120124-PT-MechanismConsilience-BR.ppt

120124-PT-MechanismConsilience-BR.ppt - 1/31/12 ca. 1915...

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Unformatted text preview: 1/31/12 ca. 1915 Fig. 3-3, p. 51 Overlaps (red) Underlaps (blue) Overlaps (red) Underlaps (blue) Is there a fit of the continents, or not? Is there a fit of the continents, or not? http://www.indiana.edu/~geol116/ 1 1/31/12 PATTERNS ? END LECTURE 12-01-19 Speed of waves depends on material being traversed. Seismic velocity of P waves. Depth Denser material transmits sound faster (higher sound velocity) 2 1/31/12 Seismic velocity of P waves. Depth Seismic velocity of P waves. Depth Why this pattern of seismic velocity? Denser material transmits sound faster (higher sound velocity) Denser material transmits sound faster (higher sound velocity) Layers of the Earth Te solid mp era tur e Partial Melting 100 - 250 km depth Depth S - waves can NOT penetrate liquids. (liquids have little shear strength) P - waves can. Aesthenosphere plastic Plastic solid What does this mean? Speed of waves depends on material. Waves slow and bend into slower material. The speed and bending of waves depends on the material the waves are travelling through. 3 1/31/12 Expected if Earth is homogeneous. Shadow zone Because materials inside the earth have variable density (and ability to transport seismic vibrations), seismic waves do not travel in straight paths, but bend. S-Waves can t travel through liquids. By measuring the bend (refraction), smart people can estimate the kind of material the waves are travelling through. LAYERS of Earth:! Gas layer; " 30 km thick; mostly N2 and O2; some H2O and Ar; trace amounts of CO2 , O3 , etc.! ATMOSPHERE! Fig. 3-7, p. 53 LAYERS of Earth:! ATMOSPHERE! Gas layer; " 30 km thick; mostly N2 and O2; some H2O and Ar; trace amounts of CO2 , O3 , etc.! ! Liquid layer ; " 4 km thick; almost pure H2O ! LAYERS of Earth:! ATMOSPHERE! Gas layer; " 30 km thick; mostly N2 and O2; some H2O and Ar; trace amounts of CO2 , O3 , etc.! HYDROSPHERE! Liquid layer ; " 4 km thick; almost pure H2O ! HYDROSPHERE! ! LITHOSPHERE! The outer layer; solid; very thin (0 to 50 km); variable composition.! 4 1/31/12 LAYERS of Earth:! ATMOSPHERE! Gas layer; ! 30 km thick; mostly N2 and O2; some H2O and Ar; trace amounts of CO2 , O3 , etc." HYDROSPHERE! Liquid layer ; ! 4 km thick; almost pure H2O ! LITHOSPHERE! The outer layer; solid; very thin (0 to 50 km); variable composition." ATMOSPHERE! Gas layer; ! 30 km thick; mostly N2 and O2; some H2O and Ar; trace amounts of CO2 , O3 , etc." HYDROSPHERE! Liquid layer ; ! 4 km thick; almost pure H2O ! LITHOSPHERE! The outer layer; solid; very thin (0 to 50 km); variable composition." ASTHENOSPHERE! Mushy (liquid) layer; ! 200 km thick; part of upper mantle." LAYERS of Earth:! MANTLE (mesosphere)! ASTHENOSPHERE! Mushy (liquid) layer; " 200 km thick; part of upper mantle.! Semi-solid; can flow (like glass); very thick layer (2900 km)! ATMOSPHERE! Gas layer; ! 30 km thick; mostly N2 and O2; some H2O and Ar; trace amounts of CO2 , O3 , etc." HYDROSPHERE! Liquid layer ; ! 4 km thick; almost pure H2O ! LITHOSPHERE! The outer layer; solid; very thin (0 to 50 km); variable composition." ASTHENOSPHERE! Mushy (liquid) layer; ! 200 km thick; part of upper mantle." MANTLE (mesosphere)! Semi-solid; can flow (like glass); very thick layer (2900 km)" LAYERS of Earth:! OUTER CORE! Liquid; iron (Fe) rich; " 2300 km thick! ATMOSPHERE! Gas layer; ! 30 km thick; mostly N2 and O2; some H2O and Ar; trace amounts of CO2 , O3 , etc." HYDROSPHERE! Liquid layer ; ! 4 km thick; almost pure H2O ! LITHOSPHERE! The outer layer; solid; very thin (0 to 50 km); variable composition." ASTHENOSPHERE! Mushy (liquid) layer; ! 