1. No category

Paleozoic Earth History
North America
Catskill Mountains
Appalachian Mountains
Coal Deposits
Dinosaur Fossils
Minerals
Pangaea
Chapter 20
Introduction

In 1815, William Smith, a canal builder, published the
world’s first geologic map. His hand-painted map
represented over 20 years of work.
Introduction
England is rich in geologic
history. Development of geology
proceeded rapidly with the
naturalists of the 19th century.
 The Paleozoic history is well
represented there, involving
several episodes of mountain
building and sea level changes,
mostly related to plate tectonics
and glaciation.

Continental Architecture:
Cratons and Mobile Belts

Most continents consist of two major
components:
 1.
relatively stable craton
over which epeiric seas
transgressed and regressed
 2. surrounded by mobile
belts in which mountain
building took place
Fig. 20.1, p. 505
Continental Architecture:
Cratons and Mobile Belts
seas – shallow
seas covering part of
the craton
 Mobile belts – elongate
areas of mountain
building, primarily
created during plate
convergence
 Epeiric
Fig. 20.1, p. 505
Paleozoic Paleogeography

Six major continents existed at the beginning of the
Paleozoic Era.
 Four were located near the paleoequator

Baltica, China, Gondwana, Kazakstania,
Laurentia and Siberia
Fig. 20.2a, p. 506
Fig. 20.2a, p. 506
Paleozoic Paleogeography

Early-Middle Paleozoic Global History

During the Early Paleozoic (Cambrian-Silurian):
 Laurentia
was moving northward and
 Gondwana moved to a south polar location, as
indicated by tillite deposits
Fig. 20.2a, p. 506
Paleozoic Paleogeography

Late Paleozoic Global History
the Late Paleozoic (Devonian – Permian):
 Baltica and Laurentia collided to form Laurasia.
 Siberia and Kazakhstania collided and finally
were sutured to Laurasia.
 During
Fig. 20.3b, p. 508
Fig. 20.3b, p. 508
Paleozoic Paleogeography

Late Paleozoic Global History
the Late Paleozoic (Devonian – Permian):
 Gondwana, at the South Pole, experienced
several glacial-interglacial periods, resulting in
global sea-level changes and transgressions and
regressions along the low-lying craton margins.
 During
Fig. 20.3b, p. 508
Paleozoic Paleogeography

Late Paleozoic Global History
 Laurasia
and Gondwana underwent a series of
collisions beginning in the Carboniferous.
 During the Permian, the formation of Pangaea
was completed. Surrounding the
supercontinent was a global ocean,
Panthalassa.
Fig. 20.4b, p. 510
Fig. 20.4b, p. 510
Paleozoic Evolution of North
America

The geologic history of North America can be
divided into cratonic sequences that reflect
cratonwide sea transgressions and regressions.

There are 6 cratonic
sequences recognized in
North America.
Fig. 20.5, p. 511
Paleozoic Evolution of North
America
The study of cratonic
sequences is called
sequence stratigraphy.
 In sequence stratigraphy
rocks are studied within a
time-stratigraphic
framework related to
facies and bounded by
unconformities.

Fig. 20.5, p. 511
Fig. 20.5, p. 511
The Sauk Sequence

Neoproterozoic – Early Ordovician: The Sauk Sea was
the first major sequence to transgress onto the North
American craton.
Fig. 20.7, p. 513
The Sauk
Sequence

During the transgressive portions of each cycle, the
North American craton was partially to completely
covered by shallow seas in which a variety of clastic
and carbonate sediments were deposited.
Fig. 20.7, p. 513
The Sauk Sequence

At its maximum during the Late Cambrian, a sea
covered the craton except for parts of the Canadian
Shield and the Transcontinental Arch.

Transcontinental Arch
- a series of large,
northeast-southwest
trending islands.
Fig. 20.6, p. 512
Cambrian Paleogeography of North America
Fig. 20.6, p. 512
The Tippecanoe
Sequence

Middle Ordovician – Early Devonian: The
Tippecanoe sequence began with deposition of an
extensive sandstone over the eroded Sauk.

During Tippecanoe time,
extensive carbonate
deposition took place.
Fig. 20.8, p. 514
Ordovician Paleogeography of North America
Fig. 20.10, p. 514
The Tippecanoe Sequence

Middle Ordovician – Early Devonian
 In
the Middle-Late
Silurian, large barrier
reefs enclosed basins,
resulting in evaporite
deposition within these
basins.
Fig. 20.10, p. 516
Tippecanoe
Reefs
Fig. 20.9, p. 515
The Tippecanoe Sequence
 Reefs
in the Michigan
Basin restricted the
flow of sea water and
allowed excessive
evaporation to
precipitate salt
deposits (evaporites).
Fig. 20.10, p. 516
Fig. 20.12, p. 520
Silurian Paleogeography of North America
Fig. 20.10, p. 516
Tippecanoe Reefs and Evaporites:
Michigan Basin
Fig. 20.11, p. 517
Barrier
reef
Laminar
Anhydrite
stromatoporoid
Halite
Evaporite
Carbonate
Pinnacle
reef
Stromatoporoid
barrier reef
Limestone from the carbonate facies.
Stromatolites
Algal
Coral algal
Crinoidal
Laminar
stromatoporoid
Cross section of a stromatoporoid colony from the
stromatoporoid barrier reef facies.
Niagara
Formation
Clinton
Formation
Core of rock salt from the
evaporite facies.
Stepped Art
Fig. 20-11, p. 517
The Tippecanoe Sequence

