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GY 112: Earth History

GY 112: Earth History. Proterozoic Fossils. Agenda. Key Events of the Proterozoic Proterozoic Plate Tectonics Proterozoic Glaciation Background Proterozoic Life Forms Evidence of Proterozoic Life Factors Affecting Development of Proterozoic Life Implications of Proterozoic Info.

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GY 112: Earth History

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  1. GY 112: Earth History Proterozoic Fossils

  2. Agenda Key Events of the Proterozoic Proterozoic Plate Tectonics Proterozoic Glaciation Background Proterozoic Life Forms Evidence of Proterozoic Life Factors Affecting Development of Proterozoic Life Implications of Proterozoic Info

  3. Key Events of the Proterozoic

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  6. Key Events • 2 Supercontinent Episodes • 3 Glacial Episodes (Snowball Earth) • Change from O2 Poor to O2 Rich • 2 Major Meteor Impacts • BIFs (Major Source of Iron) • Major Copper Deposits • Evolution of Life from One Cell to Multi-Cell

  7. Proterozoic Super Continent Episodes

  8. Plate Tectonics • Wilson Cycle (3 Parts) • Opening of an Ocean Basin • Sedimentation • Closing of an Ocean Basin • Supercontinent Episodes • Rodinia: 1.6 to 1.0 bya • Columbia (Laurentia): 2.5 to 1.6 bya • Orogenic Episodes • Wopmay (Laurentia) • Keeweenewan (Laurentia) • Greenville (Rodinia)

  9. Proterozoic Glaciation

  10. Glaciation Snowball Earth (635 – 750 MA) • Marinoan (635 – 700 MA) • Sturtian (700 – 750 MA) • Huronian (2.5 – 1.6 GA)

  11. PROTEROZOIC DETAILS

  12. Background Info Proterozoic is the largest Eon of the 4 Eons (542 MA to 2.5 GA: ~ 2 Billion years old) • Consists of 3 Eras - Each is as large or larger than the entire Phanerozoic Eon. • Neoproterozoic (542 MA to 1.0 GA) • Mesoproterozoic (1.0 GA to 1.6 GA) • Paleoproterozoic (1.6 GA to 2.5 GA)

  13. Proterozoic Era Highlights Paleoproterozoic (2.5 GA to 1.6 GA ) • Evolution of Cyanobacteria (O2 Producers) • O2 Catastrophy • BIFs (Banded Iron Formations) • Huronian Glaciation • 2 Largest Impact Events in Earth’s History • South Africa – Vredefort • Ontario Canada – Sudbury Basin • Earth’s Atmosphere Changed to an O2 Environment • Columbia Supercontinent Formed

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  15. Proterozoic Era Highlights Mesoproterozoic (1.6 GA to 1.0 GA) • Red Algae • First Sexual Reproduction • Earliest Complex Multicellular Organism • Columbia Supercontinent Broken up • Rodinia Supercontinent Formed

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  17. Proterozoic Era Highlights Neoproterozoic (1.0 GA to 542 MA) • Extreme Glaciation (Snowball Earth) • Earliest Multicellular Organisms (Ediacaren) • Break-up of Rodinia Supercontinent

  18. Oxygen Catastrophy(1.6 – 2.5 bya) • Oxygen created from photosynthesis • Oxygen toxic to anaerobic organisms • Initial lag of 300 million years for free oxygen in the atmosphere • Oxygen initially combined with free iron in the oceans to form magnetite.

