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Slide 1

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Geology of the
lithosphere…read more

Slide 2

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Key idea 1
The loss of heat through the earth's surface leads to cooling and
the development of the outer shell of high strength known as the
lithosphere underlain by a layer of lower strength known as the
asthenosphere.…read more

Slide 3

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Heat flow
· Heat flow is measure in milli
watts per square metre (Mwm-
· Mjs-1m-2 milli joule per second
per square meter
· Thinner lithosphere is a higher
heat flow
· High follows subduction and
spreading centre
· Cold on the continents
· Heat correlates with geological
features.…read more

Slide 4

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Oceanic crust
· Heat flow decreases with age
· Difficult to gage heat flow for
young oceanic crust
· Cooling due to hydro thermal
· Becomes steady as sediments
form a "cap"
· Young = high hydrothermal
circulation so large error bars
because its hard to measure but
after a 60ma circulation it
stabilizes…read more

Slide 5

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Origins of the thermal energy, how
is it transferred ?
Inter planetary accretion - "binding energy" generated as the
planet merges
Gravitational collapse of core ­ gravitational potential energy
released as the core forms and compacts
Radiogenic heating (40%)
Tidal heating
Other planets distant earth's rocks heat generated from
radiogentic decay other planets pull the earth, rocks move,
causes friction. Heats up
Transffered mostly by convection ... driving force of plate
tectonics or is it gravity
Circulation cells in the mantle that help drive plate tectonics
Circulation of sea water through the oceanic crust.…read more

Slide 6

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Heat flow and
The heat flow is proportional to the geothermal
gradientover an area
The constant is the thermal conductivity of the
rocks it has to travel through
Areas with high heat flow will also have a high
geothermal gradient
Heat flow in oceanic crust higher than continental
Q=k.T/D…read more

Slide 7

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