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<div class=Section1>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>Nature<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>doi:10.1038/nature.2016.20334<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>A volatile
arrangement of tectonic plates millions of years ago gave us the Pacific.</span><span
style='font-size:12.0pt;font-family:"Arial","sans-serif"'><o:p></o:p></span></p>
<p class=MsoNormal><b><span style='font-size:18.0pt;font-family:"Arial","sans-serif";
color:#222222;letter-spacing:-.4pt'>The fiery birth of Earth's largest ocean
exposed</span></b><span style='font-size:18.0pt;font-family:"Arial","sans-serif";
color:#222222;letter-spacing:-.4pt'><o:p></o:p></span></p>
<p class=MsoNormal><span class=vcard><span style='font-family:"Arial","sans-serif"'><a
href="http://www.nature.com/news/the-fiery-birth-of-earth-s-largest-ocean-exposed-1.20334?WT.ec_id=NEWS-20160728&spMailingID=51933150&spUserID=MTc2NjE2MjAwMAS2&spJobID=964075662&spReportId=OTY0MDc1NjYyS0#auth-1"><span
style='color:windowtext;border:none windowtext 1.0pt;padding:0in'>Alexandra
Witze</span></a></span></span><span style='font-family:"Arial","sans-serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>27 July 2016<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><a
href="http://www.nature.com/news/the-fiery-birth-of-earth-s-largest-ocean-exposed-1.20334?WT.ec_id=NEWS-20160728&spMailingID=51933150&spUserID=MTc2NjE2MjAwMAS2&spJobID=964075662&spReportId=OTY0MDc1NjYyS0"><span
style='color:windowtext'>http://www.nature.com/news/the-fiery-birth-of-earth-s-largest-ocean-exposed-1.20334?WT.ec_id=NEWS-20160728&spMailingID=51933150&spUserID=MTc2NjE2MjAwMAS2&spJobID=964075662&spReportId=OTY0MDc1NjYyS0</span></a><o:p></o:p></span></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal align=center style='text-align:center;line-height:17.85pt;
background:#ECECEC'><span style='font-size:10.0pt'><img border=0 width=630
height=354 id="Imagen_x0020_1" src="cid:image001.jpg@01D1E997.28CB9860"
alt="http://www.nature.com/polopoly_fs/7.38074.1469628625!/image/Pacific%20plates_c0089968_900px.jpg_gen/derivatives/landscape_630/Pacific%20plates_c0089968_900px.jpg"></span><span
style='font-size:10.0pt'><o:p></o:p></span></p>
<p class=credit align=center style='margin:0in;margin-bottom:.0001pt;
text-align:center;background:#ECECEC'><i><span style='font-size:7.5pt'>NOAA/Science
Photo Library<o:p></o:p></span></i></p>
<p class=caption align=center style='margin:0in;margin-bottom:.0001pt;
text-align:center;line-height:17.85pt;background:#ECECEC'><span
style='font-size:10.0pt'>A computer model simulates the seafloor in the North
Pacific.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><o:p> </o:p></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>The Pacific
Ocean was born from a geological spasm that started 190 million years ago, when
<a
href="http://www.nature.com/news/new-origin-seen-for-earth-s-tectonic-plates-1.14993"><span
style='color:#5C7996'>Earth’s crust ripped apart</span><span
class=apple-converted-space><span style='color:#5C7996;text-decoration:none'> </span></span></a>and
fresh lava welled up from below. Now, a new analysis suggests that this
seafloor birth was a lot more complex than researchers had thought.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>The study is a
rare step forward in understanding the origin of the Pacific, one of geology’s
most enduring mysteries.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>“This is
one big piece of the puzzle that we’ve now put into place,” says
Lydian Boschman, a geologist at Utrecht University in the Netherlands. She and
her colleague Douwe van Hinsbergen report the discovery on 27 July in<span
class=apple-converted-space> </span><i>Science Advances</i></span><sup><span
style='font-size:9.0pt;font-family:"Arial","sans-serif"'><a
href="http://www.nature.com/news/the-fiery-birth-of-earth-s-largest-ocean-exposed-1.20334?WT.ec_id=NEWS-20160728&spMailingID=51933150&spUserID=MTc2NjE2MjAwMAS2&spJobID=964075662&spReportId=OTY0MDc1NjYyS0#b1"
title="Boschman, L. M. & van Hinsbergen, D. J. J. Sci. Adv. 2, e1600022 (2016)."
