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Asteroid belt

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Asteroid belt. Kuiper Belt and Oort Cloud. IMPACT EVENTS. Known impact craters ... Too dark to see for 1-6 months. No photosynthesis for 2 months to year ... – PowerPoint PPT presentation

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Title: Asteroid belt


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Asteroid belt
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Kuiper Belt and Oort Cloud
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IMPACT EVENTS
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Known impact craters
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http//www.lpl.arizona.edu/SIC/impact_cratering/Ch
icxulub/Animation.gif
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Barringer Meteor Crater, AZ (49,000 yrs)
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Manicouagan Crater, Canada (212 Ma)
100 km
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Clearwater Lakes, Canada(290 Ma)
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Chesapeake Bay Crater (35 Ma)
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Chicxulub Crater, Mexico(65 ma)
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Map of Cenotes
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Global Effects
  • Dust in the atmosphere
  • Too dark to see for 1-6 months
  • No photosynthesis for 2 months to year
  • Drop in land surface temperatures
  • Carbonates and evaporites vaporized into sulfur
    gases and CO2 (with resulting acid rain
  • Massive forest fires (evidenced by charcoal and
    soot deposits)

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http//www.lpl.arizona.edu/SIC/news/chicxulub2.htm
l
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Mass Extinctions
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Causes of Mass Extinction
  • Changes in seafloor spreading rates
  • Causes flooding of land
  • 110-85 Ma, sea level was over 200 m higher than
    today
  • Shallow seas doubled, land mass reduced, warmer
    climate
  • Sea level changes from glaciation

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Causes (continued)
  • Number and sizes of continents
  • More continents can generate new species
  • Less continents can cause competition for space
    and niches
  • Continental position (near or away from poles)
  • Volcanism
  • Lava can displace ocean water
  • Expels atmospheric gases
  • Ocean composition
  • Circulation changes can cause anoxic bottom water
  • Salinity changes from glacial meltwater runoff or
    excessive evaporation

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Causes (continued)
  • Extraterrestrial
  • Impact events
  • Excessive radiation (weakened magnetic field)
  • Biological
  • Random extinction
  • Predation or disease

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Permo-Triassic Extinction(250 Ma)
  • Formation of Pangaea (reducing area of tropical
    seas)
  • Sea level fall from slower seafloor spreading
    (less overall sea area)
  • Climate change (drier interior of continents)
  • Cold ocean water disappeared and no sinking for
    circulation
  • Siberian Traps flood basalts (700,000 cubic miles
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