CHAPTER 5

PLATE TECTONICS AND CLIMATE

莊凱勳

Plate Tectonic Process

Plate TectonicsModel Simulation of Pangaea ClimateThe Polar Position HypothesisTectonic Control of CO2 InputTectonic Control of CO2 RemovalWhat Controls Chemical Weathering?

Plate TectonicsChemical Composition

1. Ocean crust-Basalt2. Continental crust-

Granite3. Mantle-in the heavy

Fe and MgPhysical Behavior

1. Lithosphere-Rigid plates

2. Asthenosphere-Soft & viscous fluid

Tectonic Plates

Manners of Plate Motions

Earth’s Magnetic Field

Magnetic stripes in the oceanThis 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 PangaeaLaurasia: North America, Europe, and north-central AsiaGondwana: Antarctica, Australia, Africa, South America, and India

Laurasia

Gondwana

Reconstruction of Tectonic Plates

Supercontinent of PangaeaLaurasia: North America, Europe, and north-central AsiaGondwana: Antarctica, Australia, Africa, South America, and India

Laurasia

Gondwana

Model Simulation of Pangaea Climate

Input to the Model Simulation of Pangaea ClimateOutput from the Model Simulation of Pangaea Climate

Input to the Model Simulation of Pangaea Climate

Distribution of land and seaGlobal sea level Topography Sun’s energy weaker 1% than today’sCO2 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

Ice sheets should appear on continents when they are located at polar or near-polar latitudes. No ice should appear anywhere on Earth if no continents exist anywhere near the poles.

The Polar Position Hypothesis

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

Robert Berent，Antonio Lasaga，and Robert BernerTectonic Control of CO2 InputClimate 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 CO2degree in the atmosphere

The decrease of CO2 in the atmosphere have been driven mainly by the weathering of the carbonate.CaCO3+H20+CO2 Ca2++2HCO32CaFeSi2O6+0.5O2+10H2O+4CO2Fe2O3+4H4SiO4+2Ca2++4HCO3

Rock Exposure and Chemical Weathering

The BLAG hypothesis views chemical weathering as the responding to three climate-related factors: temperature, precipitation, and vegetation.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

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/volcanology_all.htm）

Carbon Cycling

The Effects of the Seafloor Spreading Rate to CO2 in the Atmosphere

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.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 weatheringC. The high speed weathering increases the depletion of CO2

D. Global Cooling

WeatherIn the

Amazon area

Compare the three Hypothesis

Evaluation of BLAG SpreadingRate (co2 input) Hypothesis

Evaluation of Uplift Weathering (CO2 removal) hypothesis

SUMMARY

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.The stronger the weathering, the colder the climates.

more tectonic plates movements morevolcanoes activite more CO2 released warmer climate