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CHAPTER 5
PLATE TECTONICS AND CLIMATE
莊凱勳
Plate Tectonic Process
ƒ Plate Tectonics
ƒ Model Simulation of Pangaea Climate
ƒ The Polar Position Hypothesis
ƒ Tectonic Control of CO2 Input
ƒ Tectonic Control of CO2 Removal
ƒ What Controls Chemical Weathering?
Plate Tectonics
ƒ
ƒ
ƒ
Chemical Composition
1. Ocean crust-Basalt
2. Continental crustGranite
3. Mantle-in the heavy
Fe and Mg
Physical Behavior
1. Lithosphere-Rigid
plates
2. Asthenosphere-Soft
& viscous fluid
Tectonic Plates
Manners of Plate Motions
Earth’s Magnetic Field
Magnetic stripes in the ocean
This is along a section of the Mid-Atlantic Ridge of Iceland.
Colored stripes mark regions with highly magnetized crust.
Magnetization of Ocean Crust
The Movement of Tectonic
Plates
Supercontinent of Pangaea
ƒ Laurasia: North America, Europe, and
north-central Asia
ƒ Gondwana: Antarctica, Australia, Africa,
South America, and India
Laurasia
Gondwana
Reconstruction of Tectonic Plates
Supercontinent of Pangaea
ƒ Laurasia: North America, Europe, and
north-central Asia
ƒ Gondwana: Antarctica, Australia, Africa,
South America, and India
Laurasia
Gondwana
Model Simulation of Pangaea
Climate
ƒ Input to the Model Simulation of Pangaea
Climate
ƒ Output from the Model Simulation of
Pangaea Climate
Input to the Model Simulation
of Pangaea Climate
ƒ Distribution of land and sea
ƒ Global sea level
ƒ Topography
ƒ Sun’s energy
weaker
1% than today’s
ƒ CO2 level in
atmosphere
Output from the Model Simulation of
Pangaea Climate
Output from the Model Simulation
of Pangaea Climate
(Summer-Winter Seasonal
temperatures)
Output from the Model Simulation of
Pangaea Climate
(Monsoon and Its Precipitation)
A. Summer causes heated
air to rise over the land
and a strong low-pressure
cell to develop at surface.
B. The rising of heated
air causes a net inflow of
moisture-bearing winds
from the ocean bringing
heavy rains to the east coast.
C. The situation in the winter
is exactly reverse.
The Polar Position Hypothesis
ƒ Ice sheets should appear on continents
when they are located at polar or near-polar
latitudes.
ƒ No ice should appear anywhere on Earth if
no continents exist anywhere near the poles.
The Polar Position Hypothesis
ƒ
The evidences of the Polar position hypothesis
are the polar continents of Antarctica and the
near-polar landmass of Greenland.
1. (Cold temperatures) caused by low angles of
incident solar radiation.
2. High albedos resulting from the prevalent cover
of snow and sea ice
Contrast Glaciations with the
Polar Position Hypothesis
The BLAG Spreading Rate
Hypothesis
ƒ Robert Berent，Antonio Lasaga，and
Robert Berner
ƒ Tectonic Control of CO2 Input
Climate changes during the last several
hundred million years have been driven
mainly by changes in the rate of CO2 input
to the atmosphere by plate tectonic
processes.
The Weathering decreases CO2
degree in the atmosphere
ƒ The decrease of CO2 in the atmosphere
have been driven mainly by the weathering
of the carbonate.
ƒ CaCO3+H20+CO2
Ca2++2HCO3
ƒ 2CaFeSi2O6+0.5O2+10H2O+4CO2
Fe2O3+4H4SiO4+2Ca2++4HCO3
Rock Exposure and Chemical
Weathering
ƒ The BLAG hypothesis views chemical
weathering as the responding to three
climate-related factors: temperature,
precipitation, and vegetation.
ƒ The surface area of the rocks exposure
more, the effect of the chemical weathering
stronger.
Volcanic activity increased the degree of
the CO2 in the atmosphere
ƒ The mainly gas from the volcano:
H2O(70.75%)、CO2(14.07%)、
SO2(6.40%)、N2(5.45%) 、SO3(1.92%)、
H2(0.33%)、Ar(0.18%)、S(0.10%) （資料來
源：
http://volcano.gl.ntu.edu.tw/class/volcanolog
y_all.htm）
Carbon Cycling
The Effects of the Seafloor Spreading
Rate to CO2 in the Atmosphere
ƒ At the margins of convergent plates, where
portions of subducting plates melt and form molten
magmas that rise to the surface in mountain belt
volcanoes, carrying CO2 and other gases from
Earth’s interior to it’s atmosphere.
ƒ At the margins of divergent plates (ocean ridges),
where hot magma carrying CO2 erupts directly into
ocean water.
The activities of volcanoes and Mid-Atlantic
Ridge bring the CO2 to the surface.
Spreading rates and CO2 input rate
The Effects of the Seafloor
Spreading Rate to CO2
The Relationship Between CO2 and
Cooling Effect
A. The changes are
brought by the uplift
B. The fragmentation
speed the weathering
C. The high speed weathering
increases the depletion of CO2
D. Global Cooling
Weather
In the
Amazon area
Compare the three Hypothesis
Evaluation of BLAG Spreading
Rate (co2 input) Hypothesis
Evaluation of Uplift Weathering
(CO2 removal) hypothesis
SUMMARY
ƒ Besides the position of the continents, the mainly
factors affect the climates in the natural
environment are weathering, the tectonic plates
process, and the degree of the volcano process.
ƒ The stronger the weathering, the colder the
climates.
ƒ more tectonic plates movements
volcanoes activite
warmer climate
more
more CO2 released