Download Chapter 11—Late Paleozoic Events

The Earth Through Time
CHAPTER 11—LATE PALEOZOIC EVENTS
CHAPTER OUTLINE FOR TEACHING
I. Late Paleozoic
A. Devonian: began 416 million years ago
B. Mississippian
C. Pennsylvanian
D. Permian: ended 251 million years ago
II. Overview of Pangaea: supercontinent of Late Paleozoic
A. Caledonian and Acadian orogenies: Brought together Laurentia (North
America) and Europe
B. Hercynian orogeny: Gondwana-Laurasia plate collision
C. Alleghenian orogeny: eastern North America
III. Craton of North America (Laurentia)
A. Kaskaskia Sequence
1. Oriskany Sandstone (eastern U.S.)
a. initial deposit of transgression over unconformity
b. pure, clean sand (glass-making ore)
2. Upper Devonian clastics: shed off rising Appalachians
a. Catskill clastic wedge: near mountains (red sands)
b. Chattanooga Shale (black shale)
3. Uppermost Devonian and Mississippian strata
a. “great Mississippian lime bank”
b. thin clastics above
4. Late Mississippian regression
a. widespread erosion and karst development
b. regional and global unconformity
c. SW stream flow across interior Laurentia
B. Absaroka Sequence
1. Deposited on top of regional unconformity
a. thicker near the eastern highlands
b. change in rock type from clastics (east) to carbonates (west)
2. Unique cyclic sediments (Pennsylvanian): “cyclothems” consist of 10
beds with minor disconformities at top and bottom of cyclothem
a. shale (marine): youngest layer
b. limestone (marine)
c. shale (marine)
d. limestone (marine)
e. shale (near-shore)
f. coal (swamp)
g. gray underclay (lake)
h. freshwater limestone (lake)
i. sand shale/siltstone (lake)
j. sandstone (river deposits): oldest layer
3. Origin of cyclothems: repeating sea-level rise and fall due to glacial eustasy
a. glacial eustasy: Gondwanaland at South Pole with ice cap
b. regional subsidence: alternative hypothesis
IV.
Instability in southwestern continental interior
A. New Mountains in the West
1. Colorado Mountains (includes Front Range-Pedernal, Uncompahgre, and
Zuni-Defiance uplifts)
2. Oklahoma Mountains (Amarillo, Washita, and Arbuckle uplifts)
B. Paradox and other nearby basins:
1. Filled with sediment from the Uncompahgre Mountains
a. Paradox Basin initially open to the sea
b. Paradox became blocked and evaporites formed
c. Paradox now important petroleum reservoir
2. All became restricted in their connection to Permian seas
C. Permian Basin (western Texas)
1. Exposed in the Guadalupe Mountains
2. Over 14,000 feet of lagoon, reef, and open basin carbonate sediments
3. Estimated water depth: 500 meters
V. Eastern Margin of North America (Laurentia)
A. Acadian orogeny
1. Collision with Baltica
2. Collision with Avalon terrane (microcontinent)
B. Alleghenian orogeny
1. Collision with northwestern Africa that affected southern Appalachians
2. Effects felt in western U.S. such as raising Colorado and Oklahoma
C. Acadian orogeny: built northern Appalachian Mountains
1. Catskill clastic wedge (Devonian)
a. sandstone/shale facies document orogenic pulses
b. deposited in a tropical climate; lots of vegetation
c. major new source for oil and gas, especially in the Marcellus Shale where
there is new horizontal drilling and fracturing activity
2. Catskill equivalent in Europe: Old Red Sandstone of the Caledonian orogeny
D. Post-Acadian Events
1. Pocono facies: younger mimic of Catskill
a. black shale (anoxic sea): west
b. shale
c. sandstone (shoreline)
d. conglomerate (mountain front): east
2. Coal-bearing facies: channel sandstones cut in gray shales with coals
E. Alleghenian Orogeny
1. Northern Gondwanaland collides with Laurussia (N. Africa-eastern U.S.
and S. America-Gulf Coast)
2. Builds southern Appalachians and Ouachita Mountains
3. Result of “thin-skinned” tectonics
4. Characteristic orogenic structures
a. Valley and Ridge Province and the Appalachian Plateau
b. vast metamorphic Blue Ridge and Piedmont regions
5. Characteristic post-orogenic sediments
a. red sandstone and shale (non-marine)
b. geometry like Queenston and Catskill clastic wedges
c. examples: Dunkard and Monongahela Series of eastern U.S.
