1. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED. 1 THE EARTH THROUGH TIME TENTH EDITION H A R O L D L. L E V I N

2. Early Paleozoic Events © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

3.  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) © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

4. Paleozoic periods can be divided into:  Early Paleozoic = Cambrian, Ordovician and Silurian  Late Paleozoic = Devonian, Mississippian, Pennsylvanian, and Permian © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

5. FIGURE 10-1 Major events of the Paleozoic Era. Harold Levin © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

6. Orogenic belts are the result of the rebuilding of a supercontinent during the Paleozoic. FIGURE 10-7 Cratons and orogenic belts of North America and Europe. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

7. 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. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

8. In the Appalachian region, there were three Paleozoic mountain-building events (or orogenies):  Taconic orogeny  Acadian orogeny  Alleghanian orogeny © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

9. Across the platform, in the continental interior, Paleozoic strata are relatively flat-lying to gently dipping, and warped into basins, domes, arches, and broad synclines. FIGURE 10-5 Central platform of the United States showing major basins and domes. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

10.  Paleogeography = "ancient geography." The ancient geographic arrangement of the continents.  Reconstructing the paleogeography requires paleomagnetic, paleoclimatic, geochronologic, tectonic, sedimentologic, and biogeographic fossil data. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

11.  Paleoclimatic evidence comes from environmentally-sensitive sedimentary rocks (glacial deposits, coal swamp deposits, reef carbonates, evaporites).  Early Paleozoic climate was affected by several factors:  The Earth spun faster and had shorter days.  Tidal effects were stronger because the Moon was closer to Earth.  No vascular plants were present on the land. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

12. Just before Paleozoic began, the Precambrian supercontinent, Rodinia, had rifted apart to form six large continents and several smaller continents. When continents are located on a pole, if conditions are right, glaciers will form. During glaciations, sea level is lowered worldwide because the water is tied up in the ice sheets. Shallow epicontinental seas are unlikely during glaciations. FIGURE 10-2 Landmasses during the Neoproterozoic, about 750 million years ago. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

13. 1. Laurentia (North America, Greenland, Ireland, and Scotland) 2. Baltica (Northern Europe and western Russia) 3. Kazakhstania (between the Caspian Sea and China) 4. Siberia (Russia east of the Ural Mtns and north of Mongolia) 5. China (China, Indochina, and the Malay Peninsula) 6. Gondwana (Africa, South America, India, Australia, Antarctica) FIGURE 10-2 Landmasses during the Neoproterozoic, about 750 million years ago. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

14. By Late Cambrian, the continents moved off the pole. Some continents lie on the equator. Glaciers melted, sea levels rose, and shallow epicontinental seas flooded the continents. (C. R. Scotese, 2001, Atlas of Earth History, Vol., 1, Paleogeography, PALEOMAP Project.) © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

15. Wave-washed sands, muds, and carbonates were deposited in the shallow epicontinental seas. The epicontinental seas were sites of major diversification of marine life. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

16. Shallow epicontinental seas transgressed (onlap or advance onto the continent) across the Laurentian (North American) craton during Early Paleozoic as the glaciers melted and sea level rose. The seas regressed (offlap or retreat off the continent) as the glaciers enlarged and sea level dropped. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

17. 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. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

18. During regressions, the former seafloor was exposed to erosion, creating extensive unconformities that mark the boundaries between the transgressive-regressive sequences. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

19.  The unconformities can be used to correlate particular sequences from one region to another.  The unconformity-bounded sequences are sometimes called cratonic sequences.  Two major transgressions occurred during Early Paleozoic in North America:  Sauk sequence (older - primarily Cambrian)  Tippecanoe sequence (Ordovician-Silurian) © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

20. Green = sedimentary deposits Yellow = missing strata associated with unconformities © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

21.  Similar transgressive-regressive sequences are found on other continents, suggesting that 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 sea water onto the continents. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

22.  Laurentia is nearly covered by shallow epicontinental seas.  Laurentia lies on the equator, so water is warm.  Deposition of sand & carbonate sediments  Water deepens toward edges of continent, where shale is deposited FIGURE 10-4 North America during the Cambrian Period. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

23.  The base of Cambrian was formerly identified by the first-occurrence of shell-bearing organisms such as trilobites.  During the 1970s, small shelly fossils were found below the first trilobites, and dated at 544 m.y The base of Cambrian is now placed at the oldest occurrence of feeding burrows of the trace fossil Trichophycus, and dated at 542 m.y. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED. FIGURE 10-8 The trace fossil Trichophycus.

