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Early Paleozoic. Periods of the Early Paleozoic. Cambrian: 570-505 mya Ordovician: 505-438 mya Silurian: 438-408 mya. Overview of Paleozoic. Broad Sequence of Events Gradual Marine invasion of low continents Wide epeiric (shallow) seas; moderated climate

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periods of the early paleozoic
Periods of the Early Paleozoic
  • Cambrian: 570-505 mya
  • Ordovician: 505-438 mya
  • Silurian: 438-408 mya
overview of paleozoic
Overview of Paleozoic
  • Broad Sequence of Events
    • Gradual Marine invasion of low continents
    • Wide epeiric (shallow) seas; moderated climate
      • Wide shallow habitats for marine organisms
    • Epeiric seas retreated; instability occurred
      • Thick sedimentary layers and Volcanic deposits developed
    • Collisional Mountain ranges built
plate tectonic events
Plate Tectonic Events
  • Break-up of Rodinia
  • Oceanic closing and orogeny to form Pangaea
        • Taconic orogeny
        • Acadia orogeny
        • Alleghenian orogeny
        • Caledonian Orogeny
        • Hercynian Orogeny
clues to paleogeography
Clues to Paleogeography
  • Paleomagnetic evidence
  • Lithologic evidence
      • Limestone (shallow marine)
      • Evaporites (equatorial dry conditions)
      • Lithic Sandstone and greywacke (mountain uplift)
      • Arkose (arid conditions)
      • Tillites
      • Quartz sandstone
      • Shales
laurentia n america and gondwanaland first stage of pangaea
Laurentia (N. America) and Gondwanaland (first stage of Pangaea )
  • Gondwanaland
      • formed in southern hemisphere
      • consists of S. America, Africa, and other shields
      • Drifter south to polar position
  • Laurentia
      • Lay on equator
      • rotated counter clockwise
continental framework
Continental framework
  • Stable interior
      • Arches
      • Synclines
      • Basins
      • Domes
  • Orogenic Belts
      • Cordilleran Mtn
      • Franklin Mtn
      • Appalachian Mtn
      • Caledonian mnt
paleogeography of laurentia
Paleogeography of Laurentia
  • Equator: North-central Mexico to Ellsmere Island, Canada
  • Vast epeiric Sea (30o Latitude; vast carbonate deposits)
  • Vast lowlands of Canada Shield were exposed (desert)
  • Volcanic Mnts: Texas and New England
  • Appalachians (on east)
  • Cordilleran (on west)
  • Franklinian (on north)
  • Caledonian (on northwest)
    • Extensive Sediment belts
      • Shales in seaways
      • limestone in empieric seas
      • Quartz sand on shoreline and deserts
base of cambrian
Base of Cambrian
  • Sedgwick’s original base (1835)
    • At top of nonconformity in Wales
    • At the first trilobite bearing fossiliferous beds
    • Later dated at 560 my
  • New concept: Tommotian Stage (1970)
        • Base of Cambrian set at 570 my
          • New stage included fossiliferous rocks above Vendian and some fossiliferous rocks
          • Fossils in new stage: porifera, brachiopods, and organisms of unknown affinity
cratonic sequence of paleozoic
Cratonic Sequence of Paleozoic
  • Sauk Sequence: Late Proterozoic to early Ordovician
  • Tippecanoe Sequence: Early Ordovician to early Devonian
  • Kaskakia Sequence: Early Devonian to end of Mississippian
  • Absaroka Sequence: Pennsylvanian to Early Jurassic
early paleozoic history
Early Paleozoic History
  • Synopsis of Sauk Transgression
    • Canadian Shield eroded for 50 my prior to transgression
    • Gradual transgression covered shield
    • Transcontinental Arch (highlands) became island chain in shallow epeiric sea
        • Transcontinental Arch: Ontario to Mexico, parallel to Cambrian equator
  • As a Result:
    • Late Cambrian seas: MT to NY
    • Cordilleran deposits of Grand Canyon
      • Tapeat Sandstone (oldest)
      • Bright Angel Shale
      • Mauv Limestone (youngest)
time and facies slight tangent
Time and Facies (Slight tangent)
  • Bright Angel Shale: good example of temporal transgression of facies
        • Early Cambrian (CA)
        • Middle Cambrian (AZ)
back to the sauk sequence
Back to the Sauk Sequence
  • By the early Ordovician sea regresses and deposition ends
        • Vast continental-scale uncomformity
        • Karst topography on carbonates rocks
tippecanoe sequence
Tippecanoe Sequence
  • Massive unconformity separates the Tippecanoe from the Sauk Sequence
    • Known for:
      • the “Super Mature” Sandstone, St. Peter Sandstone
        • What could “Super Mature” mean?
      • Carbonate deposits contain abundant marine fauna
fauna found in tippecanoe
Fauna found in Tippecanoe
  • Shallow Marine limestones with vast fauna
    • Brachiopods
    • Bryozoans
    • Echinoderms
    • Mollusks
    • Corals
    • Algae
close of the tippecanoe
Close of the Tippecanoe
  • Landlocked, reef-fringed basins develop in Great Lake region
evaporite region
Evaporite region
  • In some areas evaporites accumulated to 750 meters
    • If this occurred due to evaporation of a single body of water, the water would have to have been ~1000 kilometers deep

