Geo101.07.EarthDifferentiation

Geo101.07.EarthDifferentiation - Earth Forming the planets...

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1 Earth …formation and differentiation of a planet Formation of Proto-Planet Dust particles collide and stick together, forming planetesimals. Key here are gravitational attractions and kinetic energy Forming the planets from planetesimals: Planetesimals grow by continuous collisions. Gradually, an irregularly shaped proto-Earth develops. The interior heats up and becomes soft… What was the composition of the material that formed the planetesimals? Chondrites: a type of meteorite composed of left over debris from the formation of the Soalr System. These give us insight as to he original composition of the planetary forming materials A chondritic meteorite chondrules Formation of Proto-Planet Dust particles collide and stick together, forming planetesimals. Forming the planets from planetesimals: Gravity reshapes the proto-Planet into a sphere. The interior of the Planet begins to differentiate due to density differenc and gravitational forces With the kinetic energy from the continued bombardment and from gravitational forces, the early Earth becomes molten, it begins to differentiate into layers… Radius = 6370 kilometers = 4000 miles …molten Fe because of its density and gravitational interactions, began to sink to the center of the early Earth, … an Fe-rich core formed, leaving behind the shell of rock we call the mantle and overlying crust…we refer to this as the iron catastrophe This is also referred to as Planetary Differentiation, a process that occurs during the formation of planetary bodies
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2 Processes during Planetary Differentiation Fractional (partial) melting since materials melt at different temperatures, raising temperatures high enough to melt silicates can result in those materials with higher melting temperatures to fall out of solution Gravitational separation those materials with a high density tend to sink through lighter materials and lighter materials try to rise through material with a higher density. And… Fractional crystallization when magma rises above a certain depth the dissolved materials may crystallize at certain pressures and temperatures. The resulting solids remove various elements from the melt, and melt is thus depleted of those elements. As Earth’s differentiates, the upper part of the Earth
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This note was uploaded on 12/28/2009 for the course 460 101 taught by Professor Swisher during the Fall '09 term at Rutgers.

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Geo101.07.EarthDifferentiation - Earth Forming the planets...

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