Global tectonic theme of the Paleozoic assembly of the supercontinent, Pangaea. Global tectonic theme of the Paleozoic assembly of the supercontinent, Pangaea


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Global tectonic theme of the Paleozoic - assembly of the supercontinent, Pangaea.

  • 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.



Six major Paleozoic continents are recognized after Rodinia breakup

  • 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

  • Kazakhstaniapart Central Asia

  • China - All of SE Asia and SE China







  • 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





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








    • 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.






  • 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





After the suturing of Gondwana and Laurasia (includes Hercynian and Allegheny Orogenies),

  • 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.





  • That’s the overview

  • Now let’s look in more detail at the collision, i.e. orogenies





In the Cambrian, several small terranes lay to the south of Laurentia as it separated from Baltica. The shores were passive margins.

  • 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.









Inland, the Taconic collisions caused the crust to be warped down, forming the Appalachian FORELAND BASIN

  • 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.









  • Baltica sutured onto Laurentia

  • Result called Laurasia





Continued subduction of Iapetus ocean floor

  • 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














Initial contact Late Mississippian

  • 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















Laurence Sloss: Major transgressive-regressive cycles

  • 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












Transgression starts M Pennsylvanian

  • 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 mostly warm, but two glacial times, Ordovician and Pennsylvanian to Late Permian.

  • 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


Cool Pennsylvanian – M Permian

  • 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












(2) The Late Permian WARM

  • (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





Inland sea limited to w Texas & s NM

  • Inland sea limited to w Texas & s NM

  • Extensive evaporite deposits KS – OK

  • Redbeds over interior – strong seasons




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