Barred Basin

cordilleran region history
Cordilleran Region History
  • Sauk Interval
    • Passive Margin on opening ocean; deep marine basin on west
    • Western ocean opened; block rotated out; included Siberian region of Asian continent
    • Arms of rift filled with thick sediments
      • Belt supergroup (MT, ID, BC)
      • Uinta Series (UT)
      • Pahrump Series (CA)
      • Canadian Rockies (BC, Alberta)
tippecanoe interval
Tippecanoe Interval
  • Conversion to active margin with subduction (Wilson Cycle)
  • Volcanic Chain formed along western trench
  • Trench deposits; greywacke and volcanics
  • Western ocean deposits: Siliceous black shales and bedded cherts with graptolites (graptolite facies)
  • East of subduction zone: shelly facies- deposited in back arch basins (fossiliferous carbonates)
appalachian history
Appalachian History
  • Appalachian Trough: Deformed three times during Paleozoic
    • Subdivisions of trough:
      • Eastern sediment belt: greywacke, volcanic siliceous shale
      • Western sediment belt: Shale, sandstone, limestone
    • Physiographic region of today
      • Eastern belt: Blue Ridge and Piedmont
      • Western Belt: Valley and Ridge and Plateau
sauk interval
Sauk Interval
  • Trough was a passive margin on opening ocean
    • Shelf sediments: sandstone and limestone
    • Oceanic sediments: shales
  • Transgression spread deposits westward across craton; thick carbonates formed on subsiding shelf
  • Abrupt end with onset of subduction and ocean closure during Middle Ordovician
tippecanoe interval24
Tippecanoe Interval
  • Carbonate sedimentation ceased; platform downwarped by subduction
  • Thick graptolite black shale and shoreline immature sands spread west
  • Volcanic flows and pyroclastic beds formed when volcanoes emerged on coast
    • Rapid closing of eastern ocean (Iapetus); coastal and volcanic arc developed
      • Millerburg Volcanic ash bed formed (454 my; 1-2 m thick)
taconic orogeny
Taconic Orogeny
  • Appalachian Mountains built in collision with part of western Europe
  • Compression folded shelf sediments into mnt and Logan’s Thrust formed (48 km displacement)
Giant granitic batholiths produced by Taconic melting
    • Taconic Mountains weathered to form vast sandstones of PA, WY, OH, and NY
      • Great clastic wedges spread westward (age tracts deformation)
  • Transgressions= Mild Climates, windswept low terrains
  • Regressions and Orogenic Episodes= Harsher more diverse climates; winds diverted by mountains
  • Earth Rotation was faster (shorter days, greater tidal effects)
  • No land Plants
    • Solar Radiation reflected, not absorbed
    • Sever temperature differences resulting
  • End of Late Proterozoic Glacial Cycle: Cool beginning for Early Paleozoic
  • Melting Polar Caps= Rising sea levels and warming
  • Equitorial Position= tropical climates for Laurentia, Baltica, and Antarctica
      • No Ice caps= warm polar seas
  • Cross Bedding in Desert Sand Deposits
    • Shows wind blew NE to SW across eastern
  • Sea Levels and Biotic Extinctions
    • African Glaciation lowered sea levels and cooled global temperatures
    • End-Ordovician extinctions in many families
      • Bryozoans
      • Tabulate corals
      • Brachiopods
      • Sponges
      • Nautiloid cephalopods
      • Crinoids
silurian climate
Silurian Climate
  • Temperature Zonation
    • Glacial deposits above 65o latitude
    • Reefs, evaporates, eolian sands below 40o latitude
late paleozoic
Late Paleozoic
  • Devonian (480-360 m.y.a.)
  • Mississippian (360-320 m.y.a.)
  • Pennsylvanian (320-286 m.y.a.)
  • Permian (286-245 m.y.a.)
  • During Silurian Iapetus sea closes - joins Baltica and Lauretia (Caledonian Orogeny)
  • Devonian-Orogeny continues to south forming Laurussia
  • Pennsylvanian collision joins Gondwanna Land and Laurussia (Hercynian in Europe, the Alleghenian in N. America
  • By the Late Permian Pangea is complete
kaskaskia sequence
Kaskaskia Sequence
  • Oriskany sandstone- initial transgression
  • Devonian Clastics- material shed off rising Appalachians
  • Upper Devonian-Mississippian
    • Massive marine deposits
  • Late Mississippian- Regression
    • Widespread erosion and development of Karst topography
absaroka sequence
Absaroka Sequence
  • Yet another transgression
  • Unique cyclical sediments
    • Cyclothems
      • Shale
      • Limestone
      • Shale
      • Limestone
      • Coal
  • Caused by either eustatic rise in sea level (Glacial melting) or by subsidence.
  • Zonation paralled latitude
    • Warm to hot within 40o of equator
  • Reduced CO2 in late Paleozoic causes cooling and then late Paleozoic Ice Age
mineral deposits
Mineral Deposits
  • Fossil Fuels
    • Coal
      • Present in all post Devonian rocks
    • Oil and Gas
      • Devonian Reefs Alberta, MT, SD
      • Appalachian basin PA, WV