  19. Snowball Earth(630 – 850 mya) • Glacial Periods: Startian & Marinoan/Varanger • Causes • Reflective surface of continents • Removal of CO2 from atmosphere • Change in ocean circulation patterns • Intro of pure oxygen which converted methane into CO2 • Reduction in Organic Activity • Subsequent melting caused by emission of CO2 from volcanic activity

  20. ICE THICKNESSES

  21. Proterozoic Life Forms

  22. Proterozoic Life Forms

  23. Proterozoic Life Forms • Life Forms • Acritiarchs (Single Celled) • Ediacarens (Multi-Celled) • Evolutionary Development • From Prokaryotic to Eukaryotic • Onset of Sexual Reproduction • From Single Cell to Multi-Cell • Soft-Bodied to Shell Covering

  24. Proterozoic Life Forms • During the Archean, we saw the rise of the prokaryotes: • Small • No nucleus • DNA spread throughout the cell • Asexual reproduction • Could only be single-celled

  25. Proterozoic Life Forms • During the Proterozoic, something wonderful happens: • the rise of the eukaryotes: • Larger (>0.06 mm) • A nucleus and organelles • DNA contained within the nucleus • Sexual reproduction • Could be multi-celled (metazoans)

  26. Proterozoic Life Forms The first eukaryotes appeared around 2 GA. Archritarchs were small, single celled silica beasties that floated in the oceans (pelagic). They peaked in abundance at 750 MA and then went away… 0.1mm

  27. Proterozoic Life Forms … or did they? They might in fact be ancestors to equally small single celled organisms that are around today called dinoflaggelates. 0.1mm

  28. Proterozoic Life Forms Another big change in the Proterozoic was the appearance of the first Metazoans 5 cm

  29. Proterozoic Life Forms They are known as the Ediacarin Fauna http://www.snowballearth.org/end.html http://www.cartage.org.lb/en/themes/Sciences

  30. Proterozoic Life Forms They are known as the Ediacarin Fauna And they are found around the world http://www.snowballearth.org/end.html http://www.cartage.org.lb/en/themes/Sciences

  31. Proterozoic Life Forms What were the Ediacarins? Three major “forms” http://www.cartage.org.lb/en/themes/Sciences

  32. Proterozoic Life Forms What happened to them?

  33. Proterozoic Life Forms What happened to them? 1) a now extinct line of beasties

  34. Proterozoic Life Forms What happened to them? 1) a now extinct line of beasties 2) ancestors to living phyla Kimberella sp. http://www.ucmp.berkeley.edu/vendian/kimberella.jpg

  35. Proterozoic Life Forms What were the Ediacarins? 1) a now extinct line of beasties 2) ancestors to living phyla Dickinsonia sp.

  36. Proterozoic Life Forms Whatever they were, they “exploded” onto the scene immediately after the last Snowball Earth. http://pharyngula.org/index/science/2004/08/

  37. Evidence of Proterozoic Life

  38. Evidence of Proterozoic Life Direct Evidence Fossils Trace Fossils

  39. Evidence of Proterozoic Life Indirect Evidence BIFs (Banded Iron Formation)

  40. Factors Affecting Development of Proterozoic Life

  41. Proterozoic Fossils Severe environmental changes drives evolutionary adaptation. http://www.snowballearth.org/end.html

  42. Proterozoic Fossils Severe environmental changes drives evolutionary adaptation. We need bad things to happen in order to evolve. http://www.snowballearth.org/end.html

  43. Factors Affecting Development of Proterozoic Life Terrestrial Atmospheric Changes Climate Geography

  44. Factors Affecting Development of Proterozoic Life “Atmospheric Changes”

  45. Factors Affecting Development of Proterozoic Life “Atmospheric Changes”

  46. Factors Affecting Development of Proterozoic Life “Climatic Changes” We now recognize three major Earth phases 1) Greenhouse Earth (no continental glaciers present) 2) Icehouse Earth (continental glaciers present) 3) Snowball Earth (Frozen oceans at equator) http://www.snowballearth.org/end.html

  47. Factors Affecting Development of Proterozoic Life Extra-Terrestrial Solar Radiation Impact Events

  48. Implications of Proterozoic Info

  49. Implications of Proterozoic Info Ediacarin Evolutionary Development Diversity of Life Present Day Global Warming

  50. THE END

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