(Test 3 material) Paleozoic Big EventsEntering the Phanerozoic Eon-Consists of three eras (from oldest to youngest)-Paleozoic= “ancient life” (542-251 m.y. ago)-Mesozoic= “middle life” (251-65.5 m.y. ago)-Cenozoic= “recent life” (65.5 m.y. ago – present) ***Study Geologic Time ScalePaleozoic Era-Paleozoic can be divided into:-Early Paleozoic= (COS) Cambrian, Ordovician and Silurian-Late Paleozoic= (DMPEarly Paleozoic Continents1. Laurentia2. Baltica3. Kazakhstanie4. Siberia5. China6. Gondwana Late Paleozoic plate geography-The continents collide during late Paleozoic-Larger continents grew by addition of island arcs and microcontinents around theiredges. Is Sea level constant?-Transgression and Regression-Shallow epicontinental seas transgressed across the Laurentian (North American) craton during Early Paleozoic as the glaciers melted and sea level rose. The seas regressed as the glaciers enlarged and sea level dropped. Transgression-Regression Sequence-The transgression and regression of the seas deposited sequences of sedimentary rocks that reflect the deepening and shallowing of the waters. These are called transgressive-regressive sequences. Unconformities-During regressions, the former seafloor was exposed to erosion, creating extensive unconformities that mark the boundaries between the transgressive-regressive sequences. -Gap in the geologic recordWorldwide Sea Level Change-Worldwide sea level change caused the transgressions and regressions.-Worldwide sea level changes were probably related to glaciations and/or sea floor spreading.-During times of rapid sea floor spreading, mid-ocean ridge volcanism displaces seawater onto the continents. Is there going to be Mountain building? Yes-Orogenic belts are present along the edges of the continent-In the orogenic belts, strata are intensely deformed, with folding, faulting, metamorphism, and igneous intrusions.-Deformation occurred as a result of continental collision. Orogenies-In the Appalachian region, there were three Paleozoic mountain-building events (orOrgoenies)-Taconic orogeny: Ordivician-Acadian orogeny: Devonian-Alleghanian orogeny: Miss-Permian North American through the Paleozoic Cambrian PaleogeographySauk sequence: (SS, SH, LS) Ordovician Paleogeography-Taconic Orogeny: Note mountains erode-Cratonic sequence: Tippacanoe transgression (qtz SS, Carbonates, SH) Subduction zone= chain of island volcanoesA. Eastern North America during Cambrian and Early Ordovician, following the breakup of Rodinia. B. Large Volcanic island arc nears eastern North America.C. Volcanic island arc collides wit eastern North America causing Taconic orogeny. Silurian Paleogeography-Mountains in eastern N. America are eroding >Sandstone and conglomerate deposits-Tippacanoe regression>Widespread carbonate deposition-Deep marine deposits in NW and SE U.S.-Evaporites in basins. Devonian Paleogeography-Kaskaskian transgression-Acadian (Caledonian) Orogeny>Uplift and erosion of Acadian highlands> Redbeds-Transcontinental Arch exposed>Sands and Carbonates-Antler Orogeny (end of Devonian)> Antler Mountains form islands-Shales and carbonate reefsMississippian Paleogeography-Antler Orgoeny-Arcadian Highlands eroding> Continental depositional environments-Carbonate deposition-Kaskaskian transgression max in mid-miss, then widespread unconformity forms-Note Africa is approaching Alleghanan Orogeny-During late Paleozoic northwestern Africa collide with southeastern North America, causing the Alleghanian orogeny, and building the Appalachian Mountains.-The orogeny began during Mississippian and continued through Pennsylvanian andPermian. Pennsylvanian Paleogeography-Coal swamps formed along the western edge of the Appalachian Mountains in what was basically a tropical rainforest setting-Antler Mts eroding coarse clastics-Compression causes uplifts in central craton (incl. ancestral Rockies)-Absaroka transgression-mid to end of Pennsylvanian Permian Paleogegraphy -Alleghenian orogeny cont.-Redbeds-Appalachian Mtn continue to rise> Alluvial Fans-In west, shales, carbonates, evaporates-Absaroka regression -During Permian, the continents collide and joined to form the supercontinent, Pangea.-Pangea was surrounded by a huge ocean called Panthalassa-The oceanic area east of Pangea, and between Africa and Europe was called the Tethys Sea. Orogeny and Climate-Orogenies probably also affected the climate. -Locations of mountains can affect limate and control precipitation (rain-shadow effect)-Deserts form on the downwind side ofmountain rangesWhat are some notable rock types?Paleozoic-Paleozoic had long periods of tranquil sedimentation with intervals of convulsive mountain building-Give us thick sedimentary sequences-Mississippian limestone> The name “Mississippian” is derived from exposures of rock in the valley region of the Mississippi River.> Mississippian sedimentary deposits contain abundant limestone with fossils of crinoids, blastoids, bryozoans, and fusulinid foraminifera.> In places, Mississippian limestones are more than 700 m thick. -Pennsylvanian coal and cyclothems> Pennsylvanian rocks are dominated by coal-rich sediments that were deposited in swamps and deltas.> Coal deposits are particularly well developed in Pennsylvania.> Coal swamps formed along the western edge of the Appalachian Mountains,in what was basically a tropical rainforest setting. -Pennsylvanian Cyclothem> A typical Pennsylvanian cyclothem contains 10 unites.> The lower half consists of nonmarine sediments, topped by a coal deposit.> The coal is overlain by marine deposits, indicating the advance of the sea inthe swampy, vegetated area. -Marine and Non-marine deposits>The repetitious interbedding of non-marine and marine sedimentary deposits indicates either:-Episodic regional subsidence and upliftOR-Eustatic (worldwide) sea level changes related to Carboniferous-Permian glaciation in Gondwana-Coal and Plant Fossils> Pennsylvanian coal deposits are mined extensively in the Appalachian area,the Illinois basin, and in Europe.>They are commonly associated with rocks containing plant fossils.-Pennsylvanian and Permian sandstone deposits> Erosion produced great wedge-shaped deposits of red arkosic sandstone during Pennsylvanian and Permian, some of which is exposed in Colorado as:-The “flatirons” near Boulder-The rocks at Red Rocks Amphitheatre near Morrison, west of Denver.-The Garden of the Gods, near Colorado Springs. -Penn-Permian wedges of red arkosic