An upsurge of material from deep in the earth's crust could push the continents of North and South America away from Europe and Africa, a new search found
The plates attached to the Americas deviate from those attached to Europe and Africa by four centimeters per year. Between these continents lies the Mid-Atlantic Ridge, a site where new plaques form and a dividing line between the plaques moving west and those moving east; under this ridge, material rises to replace the space left by the plates when they move apart
The conventional wisdom is that this process is normally driven by distant forces of gravity as the denser parts of the plates fall back into the Earth.. However, the engine behind the separation of the Atlantic plates has remained a mystery because the Atlantic Ocean is not surrounded by dense and sinking plates.
Now, a team of seismologists, led by the University of Southampton, found evidence of a rise in the mantle – the material between the earth's crust and its core – at depths of more than 600 kilometers under the Mid-Atlantic Ridge, who could push the plates from below, which could move the continents further It is generally believed that upwelling under ridges comes from much shallower depths of about 60 km.
The results, published in the journal Nature, provide a better understanding of the plate tectonics that causes many natural disasters around the world, especially earthquakes, tsunamis and volcanic eruptions.
During two research campaigns on the RV Langseth and RRV Discovery, the team has deployed 39 seismometers at the bottom of the Atlantic as part of the PI-LAB experiment (Passive Imaging of the Lithosphere-Asthenosphere Boundary) et EURO-LAB (Experiment) unearth the rheological boundary between oceanic lithosphere and asthenosphere) The data provides the first large-scale, high-resolution imagery of the mantle beneath the Mid-Atlantic Ridge.This is one of the few experiments of this magnitude ever conducted in the oceans that allowed the team to imagine variations in the structure of the Earth's mantle at depths of 410 km and 660 km – depths associated with sudden changes in mineral phases. The observed signal indicated a deep upwelling, slow and unexpected from the deeper mantle
The main author, Matthew Agius, former postdoctoral researcher at the University of Southampton and currently at the Università degli studi Roma Tre, said: «It was a memorable mission that took us altogether 10 weeks at sea in the middle of the Atlantic Ocean The incredible results shed new light on our understanding of how the Earth's interior is connected to plate tectonics, with observations never seen before.”
Dr Kate Rychert and Dr Nick Harmon of the University of Southampton and Professor Mike Kendall of the University of Oxford led the experiment and were the chief scientists of the cruises. The experiment was funded by NERC (Natural Environment Research Council, UK) and the ERC (European Research Council)
Dr Harmon said: “There is an increasing distance between North America and Europe, and it is not motivated by political or philosophical differences – it is caused by convection of the mantle!”
In addition to helping scientists develop better models and warning systems for natural disasters, plate tectonics also have an impact on sea level, and therefore affects estimates of climate change at geological time scales
Dr Rychert said: «It was completely unexpected It has vast implications for our understanding of the evolution and habitability of the Earth It also shows how crucial it is to collect new data on the oceans There is so much more to explore! »
Professor Mike Kendall added: «This work is exciting and refutes long-held assumptions that mid-ocean ridges may play a passive role in plate tectonics.. This suggests that in places such as the mid-Atlantic, ridge forces play an important role in the separation of newly formed plates.”
Europe, Atlantic Ocean, Terre, South America, middle atlantic dorsale, tectonic plates, Africa, geology, scientist
News – FR – The Atlantic Ocean is widening – here's why – About Manchester
Associated title :
– The Atlantic Ocean Widens Wider-Here& # 39; s why