24.  During Cambrian, there were no vascular plants on the land, so the landscape was barren. Erosion was active and severe without plant roots to hold the soil.  After Neoproterozoic glaciation, the sea transgressed onto the craton.  Shoreline (beach) deposition produced a vast apron of clean quartz sand.  Carbonate deposition occurred farther from land. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

25. In the Grand Canyon region, the Lower Cambrian Tapeats Sandstone is an example of the sandy beach deposits unconformably overlying Precambrian rocks. FIGURE 10-12 East-west section of Cambrian strata exposed in the Grand Canyon. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

26. Tapeats Sandstone is overlain by Bright Angel Shale, an offshore deposit. Bright Angel Shale is overlain by Muav Limestone, deposited farther from land. These rocks form a transgressive sequence. FIGURE 10-12 East-west section of Cambrian strata exposed in the Grand Canyon. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

27. These sedimentary units are diachronous (i.e., they cut across time lines). In each case, the sedimentary units are older in the west than in the east. The red lines are trilobite zones, which approximate time lines. FIGURE 10-12 East-west section of Cambrian strata exposed in the Grand Canyon. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

28. The three facies (sandstone, shale, and limestone) coexisted and migrated laterally as sea level rose. The Bright Angel Shale is Lower Cambrian in the west, and Middle Cambrian in the east. FIGURE 10-12 East-west section of Cambrian strata exposed in the Grand Canyon. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

29. Near the end of Early Ordovician, the seas regressed (due to glaciation). The Muav Limestone was exposed to subaerial erosion and a widespread unconformity developed. FIGURE 10-12 East-west section of Cambrian strata exposed in the Grand Canyon. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

30. (C. R. Scotese, 2001, Atlas of Earth History, Vol., 1, Paleogeography, PALEOMAP Project.) © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

31. Note the mountains and volcanoes in the Appalachian region. Volcanic ash deposits are found in Ordovician rocks throughout the eastern U.S. (Now altered to a clay called bentonite). FIGURE 10-27 Paleogeography of Ordovician North America. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

32. The Taconic Orogenic Belt lay between Laurentia (North America) and Baltica (Europe and western Russia) during Ordovician. (C. R. Scotese, 2001, Atlas of Earth History, Vol., 1, Paleogeography, PALEOMAP Project.) © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

33. Plate tectonic cross-section showing forces that caused the Taconic Orogeny. FIGURE 10-23 © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

34. A. 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 with eastern North America causing Taconic orogeny. FIGURE 10-23 Plate tectonic forces that caused the Taconic orogeny. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

35.  As the Iapetus Ocean narrowed, a volcanic island arc approached and collided with the North American craton, causing folding, faulting, metamorphism, and mountain building.  This mountain-building event in the Appalachian region is called the Taconic orogeny (480 - 460 m.y. ago). © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

36. As the Taconic mountain belt eroded, Upper Ordovician to Lower Silurian red sandstones and shales were deposited to the west in huge delta systems. FIGURE 10-26 Great wedges of clastic sediments spread westward. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

37. These sediments formed a wedge-shaped deposit known as the Queenston clastic wedge, or the Queenston delta. Red deltaic sediments coarsen and thicken to the east (toward the mountainous source area), and become thinner and finer grained to the west. FIGURE 10-26 Great wedges of clastic sediments spread westward. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

38.  The size of the clastic wedge suggests that the mountains may have been more than 4000 m (13,100 ft) high.  There were two main highland areas; the higher of the two was in the northern Appalachians. FIGURE 10-26 Great wedges of clastic sediments spread westward. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

39. The Caledonian orogenic belt (which extends along the northwestern edge of Europe) is part of the same trend as the Taconic orogenic belt. The Caledonian orogeny reached its climax slightly later, during Late Silurian to Early Devonian. The Caledonian event is recognized in the Canadian Maritime Provinces, northeastern Greenland, northwestern Great Britain, and Norway. FIGURE 10-7 Cratons and orogenic belts of North America and Europe. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

40. (C. R. Scotese, 2001, Atlas of Earth History, Vol., 1, Paleogeography, PALEOMAP Project.) © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

41.  Silurian sea levels were high worldwide.  In Laurentia (North America), much of the craton was flooded, indicating melting of Late Ordovician glaciers.  This was the second major transgression during Paleozoic, which deposited the Tippecanoe Sequence. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

42.  Mountains in eastern N. America are eroding.  Sandstone & conglomerate deposits.  Widespread carbonate deposition.  Deep marine deposits in NW and SE U.S.  Reefs and evaporites. FIGURE 10-31 Silurian North America Paleogeography. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

