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THE EARLY PALEOZOIC

THE EARLY PALEOZOIC

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THE EARLY PALEOZOIC

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  1. THE EARLY PALEOZOIC THE CAMBRIAN 544-505 MY CAMBRIA>>WALES ADAM SEDGWICK 1835 THE ORDOVICIAN 505-438 MY ORDOVICE>>WELSH TRIBE CHARLES LAPWORTH 1879

  2. 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 MYTYPE LOCALITY>>BURIN PENINSULA, NEWFOUNDLANDCAMBRIAN DIVISIONS BASED TRILOBITEZONES[BIOMERES -INTERVALS OF TIMES BETWEEN TRILOBITE EXTINCTIONS]

  3. 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

  4. 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

  5. PLATE TECTONIC MOVEMENTS FROM THE NEOPROTEROZOIC TO THE DEVONIAN (750 MY TO 370MY) BREAK UP OF RODINIA AVALONIAN OROGENY OPENING OF IAPETUS OPENING OF RHEIC TACONIC OROGENY CLOSING OF IAPETUS ACADIAN OROGENY

  6. 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

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

  8. CAMBRIAN PALEOGEOGRAPHY: SHALLOW EPICONTINENTAL SEAS COVERED THE CENTRAL US Earliest Paleozoic time of lowest sea level due to Proterozoic glaciations By middle Cambrian sea had flooded the continent

  9. LITHOLOGIC FACIES OF THE CAMBRIAN The transgression of the Cambrian is visible in the rocks of the Grand Canyon

  10. NEOPROTEROZOIC TO CENOZOIC TRANSGRESSIONS AND REGRESSIONS OBSERVED ON THE CRATON Variable sea level represented sequences of sediments bounded by unconformities on all of the cratons - e.g. Sauk, Tippecanoe

  11. ORDOVICIAN-PALEOGEOGRAPHY Tippecanoe Transgression St. Peter’s Sandstone

  12. The Queenston Clastic Wedge Redbeds coarser towards the source area, Taconic Highlands (4000m)

  13. 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

  14. 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

  15. THE TOMMOTIAN FAUNA Small Shelly Fossils 1-2 mm Calcium phosphate Calcium cqarbonate Most phyla represented 1 to 2 MY duration

  16. 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

  17. THE BURGESS SHALE Fine grained turbidite deposit at the base of a reef

  18. THE BURGESS FAUNA Hallucigenia Anomalocaris Opabinia

  19. Archaeocyathids & Stromatoporoid Reefs • Archeocyathid Reefs begin during the Tommotian Stage in Siberia • Spread rapidly through world • Extinct by Early Cambrian • Stromotoporoid Reefs begin during the Middle Cambrian • They remain a dominant reef builder until the Devonian

  20. 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

  21. 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

  22. 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

  23. INTRODUCTION • Silurian • 30 MY Duration • 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

  24. Paleogeography

  25. 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)

  26. Cratons and Mobile Belts of North America and Europe

  27. 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

  28. OrogenicDevelopmentOf the EasternUS Acadian Orogeny produced a thick clastic wedge (the Catskill Wedge) of red beds [conglomerates and sandstones]

  29. East-West Cross Section across the Devonian Catskill Wedge During the Devonian the rate of sedimentation increased from 7m/MY to 17m/MY to 70m/MY Chattanooga Shale- Anoxic black shale, marker bed

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

  31. 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

  32. Physiographic Provinces of the Appalachian Region

  33. Highland Areas Associated with the Antler Orogeny of California- Nevada

  34. Domes and Basins Vertical Uplift and Subsidence Erosional and Depositional Features

  35. Depositional Basins of the North American Craton

  36. Model Illustrating the Deposition of EvaporitesMichigan Basin Cyclic: Dolomite, Anhydrite, Halite 1500 m of carbonates, rock salt and gypsum in 5 major cycles

  37. NEOPROTEROZOIC TO CENOZOIC TRANSGRESSIONS AND REGRESSIONS OBSERVED ON THE CRATON Variable sea level represented sequences of sediments bounded by unconformities on all of the cratons - Highest Stand of sea Level

  38. Oriskany SandstoneKaskaskiaTransgression

  39. 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

  40. 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

  41. Clinton Iron Ore Silurian Clinton Group near Birmingham, AL The ore is an oolite of hematite (iron oxide)

  42. 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

  43. 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 • Laurentia, Baltica and Siberia were warm

  44. 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

  45. Life of the Silurian Eurypterids Devonian forms reached 2 m Huge eyes and pincers

  46. 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

  47. Evolution of the 5 Major Groups of Fishes

  48. Ostracoderms A: Thelodus B: Pteraspis C: Jamoytius D: Hemicyclaspis

  49. Evolution of Jaws in Fish

  50. Placoderms Skull 1 m high fish 10m long Dunkleosteus