R.M. Clary, Ph.D., F.G.S.
Department of Geosciences
Mississippi State University
CHAPTER 10
EARLY PALEOZOIC EARTH HISTORY
OUTLINE
INTRODUCTION
CONTINENTAL ARCHITECTURE: CRATONS AND MOBILE BELTS
PALEOZOIC PALEOGEOGRAPHY
Early Paleozoic Global History
EARLY PALEOZOIC EVOLUTION OF NORTH AMERICA
THE SAUK SEQUENCE
PERSPECTIVE 10: The Grand Canyon—A Geologist’s Paradise
The Cambrian of the Grand Canyon Region: A Transgressive Facies Model
THE TIPPECANOE SEQUENCE
Tippecanoe Reefs and Evaporites
The End of the Tippecanoe Sequence
THE APPALACHIAN MOBILE BELT AND THE TACONIC OROGENY
EARLY PALEOZOIC MINERAL RESOURCES
SUMMARY
CHAPTER OBJECTIVES
The following content objectives are presented in Chapter 10:
 Six major continents were present at the beginning of the Paleozoic Era and plate
movement during the Early Paleozoic resulted in the first of several continental
collisions leading to the formation of Pangaea at the end of the Paleozoic.
 The Paleozoic history of North America can be subdivided into six cratonic
sequences, which represent major transgressive-regressive cycles.
 During the Sauk Sequence, warm, shallow seas covered most of North America,
leaving only a portion of the Canadian shield and a few large islands above sea level.
 Like the Sauk Sequence, the Tippecanoe Sequence began with a major transgression
resulting in widespread sandstones, followed by extensive carbonate and evaporite
deposition.
 During Tippecanoe time, an oceanic-continental convergent plate boundary formed
along the eastern margin of North America (known as the Appalachian mobile belt)
resulting in the Taconic orogeny, the first of several orogenies to affect this area.
 Lower Paleozoic rocks contain a variety of important mineral resources.
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R.M. Clary, Ph.D., F.G.S.
Department of Geosciences
Mississippi State University
LEARNING OBJECTIVES
To exhibit mastery of this chapter, students should be able to demonstrate comprehension
of the following:
 Reconstruction methods for paleogeography
 the formation of and evidence for cratons, domes, and mobile belts
 the six major Paleozoic continents and oceans
 the pattern and sequence of continental movement during the Early Paleozoic
 the major cratonic sequences of the Early Paleozoic
 the importance of transgressions and regressions in the cratonic history of North
America, especially as seen at the Grand Canyon
 the major events of the Sauk sequence
 the major events of the Tippecanoe sequence, with an emphasis on modern and
ancient reefs and evaporites
 the general evolution of the Appalachian mobile belt during the Early Paleozoic with
emphasis on the evidence for the Taconic orogeny
 the types and occurrences of Early Paleozoic mineral deposits.
CHAPTER SUMMARY
1. Most continents consist of two major components: a relatively stable craton over
which epeiric seas transgressed and regressed, surrounded by mobile belts in which
mountain building took place. Four mobile belts formed around the margin of the
North American craton during the Paleozoic: the Franklin, Cordilleran, Ouachita,
and Appalachian.
Figure 10.1 Major Cratonic Structures and Mobile Belts
2. Six major continents and numerous microcontinents and island arcs existed at the
beginning of the Paleozoic Era. During the Early Paleozoic (Ordovician-Silurian),
Gondwana moved to a southward, as indicated by tillite deposits. The
microcontinent Avalonia collided with Baltica. An active convergent plate margin
formed along the eastern margin of Laurentia during the Ordovician. AvaloniaBaltica collided with Laurentia to form the larger continent of Laurasia, which
closed the northern Iapetus Ocean.
Figure 10.2 Paleozoic Paleography
3. The geologic history of North America can be divided into cratonic sequences that
reflect cratonwide transgressions and regressions.
Figure 10.3 Cratonic Sequences of North America
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R.M. Clary, Ph.D., F.G.S.
Department of Geosciences
Mississippi State University
4. The first major marine transgression onto the craton took place during the Sauk
Sequence. At its maximum, the Sauk Sea covered the craton except for parts of the
Canadian shield and the Transcontinental Arch, a few large islands above sea level.
Figure 10.4 Cambrian Paleogeography of North America
Figure 10.5 Cambrian Rocks of the Grand Canyon
Figure 10.6 Time Transgressive Cambrian Facies
Enrichment Topic 1. Transgressing Seas
Although climate change and rising sea levels are a current topic in the news, the
transgression of the Sauk Sea reveals in the geologic record that rising sea levels have
occurred at different times in our geologic past. Have students investigate projected
coastlines if the East Antarctic Ice Sheet would melt. How do these projected coastline
changes compare with the amount of continental crust above sea level when the Sauk Sea
trangressed? Nova Online provides graphics depicting the scientific interpretation of
coastlines (http://www.pbs.org/wgbh/nova/warnings/waterworld/)
5. The Tippecanoe sequence began with a transgression that deposited clean, wellsorted sandstone over most of the craton. This was followed by extensive carbonate
deposition. In an addition, large barrier reefs enclosed basins, resulting in evaporite
deposition within these basins.
