What causes minerals in the mantle to change as depthincreases?
a. Changing composition.
b. Increasing pressure.
c. The liquid outer core.
d. Increasing temperature.
True or false: octahedral silicates are more dense thantetrahedral silicates.
The appearance of postperovskite in the early Earth’s historyhas been linked to
a. faster rotation of the Earth.
b. slower mantle convection.
c. faster mantle convection.
d. a weaker magnetic field.
At 2,400 km in the mantle beneath the Earth’s surface, thetemperature is ~ 2,300 K. What mineral would you expect tofind?
Before the discovery of postperovskite, our best informationregarding the Earth’s layers > 150 km depth came from
a. x-ray diffraction techniques that allows detailed mineralidentification.
b. mineral inclusions in diamonds.
c. hot spots where mantle plumes bring deep rocks to thesurface.
d. seismic waves from earthquakes that travel through theearth.
Silicon and oxygen are two important mineral-forming elements inthe mantle. The third element that is also abundant in mantleminerals is