June 18, 2013
US And Europe Could Unite Due To Newly Forming Subduction Zone
redOrbit Staff & Wire Reports - Your Universe Online
“What we have detected is the very beginnings of an active margin — it's like an embryonic subduction zone,” lead author Dr. JoÃ£o Duarte of the university´s School of Geosciences, explained in a statement on Monday.
“Significant earthquake activity, including the 1755 quake which devastated Lisbon, indicated that there might be convergent tectonic movement in the area,” he added. “For the first time, we have been able to provide not only evidences that this is indeed the case, but also a consistent driving mechanism.”
Subduction zones are regions where one of the tectonic plates covering the Earth´s surface has moved beneath another tectonic plate, sinking into the mantle. The one located by Dr. Duarte and his colleagues is forming near the Iberian Peninsula in southwest Europe.
The researchers mapped the ocean floor and discovered it was beginning to fracture, which indicates tectonic activity in the Southwest Iberia plate margin — a boundary they believed to be inactive. Activity in the Iberian zone could signal the beginning of a new phase of a phenomenon known as a Wilson Cycle.
In the Wilson Cycle, plate movements break apart supercontinents (such as Pangaea) and open oceans, the researchers explained. They then stabilize and form new subduction zones, which close the oceans and bring the land masses that had been scattered back together again.
This process of supercontinents breaking apart and then reforming has been repeated at least three times over the course of more than four billion years, the authors noted. The Iberian subduction will gradually pull the area towards the US — a process that will take approximately 220 million years.
Furthermore, the occurrence will also give geologists an opportunity to observe what happens when a passive margin becomes active. That process is expected to take roughly 20 million years, but even during its earliest stages, scientists will be able to collect data which they can use to fine-tune geodynamic models.
“Understanding these processes will certainly provide new insights on how subduction zones may have initiated in the past and how oceans start to close,” Dr. Duarte said. Other co-authors on the study represent the University of Lisbon, the French National Centre for Scientific Research (CNRS) / University of Brest Oceanic Domains research laboratory and the Portuguese Institute for the Sea and the Atmosphere.