Figure 10.7 Ordovician Paleogeography of North America
Figure 10.8 Transgressing Tippecanoe Sea
Figure 10.9 Organic Reefs
Figure 10.10 Silurian Paleogeography of North America
Figure 10.11 The Michigan Basin
Figure 10.12 Evaporite Sedimentation
Enrichment Topic 2. The St. Peter Sandstone
The St. Peter sandstone is one of the chief deposits of glass sand of the north-central US.
This Ordovician sandstone is derived from the weathering of Precambrian quartzites of
the Canadian Shield, which may have been a second-generation sandstone in itself. The
St. Peter Sandstone is a clean sandstone, meaning that it was reworked for many years,
resulting in the removal of clay-sized material. The Ford Motor Company in St. Paul
actually used the St. Peter Sandstone as a source for its windshield glass for several years.
E.W. Heinrich, “Geologic types of glass-sand deposits and some North American
representations,” Geological Society of America Bulletin, v.92. n.9, p.611-613.
A brief history of the glass industry may be found online at
http://www.glassonline.com/infoserv/history.html.
6. The eastern edge of North America was a stable carbonate platform until the
Middle Ordovician. During Tippecanoe time an oceanic-continental convergent
plate boundary formed, resulting in the Taconic orogeny, the first of several
orogenies to affect the Appalachian mobile belt.
Figure 10.13 Neoproterozoic to Late Ordovician Evolution of the Appalachian
Mobile Belt
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R.M. Clary, Ph.D., F.G.S.
Department of Geosciences
Mississippi State University
7. The newly formed Taconic Highlands shed sediments into the western epeiric sea,
producing a clastic wedge geologists call the Queenston Delta.
Figure 10.14 Reconstruction of the Taconic Highlands and Queenston Delta
Clastic Wedge
8. Early Paleozoic-aged rocks contain a variety of mineral resources including
building stone, limestone for cement, silica sand, hydrocarbons, evaporites, and
iron ore.
LECTURE SUGGESTIONS
1. Point out the importance of river deltas in the growth of trading and cultural
centers. Modern deltas such as on the Nile, Yangtze, and Mississippi Rivers have
prominent cultural development. The Queenston Delta formed in much the same
way as a fluvial system; it flowed from growing highlands into the proto-Atlantic
Ocean.
2. Reinforce the importance of time-stratigraphic markers by talking about the
significance of Ordovician age bentonite deposits in the Appalachians. These
regionally extensive bentonite deposits are interpreted to be volcanic ash layers
related to island arc volcanism during the early mountain building stages of the
Appalachians. They provide a widespread, datable, stratigraphic unit of uniform age
within the sedimentary rocks.
3. Review how geologists reconstructed the paleogeography of the Early Paleozoic.
What evidence exists for identifying continents around a paleoequator?
CONSIDER THIS
1. How high were the Appalachian Mountains in the early stages of growth? Can
you think of a modern analogy on Earth today? In your modern analogy, can you
identify the location of where the clastic wedge is forming, or will form?
2. How does the size of one of Schloss’ cratonic sequences compare with the
lithostratigraphic units (formation, group, supergroup) that were introduced in
Chapter 5?
3. If the organisms throughout the Early Paleozoic resembled the Ediacaran fauna,
would the carbonate deposits of the Early Paleozoic have been formed
organically, or inorganically? Keep this in mind as Early Paleozoic life is
discussed, in the next chapter.
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R.M. Clary, Ph.D., F.G.S.
Department of Geosciences
Mississippi State University
IMPORTANT TERMS
Appalachian Mobile Belt
Baltica
China
clastic wedge
Cordilleran mobile belt
craton
cratonic sequence
epeiric sea
Gondwana
Iapetus Ocean
Kazakhstania
Laurentia
mobile belt
organic reef
Ouachita mobile belt
Queenston Delta
Sauk Sequence
sequence stratigraphy
Siberia
Taconic orogeny
Tippecanoe Sequence
Transcontinental Arch
SUGGESTED MEDIA
Videos
1. The Earth HAS a History, Geological Society of America
2. Sequence Stratigraphy: The Book Cliffs of Eastern Utah, Open University
3. The Record of the Rocks, Films for the Humanities and Sciences
4. Rainbow of Stone: A Journey through Deep Time in the Grand Canyon, Terra
Slides and Demonstration Aids
1. Earth from Space, slide set, Educational Images, Ltd.
2. Interpretation of Roadside Geology, slide set, Educational Images, Ltd.
3. Ores of Common Metals, rock collection, Science Stuff
CHAPTER 10 – ANSWERS TO QUESTIONS IN TEXT
Multiple Choice Review Questions
1.
