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

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

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.

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

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

Paleozoic Era key events Transgression and Regressions Extinctions: http://www.fmnh.helsinki.fi/users/haaramo/Meteor_Impacts/Middle_Paleozoic_impacts.htm 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

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

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

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

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

L. Ordovician biogeography of Carolinites genacinaca How do we know? L. Ordovician biogeography of Carolinites genacinaca Confirms paleomagnetic latitudes From McCormick & Fortey 1999. J. Paleontol. 73(2):202-18.) Trilobite Paleogeography

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)

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

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.

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.

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

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

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

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.

Paleogeography Late Permian Hercynian N Eur-S Eur Allegheny Orogeny

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)

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

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.

Global paleogeography for the Cambrian period Avalonia Terranes

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

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

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.

Cambrian paleogeography Pre –collisions Note equator

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

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

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

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

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

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

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

Late Devonian paleogeography of North America

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

Catskill clastic wedge thickness Coarse near source Wedge thins away

Clastic Wedges fill Foreland Basins Highlands source of sediment

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

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

Allegheny and Ouachita Orogenies Hercynian Allegheny Ouchita

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

Late Devonian paleogeography of North America Here it is

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

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

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

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

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

Time-transgressive Cambrian rocks Grand Canyon Sauk Sequence WEST EAST Transgression Middle Cambrian http://www.geo-tools.com/trilobites.htm Lower Cambrian http://www.wmrs.edu/projects/trilobites/images/trilo7-2.jpg Note how western BAS is older than eastern BAS

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

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

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

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

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

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

Glacial Abrasion in Bedrock Source: Tom Bean

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

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

Coal formation Pennsylvania cyclothems Highland source to east

Pennsylvanian-age coal deposits

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

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

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