The End of the Tippecanoe Sequence
 By
early Devonian, the
Tippecanoe Sea had regressed
to the cratonic margin, exposing
extensive low-lands.
 Mild warping of the craton
produced many domes, arches
and basins in North America.
 Most of these were eroded
down by the time a new sea,
the Kaskaskia, transgressed.
Fig. 20.1, p. 505
Fig. 20.1, p. 505
The Kaskaskia Sequence

(Middle Devonian – Late Mississippian)

The basal beds of the
Kaskaskia sequence
deposited on the exposed
Tippecanoe surface were
either:
 sandstones
that formed
from sands derived
from the eroding
Acadian Highlands or
 carbonates
Fig. 20.13, p. 521
Devonian Paleogeography of North America
Fig. 20.13, p. 521
The Kaskaskia Sequence

Middle to Late Devonian Reef Development
in Western Canada
 Most
of the Kaskaskia
sequence is dominated by
carbonates and associated
evaporites.
 The Devonian Period was a
time of major reef building.
 A large barrier reef system
restricted the flow of oceanic
water, creating conditions for
evaporite precipitation.
Fig. 20.14, p. 522
The Kaskaskia Sequence

Black Shales

Widespread black shales were
deposited over large areas of the
craton during the Late Devonian and
Early Mississippian.

Chattanooga Shale –
 Thin-bedded
 Highly-radioactive
(uranium-rich)
 Source rock for oil and gas
Fig. 20.15, p. 522
The Kaskaskia Sequence

Black Shales
 Origin
highly debated
 Probable depositional
environment:
 Undisturbed anaerobic bottom
waters
 Reduced supply of coarse
sediment
 High organic productivity in
overlying waters
Fig. 20.15, p. 522
The Kaskaskia Sequence

The Late Kaskaskia—A Return to Extensive
Carbonate Deposition
 The
Mississippian
Period was dominated
for the most part by
carbonate deposition.
 The broad Kaskaskian
epeiric sea covered
most of North America.
Fig. 20.16, p. 523
Mississippian Paleogeography of North America
Fig. 20.16, p. 523
Pennsylvanian Paleogeography of North America
Fig. 20.17, p. 524
The Absaroka Sequence
(Pennsylvanian – Early Jurassic)

What Are Cyclothems and Why
Are They Important?
Pennsylvanian Period
 Gondwanan ice sheets were
probably responsible for
multiple transgressions and
regressions of sea level over
the low-lying North American
craton.

Fig. 20.17, p. 524
The Absaroka Sequence
(Pennsylvanian – Early Jurassic)

What Are Cyclothems and
Why Are They Important?
 The
transgressions and
regressions resulted in:
 cyclothems and
 the formation of coal
swamps
Fig. 20.17, p. 524
Cyclothems
Fig. 20.18, p. 525
The Absaroka Sequence

Cratonic Uplift—The Ancestral Rockies
 Cratonic
mountain
building, specifically
the Ancestral Rockies,
occurred during the
Pennsylvanian Period.
 Resulted in thick
nonmarine detrital
rocks and evaporites
being deposited in the
intervening basins.
Fig. 20.19, p. 527
The Absaroka
Sequence

The Late Absaroka—More
Evaporite Deposits and Reefs



By the Early Permian, the Absaroka
Sea occupied a narrow zone of the
south central craton.
Here, several large reefs and
associated evaporites developed.
By the end of the Permian Period, the
Absaroka Sea had retreated from the
craton.
Fig. 20.22, p. 529
Fig. 20.23, p. 529
Permian Paleogeography of North America
Fig. 20.20, p. 528
History of the Paleozoic Mobile
Belts

Mountain-building activity took place primarily
along the eastern and southern margins (known
as mobile belts) of the North American craton
during the Paleozoic Era.

Appalachian Mobile Belt
 Several
orogenies occurred in the Appalachian belt
during the Paleozoic:
 Taconic
 Caledonian (Europe)
 Acadian
 Hercynian-Alleghenian
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Taconic Orogeny
 Throughout
Sauk time (Neoproterozoic to Late
Ordovician), the Appalachian region was a
broad, passive continental margin.
Fig. 20.24a, p. 530
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Taconic Orogeny
 During
Sauk time, a divergent boundary existed
along the eastern side of Laurentia widening the
Iapetus Ocean.
Fig. 20.24a, p. 530
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Taconic Orogeny
 In
the mid-Ordovician, carbonate deposition
ceased and was replaced by deepwater black
shales, graywackes and volcanics, marking the
development of a subduction zone and the
beginning of the orogeny.
Fig. 20.24b, p. 530
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Taconic Orogeny

The final stage of the
orogeny was marked by
a thick sandstone
deposit, the Queenston
clastic wedge, thinning
away from the Taconic
mountains.
Fig. 20.25, p. 531
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Taconic Orogeny

The Queenston wedge
represents a delta that
formed from the erosion
of the Taconic Highlands
mountain belt in eastern
New York, central
Massachusetts and
Vermont.
Fig. 20.25, p. 531
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Caledonian Orogeny
The Caledonian mobile
belt is the European
equivalent of the Taconic
mobile belt, forming the
western border of Baltica
facing the Iapetus Ocean.
 The orogeny peaked
during the Late Silurian
and Early Devonian.

