NATS 1750 Lecture Notes - Lecture 5: Continental Crust, Seismic Wave, Oceanic Crust
7 Jan 2018
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Document Summary
Topic: journey to the centre of the earth. Clues from the study of earthquakes: refining the image of the interior waves provide insight into earth"s interior. We can determine the depth of seismic velocity changes. Hence, we can tell where densities change in earth"s interior. Geologists strived to understand the nature of the layers. Studied meteorites as analogs for core and mantle. Conducted laboratory experiments density measurements of rocks from the interior. Characteristics of mantle-derived rocks and minerals determined high p and t stability field of rocks and minerals. Thickness varies from 7 70 km continental crust is thicker than oceanic crust. The base of the crust is called the moho. There are two kinds of crust: continental and oceanic. Thickness ranges from 25 70 km highly variable, felsic (granitic) to intermediate. Oceanic crust underlies the oceans average density of ~3. 0 g/cm3 composition. Thickness ranges from 7 10 km mafic (basaltic and gabbroic) composition.
