Scientists look into how our planet evolved
By demonstrating how salty water and gases transfer from the atmosphere into Earth's interior, an international team of scientists has re-started the debate about the processes behind the evolution of the planet. Writing in the journal Nature Geoscience, the team from Italy and Australia has re-opened the age-old scientific debate about how the Earth evolved from a primitive state in which it was covered by an ocean of molten rock into the planet we know today made up of a solid crust comprised of moving tectonic plates, oceans and an atmosphere. Lead study author Dr Mark Kendrick from the University of Melbourne's School of Earth Sciences explains that this new study challenges the theory that the Earth evolved solely because of meteorites 'crashing into the planet.' As the composition of neon in Earth's mantle is very similar to that in meteorites, it has been suggested by scientists that most of Earth's gases were delivered by meteorites during a late meteorite bombardment that also generated visible craters on Earth's moon. Dr Mark Kendrick believes their study 'suggests a more complex history in which gases were also dissolved into the Earth while it was still covered by a molten layer, during the birth of the solar system.' The team found important clues in the processes responsible for the birth of the planet and the subsequent evolution of its oceans and atmosphere in inert gases trapped inside Earth's interior. The study shows atmospheric gases were mixed into the mantle, inside the planet's interior during a process called 'subduction', when tectonic plates collide and submerge beneath volcanoes in subduction zones. 'This finding is important because it was previously believed that inert gases inside the Earth had primordial origins and were trapped during the formation of the solar system,' explains Dr Kendrick. It was previously assumed that gases could not sink with plates in tectonic subduction zones but escaped during eruption of overlying volcanoes. This new study moves forward our knowledge by showing that this is not entirely true and that gases released from Earth's interior have not faithfully preserved the fingerprint of solar system formation. The study is based on collected serpentinite rocks from mountain belts in Italy and Spain. These rocks were originally formed on the seafloor and were partially subducted into the Earth's interior before they were uplifted into their present positions when the European and African plates collided. Serpentinite rocks can trap large amounts of seawater in their crystal structure and can be transported to great depths in the Earth's mantle by subduction. By analysing the inert gases and halogens trapped in these rocks, the team managed to show that gases are incompletely removed by the mineral transformations that affect serpentinites during the subduction process, and provide new insights into the role of these trapped gases in our planet's evolution.For more information, please visit:University of Melbourne:http://www.unimelb.edu.au/
Countries
Australia, Italy