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Announcements: Final Exam Monday, Dec. 16, 11-1 this room

Announcements: Final Exam Monday, Dec. 16, 11-1 this room. TODAY: Structural Evolution of W. North America: From Proterozoic to Present Goals: (1) Appreciation of "local" geology (2) Interplay between plate tectonics and deformation

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Announcements: Final Exam Monday, Dec. 16, 11-1 this room

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  1. Announcements: Final Exam Monday, Dec. 16, 11-1 this room

  2. TODAY: Structural Evolution of W. North America: From Proterozoic to Present Goals: (1) Appreciation of "local" geology (2) Interplay between plate tectonics and deformation (3) Long and dynamic history of growth and deformation of continents

  3. Archean – Middle Proterozoic growth of North America Good old "Yankee" basement Youngs from N to S

  4. Middle Proterozoic to Cambrian rifting of W. U.S. What rifted away???

  5. Sedimentary evidence for a rifted continental margin: Late Proterozoic - Cambrian Thermal subsidence following rifting

  6. The margin of W. North America 500 Myr ago All the crust to the west is either younger or was torn off of some other continent and subsequently attached to N.A.

  7. Paleozoic passive margin sedimentation along continental margin- beautifully preserved in the Grand Canyon

  8. But!: There was action going on to the west during some of this time- Antler Orogen (Devonian-Mississippian)

  9. Cross section of the middle Paleozoic Antler Orogen Growth of an outboard arc and disruption (by thrusting) of the passive margin

  10. There was also action to the east during late Paleozoic time Collision between S. America / Africa with SE U.S. to form ancestral Rocky Mountains

  11. The Permo-Triassic Sonoma orogeny: "retro-arc" thrusting

  12. The Sevier orogeny: E-directed thrusting behind a magmatic arc– "retro-arc" fold-thrust belt and associated foreland basin system

  13. What's going on at this time (~60 myr ago?) Eastward sweep in magmatism Basement-involved deformation "Laramide" orogeny

  14. Magmatism starts sweeping back to west – 45 Myr ago More "Laramide" deformation

  15. More westward sweep in magmatism- Major change in style of deformation!

  16. Rifting and development of Cordilleran metamorphic core complexes related to major crustal extension

  17. Basin and Range Extension Eruption of Columbia River basalts Magmatism back to west

  18. Growth of Basin and Range Province

  19. Today!

  20. Relating plate tectonics to continental deformation

  21. Bigger picture: formation of the Cordilleras due to long-lived oceanic subduction

  22. Concept of "Suspect" terranes- possibly far-traveled and torn off of other continents, rafted across large tracts of oceans and finally accreted to W. N.A. Crustal "immigration"

  23. Reminder!: Final Exam Monday, Dec. 16, 11-1 this room Next Lecture: Review for final

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