Introduction to Earth System

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Introduction to Earth System

• Solid Earth part
• Rocco Malservisi
• roccom_at_lmu.de
• Phone [phone]

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Half-life
The half-life of a radioactive isotope is defined
as the time required for half of it to decay.
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Isotopic dating

• Radioactive elements (parents) decay to
  nonradioactive (stable) elements (daughters).
• The rate at which this decay occurs is constant
  and knowable.
• Therefore, if we know the rate of decay and the
  amount present of parent and daughter, we can
  calculate how long this reaction has been
  proceeding.

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So in particular the U Pb works quite well
because we can measure the quantity of parents
and daughter.
We need to have some idea of the global
composition of the Earth
IMPORTANT IT WORKS ONLY ON CLOSE SYSTEM
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Major Radioactive Elements Used in Isotopic Dating
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http//www.geo.uu.nl/forth/people/Guillaume/guill
aume.htm
pangea.stanford.edu/dpollard/NSF/content.html ada
pted from P. Fitzgerald, S. Baldwin, G. Gehrels,
P. Reiners, and M. Ducea
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So transferring heat is one of the primarily
engine in Earth System processes. How do we
transfer heat? (will be treated more by prof
Rummel)
http//apollo.lsc.vsc.edu
Radiation (EM waves) Convection (fluid
behavior) (Advection) Conduction (solid)
Transfer of Energy through EM waves Transfer of
Energy through material transfer Transfer of
Energy through vibration energy in the lattice
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http//apollo.lsc.vsc.edu
Sun Radiation Atmospheric processes and mantle
convection Uplift of a mountain Conduction of
heat in the shallow layers of the planet.
Radiation (EM waves) Convection (fluid
behavior) Advection Conduction (solid)
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Some definitions
Heat a form of Energy (J or
cal 1cal4.186J) Temperature a measurement
of the average kinetic energy of the system
(K) Specific heat ability of the body to
store heat, the amount of energy necessary to
increase of 1K the temperature of a unit
mass (J/Kg K, 1 cal/gC 4186 J/Kg K for water
4186 J/kg K for rocks 850 J/kg K) A
heat generation, the amount of energy
generated per unit volume and unit time
(W/kg) Q, heat flow the amount of heat per unit
area and unit time (mW/m2) Thermal
conductivity how easy is to propagate the
heat, it is a material propertyW/mK
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Some observations
Average heat flow continents 60 mW/m2
oceans 90 mW/m2 total
80mW/m2 SUN 340 W/m2 !!!!!! Heat
generation
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Average T in Munich 12C Annual
escursion 20C Depth below which Is not
freezing 1.5 m!
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The parameter that control if Convection is
easier than Conduction is the combination between
viscosities and Conductivity Rayleigh number.
Example for the solid Earth
At the surface of the Earth The viscosity is so
high that it behave as a solid (conduction)
Convection is possible in the Mantle with a
velocity of of cm/yr Thickness 2900 km This
means that is a process that take millions of
years
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From studying the formation of the Earth we can
already speculate on the 2 major endogenic forces
Gravity (that try to smooth everything to an
equipotenzial surface) Heat (that try to escape
in the cooling of the Earth and in doing this
move the engine that shapes the whole planet).

• If there were no endogenic forces
• the Earth would look like the Moon

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The major exogenic forcing? Solar radiation
(very important in atmospheric and oceanic
processes but not important on the long scale of
the solid earth processes).
At the boundary between the Atmospheric system
and the Solid Earth system all 3 source of energy
can be very important. For Example a landslide
the cooling of the solid earth create the
elevation (mountain) that the gravity want to
bring back to equilibrium but the rain is what
normally make the slope unstable.
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So transferring heat is one of the primarily
engine in Earth System processes. How do we
transfer heat? (will be treated more by prof
Rummel)
Radiation (EM waves) Convection (fluid
behavior) Conduction (solid)
Sun Radiation Atmospheric processes and mantle
convection Conduction of heat in the shallow
layers of the planet.
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From studying the formation of the Earth we can
already speculate on the 2 major endogenic forces
Gravity (that try to smooth everything to an
equipotenzial surface) Heat (that try to escape
in the cooling of the Earth and in doing this
move the engine that shapes the whole planet).

• If there were no endogenic forces
• the Earth would look like the Moon

19
The major exogenic forcing? Solar radiation
(very important in atmospheric and oceanic
processes but not important on the long scale of
the solid earth processes).
At the boundary between the Atmospheric system
and the Solid Earth system all 3 source of energy
can be very important. For Example a landslide
the cooling of the solid earth create the
elevation (mountain) that the gravity want to
bring back to equilibrium but the rain is what
normally make the slope unstable.