Plate Tectonics: Understanding the Formation of Mountains and Ocean Basins, Exams of Geology

Download Plate Tectonics: Understanding the Formation of Mountains and Ocean Basins and more Exams Geology in PDF only on Docsity! 1 Plate Tectonics GEOL 101 Lecture 22 Prop: Test 3 Invitations The Grand Tetons, Wyoming How Are Mountains Built? First a Brief Review of Sea Floor Spreading Break-Up of a Continent and Origin of an Ocean Basin Spread Centers Feed Subduction Zones 2 Missing Mechanisms for Continental Drift: Sea Floor Spreading & Subduction Continents are Passive “Boats” Subduction Zones: Ocean-Ocean Margin Subduction Zones: Ocean-Continent Margin 5 Continental Lithosphere Will NOT Flush Down Subduction Zones Orogeny Folds Rocks Review: New Lithosphere (Crust + Upper Mantle) is Created at Spread Centers, Consumed at Subduction Zones 6 What About Offsets in Spread Centers? Transform Faults & Fracture Zones Transform Faults 7 San Andreas Fault: Right-Lateral Transform Fault Left-Lateral Offset!! Why?: Fault is Produced by Offset, vs. Offset Produced by Fault Plate Margins: • Spread Centers (Mid-Ocean Ridges) • Subduction Zones (Trenches) • Transform Faults Plate Margins: Trench suction +_ Mantle Plumes Depth (km) Mantle Plumes Under Continents Se cals on uplift 10 11 • Known “Hot Spots” Hawaiian Islands Mantle Plumes - Hot Spots • Numbers = Age of Rock in Millions of Years 12 Sinking of Cool, Dense Plates Seamount Volcanoes Surrounded by Fringing Coral Reefs NASA Atolls: Submerged Volcanos Support Reefs Only in Warm Clear Seas Tuamoto Islands Piedmont Arc Carolina Arc \% | _risiandares. 3 | Ancestal atantc “> ~e A Cambrian North Piedmoat Carolina Arc ametican cenrane\ 5 \32 ancestal attic aitea a = B _Ordovician-Sillutian (Taconic Orogen North Piedmont Carclira America cerrare terrane craton : ‘ics C Devonian-Mi sits ippi (Acadian Orogeny) North piocrron: Carolina American jerane terrane cra ‘Ancestral Atlantic trea c Devonian-Mis¢esippi (Acadian Orogeny) Piedmont Carolina alleghenan lerane terrane suture ‘Altica D Pennsyl.-Permian (Alleghenian Orogeny) Future site of atlantic ‘Alleghanian North Arveri suue E Triassic 15 16 Source: http://vishnu.glg.nau. edu/rcb/ WVU WVU Source: http://vishnu.glg.nau. edu/rcb/ WVU Source: http://vishnu.glg.nau. edu/rcb/ WVU 17 Source: http://vishnu.glg.nau. edu/rcb/ WVU Source: http://vishnu.glg.nau. edu/rcb/ Taconic Orogeny Continent-Arc Collision WVU Orogeny: Eastern N. Amer. “Mirror” Image of West Coast 20 Source: http://vishnu.glg.nau. edu/rcb/ Alleghenian Orogeny Continent-Continent Collision WVU Allegehenian Orogeny Folded Appalachian Rocks “Mirror” Image of West Coast Source: http://vishnu.glg.nau. edu/rcb/Penn.jpg Pangaea = Gondwanaland + Laurasia 21 Source: http://vishnu.glg.nau. edu/rcb/ Alleghenian Orogeny WVU Source: http://vishnu.glg.nau. edu/rcb/Perm.jpg Pangaea = Gondwanaland + Laurasia Ice Sheet Erosion and Isostatic Uplift of the Appalachians Since End of Alleghenian Orogeny 22 Laurasia Gondwanaland Source: http://vishnu.glg.nau.edu/rcb/160_1st.jpg WVU Source: http://vishnu.glg.nau. edu/rcb/ WVU Source: http://vishnu.glg.nau. edu/rcb/ WVU