Scientists shed new light on seafloor growth

A University of Plymouth-led team of international scientists has pioneered a novel geological technique and used it to shed new light on how the oceans form during ‘seafloor spreading’, the process that constantly ‘re-paves’ the crust of the Earth’s seas. This new approach was developed following a multi-million dollar Integrated Ocean Drilling Program (IODP) expedition to the mid-Atlantic ridge in the heart of the Atlantic Ocean, on board the research ship the JOIDES Resolution. Over a period of three months, scientists drilled deep into the top of a huge 15km wide, 3km high mountain on the seafloor known as the Atlantis Massif. It is only in the last decade that scientists have discovered these large mountains beneath the Atlantic Ocean and realized that they form when the Earth’s crust is pulled apart by faulting. Evidence had suggested that these ‘detachment faults’ took rocks that had been formed deep down in the lower crust and brought them up to the surface to create enormous dome-like massifs – but how the faults achieved this had remained a contentious issue until now. The unique set of rock samples recovered by drilling at Atlantis Massif allowed researchers from the UK and US to use specialist magnetic equipment to discover how these faults evolve. Antony Morris, lead author of the report, and Geophysics lecturer at the University of Plymouth, said: “We realised that we could use the record of the direction of the Earth’s magnetic field, that became locked into the lower crustal rocks at Atlantis Massif when they formed, to find out whether they have been rotated during their geological journey to the surface.