1. The Geology of the Paleozoic Era
7% of Earth’s history
Permian
Pennsylvanian
Mississippian
Devonian
Silurian
Ordovician
Cambrian
Boundaries are changes in the fossil record
The Geology of the Paleozoic Era

2. Base of the Cambrian system
Starts at appearance of first easily visible fossils

3. Boundaries changes in fossils
Prof Adam Sedgwick (Cambridge) studied the
Cambrian (including the Ordovician) based on
superposition and structural geology.
Roderick Murchison described and mapped the Silurian based on fossils. Together they defined the Devonian System in Devon and Cornwall.
Murchison established the Permian in Russian, then returned and split up Cambrian based on fossils. Later Charles Lapworth separated out the Ordovician.

4. Paleozoic Overview
Global tectonic theme of the Paleozoic - assembly of the supercontinent, Pangaea.
Deposition due to transgressions, and erosion - disconformities due to regressions.
Transgressions caused shallow continental (epeiric) seas. Interiors of continents were frequently flooded.
Formation of mountain belts at edges: collisions with small and large landmasses
Collisions resulted in assembly of Pangaea.
Rifting raises water, moves plates, which later collide, make foreland basins, water drops

5. Paleozoic Global Geology
Six major Paleozoic continents are recognized after Rodinia breakup
Gondwana - S. continents, India
Laurentia - North America, Greenland, part Gr. Britain
Baltica – Northern Europe
Siberia – Most of Northern Asia
Kazakhstania – part Central Asia
China - All of SE Asia and SE China

6. Paleozoic Era key events
Transgression and Regressions
Extinctions:
Rifting raises water, moves plates, which later collide, make foreland basins, water drops
Assembly of
Pangea
Deep
Mass Extinction
Gondwana/Laurasia
Catskill Clastic Wedge
Continues subduction Iapetus ; South docks w/ rest of Avalonia
Old Red SS
Iapetus floor subducted ,
Laurentia and Baltica collide - Laurasia
Avalonia collides with Laurentia
Notice: 3 orogenies, 4 transgressions, 2 glaciations,
1 huge mass extinction

7. Devonian Reconstruction
High sea levels mostly due large MORs
and warm climates (no glaciers)

8. How can we reconstruct past continent positions?
Paleomagnetism Latitude
Biogeography - Distribution of flora and fauna.
Climatology - Climate sensitive sediments
Tectonic Patterns – continuation of mountains
Can’t use Magnetic Stripes on ocean floor- until 200 mya Triassic\Jurassic and later

9. Global paleogeography for the Cambrian period
All six continents occur at low paleolatitudes
Ocean waters circulate freely/ poles appear ice-free
Epeiric seas cover much of continents except Gondwana
Highlands in N Gondwana, Eastern Siberia, Central Kazakhistan
NOTE:
Siberia - Russia (E of Urals), Part Asia
Kazakhstania - Kazakhstan
China - All of SE Asia and SE China
Gondwana - S. continents, India
Six major Paleozoic continents are recognized after Rodinia breakup
Laurentia - North America, Greenland, Scotland Rotated 90o
Baltica - Russia (W of Urals), Scandinavia

10. Ordovician - Silurian SILURIAN Silurian collision of Baltica/Laurentia
Caledonian Orogeny, suturing forms Laurasia
ORDOVICIAN
Ordovician Gondwana moved 40o S to a South Pole location (Glaciers formed, we find L. Ord. tillites)
Baltica moved S, then N
Microcontinent & Island Arcs collided with Laurentia (led to Taconic Orogeny) narrowing Iapetus

11. L. Ordovician biogeography of Carolinites genacinaca
How do we know?
L. Ordovician biogeography of Carolinites genacinaca
Confirms paleomagnetic latitudes
From McCormick & Fortey J. Paleontol. 73(2): )
Trilobite Paleogeography

