1. The Geology of the Paleozoic Era

2. The Paleozoic Era.
Geologic periods in Paleozoic record 7% of Earth’s history
Cambrian, Ordovician, Silurian, Devonian Carboniferous (Miss., Penn.) Permian
Boundaries in the major divisions originally defined by changes in the fossil record
Start of the Paleozoic used to be defined by appearance of first easily visible fossils; later lowered to include small shelly fauna; then lowered further to first appearance of complex branching trace fossils.

3. Base of the Cambrian system
Trace fossil Phycodes pedum
New modes of locomotion

4. Welsh Lower Paleozoic 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 Sedgwick and Murchison defined the Devonian System in Devon and Cornwall.
Murchison established the Permian in Russian.
Charles Lapworth separated the Ordovician.
Review: Origin of names

5. Paleozoic Overview
Global tectonic theme of the Paleozoic - assembly of the supercontinent, Pangaea.
Deposition due to transgressions (and disconformities due regressions) of shallow continental (epeiric) seas. Interiors of continents were frequently flooded.
Formation of mountain belts at edges
Tectonic activities associated with the assembly of Pangaea.

6. 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

7. Paleozoic Era key events
Transgression and Regressions
Extinctions:
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

8. Paleogeographic Reconstructions and Maps
Geologists want to create maps of the Earth as it was in the past,
correctly position the continents for different time periods, and
reconstruct geography on the continents.

9. What data are used to do this as accurately as possible?
Paleomagnetism Latitude
Biogeography - Distribution of flora and fauna.
Climatology - Climate sensitive sediments
Glacial drift, desert pavement, laterite soils, etc.
Tectonic Patterns – continuation of mountains
Can’t use Magnetic Stripes on ocean floor- Mesozoic and later

10. 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
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

11. 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
Avalonia collided with Laurentia (Taconic Orogeny)

12. How do we check our paleolatitude data?
L. Ordovician biogeography of Carolinites genacinaca
Confirms paleomagnetic latitudes
From McCormick & Fortey J. Paleontol. 73(2): )
Trilobite Paleogeography

13. 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, rotated 30o
Gondwana moved South , land in south high latitudes(Late Ord. tillites)

14. http://www.geodynamics.no/Platemotions/500-400 M. Ordovician
Saucrorthis
Mostly distinct faunas
Continents were not close

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

16. How close were Laurasia = Euramerica and Gondwana in the Late Devonian?
Euramerica is Laurentia plus Baltica
Dalmanitidae
Looks like Oklahoma was close to Morocco
Reedops
Dicranurus
Late Devonian Faunal Similarities

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 orogeny
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. Paleozoic Era key events
Next let’s look closer at the Collisional Mountains
Rifting raises water, moves plates, which later collide.
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

22. 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, about 500 mya, the direction of plate motion reversed and Iapetus began to close.

23. Global paleogeography for the Cambrian period
Avalonia Terranes

24. The Taconic orogeny Rodinia breaking up Avalonia Terrane E. Cambrian
Plates reverse, in E. Ordovician
Laurentia moves toward Avalonia
Africa moves toward both

25. 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

26. Cambrian paleogeography
Submerged
Pre –collisions
Note equator
Submerged
Submerged
Submerged

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.

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

29. Queenston clastic wedge
(Martinsburg Shale)
Hardyston Fm
downfolded
(Allentown Dm., Jacksonburg Ls.)

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

31. Late Silurian - Early Devonian Caledonian Orogeny-Laurasia forms
To our North

32. The Acadian Orogeny Continued subduction of Iapetus ocean floor
in Devonian
Additional parts of Avalonia docked with Laurentia
Erosion resulted Catskill clastic wedge
Facies change in foreland basin – shallow marine to streams in Middle Devonian as basin fills
Field trip fossil collecting Marcellus to Mahantango Centerfield Reef

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

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

35. Late Devonian paleogeography of North America

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

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

38. Carboniferous 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 England to Alabama

39. Physiographic provinces Appalachians
little deformation
at collision suture, very metamorphosed and intruded
Northwest thrust faults and northeast anticlines and synclines
Grenvillian rocks thrust cratonward

40. Allegheny and Ouachita Orogenies
Hercynian
Allegheny
Allegheny hit by Africa
Ouchita
Ouchita hit by South America

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

42. Late Devonian paleogeography of North America
Here it is

43. Paleozoic structure of the West
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
Exposed granite eroded as arkoses (feldspar-rich sandstones)

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

45. 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 “fining upward”
Regression:
Nearshore: erosion and disconformity
Far offshore: sediments “coarsening upward”

46. Paleozoic Era key events
Transgression and Regressions
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

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

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

49. 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

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

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

52. 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

53. Next: Paleozoic Climates
Paleozoic mostly warm, but two glacial times, Ordovician and Pennsylvanian to Late Permian.
Cool Middle Ordovician
CO2 tied up in carbonates – no greenhouse
Extensive Gondwana tillites and striations
Sea level retreats as glacier holds water

54. 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

55. Pennsylvanian Glacier -Gondwana
Sea-level falls as glaciers grow, inland seas retreat

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

57. Coal formation Pennsylvania cyclothems
Melting glacier
Highland source to east

58. Pennsylvanian-age coal deposits

59. 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)
The Gondwana landmass had drifted north into warmer climates.
reduced coal formation caused carbon dioxide levels to rise
Greenhouse effect

60. 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

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

62. Next Time A survey of Paleozoic Life, and
Latest Permian Mass Extinction
Most profound in history of life.