I-ENVISION Challenge: Physics - Earth History & Fluid Flow


Entry #0113090000
 Entry #0300160000

This option requires you, as contest participants, to interpret an excerpt containing a novel idea or mechanism which is taken from

a recent research article or student thesis. Using your imagination, creativity and an animation technology, you will then illustrate

the given description in the form of animation or motion picture


  • Relating to the Grade 12 Earth and Space (SES4U0) and a lesser link to Grade 12 College Physics (SPH4C0): Earth History & Fluid Flow                    (with focus on how early tectonic process operates to create the rocks in the ancient Superior Province of Northern Ontario and

                         compare it to the plate tectonics processes of today)

                         [Excerpt is shown below the animation entries]



         

            "A growing number of researchers feel that the operation of plate tectonics on the early Earth was a vastly different that of today, primarily

          due to a higher mantle temperature. Global tectonics evolved from predominantly vertical to predominantly horizontal as the earth cools.


          Under early Archean conditions, crustal diaprirism, which is characterised by significant and rapid vertical displacements of mafic volcanic 

          activities, may have been a dominant form of tectonism. Follow-on effects from this process include a greater degree of partial melting of 

          upwelling mantle, a thicker, but softer crust, and a softer, weaker lithosphere (continental crust) due to higher geothermal gradient.

          Archean tectonic plate spreading rates would have been 2-3 times greater than today's rate, giving rise to a thicker oceanic crust and

          thinner lithosphere (continental crust). The lithosphere at the time may have been too buoyant to subduct.  In addition, recent modeling

          suggests that a hot weak lithosphere, even if dense enough to subduct, would easily break off, removing the slab pull force which is a major

          driver of modern plate tectonics. With the secular decrease in radiogenic and thermal inputs, lithospheric strength increases which

          eventually impedes crustal turnover and reorganization by diaprirism and allows continents to rise above sea level. The cooling may have

          also been aided by the formation of granite in the lithosphere. As diaprirism slows down and becomes inefficient at reorganizing the crust,

          further continental formation and development transition towards horizontal tectonism.


          This process above is felt to explain the creation of the rocks in the ancient Superior Province of Northern Ontario, which are among the

          oldest continental rocks discovered." 


          Reference:​  Robin, Catherine M.I. (2010). Diapirism on Venus and the Early Earth and The thermal effect of fluid flows in AECL's Tunnel

                                             Sealing Experiment. Doctoral of Philosophy Thesis submitted to the Department of Physics and Geology.

                                             University of Toronto. Retrieved on May 20th, 2013 via T-space library: http://hdl.handle.net/1807/24863​​​