Tuesday, June 18, 2013

Re: [Geology2] Re: More Info on New Subduction Zone



Nah. According to The Subduction Rulebook, they're the first to go. lol

Lin


On Tue, Jun 18, 2013 at 9:35 AM, sactovic <sactovic@yahoo.com> wrote:
 


Drat! Does this mean I'm going to have to learn to speak Portugese?

Vic

--- In geology2@yahoogroups.com, Lin Kerns <linkerns@...> wrote:
>
> <http://images.sciencedaily.com/2013/06/130617104614-large.jpg>
> *NOAA/NGDC image of the Atlantic crustal age of the ocean floor. Geologists


> have detected the first evidence that a passive margin in the Atlantic
> ocean is becoming active. The team mapped the ocean floor and found it was
> beginning to fracture, indicating tectonic activity around the apparently
> passive South West Iberia plate margin. (Credit: Mr. Elliot Lim and Mr.
> Jesse Varner, CIRES & NOAA/NGDC)*

> New 'Embryonic' Subduction Zone Found
>
> June 17, 2013 — A new subduction zone forming off the coast of Portugal
> heralds the beginning of a cycle that will see the Atlantic Ocean close as
> continental Europe moves closer to America.
>
> Published in *Geology*, new research led by Monash University geologists

> has detected the first evidence that a passive margin in the Atlantic ocean
> is becoming active. Subduction zones, such as the one beginning near
> Iberia, are areas where one of the tectonic plates that cover Earth's
> surface dives beneath another plate into the mantle -- the layer just below
> the crust.
>
> Lead author Dr João Duarte, from the School of Geosciences said the team
> mapped the ocean floor and found it was beginning to fracture, indicating
> tectonic activity around the apparently passive South West Iberia plate
> margin.
>
> "What we have detected is the very beginnings of an active margin -- it's
> like an embryonic subduction zone," Dr Duarte said.
>
> "Significant earthquake activity, including the 1755 quake which devastated
> Lisbon, indicated that there might be convergent tectonic movement in the
> area. 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."
>
> The incipient subduction in the Iberian zone could signal the start of a
> new phase of the Wilson Cycle -- where plate movements break up
> supercontinents, like Pangaea, and open oceans, stabilise and then form new
> subduction zones which close the oceans and bring the scattered continents
> back together.
>
> This break-up and reformation of supercontinents has happened at least
> three times, over more than four billion years, on Earth. The Iberian
> subduction will gradually pull Iberia towards the United States over
> approximately 220 million years.
>
> The findings provide a unique opportunity to observe a passive margin
> becoming active -- a process that will take around 20 million years. Even
> at this early phase the site will yield data that is crucial to refining
> the 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.
>
> ------------------------------
>
> *Story Source:*

>
> The above story is reprinted from
> materials<http://monash.edu.au/news/show/new-embryonic-subduction-zone-found>provided
> by
> *Monash University* <http://www.monash.edu.au>.
>
> *Note: Materials may be edited for content and length. For further
> information, please contact the source cited above.*
>
> ------------------------------
>
> *Journal Reference*:
>
> 1. J. C. Duarte, F. M. Rosas, P. Terrinha, W. P. Schellart, D.
> Boutelier, M.-A. Gutscher, A. Ribeiro. *Are subduction zones invading
> the Atlantic? Evidence from the southwest Iberia margin*. *Geology*,
> 2013; DOI: 10.1130/G34100.1 <http://dx.doi.org/10.1130/G34100.1>
>
>
> Monash University (2013, June 17). New 'embryonic' subduction zone found. *
> ScienceDaily*. Retrieved June 18, 2013, from http://www.sciencedaily.com­

> /releases/2013/06/130617104614.htm
> --
>
> Note---Click on image for much larger size; you may have to go to the
> website to do this.
>
>
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