(Pennsylvanian-Permian)
F. Ouachita Deformation
1. Pre-collision sediments (Early Devonian-Late Mississippian)
a. carbonates on shelves of Laurentia and Gondwanaland
b. bedded chert in basin center (novaculite)
2. Closing-phase sediments (Late Mississippian-Late Pennsylvanian)
a. carbonate shelves die
b. 8000 m of graywacke in basin
3. Collision characteristics
a. northward thrust faults
b. intensive folding
4. Permian = stable time after abrupt end to orogenesis
5. Orogenic mountains today
a. Ouachita Mountains (AR, OK)
b. Marathon Mountains (TX)
c. subsurface folded structures (U.S. Gulf Coast)
VI. Western Orogeny: Cordilleran
A. Antler Orogeny (Late Devonian-Pennsylvanian)
1.
2.
3.
4.
Island-arc collision with west coast of Laurentia
Vast thrust faulting and folding of back-arc sediments: NV, ID
Thick clastic wedges in basins: UT, WY, CA
Volcanism (Mississippian-Permian): CA, NV, ID, MT, BC
B. Later Orogenesis: due to collision with second island arc (Permian-Early
Triassic)
1. Cassier (British Columbia)
2. Sonoma (southwestern U.S.)
C. Shelf-area East of Antler Highlands
1. Quiet shallow sea, lowlands
2. Deposition of Grand Canyon area stratigraphy of Permian age: stability
and transgression
a. Kaibab Limestone (shallow marine)
b. Coconino and DeChelly sandstones (eolian sand dunes)
c. Phosphoria Formation: phosphatic shales and limestones (basinal
sediments)
VII.
Northern Europe
A. “Old Red Continent”: sedimentation from orogenic clastic wedges
B. Uralian Sea
1. Eastern side of the continent
2. Closure produced the Ural Mountains
C. Hercynian orogeny
1. Structure: intensive folding, thrust faulting, granitic intrusions, volcanism
2. Clastic Wedge: heavily vegetated thus forming “coal measures” of Europe
VIII.
Gondwanaland of Late Paleozoic
A. Movement: across South Pole to near equator where it collided with
Laurussia
(Hercynian and Alleghenian orogenies)
B. Other Marginal Orogenies
1. Andean (with South America)
2. Tasmanian (with eastern Australia)
C. Vast Glaciers of Pennsylvanian-Permian Polar Cap
1. Great tillite deposits of S. America, S. Africa, Antarctica, and India
2. Record of 4 glacial advances (330-250 million years ago)
3. Two centers of ice accumulation
a. southwest Africa
b. eastern Antarctica
4. Interglacial stages = cool, damp climates
a. thick coals produced
b. Glossopteris flora flourished
D. Post-Glacial Continent
1. Vast non-marine red beds (sandstone and shale)
2. Ancestral mammals developed on continent
IX.
Climate of Late Paleozoic
A. Zonation: paralleled lines of latitude
B. Warm to Hot: within 30o of equator
C. Reduced CO2 in Atmosphere: toward end of Paleozoic, brought cooling and
then Late Paleozoic ice age
X. Mineral Products
A. Fossil Fuels: coal, oil, gas
1. Coal: present in all post-Devonian rocks
a. Appalachian basin (eastern U.S.)
b. Illinois basin (IL, MO)
c. European basins
d. Permian coals: China, Russia, India, S. Africa, Australia
2. Oil and Gas
a. Devonian reefs of Williston Basin (Alberta, MT, SD)
b. Appalachian basin (PA, WV)
c. Mississippian-Pennsylvanian basins of mid-continent U.S. and
Rocky Mountains
d. Permian basins and reefs (TX)
e. Late Paleozoic basins (North Sea, Europe)
B. Sedimentary Deposits
1. Late Paleozoic Na and K salts
2. Late Permian phosphates
C. Metallic Ores (ores that accompany volcanism)
1. Hercynian-Alleghenian ores: Sn, Cu, Ag, Au, An, Pb, Pt
2. Uralian ores
3. Asian orogenic ores: China, Burma, Japan, Malaya
Answers to Discussion Questions
1. The southern Appalachians (Alleghenian orogeny) and the Ouachita Mountains were
built during the latter part of Late Paleozoic when Gondwanaland and Laurussia
were assembled into Pangaea. This was mainly the result of Gondwanaland’s
northern motion causing the two continents to join near the Late Paleozoic equator.
2. The Alleghenian and Hercynian orogenies occurred at about the same time because
of the convergence of plates that were assembling Pangaea.
