1. Floods, Glaciers, and The Birth of Pangea
Paleozoic Geology
Floods, Glaciers, and
The Birth of Pangea

2. Paleozoic
Late
Middle
Early
Myr

3. Key Events of the Paleozoic
Six major continents formed by the breakup of Rodinia converge to form Pangea
Sea Level rose to cover large sections of the continents four times
Two major Ice Ages chilled the planet
Life diversified and moved to the land, but was also “set back” by three major extinctions

4. 1. The Growth of Pangea

5. Important Continents & Terrains, & Oceans of the Paleozoic
Laurentia - North America
Baltica - Europe
Laurasia - formed by combination of Laurentia and Baltica
Siberia - Siberia
Gondwana - Africa, S. America, India, Ausralia, Antarctica
Pangea - late Paleozoic supercontinent
Taconic Arc - Volcanic Arc in the Iapetus Ocean
Avalonia - Microcontinent including England
Panthalasia Ocean - pre-Pacific Ocean
Iapetus Ocean - pre-Atlantic Ocean

6. Precambrian - Rodinia
Montana
New York

7. Gondwana & Laurentia
About 500 Myr

8. Map Symbols Trench (Subduction Zone) Spreading Center (Divergent Zone)
Orogony
(Collision Zone)

9. Cambrian
Siberia
Gondwana
Laurentia
Baltica

10. Ordovician

11. Silurian

12. Taconic Orogoney

14. Paleozoic “Clastic Wedges” of sediment form behind collision zone

15. Upper Ordovician Clastic Wedge
Why does a deep basin form?
Isostasy

16. Devonian

17. Mississippian

18. Pennsylvanian

19. Permain

20. Appalachian Mountains

21. Important Paleozoic Orogenies
Orogeny
Age
What collided
Taconic
Sil.
Taconic Arc with Larentia
Caledonian
Dev
Larentia with Baltica (forming Laurasia)
Acadian
Dev.
Avalonian Terrane with Laurasia
Ural
Penn.
Siberia with Baltica
Hercynian
European part of Laurasia with Gondwana
Alleganian
Penn/
Perm
N. part of Laurasia with Gondwana (forming Pangea)
Ouachita
Southern part of Laurasia with Gondwana

22. 2. The Rise and Fall of the Sea

23. “The Sea Come In, the Sea Goes Out”4 3 2
Transgression Regression 1

24. Sedimentary Sequences of NA
Blue = No deposition

25. Highs and Lows
Early Devonian
Late Ordovician
(Tippecanoe Sequence)

26. Cyclothems
Evidence of changing
Sea Level

27. Causes of Sea Level Change
Local Sea Level Change
Local Tectonic Movement
Global (Eustatic) Sea Level Change
Ice Ages (water is trapped in ice)
Rate of plate divergence at mid-ocean ridges

28. 3. Changing Climate Evidence for Climate Change
Rocks - Tillites, evaporites, coal, carbonates, etc.
Fossils - Different species live in different climates
Warning - What else could rocks & fossils record?
Movement of plates

29. Evidence for Permian Climate
Evaporites
Evidence for Permian Climate
Coal

30. 5
Paleozoic Ice Ages 4 3 2 1

31. Causes of Ice Ages
Changes in the balance between how much heat the Earth and how much it loses
How heat is distributed on the Earth

32. What Causes Ice Ages Changes in Position of the Continents
Polar continents = place to make glaciers
Restricted ocean basins = colder
Changes in Sea Level
Higher = more shallow water = hotter
Mountain ranges / timing of Orogenies
Mountian growth = colder
Change in Atmospheric Chemistry
Greenhouse gases = hotter

33. By the Permian it got hot & stayed that way for a while
Evaporites
By the Permian it got hot & stayed that way for a while
Coal

34. Mass Extinctions: Death and Destruction

35. The Five Big Extinctions
When (End of…)
Species Loss**
Major Loses to
Ordovician
85 ±3%
Brachiopods & bryozoans
Devonian
83 ± 4%
Rugose & tabulate corals, armored* & jawless fish
Permian
95 ± 2%
All life! - Trilobites*, corals*, blastoids*
Triassic
80 ± 4%
Most synapsids
Cretaceous
76 ± 5%
Dinosaurs, marine reptiles, ammonites
*Went extinct, **From Jablonski (1991,1995)

36. Causes of Mass Extinctions
Major environmental change - to fast for species to adapt
Such as:
Meteorite impacts
Massive global eruptions
Rapid climate change
Major sea level fluctuations

37. Paleozoic Causes: Leading Hypotheses
Ordovician - related to ice ages?
-lowering sea level
-cooling climate
Devonian -related to the buildup of land plants
-ultimately creating anoxic conditions in the ocean
Permian - Formation of Pangea
-loss of shallow marine environment
-climate change
-Massive volcanic eruptions
-Comet impact

38. Survivors set the stage for the next “Age”
Adaptive Radiation

39. Key Events of the Paleozoic
Six major continents formed by the breakup of Rodinia converge to form Pangea
Sea Level rose to cover large sections of the continents four times
Two major Ice Ages chilled the planet
Life diversified and moved to the land, but was also “set back” by three major extinctions