Transcript No Slide Title

Patrice Rey
Room: 407
[email protected]
Tel: 12060
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Lecture 1:
Lithosphere, asthenosphere, and Archimedes (287212 BC)
Aims: A brief reminder about
he earth and lithospheric plates
Structural geology deals with deformation of
earth materials: From minerals to tectonic plates
• ~15 plates travel at
the surface of the
earth @ a speed of a
few cm/y
• Plates travel at
various speed and in
various direction
...=>
• …seismicity and
deformation at plates
boundaries
Plate boundaries features
• Topography
Plate boundaries
features
•
Seismicity
Plate boundaries features
• Volcanism
Australian plate
Plate tectonics and things that happen @ plate boundaries
Divergent plate boundaries
Convergent plate boundaries
Transform fault, and strike slip fault boundaries
Transform fault, and strike slip fault boundaries
Earth’s structure
Continental lithosphere: Some physical characteristics
Temperature
Radiogenic upper crust
Radiogenic elements
U, Th, K
Continental lithosphere: Some physical characteristics
Density
Density lithosphere ?
(zc/zl)*rc+(zlm/zl)*rlm
Isostasy and surface
topography
Isostasy and surface topography
Isostasy: A surface exists
at a certain depth where
the pressure, from the
column of earth material
above, is the same across
and underneath the
surface.
Continental lithosphere: Some physical characteristics
Strength
•Strong upper crust
•Weak upper crust
•Strong upper mantle
•Weak lower lithospheric mantle
•Very weak asthenosphere
Lecture 1 at a glance
~15 plates move at the surface of the earth.
Plate boundaries: locus of seismicity +/- magmatic activities, and high topography.
Divergent, convergent, and transform plate boundaries.
Lithospheric plates: oceanic lithosphere only, or both oceanic and continental
lithosphere, they float on the asthenosphere.
•Thickness
Continental lithosphere: 180 +/- 100 km thick; Oceanic lithosphere: 0-100 km
Continental crust: 35+/-10 km;
Oceanic crust: 5-7 km
•Temperature
Temperature at continental Moho: 500+/-150ºC
Temperature at base of lithosphere: 1300 +/-100ºC
•Density
Density continental crust: 2800 +/-100 kg.m-3
Density lithospheric mantle: 3350 +/-100 kg.m-3
Density asthenosphere: 3300 +/-100 kg.m-3
•Strength of continental lithosphere
Strong upper crust, weak lower crust, strong upper mantle, weak lower lithospheric mantle,
very weak asthenosphere.