3. A displaced terrain will have sharp boundary discontinuities and consist of rock types
and fossil contents very unlike surrounding rocks. The terrain will likely be highly
deformed, especially at the margins. The terrain will likely be situated in a tectonic
(orogenic) zone or belt. An island-arc terrain will be composed mainly of volcanics;
a micro-continental terrain will have a variety of rock types, including sedimentary.
4. Upper Paleozoic rocks are easily divided into two great cratonic sequences
because there is a widespread, distinctive erosional surface (disconformity)
between Upper Mississippian and Lower Pennsylvanian strata across much of North
America. The lower sequence is Kaskaskia, spanning most of Devonian and
Mississippian.
The upper sequence, Absaroka, spans Pennsylvanian and
Permian, and extends into Lower Jurassic.
5. The Old Red Continent was a Middle Devonian feature named for the Old Red
Sandstone, a unit cropping out across Europe south of the Caledonian Mountains.
The Old Red Sandstone is composed mainly of sandstone red beds.
6. The Old Red Continent and its mirror-image equivalent across the mountains, the
Catskill clastic wedge, are so similar that early geologists who had seen both were
very impressed.
7. Southern hemisphere (Gondwanaland) glaciation during Late Paleozoic is
documented by extensive layers of tillite, scour marks left in bedrock by glaciers over
parts of South America, south Africa, Antarctica, and India, evidence of glacialinterglacial deposition, and patterns of ice advance over vast areas.
8. The association of red sandstone, salt, and gypsum suggests oxidizing conditions in
a dry, arid terrestrial area. Such conditions existed during Permian, after regression
of the sea from Baltics and interior Gondwanaland.
9. A cyclothem is a repetitive alternation of marine and non-marine strata recording a
single cycle of minor rise and full of sea level. Eustatic conditions are best
accounted for by periodic changes in water volume due to glacial ice buildup and
melting. Other water-level changes might be due to inflation and deflation of midocean ridges. Tectonic conditions might include periodic elevation and relation of
crustal segments due to stresses on plates.
10. The Chattanooga Shale was deposited in an anoxic marine environment. It is
difficult to imagine how a vast shallow epicontinental sea could be the site for such
deposition. In order to account for the anoxia, the historical geologist must
hypothesize vast overproduction of plankton to seriously deplete the oxygen level in
the sea water. As this does not occur to such a degree in the modern ocean, an
actualistic analogue for the Chattanooga sea does not exist.
11. The South Pole was located in the same place as today but at that time the
southern part of Pangaea covered the area. This has been determined by using
paleomagnetic data and inferences from the rock and fossil record as to latitude.
Further, analysis of the distribution of glacial sediments and ice-formed striations
shows the location of glacial centers near the pole. Coral distribution would be
confined to a belt within ± 30o latitude of the equator, thus the paleogeographic
arrangement could be checked for precision regarding the equatorial realm.
12. Upper Paleozoic rocks yield important metallic resources including: tin, zinc and
lead, and gold. These rocks yield important non-metallic resources including: coal,
oil and gas, and phosphates.
13. Pennsylvanian algal bioherms of the Paradox basin contain oil and gas because of
their porosity and setting near the margin of the basin where hydrocarbons have
been generated.
14.
d
15.
c
16. e
Chapter Activities
Student activities for in-depth learning.
1. Using the resources on the Catskill clastic wedge that is posted on the web at
http://csmres.jmu.edu/geollab/vageol/vahist/catskilenv.html, review and brief describe
the depositional environments of the Catskill clastic wedge and its same-age
(equivalent) sediments. Make a sketch of the regional environments, both in map view
and in cross-section based on information from this web page (and/or similar web
pages).
2. Take a look at the page on the Middle and Late Devonian “Old Red Continent” (ORC)
at http://csmres.jmu.edu/geollab/vageol/vahist/oldredcont.html. How was the ORC
formed? Make a sketch and/or describe in writing the modern continents that made up
parts of the “ORC.” Where was the equator at this time and what were the prevailing
winds like at this time?
CHAPTER 11—LATE PALEOZOIC EVENTS
CHAPTER OVERVIEW
Late Paleozoic represents one of the most interesting segments of geologic time. It is a
continuation of Early Paleozoic, wherein patterns of marine transgressions and regressions are
illustrated in the formation of the Kaskaskia and Absaroka Cratonic sequences. This instability
resulted in the formation of epicontinental shallow seas of the interior portion of the craton while
at the converging plate margins, orogenic deformation led to mountain building. Late Paleozoic
episodes of mountain building are illustrated in the Acadian, Allegheny, and Ouachita orogenies
of eastern North America. The western margin of North America is examined using the Antler
and Sonoma orogenies which resulted in major stratigraphic changes in sedimentation patterns.
