Plate tectonics may stop at least once again in Earths historyJanuary 4th, 2008 - 3:26 pm ICT by admin
Washington, January 4 (ANI): Carnegie Institution researchers say that Plate tectonics the geological process responsible for creating the Earths continents, mountain ranges, and ocean basins may have stopped at least once in the planets history, and that it may happen again.
A key aspect of plate tectonic theory is that on geologic time scales ocean basins are transient features, opening and closing as plates shift. Basins are consumed by a process called subduction, where oceanic plates descend into the Earths mantle.
Subduction zones are the sites of oceanic trenches, high earthquake activity, and most of the worlds major volcanoes.
Paul Silver of the Carnegie Institutions Department of Terrestrial Magnetism and former postdoctoral fellow Mark Behn say that most of the subduction zones are currently located in the Pacific Ocean basin.
Writing in the journal Science, they revealed that the Pacific basin may close in about 350 million years, when the westward-moving Americas collide with Eurasia.
Silver and Behn believe that that most of the planets subduction zones will disappear at that moment, effectively stopping plate tectonics unless new subduction zones start up.
The experts have also highlighted present geochemical evidence from ancient igneous rocks, which indicate that around one billion years ago there was a lull in the type of volcanic activity normally associated with subduction.
They say that a Pacific-type ocean basin had closed at that time, welding the continents into a single supercontinent, known to geologists as Rodinia. According to them, it might also have stopped subduction for a while.
Rodinia finally split apart when subduction and plate tectonics resumed.
Plate tectonics is driven by heat flowing from the Earths interior, and a stoppage would slow the rate of the Earths cooling, they add.
The experts believe that intermittent plate tectonics may explain why the Earth has lost heat slower than current models predict, and that the build-up of heat beneath stagnant plates may explain the occurrence of certain igneous rocks in the middle of continents away from their normal locations in subduction zones.
If plate tectonics indeed starts and stops, then continental evolution must be viewed in an entirely new light, since it dramatically broadens the range of possible evolutionary scenarios, says Silver. (ANI)
- Software shows how Earth evolved millions of years ago - Mar 17, 2011
- Gondwana supercontinent underwent 60-degree rotation during Cambrian explosion - Aug 11, 2010
- Why tectonic plates move the way they do - Jul 17, 2010
- Earth's birth: Inert gases provide clues - Sep 27, 2011
- Quake unleased 1,000 times energy of all n-weapons - Mar 13, 2011
- Global 3D map indicates presence of water in certain areas of Earth's mantle - Aug 20, 2009
- Solomon Islands quake sheds light on enhanced tsunami risk - Apr 10, 2009
- How far South American cities moved in Chile quake - Mar 09, 2010
- First dynamic model 'to explain' mystery of Mount Etna - Oct 08, 2010
- 200km deep subduction of Indian continent under Asia - May 29, 2010
- New discoveries resolve debate over oxygen in Earth's mantle - Dec 15, 2010
- Impurities in diamonds unravel earth's turbulent past - Jul 24, 2011
- Did the Japanese tsunami occur because of the 'supermoon'? - Mar 12, 2011
- Tectonic plates' movement caused Japan quake, tsunami - Mar 12, 2011
- Indian crust sank 200 km after hitting Asian landmass - May 29, 2010
Tags: carnegie institution, earthquake activity, earths interior, earths mantle, geochemical evidence, geological process, igneous rocks, journal science, ocean basins, oceanic plates, oceanic trenches, one billion years, pacific ocean basin, paul silver, plate tectonic theory, plate tectonics, rodinia, subduction zones, supercontinent, terrestrial magnetism