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Intro to Plate Tectonics
- Main compositional zones of the Earth
- 1. Densie iron rich core,
2. less dense
magnesium-silicate rich
mantle, 3. thin, light crust
composed of mainly
silicate
- 1. Densie iron rich core,
2. less dense
magnesium-silicate rich
mantle, 3. thin, light crust
composed of mainly
silicate
- Lithosphere and Athenosphere
- Lithosphere incorporates
the crust and parts of upper
mante
- Lithosphere plates - edges of plates
are sites of intense geologic activity.
Varies from 100-200 km thick.
- Include both continental and oceanic
crust and brittle parts of the upper
mantle.
- Include both continental and oceanic
crust and brittle parts of the upper
mantle.
- Lithosphere plates - edges of plates
are sites of intense geologic activity.
Varies from 100-200 km thick.
- Athenosphere- least rigid portion of
the mantle. soft, easily flexible
- Lithosphere incorporates
the crust and parts of upper
mante
- Continental drift
- Continents have moved around. Alfred Wenger - theory of a
large landmass called Pangea
- Pange broke into 2 supercontinents called Gondwana and
Laurussia. Seperatedby Tethys ocean.
- Evidence- fold belts, age of provinces, igneous
provinces, stratiographic sections.
- Evidence- fold belts, age of provinces, igneous
provinces, stratiographic sections.
- Pange broke into 2 supercontinents called Gondwana and
Laurussia. Seperatedby Tethys ocean.
- Continents have moved around. Alfred Wenger - theory of a
large landmass called Pangea
- Seafloor speading
- echo sounding data from military used to highlight
40,000 km long global mid-ocean ridge system.
median valley along the lenght
- Ocean crust is created at spreading centers by magma that rises
from deeper levels.
- Ocean crust is created at spreading centers by magma that rises
from deeper levels.
- echo sounding data from military used to highlight
40,000 km long global mid-ocean ridge system.
median valley along the lenght
- Boundaries
- Convergent- where oceanic crust
collides with continental crust = sinks
back into mantle. = SUBDUCTION or
two continental crusts collide -
mountains
- Transform- crust neither
created or destroyed.
earthquakes and volcanic
activity occur. e.e San
Andreas. WILSON CYCLE
- Divergent - spreading centre
- Convergent- where oceanic crust
collides with continental crust = sinks
back into mantle. = SUBDUCTION or
two continental crusts collide -
mountains
- Crusts
- Oceanic - mafic rocks, young on geological
timescale. 6-11 km thick, avg density -
2900/3000 kg/m3
- Continental - felsic rock, much older than
oceanic crust. 30-40 km thick, avg density
2700/2800 kg/m3
- Oceanic - mafic rocks, young on geological
timescale. 6-11 km thick, avg density -
2900/3000 kg/m3
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