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Mesozoic Era

Mesozoic Era. Geology. Phanerozoic Eon Mesozoic Era. Age of Reptiles. 3 periods. Triassic. Jurassic. Cretaceous. Mesozoic Overview. Global. Breakup of Pangaea. North America. Cordilleran. Subduction zone after N.A. moves west. Cordilleran Orogeny. Eastern Coastal Region.

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Mesozoic Era

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  1. Mesozoic Era Geology

  2. Phanerozoic EonMesozoic Era • Age of Reptiles • 3 periods • Triassic • Jurassic • Cretaceous

  3. MesozoicOverview • Global • Breakup of Pangaea • North America • Cordilleran • Subduction zone after N.A. moves west • Cordilleran Orogeny • Eastern Coastal Region • Fault block mountains

  4. MesozoicPangaea Breakup • Fracturing of continents • Associated with extension • Triple junction • Mantle plume = bulge • 2 arms join in fracturing • 3rd failed arm = aulacogen (Niger, Miss, Amazon) i.e. S. Africa Rift • Greatly influenced geology/biology/climate

  5. Continental Drift Geographic Fit • Continents seem to fit together like pieces of a puzzle

  6. Mesozoic PaleogeographyTriassic • Laurasia and Gondwana (L. Tr) • N. America from S. America and Africa (L. Tr-E. Jr) • Tethys to Atlantic • Note location along equator

  7. Mesozoic PaleogeographyJurassic • Fragmentation of Gondwana (L. Tr & Jr) • Antarctica and Australia break off (L. Tr) • India splits and moves north

  8. Pangaea RiftingJurassic • Thick evaporites

  9. Mesozoic PaleogeographyCretaceous • S. America from Africa (begin L. Jr) • E. Tethys closes; Mediterranean prototype forms • India moves northward • Australia and Antarctica separate (end of K) • K transgression

  10. Mesozoic Ocean CirculationTriassic to Cretaceous • Evolution of oceanic circulation • Simple pattern in a single ocean • Complex in newly formed oceans

  11. N.A. PaleogeographyContinental Interior • Mostly above water; no epeiric seas • See only Zuni (E. Jr-Paleo) & Absaroka sequences

  12. N.A. PaleogeographyEastern Coastal Region • Alleghenian orogeny uplifted Appalachians • Erosion = coarse sediments • Pangaea rifting = fault block basins • Newark group (6000m), poorly sorted, non-marine (L. Tr-E. Jr) • Reptilian footprints  no dinos • Dikes & sills (Palisades) • After rifting = passive margin • Uplifted mtns. planed off • K = Appalachians uplifted

  13. N.A. PaleogeographyGulf Coast • N. America and S. America get evaporites (L. Tr) • Form salt domes; no evaporites (L. Jr) • Transgressive/regressive sea, i.e. shale, LS, sandstone • End of K transgressions • K reefs common

  14. Western N.A. Paleography • Permian arc like Japanese arc • Subduction, get arc and oceanic arc plastered to continent • Produce Sonoma Orogeny • Oc-Cont convergence, i.e. S. America after orogeny • Steep subduction (L. Tr) • Oc-Cont convergence control Meso and Ceno tectonics • Modern Circum-Pacific orogenic system born

  15. Western N.A. PaleographyTriassic • Shallow – ss-sh-ls • Regression followed • Marginal marine & non-marine • Red beds (L. Tr) • Moenkopi (L. Tr) • MS, tracks-streams, flood plains • Local marine = ls • Shinarump • Unconformably overlies Moenkopi • Erosion of exposed AZ, CO, ID • Chinle (U. Tr) • Sh, siltst, - petrified forest • Ash provides silica • Amphibians, small dinos

  16. Western North AmericaTectonic Evolution • 2 opposite-dipping SZ • Franciscan deposition – trench (M.–L. Jr) • Up to 7000 m • Greywacke, chert, sh, breccia • Blueschist

  17. Western North AmericaFranciscan • Reconstruction of the depositional environment of the Franciscan Group

  18. Western North AmericaTectonic Evolution • Great Valley Group • Shelf and slope deposition • Forearc basin

  19. Western North AmericaTectonic Evolution • Cordilleran Orogeny • Several phases • Nevada Orogeny – huge batholiths (L. Jr-K) • Sevier Orogeny – Pacific Plate subducted (K) • Laramid Orogeny – anticlines & dunes (L. K)

  20. Western N.AmericaCause of Migration • As subducting plate moved at a lower angle, the depth of melting moved to east

  21. Western N.A. PaleogeographyJurassic &Cretaceous • Clean, x-bedded SS (M. Jr) • Marine, Sundance Sea • Nevadan orogeny • Stream, lake deposits • Ms, sh = Morrison • Dinos (Jr) • Cretaceous interior seaway Jurassic Navajo SS, Zion • Big inland sea – Gulf to Arctic • Accelerated spreading

  22. Western North AmericaMicroplates • >25% from accretion of microplates • Material added to continents • Different in fossils, stratigraphy, structure, paleomagnetism • Formed elsewhere, transported along faults

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