occurring beneath the seafloor.