Once the major orogenic events and cratonic sequences of North America are defined, an
overview is given of how the separate land masses formed during earlier time intervals combined
into the supercontinent Pangea.
LEARNING OBJECTIVES
By reading and completing information within this chapter, you should gain an
understanding of the following concepts:


Explain and define the major cratonic sequences—Kaskaskia, Absaroka—of
North America during Late Paleozoic.
Describe the orogenic events of eastern North America that led to the




formation of the Acadian, Allegheny, and Ouachita orogenies including
geographic location, associated lithology, and relative time of occurrence.
Explain the orogenic history of western North America that led to the Antler
and Sonoma orogenies.
Explain the probable causes of a cyclothem and how this depositional feature
helps define stratigraphic boundaries.
Describe the paleoclimates of Late Paleozoic; consider Permian evaporite
deposits in the northern hemisphere; consider tillite deposits of the southern
hemisphere during Carboniferous and Permian.
Describe the major mineral resources and the locations where they were
formed during Late Paleozoic.
CHAPTER OUTLINE
I.
The Seas Come in, the Seas Go Out
A. The Kaskia Sequence
1. Mineral Assemblages
2. Sedimentation
3. Chattanooga Shale
B. The Absaroka Sequence
1. Mississippian + Pennsylvanian = Carboniferous
2. Cyclothems
II.
Unrest along the Western Margin of the Craton
A. Colorado’s Uncompahgre Mountains
1. Paradox Basin
2. Evaporites
B. The Permian Basin of West Texas and New Mexico
III.
To the East, a Clash of Continents
A. The Catskill Clastic Wedge
B. After the Devonian
C. The Alleghenian Orogeny
D. The Ouachita Deformation
IV.
Sedimentation and Orogeny in the West
V.
Europe in the Late Proterozoic
VI.
Gonwana During the Late Paleozoic
VII.
Climates of the Late Paleozoic
VIII.
Mineral Products of the Late Paleozoic
A. Coal
B. Petroleum
C. Other Economic Minerals
KEY TERMS (pages given in parentheses)
Absaroka cratonic sequence (306): Erosion of layers of sediment deposited
on the Kaskaskia sea floor began, only to be interrupted by the advance of a
second sea, the Absaroka Sea.
Acadian Orogeny (303, 305, 315): An episode of mountain building in the
northern Appalachians during Devonian.
Alleghenian Orogeny (305, 315): Late Paleozoic episodes of mountain building
along the present trend of the Appalachian Mountains. Likely caused by the Late
Carboniferous collision between northwest Africa and the southern part of the
Appalachian belt of Laurentia.
Antler Orogeny (323): Late Devonian and Mississippian episode of mountain
building involving folding and thrusting along a belt across Nevada to
southwestern Alberta.
Avalon Terrane (315): A displaced continental fragment that had collided with
the Appalachians before Devonian.
Caledonian Orogeny (318): A major early Paleozoic episode of mountain
building affecting Europe, which created an orogenic belt, the Caledonides,
extending from Ireland and Scotland northwestward through Scandinavia.
Cassiar Orogeny (324): Permian-Triassic disturbance of the Cordilleran regions
in British Columbia.
Catskill clastic wedge (315): A buildup of Middle and Upper Devonian clastic
sediments as a broad, complex clastic wedge derived from the erosion of
highland areas formed largely as a consequence of the Acadian Orogeny.
Chattanooga Shale (306): Shale that developed in a clastic wedge located
along the western side of mountains that existed along the eastern margin of
North America during Late Devonian. It is widespread and easy to recognize. It
contains uranium and had been found to be 350 million years old. It is rich in
finely disseminated pyrite and organic matter. It is black or dark gray and
contains few, if any, fossils of bottom-dwelling invertebrates.
These
characteristics indicate that the Chattanooga accumulated in stagnant, oxygendeficient waters.
cratonic sequence (303): A large package of sedimentary rock, in some places
100s to 1000s of feet thick, which are bounded by regional unconformities; these
sequences represent sedimentary deposits formed between great transgressions
and regressions of the sea across the continents, including the North American
continent.
cyclothem (303, 308): A cyclic repetition of groups of marine and nonmarine
strata. Cyclothems are valuable because they can be correlated over great
distances. Cyclothems are particularly characteristic of Pennsylvania strata.
Dunkard Group (321): Composed of mostly continental reddish sandstones and
gritty shales of Permian-Pennsylvanian age.
Gondwana (305): The great southern hemisphere supercontinent of Late
Paleozoic.