2.
3.
4.
5.
b
d
b
b
b
6.
7.
8.
9.
10.
e
a
c
d
b
11. c
12. e
13. d
Short Answer Essay Review Questions
14. Paleozoic paleogeographic reconstructions are based primarily on structural
relationships, climate-sensitive sediments such as red beds, evaporites, and coals,
as well as the distribution of plants and animals.
15 . Cratonic sequences are large-scale lithostratigraphic units representing major
transgressive-regressive cycles bounded by craton-wide unconformities. They are
convenient for studying the geologic history of the Paleozoic because the
transgressions are commonly well preserved. They are widespread and easy to map
and correlate.
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R.M. Clary, Ph.D., F.G.S.
Department of Geosciences
Mississippi State University
16. The Cambrian Grand Canyon sequence includes the Tapeats sandstone, overlain by
the Bright Angel Shale, and the Muav Limestone. This typical transgressive
sequence shows the progradation of a shallow sea, from a nearshore environment,
to an offshore environment, to deeper offshore.
17.
Sequence stratigraphy can be used to make global correlations because the
stratigraphic units were deposited over a wide area and can be found relatively
easily in various locations. It is useful in reconstructing past events because it
allows geologists to subdivide sedimentary rocks into related units that are
bordered by time-stratigraphically significant boundaries. They can also be used for
interpreting and predicting depositional environments.
18. The Appalachian margin of the Laurentian craton changed from a passive to an
active margin in the Ordovician. The Taconic orogeny has the earmarks of a
continent-ocean collision including volcanic activity, intrusions, and facies
patterns.
19. The Michigan Basin was a nearly circular, persistently negative equatorial cratonic
basin during the Paleozoic. This area became ringed with barrier reefs, which
controlled the influx of sea water. As a result of high evaporative rates,
concentrated brines built up within the circling reefs.
20. Carbonate deposition ceased in the Middle Ordovician, and was replaced by clastic
rocks including turbidites, and volcanic sequences. Paleocurrent indicators show
the location of rising Taconic highlands. Numerous unconformities, plutonic
bodies, and the Queenston clastic wedge all attest to mountain-building (orogenic)
processes.
Apply Your Knowledge
1. Just as the Queenston Delta resulted from the erosion of the adjacent Taconic
Highlands, the Catskill Delta is also the result of erosion of the adjacent Acadian
Highlands. If we assume that all of the rocks from the highlands were deposited as
sediments in the adjacent delta, then the volume of the sediments in the Catskill
Delta was about three times the volume of the sediments in the Queenstown Delta.
That means that the volume of the Acadian Highlands must also have been about
three times as great as the volume of the Taconic Highlands. Because the volume of
a block is length * width * height (we assume that the range is shaped like a block,
which is a reasonable approximation for this exercise), we must know what the
length and width of the Taconic Highlands were. We know what the volume of the
Taconic Highlands is (600,000 km3 = volume of Queenston Delta, assuming the
Queenston Delta represents the complete erosion of the Taconic Highlands), and
the height (4000 m), so we need to know the length and width of the Taconic
Highlands. If we assume that the Taconic Highlands were 600 km long, then their
width would be 250 km. Thus, the size of the Taconic Highlands would be 600 km
3
* 250 km * 4 km = 600,000 km .
99
R.M. Clary, Ph.D., F.G.S.
Department of Geosciences
Mississippi State University
If we assume that the length and width of the Acadian Highlands are the same
(which seems unlikely), then the height would be three times greater or 12,000 m,
if the volume of the Catskill Delta was 1,800,000 km3. It also seems unlikely that
all of the sediments from both sets of highlands would end up in the adjacent
deltas.
2. Paleogeographic maps are created by synthesizing various information, including
paleoclimatic, paleomagnetic, paleontologic, sedimentologic, stratigraphic, and/or
tectonic data that are available. However, the data are often imperfect and precise.
The magnetic anomaly patterns preserved in the oceanic crust were destroyed when
much of the Paleozoic oceanic crust was subducted during the formation of
Pangaea. Depending upon which data are used in the reconstruction of
paleogeographic maps, the maps can vary. Also, progressing research adds to our
knowledge base, so older reconstructions will be (hypothetically) based on less data
than more modern reconstructions.
3. Students will include a variety of information about the Grand Canyon. Some
possible topics that students will address may be rock types, transgressions,
sequences, unconformities, fossil information, plate tectonics, and paleogeography
of the region.
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