The early paleozoic the cambrian 544-505 my


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THE EARLY PALEOZOIC

  • THE CAMBRIAN 544-505 MY

  • CAMBRIA>>WALES

  • ADAM SEDGWICK 1835

  • THE ORDOVICIAN 505-438 MY

  • ORDOVICE>>WELSH TRIBE

  • CHARLES LAPWORTH 1879


NEOPROTEROZOIC TO MIDDLE CAMBRIAN STRATIGRAPHIC COLUMN. PRINCIPLE LIFE FORMS AND STAGES OF THE EARLY CAMBRIAN PLACEMENT OF BOUNDARY AT THE PHYCODES pedum ZONE, TRACE FOSSIL, @ 544 MY TYPE LOCALITY>>BURIN PENINSULA, NEWFOUNDLAND CAMBRIAN DIVISIONS BASED TRILOBITE ZONES [BIOMERES -INTERVALS OF TIMES BETWEEN TRILOBITE EXTINCTIONS]



PALEOGEOGRAPHY

  • CAMBRIAN CONTINENTS WITHIN 60O OF PALEOEQUATOR

  • GONDWANA

    • TIBET, SE ASIA, ARABIA, AFRICA, AUSTRALIA, ANTARCTICA, S. AMERICA
  • LAURENTIA> RIFT ZONES>PASSIVE MARGINS

  • FLOODING OF INTERIORS DUE TO RIFT SYSTEMS

  • IAPETUS OPENED BET N. AMERICA & EUROPE

  • SUBDUCTION ZONES DEVELOPED LATER



TECTONIC EVENTS

      • Pan-African Orogeny
      • Caledonian-Hercynian Orogeny
        • Appalachian, Caledonian, Hercynian, Urals, Ouachita, Samfrau
      • Overall scenario is coalescence of Pangea during most of the Paleozoic
        • Taconic Orogeny mid to late Ordovician
        • Caledonian Orogeny late Silurian to early Devonian
        • Acadian Orogeny mid Devonian
        • Alleghenian Orogeny late Penn, Permian
        • Hercynian Orogeny - Ouachita Orogeny


PLATE TECTONIC MOVEMENTS FROM THE NEOPROTEROZOIC TO THE DEVONIAN (750 MY TO 370MY)



The Appalachians

  • Valley and Ridge

    • folded & faulted sedimentary rks
  • Blue Ridge Province

    • metamorphosed Precambrian and Paleozoic Rks
  • Inner Piedmont

    • high grade metamorphic rks intruded by granites
  • Charlotte & Carolina Slate Belt

    • metamorphosed & folded late Proterozoic & Cambrian sediments and volcanics


A) Cambro-Ordovician Passive Margin: Sandy Shelf Deposits B) Middle to Late Ordovician Development of Trench Along the Eastern Boundary and Subsequent Closure of the Iapetus Ocean C) Collision of Island Arc and other Accreted (exotic) Terranes with North America in the TACONIC OROGENY



CAMBRIAN PALEOGEOGRAPHY: SHALLOW EPICONTINENTAL SEAS COVERED THE CENTRAL US



LITHOLOGIC FACIES OF THE CAMBRIAN



NEOPROTEROZOIC TO CENOZOIC TRANSGRESSIONS AND REGRESSIONS OBSERVED ON THE CRATON



ORDOVICIAN-PALEOGEOGRAPHY



The Queenston Clastic Wedge



Early Paleozoic Climates

  • Climates overall warmer than today

  • Continents 600 N & S of equator

  • Arid to sub arid environments 450 N & S of equator

  • Redbeds (alluvial) 300 N & S of equator

  • Tropical reefs 300 N & S of equator

    • Cambrian Archeocyathids; Ordovician Bryozoans
  • Glaciation during the late Ordovician in Africa



PALEOZOIC LIFE

  • Cambrian Explosion>Break up of Rodinia

    • radiation of all phyla>Continental Shelves
  • Cambrian Reef Systems

  • Cambrian extinctions (2nd largest)

  • Ordovician radiation

  • Global Faunas (Cambrian vs. Paleozoic Faunas)

  • Ordovician Reef Systems

  • End-Ordovician extinction events



THE TOMMOTIAN FAUNA



Trilobite Radiation

  • Comprise 95% of all Cambrian Fossils

  • Most successful arthropod

  • Chitinous shell with an underlayer of calcite

  • 5 major extinctions during the Cambrian and associated radiations

  • Each Cambrian Biomere involved the extinction of 40 to 95% of existing trilobite genera



THE BURGESS SHALE



THE BURGESS FAUNA



Archaeocyathids & Stromatoporoid Reefs



Ordovician Life

  • Terminal Cambrian trilobite extinction led the way for rapid Ordovician radiations in other groups

  • Radiation of molluscs particularly gastropods decreased importance of stromatolites

  • Tabulate and Rugose coral reefs

  • Graptolites as index fossils

  • Emergence of land plants

  • First Vertebrates



Ordovician Extinctions

  • Blackriver-Trenton

    • Mid Ordovician, catastrophic regional extinction
    • All echinoderms and cephalopods; 90% trilobites, 83% pelecypods
  • Terminal Ordovician Extinction

    • Major glaciation in Gondwana (sea level drop]
    • 3rd largest in recorded geologic history; 80% of all genera


THE MIDDLE PALEOZOIC

  • THE SILURIAN 438-408 MY

  • SILURES>> WELSH TRIBE

  • Roderick Murchison 1835

  • THE DEVONIAN 408-360 MY

  • (Old Red Sandstone)

