What's OSCAR all about?

“The Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge” a.k.a. OSCAR, is an international project funded by NERC (Natural Environment Research Council) linking both geophysics and oceanography.

Diagram of a segmented spreading ridge, showing
the oceanic crust in black, and upwelling mantle
material (orange/yellow) (credit: NOAA)

We are looking at mid-ocean spreading ridges, where new oceanic crust is formed by upwelling magma cooling at the seafloor. This new crust then moves away from the ridge to allow more to fill in the gap, meaning the further you move away from the ridge, the older the crust will be. Generally there is a relatively high amount of heat flow from the crust into the surrounding ocean at these spreading centres, which can affect ocean temperatures, currents and circulation, which are important to Earth’s climate.

A 'black smoker' (credit: WHOI)

Much of this heat flow is thought to be due to hydrothermal circulation: where seawater percolates down into the crust, is geothermally heated, and then re-emerges into the ocean as hot water containing different elements and minerals picked up from rocks in the crust. These ‘hydrothermal plumes’ are often called ‘black smokers’ due to their dark colour from the minerals they contain. The structure of the crust is thought to affect the pattern of hydrothermal circulation, and vice versa.

During the OSCAR project, we will try and look at how the structure of the crust changes as it ages from a spreading ridge, how this is linked to changes in hydrothermal circulation, and the consequent effects on heat flow and oceanographic processes.

The last corner of Trinidad (credit: Jowan Barnes)

In other news, we set sail from Port of Spain this morning, and are now en route to Panama! We had a beautiful sunny morning to leave Trinidad, sailing past a score of smaller islands, and passing between Trinidad and Venezuela to enter the Caribbean Sea. Dolphins were seen in the distance, and pelicans were skimming the water closer to the ship. Overall, a lovely day, bar some minor sea-sickness and a bit of sunburn!

Pelican seen on quayside (credit: Jowan Barnes)