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

Paleozoic Late Middle Early 543-248 Myr

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

1. The Growth of Pangea

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

Precambrian - Rodinia Montana New York

Gondwana & Laurentia About 500 Myr

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

Cambrian Siberia Gondwana Laurentia Baltica

Ordovician

Silurian

Taconic Orogoney

Paleozoic “Clastic Wedges” of sediment form behind collision zone

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

Devonian

Mississippian

Pennsylvanian

Permain

Appalachian Mountains

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

2. The Rise and Fall of the Sea

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

Sedimentary Sequences of NA Blue = No deposition

Highs and Lows Early Devonian Late Ordovician (Tippecanoe Sequence)

Cyclothems Evidence of changing Sea Level

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

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

Evidence for Permian Climate Evaporites Evidence for Permian Climate Coal

5 Paleozoic Ice Ages 4 3 2 1

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

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

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

Mass Extinctions: Death and Destruction

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)

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

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

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

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