Transcript lecture4

PREM = Preliminary Reference Earth Model
So what is the Earth’s interior
made of?
•
Look for rocks at surface with Vp ~ 8 km/s and
density ~ 3.5 km/s
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Peridotite
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Eclogite
Does peridotite or eclogite fit the enterior?
• Need high pressure
experiments
• Principle is to
generally reduce
surface area
• Multi-anvil cell
• 25 GPa (700 km) and
2500 K
• Sample ~1mm
• Diamond anvil cell
• 350 GPa or so (centre of Earth)
• Very small sample (i.e. 0.1 mm)
• Shock experiments
• Very small samples
• very little time
• 1 TP (inside of Jupiter)
Does peridotite or eclogite fit the enterior?
 = olivine
 = wadsleyite
 = ringwoodite
1 kbar ~ 3 km
1 GPa ~ 30 km
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Bina & Wood (1987)
Short dashed = observed
Long dashed = (Mg0.9Fe0.1)2SiO4 at1700 K
Solid line = (Mg0.9Fe0.1)2SiO4 at 2000 K
Seismic tomography
CAT Scan
(uses x-rays)