Part 3 what does plate tectonics have to do with climate
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Part 3, What does Plate Tectonics have to do with Climate?. Changes the topography Changes the ocean circulation Affects the re-cycling of volatiles re-cycling of water vapor is particularly important on planets besides Earth, such as Mars, Venus & Io

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Part 3 what does plate tectonics have to do with climate l.jpg
Part 3, What does Plate Tectonics have to do with Climate?

  • Changes the topography

  • Changes the ocean circulation

  • Affects the re-cycling of volatiles

    • re-cycling of water vapor is particularly important on planets besides Earth, such as Mars, Venus & Io

  • In turn, climate affects the creation of continental crust & the long-term evolution of a planet


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Changes in Ocean Circulation

Earth: today - relatively cool

  • the arrangement of the continents affects circulation of the oceans

  • a different configuration of the continents leaves larger or smaller spaces in which water can circulate

  • more (less) efficient circulation may result in either cooler or (hotter) global weather

Earth: Cambrian Era

Earth: Jurassic -

relatively hot

note: take a look at

Windows page

on Geologic Time


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Little Ice Age Example

  • Ice sheets used to cover the Great Lakes region

  • In the14th century the last of the retreating ice sheets freed the Lawrence waterway, allowing cold, glacial ice to drain into the North Atlantic

  • The influx of cold water decreased the average temperature in the North America and northern Europe by several degrees for a few centuries.

    • freezing temperatures at Valley Forge, Pennsylvania, for example

note: take a look at Windows page on Geologic Time


Slippery continents a specialty of earth contributes to a recycling of volatiles l.jpg
Slippery Continents, a specialty of Earth, contributes to a recycling of volatiles

  • Hydrated minerals, such as kyanite, a biproduct of the breakdown of granite, help make the crust of the Earth “slippery”, and so facilitate the subduction of the plates

    • (unique to the Earth)

  • subducted plates are re-melted and returned to the surface as volcanoes

  • these re-release volatiles during eruptions


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Plate Tectonics also forms New Crust recycling of volatiles

  • Over an extremely long time, plate tectonics forms the crust and shapes the surface of a planet. This process affects:

    (1) topography, as mentioned before

    (2) recycling of volatiles

  • In earliest days, Earth resembled Jupiter’s moon Io. The slow buildup of continental crust over Earth’s history shaped the course of its evolution.


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How does That Work? recycling of volatiles

  • Silicate rocks are about 90% of the Earth’s surface.

  • They evolve in the magma chamber of a volcano.

  • (The exact chemistry will depend upon the pressure and temperature inside the chamber).


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The Bowen Series shows the evolution of minerals in the chamber

  • The progression tend to separate light materials (silica-rich) from heavy materials (silica-poor).

  • The progression is well understood for the Earth. Efforts are underway to understand the progression for Mars.


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Granite vs. Gabbro chamber

  • Thus, the continental crust of the Earth is formed of light weight rocks such as granite (silica-rich).

  • The crust of the moon is made of more silicate-poor rocks such as gabbro.

  • The crust of Mars is made of basalt of an as-yet unknown silica %.


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Subduction helps create new crust chamber

  • The scraping of the crust as it subducts also creates a lightweight component of the crust which does not further subduct.

  • The lightweight component forms the continental crust of the Earth, crust which does not sink in the subduction process.


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The Earth’s Surface has Evolved chamber

  • Earliest Earth had no ocean, no continents, and an unknown atmosphere.

  • Continents grew, changed composition, and oxygen grew in the atmosphere.

  • Gradually the oceans have increased in saltiness as weathering of the surface proceeds.

Earth: Jurassic -

relatively hot

Earth: Cambrian Era


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Summary chamber

  • Changes in topography and/or ocean circulation affect the way cooling and warming mechanisms of a region “work”.

  • Because climate affects the creation of continental crust, and vice-versa, a planet can get stuck with a single climate if there is no plate tectonics.

  • Can you name a few examples?


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Part, 4; Plate Tectonics on Other Planets - Venus chamber

Venus - a thick atmosphere, no present-day plate tectonics

  • continents, volcanic rises, coronae

  • thick lithosphere (maybe)

  • lithosphere = frozen (maybe)

  • plate tectonics is not understood

    • there is some evidence of rifting & faulting


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Cratering History chamber& theories of catastrophic turn-over of the surface

  • The surface of Venus has just as few craters as does the Earth. This means that the surface is just as young as Earth’s surface!

  • Plate tectonics does not exist as it does on Earth, however.

    • Lithosphere is probably thick, not thin

    • Plates do not move.

  • Suggests a cataclysmic turn-over process may be at work.

  • The inside heats up until, POW! The whole surface melts.


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Coronae & Island Arcs chamber

  • There are features on the surface of Venus called “coronae” which strongly resemble terrestrial island arcs - a manifestation of plate tectonics


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Volcanic Rises & Islands chamber

  • On Earth, over a hot spot deep within, lava rises and creates a volcanic “island”.

  • Because of plate tectonics, the “island” moves away from the hot spot, gradually erodes away, and a new island takes its place.

  • On Venus, because of no plate motion, volcanic islands keep growing, and create giant continents instead.

  • These are called Volcanic Rises.

Hot spot!

(deep inside the Earth)


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Mountains chamber

  • Mountains of Venus are small, but the rock may be very dense. The crust may be very thick in order to support the weight.

  • On the other hand, the crust may be thin.

  • The uncertainties imply that the surface of Venus may turn over in a manner which is completely unlike that of the Earth.


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Venus Climate chamber

  • Venus has a thick, massive atmosphere.

  • Doesn’t seem capable of changing.

  • Theoretical work is on-going to test ideas of a changing climate.

  • What happens if there is a cataclysmic turn over of the surface - does that affect the atmosphere?

  • New results may suggest ways of measuring surface rock composition to seek evidence of climate change.


Slide18 l.jpg
Mars chamber

Mars - a thin atmosphere, no present-day plate tectonics

  • continents, volcanic rises, magnetic stripes

  • thick lithosphere (maybe)

  • lithosphere = frozen in place

  • plate tectonics may have taken place in the past

    • there is some evidence of rifting & faulting


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Volcanic Rise chamber

  • The presence of a volcanic rise suggests a thick, and immobile lithosphere.


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Magnetic Stripes chamber

  • On Earth, the biggest proof of the mechanism of plate tectonics, sea-floor spreading, is in the striped ocean floor.

  • Mars has been found to have similar stripes, indicating plate tectonics in the past.


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Martian “Geologic” Time chamberassociated with past Martian Plate Tectonics

Like the Earth, Mars experienced “epochs” in its past history (like the Jurassic, or Cambrian), and these epochs have names!

  • Hesperian

    • When the super continent at the southern hemisphere formed

  • Something

    • 90% of the rest of martian history, when the cratering eased off


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