12. Global paleogeography Mid Ordovician to Silurian
Siberia moved from equatorial
to northern temperate latitudes
Small piece of Avalonia hits in Ordovician
Baltica moved S, then N
and collided with Laurentia. Note rotated 30o
Gondwana moved 40o S to a
South Pole location (Late Ord. tillites)

13. http://www.geodynamics.no/Platemotions/500-400 M. Ordovician
Saucrorthis
Mostly distinct faunas
Continents were not close
Note land at South Pole

14. Devonian Acadian Orogeny in the Appalachians
Other orogenies: Antler (W. N.Am. Cordillera) and Ellesmere (north margin of Laurentia)
Gondwana moves to higher southern latitudes. All other continents at low northern latitudes.

15. Paleogeography Early Devonian
Continued collision of Baltica/Laurentia formed Laurasia, closed Iapetus Ocean
Caledonian Orogeny in B/L finishes E. Dev
Acadian Orogeny in the Appalachians
folds older rocks M. Dev.
Antler
Caledonian
Acadian
Other orogenies: Antler (Cordillera) and Ellesmere (north margin of Laurentia)
Gondwana moves to higher southern latitudes.
All other continents at low northern latitudes.

16. Oklahoma and Morocco Trilobites from the Devonian
Looks like Oklahoma was close to Morocco
Dalmanitidae
Reedops
Devonian Faunal Similarities: CONTINENTS CLOSE
Dicranurus

17. Final Assembly of Pangea
Permian – Kazakhstania collided with Baltica, forming the Urals
Single continent surrounded by Panthalassa Ocean w Tethys Sea
________________________________________
Pennsylvanian – Siberia collided with Kazakhstania, forming Altai Mts.
Laurasia collides with Gondwana to reform Appalachians and to form Hercynian Mts. in Late Paleozoic. Hercynian collision forms Europe

18. Gondwana – Laurasia collision Hercynian and Allegheny Orogenies
North and South Europe suture
Hercynian Orogeny continuous w Allegheny Orogeny about 300 mya

19. Final Assembly of Pangaea
After the suturing of Gondwana and Laurasia (includes Hercynian and Allegheny Orogenies),
Then:
Siberia collided with Kazakhstania in the Pennsylvanian, forming the Altai Mountains.
Kazakhstania collided with Baltica in the Permian, forming the Ural Mountains.

20. Paleogeography Late Permian
Hercynian
N Eur-S Eur
Allegheny Orogeny

21. Tectonic Details That’s the overview
Now let’s look in more detail at the collision, i.e. orogenies
Angular Unconformity between Martinsburg Fm (mid-Ordovician, folded by Taconic) and overlying Shawangunk Fm (Silurian, folded by Acadian and Allegheny Orogenies)

22. Paleozoic Era key events
Next let’s look closer at the Orogenies
Rifting raises water, moves plates, which later collide, make foreland basins, water drops
Assembly of
Pangea
Gondwana/Laurasia
Catskill Clastic Wedge
Continues subd Iapetus South docks rest Avalonia
Old Red SS
Iapetus floor subducted Scotl Scan NE Can
Lauentia and Baltica collide - Laurasia
Avalonia collides with Laurentia

23. Tectonics Paleozoic North America
In the Cambrian, several small terranes lay to the south of Laurentia as it separated from Baltica. The shores were passive margins.
In the Ordovician, beginning about 500 mya, the direction of plate motion reversed and Iapetus began to close.

24. Global paleogeography for the Cambrian period
Avalonia Terranes

25. Development of the Taconic Orogeny
Rodinia breaking up
Avalonia Terrane E. Cambrian
Plates reverse, in E. Ordovician
Laurentia moves toward Avalonia
Africa moves toward both

26. Taconic orogeny (cont)
Mid – L. Ordovician, N.Avalonia
and an island arc dock with
Laurentia, beginning the
Appalachians
Rocks thrust up over margin of Laurentia

27. Interior of Laurentia, Ord.-Silurian
Inland, the Taconic collisions caused the crust to be warped down, forming the Appalachian FORELAND BASIN
Deep water sediments were deposited in the basin, until sediments eroded from the Taconic mountains filled the basin, and shallow water deposits prevailed.
The Queenston Clastic Wedge filled the foreland basin. We saw the Shawangunk and High Falls – Bloomsburg Formations at the Delaware Water Gap.

