But scientists haven't found direct evidence of the in-between phase — an ocean basin that was opening, starting instead to close — until now.
Thanks to new high-resolution surveys of the seafloor, scientists think they have evidence of that process starting in the Atlantic Ocean off the coast of Portugal. If they are right, this nascent subduction zone could close the Atlantic Ocean — in roughly 200 million years.
Geoscientists have hypothesized the existence of an earthquake-causing, volcano-forming subduction zone along the Portuguese coast. Now, based on new analyses of a series of faults and regional tensions, João Duarte, the principal investigator, suggests that his study supports that hypothesis and identifies the main tectonic mechanisms. However, this conclusion has garnered some controversy from fellow scientists, mainly because it may still be too soon to tell.
Read more about how passive margins may become active margins in this month's issue of EARTH Magazine: http://bit.ly/1bV6YLU. For other stories on Ireland's volcanic winters, how Northern Hemisphere sulfate emissions shifted tropical precipitation patterns, and the feldspar linings of clouds, visit the digital bookstand at: http://www.earthmagazine.org/digital.
Keep up to date with the latest happenings in Earth, energy and the environment news with EARTH magazine online at http://www.earthmagazine.org/. Published by the American Geosciences Institute, EARTH is your source for the science behind the headlines.
The American Geosciences Institute is a nonprofit federation of geoscientific and professional associations that represents more than 250,000 geologists, geophysicists and other earth scientists. Founded in 1948, AGI provides information services to geoscientists, serves as a voice of shared interests in the profession, plays a major role in strengthening geosciences education, and strives to increase public awareness of the vital role geosciences play in society's use of resources, resiliency to natural hazards, and interaction with the environment.
Megan Sever | EurekAlert!
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