Origin and early evolution of the Pacific plate

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2018-10-18
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The Pacific covers around a third of Earth’s surface and is the largest body of water on the planet; the origin and early evolution of the Pacific plate is a known plate tectonic mystery. Based on current plate tectonics understanding, the relative position of the Pacific plate to other plates is known since 85 million years ago, based on a connection to the Antarctica plate. Prior to connection with the Antarctic plate, the past location of the Pacific is unknown since its origin about 185 million years ago. My aim was to understand the missing 100 million years of plate tectonic evolution of the Pacific using tomography. I projected subducted plates, known as slabs, to the surface. This revealed the location of ancient plates that once filled the Panthalassa Ocean (i.e. the ocean the existed prior to the Pacific). To map the subducted plates, I analyzed published seismic tomography from the velocity of seismic waves that originated from earthquakes and were recorded by receivers placed around the world. Traditionally, analysis of tomography was done using 2D analysis of depth slices. I mapped subducted slabs in 3D and assessed their 3D continuity. My mapped slab were input into global plate modeling software GPlates that tracks plate movements through time to compare the slabs present locations with known uncertainties in global plate tectonics. This method has the potential to define the origin of the Pacific and be integrated into mantle convection models.

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