  • DEVON>> County in SW England

  • Roderick Murchison

  • Adam Sedgwick 1839



INTRODUCTION

  • Silurian

  • Devonian

    • 48 MY Duration
  • Final Collision and Suturing of Baltica and Laurentia

  • Caledonian and Arcadian Orogenies

  • High Stands of Sea Level

  • Epicontinental seas; marine deposits and thick sequences of evaporites

  • Reefs became important



Paleogeography



PALEOGEOGRAPHY

  • Closing of Iapetus Ocean

    • Baltica-Laurentia; Mongolia-Siberia
  • Closing of Rheic Ocean as Gondwana migrated to west (Laurentia/Baltica-Gondwana)

  • Laurentia continued to be a tropical craton

  • Shallow seas covered the continents during much of Silurian

  • Devonian orogenies in Northern Hemisphere

    • Caledonian (Scandinavia/Greenland) & Acadian (New England) & Antler (CA-NV)


Cratons and Mobile Belts of North America and Europe



TECTONIC EVENTS

  • Caledonian & Acadian Orogenies

    • Extension of Late Ordovician Taconic Orogeny
  • Mid Devonian Iapetus Ocean closed

  • Baltica collided with Laurentia

  • Avalonia (Island Arc) sutured to both Baltica and Laurentia

  • Norway collided Greenland forming the highlands responsible for the Old Red Sandstone



Orogenic Development Of the Eastern US



East-West Cross Section across the Devonian Catskill Wedge



Lithofacies & Thickness Map of the Upper Devonian Sequence of the Eastern US



The Appalachians

  • Valley and Ridge

    • folded & faulted sedimentary rks
  • Blue Ridge Province

    • metamorphosed Precambrian and Paleozoic Rks
  • Inner Piedmont

    • high grade metamorphic rks intruded by granites
  • Charlotte & Carolina Slate Belt

    • metamorphosed & folded late Proterozoic & Cambrian sediments and volcanics




Highland Areas Associated with the Antler Orogeny of California- Nevada



Domes and Basins



Depositional Basins of the North American Craton



Model Illustrating the Deposition of Evaporites Michigan Basin



NEOPROTEROZOIC TO CENOZOIC TRANSGRESSIONS AND REGRESSIONS OBSERVED ON THE CRATON



Oriskany Sandstone Kaskaskia Transgression



The Reef System

  • Tabulate corals and Stromotoporoid sponges

  • Fauna was vertically zoned (tiered by depth)

  • Clear ecological succession in reef building from pioneer community (clumps of twig-like colonies) to platy and domed shaped colonies to binding stage by sponges

  • Michigan, Canning Basin (Australia), British Columbia



Mineral Deposits

  • Sedimentary copper, lead and zinc sulfides and Iron ores

  • Occur in shales and carbonates

  • Disseminated or interbedded

  • Tri-state mining district (MO)

  • Howard’s Pass, Yukon, Canada

  • Wales

  • New York to Alabama



Clinton Iron Ore



Other Economic Deposits

  • Silurian Salt, Michigan and upstate New York

  • Silurian Petroleum Deposits-OH, OK,TX

  • Devonian Petroleum Deposits

    • Williston Basin- MT and Alberta
    • First oil well in US 1859 (PA)
  • Silica for glass- Devonian Oriskany Sandstone, 95-99.8% pure



Mid-Paleozoic Climates

  • Gondwana centered over the South Pole

    • climates ranged from cold to warm
    • glacial striations present in South America yet Red beds and carbonates and evaporites were also present in N. Africa, India and Australia
  • Other continents were equatorial



MID PALEOZOIC LIFE

  • The Origin of the Ammonoids

    • Cephalopods, Devonian
    • Evolved from straight chambered nautiloids
  • Eurypterids and the Origin of Arachnids

    • Chelicerata (horseshoe crabs and sea scorpions)
    • Ferocious predators of the Paleozoic seas


Life of the Silurian



Radiation of Fishes

  • During Cambrian and Ordovician only 1 order of fish, jawless, Ostracoderms (Marine)

  • Early Silurian 3 more orders of jawless fish and the first jawed fish, acanthodian, appeared and inhabited both marine and fresh water

  • By Middle Devonian all classes of jawed fish had appeared

  • All restricted to 40o of the equator

  • Extinction at end of Devonian, terminated the ostracoderms and the armored placoderms



Evolution of the 5 Major Groups of Fishes



Ostracoderms



Evolution of Jaws in Fish



Placoderms



The Origin of Tetrapods



Ichthyostega



The Radiation of Land Plants

  • Earliest Fungi appear in the Early Silurian

  • First Land Plants are Late Ordovician

  • First Vascular Plants are Late Silurian

  • With the appearance of forests in Late Devonian oxygen levels increased and reached a peak in the Late Paleozoic

  • Land erosion rates significantly decreased



The Development of Tiering

  • Vertical Separation Between Organisms

    • Removes competition between organisms of similar feeding habits
  • Different stalk heights in crinoids

  • Low herbaceous plants grading into true forest with tall trees



Terrestrial Communities

  • By Early Devonian land communities were diverse

  • Rhynie Chert (Aberdeen, Scotland)

  • Silicified peat bog

  • Preserved plants as well as spiders, mites and insects



Mass Extinction

  • Major marine extinction of the Late Devonian

    • Frasnian-Famennian epochs
  • 33% marine families became extinct

  • Nearshore marine and reef benthic species

    • corals, stromotoporoids, all but 1 order of trilobites, many brachiopods and ammonoids
  • No corresponding terrestrial extinction



Frasnian-Famennian Extinction

  • Occurred during a regression

  • Associated with low oxygenated water and high metal concentrations

  • Sharp drop in temperature (O2-Isotope studies)

  • Presence of glass spherules

  • All indicate a probable asteroid impact which caused deep anoxic and high metallic content water to poison shoal communities




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