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Dr. Jeff AmatoGeological Sciences
RocksIgneous Rocks
Themes for today:
(1) Heat and the Earth(2) Melting processes(3) Differentiation(4) Igneous rock classification(5) Plate tectonics and igneous rocks
How do we know the Earth is hot?
Why is the Earth hot inside?
(1) Early collisions create heat.
Planetesimals Protostar
Planetesimal
~1 km
(2) Radioactive decay creates heat
Geothermal Gradient
Rate of T increase with depth
Why is the Earth hot on theSURFACE?
90%
10%
What controls heat loss?
Radiation
Conduction
Convection
Themes for today:
(1) Heat and the Earth(2) Melting processes(3) Differentiation(4) Igneous rock classification(5) Plate tectonics and igneous rocks
How to form magma:
1)Raise the temperature
2)Lower the pressure
3)Add water
Phase Diagram for Water
Melting dry rocks
Melting wet rocks
How to form magma:
1)Raise the temperature: CRUSTAL MELTING
2)Lower the pressure: DECOMPRESSION MELTING
3)Add water: HYDRATION MELTING
Themes for today:
(1) Heat and the Earth(2) Melting processes(3) Differentiation(4) Igneous rock classification(5) Plate tectonics and igneous rocks
Igneous Rock Classification
UltramaficMafic
IntermediateFelsic
From Ultramafic to Felsic….
Fe, Mg, Ca decreasesDensity decreasesSiO2 increasesK, Na increases
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