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GLY 326 Structural Geology

GLY 326 Structural Geology. Lecture 7 The anatomy of continents. Autumn , 2015. The Wilson Cycle. The Wilson Cycle. The Wilson Cycle. The Wilson Cycle. The Wilson Cycle. The Wilson Cycle. The Wilson Cycle. Structures of Continents. continents are made and deformed by plate motion

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GLY 326 Structural Geology

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  1. GLY 326Structural Geology Lecture 7 The anatomy of continents Autumn, 2015

  2. The Wilson Cycle

  3. The Wilson Cycle

  4. The Wilson Cycle

  5. The Wilson Cycle

  6. The Wilson Cycle

  7. The Wilson Cycle

  8. The Wilson Cycle

  9. Structures of Continents • continents are made and deformed by plate motion • continents are (in general) older than ocean rocks

  10. This is because old oceanic crust has been recycled already!

  11. Anatomy of a continent • shields • stable platforms • folded mountain belts

  12. World Tectonic Provinces

  13. Tectonic Age The time of the most recent major episode of crustal deformation

  14. Tectonic Ages

  15. Canadian shield!

  16. Stable platforms: Shallow ancient seas

  17. The Great Unconformity Thermopolis, Wyoming

  18. 550 Million Year old Sandstone Ancient Soil (550 Ma) 3 Billion Year old Granite The Great Unconformity Thermopolis, Wyoming

  19. Mountain Belts

  20. Mountain Belts

  21. How Continents Grow • Magmatic differentiation: magma transferred to continents at subduction zones • Continental accretion: buoyant fragments of continents attached to continents as the result of plate motions

  22. Island Arcs - the Beginning of Continental Accretion

  23. Accreted Terrains Allochthon Autochthon Parautochthon

  24. “Suspect Terranes” of Western North America Multiple accretions of older island arcs, oceanic plateaus, oceanic crust, and marine sedimentary rocks.

  25. How continents are modified • Orogeny: mountain-building process of folding, faulting, magmatism, and metamorphism • Epeirogeny: vertical motions of largely flat-lying rocks without faulting or significant folding

  26. Orogeny • mountain building • particularly by folding and thrusting of rock layers • often accompanied by magmatic activity

  27. Orogeny

  28. Orogeny

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