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Basic concepts of plate tectonics. 1. Lithosphere/asthenosphere 2. A number of plates (more than one) 3. Differential movements 4. Deformation occurs at plate boundaries. Fig.1. Lithosphere = strong. Asthenosphere = weak. Fig.2. F. F. e = D L/L. Strain. Strain rate. - PowerPoint PPT Presentation
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• 1. Lithosphere/asthenosphere
• 2. A number of plates (more than one)
• 3. Differential movements
• 4. Deformation occurs at plate boundaries
Basic concepts of plate tectonics
Fig.1
Lithosphere= strong
Asthenosphere= weak
Fig.2
F/s =
F F
= 2 d/dt
d/dt = / 2
Strain L/L
Stress
Strain rate d /dt = /t
viscosity
s: Fractional area
Fig.3
Conductive Earth
Tm
750°C 1300°C
3000 km
0
Fig.4
TemperatureStream lines Temerature averaged at depth
Thermal boundary layer
Thermal boundary layer
Convection
Thermal boundary layer
Fig.5Modified from Parsons and Richter (1981)
Subduction
Oceanic plate
Fig.6
750°C 1300°C
Efficiency of convection vs conduction
Tm
Heatflow q = kdT/dz
Fig.7
Conduction
Convection
3000 km
0
Fig.8
Wiens & Stein (1985)
Earthquakes within oceanic plates
Fig.9
Low velocity zone
Shear-wave velocity (km/s)
Depth
(km)
Anderson & Toksoz (1963)
Fig.10
Free-air gravity anomaly
Load
Lithosphere
Asthenosphere
Continental plate
Oceanic plate
Subduction
VolcanismContinents
No recycling
Recycling
Fig.11
ArcheanProterozoic
Phanerozoic
Fig.12
Continental area growth
Fig.13Pollack (1986)
Hotspot trace
Fig.14Data: ETOP5
Seismicity( depth<100 km)
Pacific plate
Eurasian plate
Antarctic plate
N. American plate
S. American plateAfrican plate
Indo-Australian plate
Major platesFig.15
Philippine Sea Pl.
Scotia plate
Cocos plate
Juan de Fuca plate
Nazca plate
Carribean plate
Arabian plate
Minor platesFig.16
Caroline plate
Venus
Fig.17
Saunders et al. (1992)
Mars
Fig.18
Venus: topography
Fig.19Ford & Pettengill (1992)
Earth’s topography
Fig.20NOAA (1985)
Topography distribution of the planets
Fig.21
Warren (1993)
Solomatov & Moresi (1996)
Fig.22
Venus: Stagnant-lid convection