1. Constitucion y dinamica del planeta
Conduccion del Calor.

2. Heat in the Earth
Volcanoes, magmatic intrusions, earthquakes, mountain building and metamorphism are all controlled by the generation and transfer of heat in the Earth.
The Earth’s thermal budget controls the activity of the lithosphere and asthenosphere and the development of the basic structure of the Earth.

4. Heat Transfer Mechanisms
Conduction
Transfer of heat through a material by atomic or molecular interaction within the material
Radiation
Direct transfer of heat as electromagnetic radiation
Convection
Transfer of heat by the movement of the molecules themselves
Advection is a special case of convection

8. The heat arriving from the Sun is by far the greater of the two
Heat arrives at the surface of the Earth from its interior and from the Sun.
The heat arriving from the Sun is by far the greater of the two
Heat from the Sun arriving at the Earth is 2x1017 W
Averaged over the surface this is 4x102 W/m2
The heat from the interior is 4x1013 W and 8x10-2 W/m2
However, most of the heat from the Sun is radiated back into space. It is important because it drives the surface water cycle, rainfall, and hence erosion. The Sun and the biosphere keep the average surface temperature in the range of stability of liquid water.
The heat from the interior of the Earth has governed the geological evolution of the Earth, controlling plate tectonics, igneous activity, metamorphism, the evolution of the core, and hence the Earth’s magnetic field.

11. Conductive Heat Flow Heat flows from hot things to cold things.
The rate at which heat flows is proportional to the temperature gradient in a material
Large temperature gradient – higher heat flow
Small temperature gradient – lower heat flow

13. Imagine an infinitely wide and long solid plate with thickness δz .
Temperature above is T + δT
Temperature below is T
Heat flowing down is proportional to:
The rate of flow of heat per unit area up through the plate, Q, is:
In the limit as δz goes to zero:

14. Heat flow (or flux) Q is rate of flow of heat per unit area.
The units are watts per meter squared, W m-2
Watt is a unit of power (amount of work done per unit time)
A watt is a joule per second
Old heat flow units, 1 hfu = 10-6 cal cm-2 s-1
1 hfu = 4.2 x 10-2 W m-2
Typical continental surface heat flow is mW m-2
Thermal conductivity k
The units are watts per meter per degree centigrade, W m-1 °C-1
Old thermal conductivity units, cal cm-1 s-1 °C-1
0.006 cal cm-1 s-1°C-1 = 2.52 W m-1 °C-1
Typical conductivity values in W m-1 °C-1 :
Silver 420
Magnesium 160
Glass 1.2
Rock
Wood 0.1

16. Oceanic Heat Flow
Heat flow is higher over young oceanic crust
Heat flow is more scattered over young oceanic crust
Oceanic crust is formed by intrusion of basaltic magma from below
The fresh basalt is very permeable and the heat drives water convection
Ocean crust is gradually covered by impermeable sediment and water convection ceases.
Ocean crust ages as it moves away from the spreading center. It cools and it contracts.

17. These data have been empirically modeled in two ways:
d= t (0-70 my)
and
d=6.4 – 3.2e-t/ ( my)

19. The model of plate cooling with age generally works for continental lithosphere, but is not very useful.
Variations in heat flow in continents is controlled largely by changes in the distribution of heat generating elements and recent tectonic activity.

22. Range of Continental and Oceanic Geotherms in the crust and upper mantle

29. Convection