GEOL 104 Lecture Notes - Lecture 2: Continental Crust, Oceanic Crust, Granodiorite
31 Oct 2017
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Earth: between 6-4ga earth was a molten blob formed thin crust shortly after words, nebular theory: the solar nebula consisted of hydrogen and helium, in addition to microscopic dust grains. A disturbance caused the solar nebula to slowly contract and rotate. The solar nebula assumed a flat, disk shape with the protosun (pre-sun) at the center. Inner planets began to form from metallic and rocky substances. Large outer planets began forming from fragments of ices (h2o, co2, and others). Started to segregate heavier parts towards core of earth. 4000 degrees c interior: earth is divided into three major layers by composition, continental crust is 35-70km and composed primarily of granodiorite, oceanic crust is approx. 7km thick and composed of basalt (fe & mg rich: formation of earth"s layered structure. A primitive atmosphere evolved from volcanic gases. The earliest primitive crust was lost to erosion and geological processes.