200 km thick; part of upper mantle." MANTLE (mesosphere)! Semi-solid; can flow (like glass); very thick layer (2900 km)" OUTER CORE! Liquid; iron (Fe) rich; " 2300 km thick! LAYERS of Earth:! INNER CORE! Solid; Fe-rich; " 1300 km thick! Fig. 3-5, p. 52 Fig. 3-5, p. 52 5 1/31/12 Fig. 3-8, p. 54 WHY ? Fig. 3-8, p. 54 Fig. 1-8b, p. 9 Fig. 1-9, p. 10 Fig. 1-11, p. 11 6 1/31/12 Less Dense compounds residual on surface of the Earth Fig. 1-11, p. 11 Fig. 1-11, p. 11 Thicker material floats higher and has deeper roots. Possibly: but also: density of ocean crust is greater than density of continental crust. Thicker material floats higher and has deeper roots. Thicker material floats higher and has deeper roots. But: seismic velocity of ocean basin floor # continents! 7 1/31/12 Not just thicker material. More explanation is needed Thicker material floats higher and has deeper roots. density of ocean crust is greater than density of continental crust. Density" Details of upper portion of Earth Continental Crust Avg. density ! 2.8 Denser material floats lower than less dense material. Perhaps oceanic crust is denser than continental crust. Oceanic crust is both thinner and denser than continental crust. BASALT Moho GRANITE Perhaps BOTH ideas are true. Thickness and Density. Denser ocean, thicker continent. Oceanic Continental 8 1/31/12 Earth Elevations are Bimodal Land Elevation? Sediment thickness? Patterns of time? Other patterns Why? and Why ? How does it happen? Overlaps (red) Underlaps (blue) Is there a fit of the continents, or not? ca. 1915 Fig. 3-11, p. 57 9 1/31/12 Other data Nature s subtle signs . . . Are we certain? Fig. 3-11, p. 57 http://4.bp.blogspot.com/_KmeU879465A/SxPtpRQB63I/ AAAAAAAAA3I/0MsRVbDWLZQ/s400/compass.jpg Fig. 3-25a, p. 68 Garrison, 2008 Trujillo and Thurman, 2010 Trujillo and Thurman, 2010 10 1/31/12 A spinning Fe liquid around a solid iron core inside a spinning mantle and crust .. produces Earth s magnetic field. This field is not constant - it varies in strength and direction. Fluid - free to move - aligned with field Rock - frozen in place Garrison, 2008 Fig. 3-26, p. 68 Trujillo and Thurman, 2010 Magnetic particles in magma are magnetized by Earth s magnetic field. Trujillo and Thurman, 2010 Magnetic reversals in much older rocks. 11 1/31/12 ANOMALIES = caused by reversals Vine and Matthews, 1963 axis of ridge overlays (tests) Pacific Ridge Atlantic Ridge Carlsberg Ridge (Indian Ocean) Vine and Matthews, 1963 Vine and Matthews, 1963 http://www.rammfence.com/shop/images/ ring_shank_nail_m.jpg 12 1/31/12 Fig. 3-27, p. 69 Normal Magnetism Trujillo and Thurman, 2010 Trujillo and Thurman, 2010 Spreading and insertion of Magma during a REVERSED Magnetic phase Continued spreading and insertion of Magma during a NORMAL Magnetic phase Trujillo and Thurman, 2010 Trujillo and Thurman, 2010 13 1/31/12 Normal Magnetism Reversed Magnetism Normal Magnetism Trujillo and Thurman, 2010 Trujillo and Thurman, 2010 Heat Upwelling Garrison, 2008 14 1/31/12 1. 2. 3. 4. Age / Magnetic signature Elevation Sediment thickness Heat flux Trujillo and Thurman, 2010 Garrison, 2008 Fig. 4-19, p. 91 Trujillo and Thurman, 2010 15 1/31/12 Trujillo and Thurman, 2010 Trujillo and Thurman, 2010 Continental Drift (rifting) Trujillo and Thurman, 2010 Trujillo and Thurman, 2010 Thermal Convection Downwelling Garrison, 2008 younger, heated, expanded, elevated 16 1/31/12 cooling and sinking younger, heated, expanded, elevated cooling and sinking younger, heated, expanded, elevated older, cooled, denser, sinks Garrison, 2008 Convection in the Earth Composite idea of forces of plate tectonics: Push Pull Drag Trujillo and Thurman, 2010 17 1/31/12 Trujillo and Thurman, 2010 Trujillo and Thurman, 2010 Earthquakes End of Lecture 12-01-24 18 ...
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This note was uploaded on 02/15/2012 for the course GLG 244 taught by Professor Sikorski during the Spring '05 term at Miami University.

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