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Tiny minerals may have shaped Earth's first plate boundaries

Weakened rock may explain the origin of plate tectonics, a simulation finds

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1:05pm, April 6, 2014

CRACKING EARTH’S SKIN  Intermittent weakening of corridors of crust on early Earth could have created plate boundaries through proto-subduction, a new simulation finds. Once weak zones became established plate boundaries, a plate could move and rotate, something like the present-day Pacific plate. The plate’s movement is evidenced by the sharp bend in the Emperor-Hawaiian island chain, a series of volcanoes that includes the Hawaiian Islands. The warm colors mark the plate boundaries.

The first ruptures in early Earth's skin formed because of the weakness of rock minerals merely a millimeter wide, two scientists propose. The small minerals’ behavior created boundaries defining Earth’s first crustal plates and set the stage for plate tectonics, according to a new computer simulation appearing April 6 in Nature.

Plate tectonics is special to Earth: The planet’s crust is divided into giant, mobile plates. A plate can bump up against another plate at a fault zone, or dive beneath one at a subduction zone. The outcome can be an earthquake or volcano. Where plates split apart, new crust forms. This occurs, for example, at the rift in the seafloor below the Atlantic Ocean. Venus, Earth’s near twin in size and composition, may once have had the conditions to start plate tectonic processes, but it didn’t.

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