Late Paleozoic Earth History

Chapter 11

Appalachians are built

North America is formed

Catskill Delta in NY is deposited

Coal formation is widespread

Limited transgression; reefs and basins

Supercontinent forms

Climate change occurs

• Gondwana continued moving over the South Pole

• Major glacial episodes:Late Mississippian to Early Permian

• Continental glaciers profoundly affected the world's biota

and global sea level changes

Gondwana Continental Glaciers

Continental glaciers or ice Sheets are always over land masses!

• Collisions between continents – formation of supercontinent Pangaea by the

end of the Permian, – mountain building – influenced oceanic and atmospheric

circulation patterns

• By the end of the Paleozoic, – widespread arid and semiarid conditions

had prevailed over much of Pangaea

Continental Collisions

• During the Silurian (early paleozoic), – Laurentia and Baltica collided– larger continent of Laurasia

• Northern Iapetus Ocean closed: Caledonian orogeny

• During the Devonian, – Southern Iapetus Ocean narrowed

between Laurasia and Gondwana, Acadian orogeny

The Devonian Period

• For the Late Devonian Period

Paleogeography of the World

• For the Early Carboniferous Period

Paleogeography of the World

• For the Late Carboniferous Period

Paleogeography of the World

• For the Late Permian Period

Paleogeography of the World

• The erosion of the resulting highlands from the Acadian Orogeny– provided Old Red Sandstone

– covered large areas of northern Europe

– and eastern North America• Evidence: the Catskill Delta, Scotland

and others

Evidence of Acadian Orogeny:“Old Red Sandstone”

Reddish Fluvial Sediments formed during the Devonian Age

Catskill Delta red sandstone beds are exposed in NY/PA

Old Red Sandstone in Europe

• Scotland

Catskill Delta Clastic Wedge

• The Devonian rocks of New York are among the best studied on the continent

• A cross section of the Devonian strata – clearly reflects an eastern source for the Catskill

facies • from the Acadian Highlands

• These clastic rocks can be traced – from eastern Pennsylvania,

• where the coarse clastics are approximately 3 km thick,

– to Ohio, • where the deltaic facies are only about 100 m thick • and consist of cratonic shales and carbonates

Devonian Rocks of New York

composed of – coastal parts of New England, – southern New Brunswick, – Nova Scotia, – eastern Newfoundland, – southeastern Ireland, – Wales, England, --Belgium and Northern France

**later rifting took this land to present locations

Avalonia: microcontinent on the move

Acadian Orogeny

Acadian Orogeny

Acadian Orogeny

2800 feet of sediment on eastern margin

• Marcellus ShaleDevonian marine facies

• Natural gas reserves

• Uniform global climate • reefs, • evaporites, • and red beds,

– throughout the world,

Before Pangaea….

• The advance and retreat of Gondwana’s polar glaciers – produced global changes in sea level – and affected sedimentation pattern on the

cratons

• As Gondwana moved northward– it first collided with Laurasia

• during the Early Carboniferous

– and continued suturing with it during the rest of the Carboniferous

The Carboniferous Period:Mississippian & Pennsylvanian

• The Taconic, Caledonian, and Acadian orogenies – were all part of the same Paleozoic orogenic

event – closing of the Iapetus Ocean

• Laurentia and Baltica became sutured as Laurasia

Closing of the Iapetus Ocean

• For the Early Carboniferous Period

Paleogeography of the World

• For the Late Carboniferous Period

Paleogeography of the World

• Evidence:Ouachita Mountains of Oklahoma– Late Carboniferous and Early Permian

• By the end of the Carboniferous, – the various continental landmasses were fairly

close together – as Pangaea began taking shape

Gondwana/Laurasia Collision

• For the Late Permian Period

Paleogeography of the World

• The Carboniferous coal basins of – eastern North America, – western Europe,

• all lay in the equatorial zone, – where rainfall was high and temperatures

were consistently warm

• The absence of strong seasonal growth rings – in fossil plants from these coal basins – is indicative of such a climate

Carboniferous Coal Basins

• A cyclical pattern of alternating marine and nonmarine strata– Characteristic of Pennsylvanian rocks – usually in areas of low relief

What Are Cyclothems?

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

U.S. Coal Deposits

Appalachian region are mostly Pennsyl-vanian

• whereas those in the west are mostly Cretaceous and Cenozoic

• Columnar section of a complete cyclothem

Cyclothem

• Pennsylvanian coal bed, West Virginia

• part of a cyclothem

Pennsylvanian Coal Bed

• Reconstruction of the environment of a Pennsylvanian coal-forming swamp

Coal-Forming Swamp

The Okefenokee Swamp• in Georgia, is a modern coal-forming environment, similar to those occurring during the Pennsylvanian Period

• Paleogeography of North America

during the Pennsylvanian Period

Pennsylvanian Period

• the Mississippi delta, • the Okefenokee Swamp, Georgia• the Florida Everglades, • and the Dutch lowlands

– similar to those that existed during the Pennsylvanian Period

Modern coal forming environments

The Permian

• Paleogeography of North America during the Permian Period

Permian Period

– west Texas and southern New Mexico,

• lagoonal environments,

• reef environments, • and open-shelf

environments

• Permian Basins form

Restricted Absaroka Sea

Permian Reefs and Basins

• Reconstruction Middle Permian Capitan Limestone reef environment

• brachiopods, corals, bryozoans and large glass sponges

Capitan Limestone Reef Reconstruction

• An enormous single ocean,– Panthalassa, – surrounded Pangaea and – spanned Earth from pole to pole– arid and semiarid conditions were widespread

over Pangaea

• The mountain ranges produced by – the Alleghenian, and Ouachita orogenies – created rain shadows

Pangaea Surrounded

The stage is set for Earth’s greatest mass extinction