Geochemical Analysis and Integrated Modelling of Basalt Samples from V-Shaped Ridges of North Atlantic Ocean

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Deep within the Earth's interior underneath Iceland there sits a gigantic hot upwelling or plume. This plume is the biggest on Earth and has been in existence for about sixty million years. It has had a profound effect upon the shape of the seabed beneath the North Atlantic Ocean which is about two kilometres shallower than it should be. The existence of this plume also explains why the British Isles stick up in the air. There is considerable interest in the way these hot plume change over time. Luckily, the North America tectonic plate and the European tectonic plate are spreading apart exactly on top of the Icelandic plume. As a result, we have a really convenient window into the way in which this particular plume evolves over time. Changes within the plume are faithfully recorded by thickened trails of crust along the ocean floor. This summer, a group of scientists will sail into the middle of the Atlantic Ocean south of Iceland and drill holes into these crustal trails. These holes will be about ten centimetres across and hundreds of metres deep. The samples of lava recovered by this complex operation provide an invaluable record of the way temperature has changed through time deep within the plume's interior. In that sense, we will be using the rock samples as plume thermometers. Once the samples are recovered, we will bring them back to the lab and measure concentrations of familiar elements such as iron, potassium, lead and many others. These concentrations will be used to aid computer modeling of deep temperature changes. In the end, we will be able to take the 'pulse' of the Icelandic plume over many millions of years. The final piece of the jigsaw puzzle concerns how plume activity has made the seabed around Iceland bob up and down over long periods of time. This bobbing about has affected how deep water currents flow southwestward from the Greenland-Norwegian Sea into the rest of the Atlantic Ocean. It is a bit like a canal lockgate mechanism where the ridge between Greenland and Scotland that crosses Iceland moves up and down. This motion affects how much deep water escapes into the rest of the Atlantic Ocean. Fossil bugs that once lived on the seabed and which are can be sampled in exactly the same hole that are drilled into lava help us to measure how much deep water flows across the canal lockgate at different times in the past. This trick works because the bugs once lived in deep water and made their shells from the tiny amounts of calcium carbonate dissolved in that deep water. When the flow of deep water shuts on and off, the bugs inadvertently record these changes in the composition of their shells. Hey Presto! Our ultimate goal is to link the bobbing of the seafloor which changes deep water flow with the throbbing pulse of the hot plume.In this way, we hope to show how processes going on deep within the Earth influence ocean currents which in turn control our climate.