Fig. 20.24b, p. 530
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Acadian orogeny

The Acadian mobile belt
occurred along a convergent
oceanic-continental
boundary between Laurentia
and Baltica during the Late
Silurian into the Devonian.
The Acadian orogeny marks
the continental-continental
collision during the
Devonian.
Fig. 20.26, p. 531
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Acadian orogeny
The closing of the Iapetus
Ocean ended by forming a
new continent called
Laurasia.
 A new clastic wedge, the
Catskill Delta, formed on
the west side.
 This delta contains
conglomerates,
sandstones and shales.

Fig. 20.26, p. 531
History of the Paleozoic Mobile
Belts

The Old Red Sandstone  The Catskill clastic wedge has
a European counterpart in the
Old Red Sandstone.
 The Old Red Sandstone
formed from the clastics of the
Caledonian Highlands, and
spread eastward onto the
Baltica craton in the Devonian.
 It is famous, as is the Catskill
Delta, for its freshwater fish
and early amphibian fossils, as
well as early land plants.
Fig. 20.26, p. 531
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Hercynian-Alleghenian
Orogeny
The Taconic, Caledonian, and Acadian orogenies were
all related to the closing of the Iapetus Ocean and the
formation of Laurasia.
 The Hercynian mobile belt in Europe and the
Alleghenian mobile belt (Appalachian) in North America
mark the zone where Laurasia collided with Gondwana.
 The Hercynian-Alleghenian orogeny begins at its north
end in Mississippian time and slowly moves to the south
suturing together the continents as it goes.

History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Hercynian-Alleghenian Orogeny

The first continent-continent collision in the Mississippian is
between eastern Laurasia and Gondwana - Hercynian Orogeny
(Mississippian-Permian).
Fig. 20.3b, p. 508
Fig. 20.3b, p. 508
History of the Paleozoic Mobile
Belts

Appalachian Mobile Belt: Hercynian-Alleghenian
Orogeny

Next, the central and southern parts of the Appalachian
mobile belt from New York to Alabama were folded and
thrust toward the craton as eastern Laurasia and
Gondwana collided – Alleghenian Orogeny
(Pennsylvanian-Permian).

The Hercynian, Alleghenian and Ouachita orogenies
represent the final joining of Laurasia and Gondwana to
form the supercontinent of Pangaea.
Fig. 20.4b, p. 510
History of the Paleozoic Mobile
Belts

Cordilleran Mobile Belt: Antler Orogeny
 In
middle Paleozoic, a
volcanic arc formed off the
western margin of Laurentia.
 The subduction created thick
deep water deposits that
were thrust upon the craton
when the volcanic arc
collided with the craton in
Late Devonian.
Fig. 20.13, p. 521
History of the Paleozoic Mobile
Belts

Cordilleran Mobile Belt: Antler orogeny
The
Antler orogeny marks
the collision. The Antler
Highlands are composed of
the deep water deposits that
were thrust onto the craton.
Fig. 20.27, p. 532
History of the Paleozoic Mobile
Belts

Ouachita Mobile Belt
 Ouachita Orogeny

Mountain building occurred in the
Ouachita mobile belt beginning in
Late Mississippian, Pennsylvanian
and Early Permian.

Thrusting created a large mountain
range extending from the Ouachita
mountains in Arkansas to the
Marathon mountains in far West
Texas.
Fig. 20.28, p. 533
What Role Did Microplates and Terranes
Play in the Formation of Pangaea?
 During
the Paleozoic Era, numerous terranes such
as Avalonia, existed and played an important role in
forming Pangaea.
Fig. 20.4b, p. 510
What Role Did Microplates and Terranes
Play in the Formation of Pangaea?


In addition to large-scale plate interactions, microplate activity
played an important role in the formation of Pangaea. There
were many microplates and terranes of various sizes present
during the Paleozoic.
These were all involved in the formation of Pangaea.
Fig. 20.4 b, p. 510
Paleozoic Mineral Resources

Paleozoic-age rocks
contain a variety of
mineral resources,
including:
 petroleum
 coal
 ores of iron, lead,
zinc, and other
metallic deposits
Fig. 20.29, p. 534
Paleozoic Mineral Resources
 building
stone
 limestone for cement
 silica sand
 evaporites
Fig. 20.29, p. 534
End of
Chapter 20