id=ref-link-1><span style='color:#5C7996'>1</span></a></span></sup><span
style='font-family:"Arial","sans-serif"'>.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>Oceans are born
at unstable seams in Earth’s crust,<span class=apple-converted-space> </span><a
href="http://www.nature.com/news/unusual-indian-ocean-earthquakes-hint-at-tectonic-breakup-1.11487"><span
style='color:#5C7996'>where plates pull apart</span></a>, allowing molten rock
to fill the gap and solidify. The fresh crust pushes older crust away from the
seam and towards the edge of a continent. Eventually, the ocean crust crashes
into continental crust and, through the process of plate tectonics, gets <a
href="http://www.nature.com/news/seabed-samples-cast-doubt-on-earthquake-risk-for-pacific-northwest-1.15655"><span
style='color:#5C7996'>sucked down and recycled</span></a><span
class=apple-converted-space> </span>deep within the planet.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>Because of this
continuing cycle of creation and destruction, no seafloor is older than about
200 million years. To see how oceans behaved further back in time, geologists
must try to reconstruct the three-dimensional geometry of long-vanished crustal
plates.<o:p></o:p></span></p>
<h2 style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;
font-family:"Arial","sans-serif";color:#111111'>Mind the gap<o:p></o:p></span></h2>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>Boschman and
van Hinsbergen studied the oldest part of the Pacific plate, which lies just
east of the Mariana Trench. Previous work suggested that the Pacific was born
in what’s known as a geological triple junction, with fresh seafloor
spreading outward from each of three intersecting ridges. But that
configuration is geologically stable; in the south Atlantic Ocean, a similar
triple junction has endured for more than 100 million years without forming a
new plate. “There’s no reason to,” says Boschman.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>Instead, she
says, the Pacific must have been born at an unstable type of triple junction.
The three intersecting seams would have had to have been transform faults, in
which the two sides of a fault slide past one another. California’s San
Andreas fault moves in this fashion.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>Three transform
faults coming together would have created a triangular gap in the centre.
“A triple junction with ridges is not going to make a new plate,”
says Boschman. ”A triple junction with transform faults does.” The
configuration was probably an accident, she adds.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>The work shows
how basic thinking about plate tectonics can still yield surprises, says
Bernhard Steinberger, a geophysicist at the GFZ German Research Centre for
Geosciences in Potsdam, Germany. “This is one of those rare cases where a
discovery could be made simply by an elegant thought,” he says.<o:p></o:p></span></p>
<p style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:19.8pt;
margin-left:0in'><span style='font-family:"Arial","sans-serif"'>Boschman would
like to push even further back in time, to unravel the history of the ocean
that preceded the Pacific and surrounded the supercontinent Pangaea. She is
currently doing fieldwork in Costa Rica, looking for evidence of ancient
seafloor rocks scraped up on the side of the continent as the ocean crust was
dragged under and destroyed.<o:p></o:p></span></p>
<h1 style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:6.75pt;
margin-left:0in'><span style='font-size:12.5pt;font-family:"Arial","sans-serif";
color:#444444;letter-spacing:-.4pt'><a href="javascript:;"><span
style='color:#444444'>References</span></a><o:p></o:p></span></h1>
<p style='mso-margin-top-alt:7.5pt;margin-right:0in;margin-bottom:7.5pt;
margin-left:0in;text-indent:-.25in;mso-list:l0 level2 lfo3'><![if !supportLists]><span
style='font-size:10.0pt;font-family:"Courier New"'><span style='mso-list:Ignore'>o<span
style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span
class=fn><span style='font-family:"Arial","sans-serif"'>Boschman, L. M.</span></span><span
class=apple-converted-space><span style='font-family:"Arial","sans-serif"'> </span></span><span
style='font-family:"Arial","sans-serif"'>&<span
class=apple-converted-space> </span><span class=fn>van Hinsbergen, D. J.
J.</span><span class=apple-converted-space> </span><span
class=source-title><i>Sci. Adv.</i></span><span class=apple-converted-space> </span><span
class=volume><b>2</b></span>, e1600022 (<span class=year>2016</span>) <a
href="http://dx.doi.org/10.1126/sciadv.1600022"><span style='color:#5C7996'>Article</span></a>
<a href="javascript:;"><span style='color:#5C7996'>Show context</span></a><o:p></o:p></span></p>
<p class=MsoNormal><o:p> </o:p></p>
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