43.  As the Tippecanoe Sea flooded North America in the late Ordovician to Silurian, deposition began with nearshore sands.  These include the famous St. Peter Sandstone, an unusually pure, well sorted, well rounded quartz sandstone.  The purity of the St. Peter Sandstone is the result of reworking of older sedimentary rocks.  Silurian Tuscarora Sandstone was deposited in the central Appalachian region. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

44.  Sandstone is overlain by extensive limestone deposits, locally replaced by dolomite.  In eastern U.S., limestones are overlain by and interbedded with shales along the periphery of the Queenston delta. Niagara Falls is a classic locality where these rocks are exposed. FIGURE 10-15 Niagara Falls © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

45.  Near the end of the Tippecanoe sequence, reef- fringed basins developed, such as the Michigan Basin.  Evaporation led to the precipitation of immense quantities of rock salt and gypsum within the basin, indicating an arid paleoclimate.  Evaporite minerals total over 2500 ft (750 m) thick in the Michigan Basin.  Thick accumulation of salt it is likely the result of a restricted basin where a structure such as a organic reef would periodically allow communication with the ocean. FIGURE 10-17 Isopach map shows thickness of late Silurian evaporite basins. FIGURE 10-18 Cross section shows a deposition model for evaporites in a barred basin. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

46.  Economically important sedimentary iron ore deposits accumulated during Silurian in the southern Appalachians, particularly around Birmingham, Alabama.  Steel was produced for many years in Birmingham from this iron ore.  Fuel was supplied by nearby Late Paleozoic coal deposits.  Limestone, also found nearby, was used as flux in the blast furnace. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

47.  Orogenic activity (mountain building) was more or less continuous at one place or another during Silurian and Devonian.  The Caledonian orogeny was most intense in Norway, as the Iapetus Ocean closed.  The folded rocks of the Caledonians end in Ireland, but can be traced to NE Greenland, Newfoundland, and Nova Scotia, Canada. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

48.  Passive margin during early Paleozoic  Tentional basins deposits – Belt Supergroup (Montana-Idaho-British Columbia, Uinta (Utah), Pahrump (California)  Starting in the Ordovician and Silurian the passive margin gave way to an active margin. Subduction zone  Thick sequences of graywackes and volcanic rocks deposited in a trench FIGURE 10-20 Interpretive cross section of conditions across the Cordilleran region during early Paleozoic time. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

49. FIGURE 10-1 Major events of the Paleozoic Era. © 2013 JOHN WILEY & SONS, INC. ALL RIGHTS RESERVED.

50. FIGURE 10-1 Major events of the Paleozoic Era. Source: Courtesy R. F. Dymek. FIGURE 10-7 Cratons and orogenic belts of North America and Europe. Source: Harold Levin. FIGURE 10-5 Central platform of the United States showing major basins and domes. Source: Harold Levin. FIGURE 10-2 Landmasses during the Neoproterozoic, about 750 million years ago. Source: Harold Levin. TABLE 10-1 Cratonic Sequences of North America. Source: Sloss, L., 1965, Bulletin of the Geological Society of America 74:93-114. FIGURE 10-8 The trace fossil Trichophycus. Source: Jensen, S., The Proterozoic and Earliest Cambrian Trace Fossil Record; Patterns, Problems and Perspectives, Integrative and Comparative Biology: Oxford University Press. FIGURE 10-12 East-west section of Cambrian strata exposed in the Grand Canyon. Source: After E. D. Mckee, 1945, Cambrian Stratigraphy of the Grand Canyon Region, Washington, Carnegie Institute, Publication 563. FIGURE 10-27 Paleogeography of Ordovician North America.Source: Harold Levin. FIGURE 10-23 Plate tectonic forces that caused the Taconic orogeny. Source: Harold Levin. FIGURE 10-26 Great wedges of clastic sediments spread westward. Source: Harold Levin. FIGURE 10-7 Cratons and orogenic belts of North America and Europe. Source: Harold Levin. FIGURE 10-31 Silurian North America Paleogeography. Source: Harold Levin. FIGURE 10-15 Niagara Falls (A) stratigraphic section and (B) block diagram. Source: Harold Levin. FIGURE 10-17 Isopach map shows thickness of late Silurian evaporite basins. Source: After Alling, H. and Biggs, L., AAPG (c) 1961, 45:515–547. Reprinted by permission of AAPG, whose permission is required for further use. FIGURE 10-18 Cross section shows a deposition model for evaporites in a barred basin. Source: Einsele, G., 2000, Sedimentary Basins: Evolution, Facies, and Sediment. New York, p. 261. With kind permission of Springer Science+Business Media. FIGURE 10-20 Interpretive cross section of conditions across the Cordilleran region during early Paleozoic time. Source: Harold Levin. IMAGE CREDITS