28. Cambrian paleogeography
Pre –collisions
Note equator

29. Paleogeography N. Am. M Ord-Sil.
Post collisions
Queenston Clastic Wedge
Barrier Reefs Highstand
Evaporites Lowstand

30. Queenston clastic wedge
Hardyston Fm
downfolded
(Martinsburg Shale)
(Allentown Dolo., Jacksonburg Ls.)

31. The Caledonian Orogeny
Baltica sutured onto Laurentia
Mountains - Nova Scotia to Scandinavia
Erosion resulted clastic wedge
Devonian Old Red Sandstone
Result called Laurasia

32. Late Silurian - Early Devonian Caledonian Orogeny-Laurasia forms
Baltica sutured onto Laurentia
To our North

33. The Acadian Orogeny Continued subduction of Iapetus ocean floor
in Devonian
Additional parts of Avalonia docked with Laurentia
Re-folding of Old Mountains – Virginia to Maritimes
Old rocks even more folded and metamorphosed
Erosion resulted in Catskill clastic wedge
Facies change in foreland basin – shallow marine to streams in Middle Devonian as basin fills
Field trip Marcellus to Mahantango => Centerfield Reef
Catskill delta as basin filled

34. Early - Mid Devonian Acadian Orogeny-Laurasia forms
Southern Avalonia into Laurasia

35. Accreted terranes (Does this remind you of somewhere else?)

36. Late Devonian paleogeography of North America

37. Catskill Formation
Clastic Wedge from Acadian collision w rest of Avalonia
E-Mid Devonian docking, folding.
By L. Dev. filled, mostly stream deposits, floodplains have fossils of land plants and amphibians
Oxidation state of Iron depended on oxygen levels

38. Catskill clastic wedge thickness
Coarse near source
Wedge thins away

39. Clastic Wedges fill Foreland Basins
Highlands source of sediment

40. BIG Collision with Gondwana The Allegheny Orogeny
Initial contact Late Mississippian
Northwest Africa collided
Folding of Pennsylvanian rocks proves long duration
Deformation much more extensive than the Taconic or Acadian – New York to Alabama

41. Physiographic provinces Appalachians
Piedmont Province: at collision suture, very metamorphosed and intruded
Blue Ridge: Grenvillian rocks thrust toward craton.
Valley and Ridge: northwest thrust faults and northeast anticlines and synclines
Thin-skinned tectonics platform rx folded more than basement. Resistant Ridges
Plateau: little deformation

42. Allegheny and Ouachita Orogenies
Hercynian
Allegheny
Ouchita

43. Antler Orogeny
In the Devonian, a westward dipping subduction zone formed off Western Laurasia.An Island Arc formed, the Klamath Arc,ocean floor subducted as the arc approached and collided with the continent
Late Devonian to Early Mississippian, Basin thrust East
Klamath Mts. and North Sierra Nevada
Antler Mts. are folded basin sediments, Devonian and Mississippian
This is the beginning of Cordillera Construction

44. Late Devonian paleogeography of North America
Here it is

45. Paleozoic structure of the West
Exposed granite eroded as arkoses
(feldspar rich sandstones)
Late Paleozoic also saw the
beginnings of the Rockies
Devonian – Ouachita Orogeny creates compressional stress
Pennsylvanian – blocks push up along high angle faults, relieving the stress. PreCambrian basement exposed.
Resulted in Front Range Uplift CO & WY
Uncompahgre Uplift CO & NM

