Geos 306, Lecture 13
Mineralogy of the Earth and its Core



The Preliminary Reference Earth Model (PREM) of compressional velocity (Vp), shear velocity (Vs), and density (ρ) as a function of depth in the Earth.
(After Oziewonski and Anderson, 1981)
Region (depths)
Mineralogy
Inner core (6371-5150 km)
HCP iron
Outer core (5150- 2891 km)
Liquid iron
Lower mantle (2891-670 km)
Magnesio-wüstite, bridgmanite, stishovite
Transition zone (670-410 km)
Structures with both SiO4 and SiO6 groups, e.g., majorite garnet
Upper mantle (410-40 km)
Olivine, pyroxene, garnet, spinel
Crust (average depth 40 km)
Feldspar, quartz

Pressure

The core
Depth (km)
P (GPa)
T (K)
2571(D``/m)
117
3018
2741
127
3564
2891 (c/D``)
135
3750
3571
206
4265
3971
243
4500
4371
277
4693
4771
306
4846
5150 (ic/oc)
329
4961
5571
349
5041
5971
360
5087
6371 (Center)
364
5151

Steel

Reading:
Wenk and Bulakh, Chapter 35