circulation in the solid earth & plate tectonics geos 110 lectures: earth system science chapter...
TRANSCRIPT
![Page 1: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/1.jpg)
Circulation in the Solid Earth& Plate Tectonics
Geos 110 Lectures: Earth System ScienceChapter 7: Kump et al 3rd ed.
Dr. Tark Hamilton, Camosun College
![Page 2: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/2.jpg)
Wegener’s Pangea
• Late Paleozoic (Permian – Early Jurassic)
• Supercontinent closer to S. Pole
• Permian glaciations
• Jurassic supercontinent desert
![Page 3: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/3.jpg)
Geological & Geophysical Evidence for Pangea (Continental Drift & Plate Tectonics)
• Widespread evidence for S. Hemisphere glaciation: (S.America, Africa, Antarctica, Australia & Antarctica) = Gondwanaland
• Fossil ties between separated continents: Glossopteris – giant seed ferns + Mesosaurus ~ croc
• Geological ties: belts of correlative Precambrian through Paleozoic geology: plutons, sediment basins
• Fit of Continents – especially at 2000 m isobath• Paleomagnetism, inclinations, apparent polar
wander• Now recognized to be caused by seafloor spreading
![Page 4: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/4.jpg)
Geophysical Evidence for Earth’s Interior Structure & Composition
• Earthquakes occur in Earth’s outermost 700 km of cold, brittle, rigid, lithosphere
• For the largest earthquakes, the earth “rings like a bell” and vibrates for days.
• Elastic waves reflect from and refract through internal layers with different rigidity & density
• Speed of sound in rock varies as a function of temperature, pressure and composition
• This is useful to provide internal seismic tomography
![Page 5: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/5.jpg)
Seismic Evidence for Earth’s Interior
• Big earthquakes occur on pre-existing faults• Elastic wave vibrations spread out, bounce & bend• Arrival times indicate distances, locations & physical properties
![Page 6: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/6.jpg)
Seismic P-Waves: Volume Compresses
• Elastc waves have different modes of vibration, travel & velocities• Body Waves travel through by restorably deforming it or making it
vibrate. 2 kinds: Primary – P waves and Secondary – S waves• Compressional waves (push-pull), the fastest body wave arrives 1st
• Speed increases with depth because rocks become stiffer at higher pressure than they become denser denser M = K + 4µ/3
![Page 7: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/7.jpg)
Seismic Shear S-Waves (shape deforms)
• Elastc waves have different modes of vibration, travel & velocities• Body Waves travel through by restorably deforming it or making it
vibrate. 2 kinds: Primary – P waves and Secondary – S waves• Secondary (Shear) waves side to side or up and down, 0.7 speed of P• Speed increases at a slower rate with depth than P does• Liquids have no shear strength or S waves, outer core shadow zone
![Page 8: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/8.jpg)
Seismic Tomographic Imaging of Earth• Transect
under Nam• To 2700 km
depth = base of Mantle
• Dark (blue) = fast speeds or colder
• Light (red) = slow speeds or warmer
• Image shows the last of the subducted Farallon Plate under Texas
![Page 9: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/9.jpg)
Horizontal Motion Seismograph• Anchored to bedrock or pier• The mass stands still while the
Earth moves around it• Magnet and pick up coil• Lateral motion versus time is
a wave• Now this is done digitally
except for temporary field instruments
![Page 10: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/10.jpg)
Seismic Damage: 1989 Loma Prieta Quake• October 17, 1989 RM = 6.9, San
Andreas Fault biggest since 1906
• Collapsed 2 level highway CF880 Cypress viaduct
• 68 dead, >4,000 injured
• $7,000,000,000 property damages
• To be a damaging earthquake it needs to be large >/= 6.4 and shallow
• Each number on the richter scale is X 31.66 more energy release and x 10 higher amplitude of ground motion
![Page 11: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/11.jpg)
Seismograms: 1989 Loma Prieta Quake
• Thick fill or unconsolidated sediment amplifies ground motion due to surface waves: local geology & proximity both affect amplitude
• More ground motion, more & infrastructure building damage
![Page 12: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/12.jpg)
Earth’s Composition• Carbonaceous chondrites = most primitive solar
system material: silicates, oxygen, rock forming elements, Carbon, water (oldest type of meteorite)
• The Crust + Hydrosphere + Atmosphere is enriched in light elements
• Mantle & Core are depleted in light elements and enriched in heavier and more refractory (high melting point) elements
• While layering formed early in a few hundred Ma, the inner core and crust appear to have been growing throughout Earth history
