1. PLATE TECTONICS A Summary & Review GEOL 1033 Lecture ppt file 103-19) (Lesson 21)

2. PANGAEA - about 250 Ma ago CONTINENTAL DRIFT THEORY: Wegener, 1915 Pangaea: –Laurasia –Gondwanaland evidence: –geographic fits, similar rocks, similar ages, similar structures, similar fossils, similar climates, similar ancient environments

4. Bullard's STATISTICAL CONTINENTAL FIT 95% fit is excellent

5. basins structures ages

6. DISTRIBUTION OF CONTINENTAL FOSSILS Glossopteris flora of southern hemisphere Reptile fossils of the southern hemisphere

7. ANCIENT GLACIATIONS Glacial deposits of southern hemisphere match

8. WEGENER'S BREAKUP OF PANGAEA Pangaea began to rift & drift apart about 200 Ma ago Note India

9. OCEANOGRAPHY of 1960’s supported continental evidence for drift theory: –Seafloor topography –Deep-sea sediments –Micropaleontology –Paleooceanography –Seafloor spreading –Plate tectonics

10. MODEL OF THE SOUTHERN ATLANTIC Seafloor topography became much better understood

11. PALEOMAGNETISM OF THE OCEAN BASINS Interpretation of magnetic polar reversals: –Confirms seafloor spreading –Dates ocean basins

12. TRANSFORM BOUNDARIES DISCOVERED Active: British Columbia Southern California (Passive: Southern Margin of Grand Banks) Leading edge continental margins In addition to divergent and convergent zones.

13. UNDERSTANDING OF THE TRENCH REGIONS OF THE WORLD Leading Edge Continental Margins

14. Deep-Sea Trenches & their plate tectonic significance Subduction zones

15. OVERVIEW OF PLATE TECTONIC PROCESSES Converging zone Diverging zone

16. Transform faults offseting oceanic ridge axis oceanic ridge Diverging Zone “ocean to ocean” Converging Zone “ocean to continent” Converging Zone

17. DRIVING MECHANISM for PLATE TECTONICS is THERMAL CONVECTION in EARTH'S INTERIOR

18. FORMATION OF SEAMOUNTS & TABLEMOUNTS Thermal contraction of lithosphere once seafloor spreads away from heat source results in subsidence of older seafloor far from spreading ridge

19. SUBSIDENCE OF SEAFLOOR WITH AGE Topographic data plotted with theoretical models

20. BASAL SEDIMENT AGES Base of sediments above basalt increase in age away from spreading ridge Core studies confirmed seafloor spreading

21. FUTURE OF SOUTH ATLANTIC South America & Africa will continue to separate

22. LITHOSPHERIC PLATE BOUNDARIES 1) Spreading centers (=divergence zones) –Ridges & rises of ocean floors –Shallow earthquakes –Volcanism –New lithosphere formation –2 kinds: Oceanic & continental 2) Transform faults –Lateral translation & shear –Two kinds: active & passive –Some volcanism (active vs. passive) –Shallow earthquakes (active vs. passive) 3) Converging zones –Shallow to deep earthquakes –Subduction & trenches –Volcanism & magmatic arcs ( volcanic island arcs & volcanic mountain belts ) –Mountain-building –Metamorphism –Plate collisions (3 kinds)

23. 2 KINDS OF Diverging Zones Oceanic –New Gulf of Aden Red Sea rift Gulf of California –Mature Mid-Atlantic Ridge East pacific rise Juan de Fuca Ridge Carlsburg Ridge Continental –East African Rift Valley system –Mesozoic (Triassic-Jurassic) basins of eastern North America

24. 3 KINDS OF PLATE COLLISIONS 3 kinds of lithospheric plate collisions –a) Oceanic to oceanic ( western Pacific examples ) –b) Oceanic to continental ( eastern Pacific examples ) –c) Continental to continental ( India colliding with southern Asia )

25. PLATE TECTONIC CLASSIFICATION OF CONTINENTAL MARGINS 1) TRAILING EDGE = divergent = passive = aseismic = Atlantic 2) LEADING EDGE = convergent = active = seismic = Pacific 3) TRANSFORM FAULT = translational – Occur along: trailing edge continental margins and leading edge continental margins – There are two kinds: active passive

26. Leading Edge Continental Margin Trailing Edge Continental Margin “head” “tail”

27. DISTRIBUTION OF PASSIVE CONTINENTAL MARGINS Trailing Edge Continental Margins

28. FEATURES OF PASSIVE CONTINENTAL MARGINS sediments

29. Eastern North America is a trailing edge continental margin

30. WESTERN CANADA HAS A COLLISION/TRANSFORM BOUNDARY Northern British Columbia: Active transform fault Southern British Columbia: Leading edge continental margin

31. END OF FILE

33. READING ASSIGNMENTS - Revised 26 Oct., 2003 7th Edition, 2003, Sverdrup & others, pages correspond to lesson topics in the Study Guide: –Lesson 1page 2 –Lesson 2p. 29-38, 45-51 –Lesson 8p. 54-59(Q7 assigned) –Lesson 3p. 38-42(E3 assigned) –Lesson 4p. 2-21, 24-26(Q3 assigned) –Lesson 5p. 40-45; 3(bottom+fig)-4(fig); 259(bottom)-260(top)(Q4 assigned) –Lesson 6p. 42-45, 87-89, 364(gases) –Lesson 7p. 99-101(top),108-109,143-144(sound),120(bottom)-124 (Q6 assigned) –Lesson 9 p. 62-63, 101(bathymetry)-112(fig) –Lesson 10 p. “ “ “ “ –Lesson 11 p. “ “ “ “ (Q9 assigned) –Lesson 12 p. “ “ “ “, 107(fig+bottom)-110(top), 464-465 –Lesson 13 p. “ “ “ “ –Lesson 14 p. 112(sediments)-127 (Q11 assigned) –Lesson 15 p. 393-413 –Lesson 37 p. 393-413, 374-379 (Q27 assigned) –Lesson 16 p. 53-61, 65 (E9 assigned) –Lesson 17 p. 64(fig), 66, 73-75, 127(Min Dep), 87, 90-96, 468-469 –Lesson 18 p. 71-79, 81(hot spots)-83 –Lesson 19 p. 64-71 –Lesson 20 “ “ “ –Lesson 21 p. 83-86, 95-96 (Q13 assigned) 6 th edition, (2000), or 5 th edition, (1997) may be used. Ask for handout for pages to be studied. Test #1 Test #2