46. Pennsylvanian arkose, CO
Fountain Arkose, CO, deposited
northeast of Front Range Uplift

47. Next: Cratonic Sequences
Laurence Sloss: Major transgressive-regressive cycles
4 in Paleozoic
Allow long range correlation “Sequence Stratigraphy”
Transgression: nearshore sand covered by muds and/or carbonates
Regression:
Nearshore: erosion and disconformity
Far offshore: sediments coarsening upward

48. Paleozoic Era key events
Transgression and Regressions
Rifting raises water, moves plates, which later collide, make foreland basins, water drops
Assembly of
Pangea
Low
High
ABS: Sea level rise (cyclic) due Gondwana glaciation Penn-Pm regression due
slowdown spreading, assembly of Pangaea, drained continent L Pm
KS: filling in of the Appalachian foreland basin by Late Devonian time
TC: glacial melting and accelerated sea-floor spreading
Sauk: High rates of sea-floor spreading

49. Cambrian – E Ord Sauk Sequence
Pre-collision, dramatic transgression due active MORs
Note extensive shallow carbonates and equator

50. Time-transgressive Cambrian rocks Grand Canyon
Sauk Sequence
WEST
EAST
Transgression
Middle
Cambrian
Lower
Cambrian
Note how western BAS is older than eastern BAS

51. Tippecanoe Transgression M Ord-Sil.
Reworking of Sauk sands gives pure sands
useful in glass manufacture.
Sands covered by carbonates
as transgression advances
Michigan Basin surrounded by reefs
Restricted circulation caused
evaporite precipitation
Source of Rock Salt
About 5 smaller T-R Pulses

52. Late Devonian Kaskasia Transgression
Carbonates over pure sands
Williston Basin surrounded by reefs
Restricted circulation caused
evaporite precipitation

53. Absoroka Sequence Transgression starts M Pennsylvanian
Regression starts L Pennsylvanian
Cyclothems Reflect Glacial sea-level var.
PERMIAN
Inland sea limited to w Texas & s NM
Extensive evaporite deposits KS – OK
Redbeds over interior

54. Paleozoic Era key events
Climate/Sedimentation
Rifting raises water, moves plates, which later collide and fold. Folding makes deep basin. If fold basin sediments, uplift.
Assembly of
Pangea

55. Next: Paleozoic Climates
Paleozoic mostly warm, but two glacial times, Ordovician and Pennsylvanian to Late Permian.
Cool Middle Ordovician
CO2 tied up in carbonates – less greenhouse
Extensive Gondwana tillites and striations
Sea level retreats as glacier holds water

56. Late Paleozoic Climates
Cool Pennsylvanian – M Permian
CO2 tied up in carbonates
Extensive Gondwana tillites and striations – sea-level fluctuations due glacial (slow regression) and interglacial (fast melt) “cyclothems”
Generated Coal deposits, carbon reservoirs, low CO2

57. Glacial Abrasion in Bedrock
Source: Tom Bean

58. Pennsylvanian Glacier -Gondwana
Sea-level falls/rises as glaciers grow/melt

59. Pennsylvanian Cyclothems
Rapid transgressions cover swamp as ice melts
Coal Swamp
swamp
estuary
Slow regression as ice sheet grows

60. Coal formation Pennsylvania cyclothems
Highland source to east

61. Pennsylvanian-age coal deposits

62. Late Paleozoic Climates - 2
(2) The Late Permian WARM
Pangaea was ice-free
Warm equatorial waters from the Panthalassa Ocean reached both poles.
No glaciers = no coal (need rapid transgression due glacial melting)
The Gondwana landmass had drifted north into warmer climates.
reduced coal formation caused carbon dioxide levels to rise
Greenhouse effect

63. L. Permian Pangaea Ice-free, dry interiors, no coal
Much of land +/- 30 degrees
Hot, dry climate
Note evaporites
Pangaea is assembled, sea-level low

64. PERMIAN N. America Inland sea limited to w Texas & s NM
Extensive evaporite deposits KS – OK
Redbeds over interior – strong seasons