![Page 13: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/13.jpg)
Seismology & Earth’s Interior
• Concentric layers by mechanics & composition: Lithosphere: solid, strong, cold, brittle & Quakes
• UM-Partial Melt~5, LM-Plastic Solid, OC-Liquid, IC-Solid
![Page 14: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/14.jpg)
Seismology & Earth’s Interior• Lithosphere = Crust plus brittle upper Mantle ~100
km thick– Mostly Intermediate density Igneous rocks (cooled from
melts), lesser Metamorphic (strained, recrystallized in solid state) & Sedimentary in uppermost few km
• Asthenosphere- weak upper mantle below the Moho is ~95% solid ultramafic (olivine) with partial melting and low strength.– Involved in convection & melt generation of basaltic
magmas at spreading ridges & under volcanoes– Low velocity zone ~30-80 km is most active
![Page 15: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/15.jpg)
Seismology & Earth’s Interior• Lower Mantle = Mesosphere
– 660 km discontinuity to ~2900 km– Most of Earths volume. Entirely hot, plastic, solid,
ultramafic (Mg-Fe rich silicates)– Insulating, slowly convecting at ~15 cm year
• Outer Core – 100% Liquid Fe-Ni, 2900-5150 km– Will not pass shear waves, shadow zone– Convects rapidly generating internal magnetic field
• Inner Core – Solid, super high density Fe-Ni– Heterogeneous, E-W, layered, ~1 km scale variation– Growing as it cools, driving convection, spins > 1/day
![Page 16: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/16.jpg)
Magnetic Dynamo & Earth’s Interior
• Outer Core – 100% Liquid Fe-Ni, 2900-5150 km• Differences in heat, spin & composition drive convection• Flowing conductor creates circular electromagnetic field
![Page 17: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/17.jpg)
Plate Tectonics & Cycling the Solid Earth
• Ocean Basins are low -3.9 km deep & young <100 Ma• Continents are +800 m asl & old ~4 Ga, high
![Page 18: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/18.jpg)
Earth’s Geocentric Dipole Field
• Dipole: Tan (I) = 2 Tan ( λ), Surveying by compass
• Cannot tell longitude, can tell geomagnetic latitude
• Rocks get thermally or chemically magnetized
![Page 19: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/19.jpg)
Detecting & Measuring Seafloor Spreading
• Mid-Ocean Ridges ~2km deep, hot & normally magnetized• Magnetic Stripes are symmetric and a proxy crustal age
![Page 20: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/20.jpg)
Detecting & Measuring Seafloor Spreading
• Mid-Ocean Ridges ~2km deep, hot & normally magnetized• Magnetic Stripes are symmetric and a proxy crustal age• Iceland a Hotspot on a Mid ocean ridge
![Page 21: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/21.jpg)
Paleogeographic Reconstruction
• Paleogeographic Earth Reconstruction, Early Cambrian (540Ma), Dr. Ron Blakley (2010)
![Page 22: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/22.jpg)
Paleogeographic Reconstruction
• Paleogeographic Earth Reconstruction, Early Devonian (400Ma), Dr. Ron Blakley (2010)
![Page 23: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/23.jpg)
Paleogeographic Reconstruction
• Paleogeographic Earth Reconstruction, Early Permian (280Ma), Dr. Ron Blakley (2010)
![Page 24: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/24.jpg)
Paleogeographic Reconstruction
• Paleogeographic Earth Reconstruction, Tertiary – Cretaceous Boundary (65 Ma), Dr. Ron Blakley (2010)
• Inset 90 Ma Late Cretaceous Highstand
![Page 25: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/25.jpg)
Composition & Behavior of Earth’s Interior• Plate tectonic motions depend on
materials strengths & rheology (response to forces, flow)
• Continental & Ocean Crust and Mantle are compositional layers
• Lithosphere & Asthenosphere are rheological discinctions
• The Lithosphere is rigid, solid and buoyant plates on a convecting mostly solid but weak dense, ductile asthenosphere
![Page 26: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/26.jpg)
Plate Tectonics & Cycling the Solid Earth
• Ocean Crust & Continental Crust both on many plates• 7 large plates & 3-4 smaller ones
![Page 27: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/27.jpg)
Plate Tectonics & Cycling the Solid Earth
• Most Large Earthquakes > Rm 6 occur on plate boundaries
• Little strain beneath or within plates
![Page 28: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/28.jpg)
3 Types of Plate Boundaries• Mid Ocean Ridges & Continental
Rifts (divergent)
• Subduction zones: ocean crust sinks beneath a more buoyant plate margin (convergent)
• Transform Faults connect the other 2 types and segment the ridge system allowing for lateral motion and shear
![Page 29: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/29.jpg)
3 Types of Motions & Faults• Divergent Normal Faults, crust in
tension atop a heat bulge in the upper mantle.– New lithosphere is made.
