Late Paleozoic Earth History

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Late Paleozoic Earth History
http//jan.ucc.nau.edu/rcb7/270_1st.jpg
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Early Paleozoic

• Marine conditions in North America
• Major orogenies
• Taconian orogeny in Ordovician

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Late Paleozoic

• Devonian, Carboniferous, and Permian periods
• Carbon-bearing worldwide coal deposits
• Mississippian and Pennsylvanian used only in
  North America
• Mississippian last widespread carbonates in
  North America
• Pennsylvanian coal deposits

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Paleogeography of the World

• For the Late Devonian Period

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Paleogeography of the World

• For the Early Carboniferous Period

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Paleogeography of the World

• For the Late Carboniferous Period

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Paleogeography of the World

• For the Late Permian Period

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Late Paleozoic History of North America

• The Late Paleozoic cratonic history of North
  America included
• extensive shallow-marine carbonate deposition
• large coal-forming swamps
• dry, evaporite-forming terrestrial conditions

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Devonian Period

• Paleogeography of North America during the
  Devonian Period

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Devonian Sedimentation
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Organic Reefs
http//www.holchanbelize.org/zonea.html
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Organic Reefs
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Devonian Reef
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Evaporites

• Evaporation of large volumes of water causes
  salts to precipitate
• Extensive in Silurian and Devonian

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Two Evaporite Environments

• Restricted basin
• seawater washed over bar, cannot escape
• hypersaline solution forms
• Supra-tidal
• few cm above average high tide
• occasionally flooded

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Two Evaporite Environments
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Michigan Basin

• gt1.5 km of evaporite deposits
• Rock salt, dolomite, anhydrite
• Probably a restricted basin
• Mined for plaster and chemical industry

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Michigan Basin
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Another Orogeny on East Coast

• Acadian orogeny in Devonian
• Superimposed on Taconian orogeny in same location
• Catskill clastic wedge

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Plate Tectonics and Evolution

• Lots of mountain-building in Devonian created
  significant amount of land above SL
• Coincided with evolution of land plants and
  animals

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Mississippian Period

• Paleogeography of North America during the
  Mississippian Period

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Mississippian Carbonates

• Cross-bedding, ripple marks, and well-sorted
  fossil fragments
• Indicative of a shallow-water environment
• Analogous to present-day Bahama Banks

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Pennsylvanian Period

• Paleogeography of North America during the
  Pennsylvanian Period

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Coal Swamps

• Low coastal plain swamps next to Appalachian
  Mountains
• Accumulation and burial of tons of plant material
• Modern analogs Florida Everglades, south
  Louisiana swamps

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Pennsylvanian Coal Bed

• Pennsylvanian coal bed, West Virginia
• part of a cyclothem

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The Okefenokee Swamp

• Georgia - modern coal-forming environment,
  similar to those of the Pennsylvanian

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Modern Analogues

• Modern coal-forming environments
• the Mississippi delta
• the Okefenokee Swamp, Georgia
• the Florida Everglades
• and the Dutch lowlands
• By studying these modern analogues, geologists
  can make reasonable deductions about conditions
  existing in the geologic past

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U.S. Coal Deposits

• The age of the coals in the Midwestern states and
  the

• Appalachian region are mostly Pennsyl-vanian
• Those in the west are mostly Cretaceous and
  Tertiary

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The Permian Period

• The assembly of Pangaea
• completed during the Permian
• result of the many continental collisions that
  began during the Carboniferous

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Climatic Consequences

• The formation of a single large landmass had
  climatic consequences for the continent
• Terrestrial Permian sediments indicate that arid
  and semiarid conditions were widespread over
  Pangaea

The mountain ranges were high enough to create
rain shadows that blocked the moist, subtropical,
easterly winds much as the southern Andes
Mountains do in western South America today
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Permian Period

• Paleogeography of North America during the
  Permian Period

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Early Permian

• Shallow sea still covered western United States
  and SW Texas
• Organic reef complex flourished at edge of 300 m
  deep basin
• El Capitan massive reef core

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Permian Reefs and Basins

• Location of the west Texas Permian basins and
  surrounding reefs

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Guadalupe Mountains
www.rozylowicz.com/retirement/guadalupe/guadalupe.
html
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El Capitan
Massive reef at edge of basin
www.rozylowicz.com/retirement/guadalupe/guadalupe.
html
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Permian Basin

• Prolific oil producer
• Ancient basins near reef source of organic
  material
• Deformation during Late Paleozoic provided
  trapping structures

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Also in Permian

• Widespread evaporites and red beds
• Indicate arid conditions as shallow seas
  retreated and evaporated
• More land than ever before collisions and
  mountain-building events

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How did this affect North America?

• Ancestral Rockies
• Marathon uplift of West Texas
• Ozarks and Ouachitas
• Great Smoky Mountains
• Appalachians (for the third time)

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Hydrocarbons

• Permian reefs and other strata in the western
  United States, particularly Texas,
• have also been prolific producers