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Sevier & Laramide Orogenies

Sevier & Laramide Orogenies. The North American Cordillera. Cordilleran Structure. Orogenic Sequence. The Orogenic Belt. Propagation of Thrust Belts. “Decollement”. Foreland Basins. Foreland Orogen Basin. Sevier Orogeny. 170 to 80 Million years ago. Sevier: horribly complex.

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Sevier & Laramide Orogenies

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  1. Sevier & Laramide Orogenies

  2. The North American Cordillera

  3. Cordilleran Structure

  4. Orogenic Sequence

  5. The Orogenic Belt

  6. Propagation of Thrust Belts

  7. “Decollement”

  8. Foreland Basins

  9. Foreland Orogen Basin

  10. Sevier Orogeny 170 to 80 Million years ago

  11. Sevier: horribly complex

  12. Middle Jurassic: 170 – 160 Million years ago

  13. Late Jurassic: 160 – 155 Million years ago • Western Plate Margin Consolidates, • accretion of Coast Range Ophiolite • Farallon Plate Subduction Begins

  14. Latest Jurassic: 155 – 142 Million years ago • Voluminous Arc Magmatism • Crustal Shortening

  15. Early Cretaceous: 142 – 110 Million years ago • Emplacement of “Mega-Thrust Sheet”

  16. Middle Cretaceous: 110 – 85 Million years ago • Onset of rapid shortening and Sevier Orogeny

  17. Sevier: oversimplified

  18. Sediments in the Foreland Basin • The diagram shows two diferent kinds of sediments in the foreland basin: • Sediment from the west is clastic sandstone and mudstone, eroded from the mountains of the thrust belt. • Sediments from the east are shales and marine sediments which developed in a shallow sea. • The dotted line shows the migration of sea level back and forth as sediments were deposited.

  19. Laramide Orogeny 80 to 40 Million years ago

  20. Sevier: another look

  21. Laramide to the east

  22. Laramide Involves Basement!

  23. Follow this link for a neat movie! http://element.ess.ucla.edu/publications/1998_Laramide/RMF_velocity_movie.gif

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