• Convergent Thrust or Reverse Faults and crustal thickening plus uplift of overriding plate.– Old ocean lithosphere is recycled
• Shear Lateral motion to right or left depending on offset of ridges or subduction zones
![Page 30: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/30.jpg)
Rifts Divide Plates: Make New Ocean Lithosphere
• Slow ridges are steep and rugged, fast are wide & low
• ~1 km3 magma per km ridge per year, quakes < 6.4 Rm
![Page 31: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/31.jpg)
Trenches Collect Sediments where Old Ocean Crust Subducts
• Megathrust earthquakes > Rm 9.4, volcanic arcs, hydrothermal mineral deposits on upper plate
![Page 32: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/32.jpg)
Transform Faults Cut Mid Ocean ridges or Subduction Zones
• Megathrust earthquakes < Rm 8.8 on active segments between ridge offsets (QCFault, San Andreas)
![Page 33: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/33.jpg)
Continental Rifts in East Africa (since Cretaceous)
• Red Sea to Lake Victoria
• Cradle of Human Evolution
• Hot Springs
• Salt Deposits
• Atlantic looked like this 200 Ma ago
![Page 34: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/34.jpg)
Deep Sea Hydrothermal Vents on Ridges & Arcs
• Chemosynthetic Life Web based on S, Fe
• Larger animals eat bacteria, tube worms, clams, crabs
• Hydrothermal massive sulphide deposits: Au, Ag, Cu, Zn, Pb, Ba
• Axial Seamount Juan de Fuca, 21 North EPR, TAG, Galapagos, Kermadec Arc, Caribbean
![Page 35: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/35.jpg)
Plate Tectonics:MOR’s, Trenches & Fracture Zones
• Most Large Earthquakes > Rm 6 occur on subducting plate boundaries
• Ridge Length = Subduction Length & 3X active transform
![Page 36: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/36.jpg)
3 Types of Convergent Plate Boundaries• Ocean Subducts under Continent
(Andes, Cascades)
• Ocean Subducts under Ocean Crust (Philippine, Indonesia, Aleutians, Antilles, South Scotia)
• Continent-Continent Convergence, no Subduction (Himalayas-Urals-Appalachians)
Oceanic
Continental
7.19mislabelled in text
![Page 37: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/37.jpg)
Transform Faults Cut Mid Ocean ridges or Subduction Zones
• Sovanco FZ connects Juan de Fuca and Gorda• Mendocino FZ connects Gorda & EPR Sea of Cortez
![Page 38: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/38.jpg)
Active 2 Kinds of Continental Margins Passive
• Passive margin rifted at beginning of Wilson Cycle
• Active Margin subducting, MOR in between
![Page 39: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/39.jpg)
Mantle Convection Drives Plate Motion
• Whole mantle convection driven from heat in Outer Core, Hotspots require this at least
![Page 40: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/40.jpg)
Mantle Convection Drives Plate Motion
• 2 Layer Mantle Convection, isolated compositional layers, depleted upper mantle, more irregular
![Page 41: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/41.jpg)
Possible Forces Affecting Plate Motion
• Gravity sliding from thermal bulge under MOR
• Negative buoyancy for old ocean crust at trenches
![Page 42: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/42.jpg)
Continental Orogenic Belts & Rock Cycle
• Continents are made of older fragments that were once at plate margins
• Cycles of accretion, rifting
• Uplift, erosion, sedimentation, metamorphism, renewed igneous activity
• Oldest rocks ~4Ga seds!
![Page 43: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/43.jpg)
Rock Cycle
• Rocks and minerals & the lements which comprise them are recycled
• Mainly at Convergent margins: buoyancy, thickening, erosion etc.
![Page 44: Circulation in the Solid Earth & Plate Tectonics Geos 110 Lectures: Earth System Science Chapter 7: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ef05503460f94c00eb0/html5/thumbnails/44.jpg)
Wilson Cycle (Supercontinent Formation)
• Plates move towards Subduction Zones• Continental crust is too thick and buoyant to subduct• Continents re-collide and amalgamate every ~500Ma• Pangea broke up at 205 Ma forming Atlantic• Eventually the Pacific will dissappear (300-400 Ma)