Hercynian Orogeny (305): A major Late Paleozoic orogenic episode in Europe
that formed the ancient Hercynian Mountains. Today, only the eroded stumps of
these mountains are exposed in areas where the cover of Mesozoic and
Cenozoic strata has been removed by erosion.
Kaskaskia cratonic sequence (303, 306):
A sequence of DevonianMississippian sediments, which is bounded above and below by regional
unconformities and recording an episode of transgression followed by full
flooding of a large part of the craton and by subsequent regression.
Laurussia (305): The Caledonian and Acadian orogenies brought North
America and Europe together as the combined landmass named Laurussia.
Subsequently, the plate bearing Gondwanaland began to close on Laurussia. By
Late Carboniferous, it had come into contact with Laurussia, bringing on the
Hercynian Orogeny of Central Europe and Allegheny Orogeny of Eastern North
America.
Monongahela Group (321):
Composed of mostly continental PermianPennsylvanian reddish sandstones and gritty shales.
novaculite (321): A term applied originally to rocks suitable for whetstones and,
in America, to white chert found in Arkansas. Now applied to very tough,
uniformly grained cherts composed of microcrystalline quartz.
Pangea (304): In Alfred Wegener’s theory of continental drift, the supercontinent
that included all present major continental masses. By Permian, most of the
separate land masses formed during earlier time intervals were assembled into
Pangea.
Pocono Group (319): Group of formations known to have particularly coarse
sediments, including conglomerates. Pocono sandstones form some of the
resistant ridges of the Appalachian Mountains in Pennsylvania. Westward, the
Pocono section thins and changes imperceptibly into marine siltstones and
shales.
Sonoma Orogeny (324): Middle Permian orogenic movements, the structural
effects of which are most evident in western Nevada. Probably caused by the
collision of an eastward-moving island arc against the North American
continental margin in west-central Nevada.
thin-skin tectonics (321): A kind of deformation in which the basement rocks
are largely unaffected and the overlying “skin” of weaker sedimentary rocks
breaks into multiple-thrust faults.
Late Paleozoic Events 2
PALEOZOIC OVERVIEW
FIGURE 10-1 Major events of the Paleozoic Era.
PALEOZOIC ERA
Paleozoic can be divided into:
Early Paleozoic = Cambrian, Ordovician and Silurian
Late Paleozoic = Devonian, Mississippian, Pennsylvanian, and Permian
160 million years long
Mississippian & Pennsylvanian Periods are also referred to with one name Carboniferous Period.
LATE PALEOZOIC PLATE GEOGRAPHY
The supercontinent Pangea assembled as the continents collided during Late
Paleozoic.
Larger continents grew by addition of island arcs and microcontinents around their
edges.
FIGURE 11-1 Paleogeography of the Late Paleozoic.
LATE PALEOZOIC OROGENIES OF EASTERN NORTH AMERICA
Continental collisions caused several orogenies or mountain-building events in
eastern North America.
Acadian orogeny and Caledonian orogeny
Laurentia + Baltica Laurasia
and
A volcanic island arc (Avalon terrane or Carolina terrane) collides with eastern North
America.
Alleghanian orogeny (eastern North America) and Hercynian orogeny (central Europe)
Laurasia + Gondwana Pangea
LATE PALEOZOIC OROGENIES IN EASTERN NORTH AMERICA
The Acadian and Alleghanian orogenies were the result of the closure of the
Iapetus Ocean and continental collisions which resulted in the formation of the
supercontinent Pangea.
PHYSIOGRAPHIC PROVINCES OF THE APPALACHIAN REGION IN EASTERN NORTH
AMERICA.
FIGURE 11-27 Eastern U.S. physiographic
provinces. LATE PALEOZOIC SEDIMENTARY SEQUENCES
Shallow epicontinental seas transgressed and regressed across Laurasia (North
America) during Late Paleozoic as the glaciers melted and enlarged.
These sequences are bounded by (or separated by) unconformities.
LATE PALEOZOIC SEDIMENTARY SEQUENCES
Two major transgressions occurred in North America during Late Paleozoic:
Kaskaskia (Devonian-Mississippian)
Absaroka (Pennsylvanian-Permian)
During regressions, such as the one between Mississippian and Pennsylvanian, the
former seafloor was exposed to erosion, creating one of the most widespread
regional unconformities in the world.
Green = sedimentary deposits
Yellow = missing strata associated with unconformities
NORTH AMERICAN CRATONIC SEQUENCES
DEVONIAN PALEOGEOGRAPHY
As Late Paleozoic began, the continents were fairly fragmented and separate,
particularly in the Northern Hemisphere.
(After C. R. Scotese, et al., 1979, Jour. Geol. 83(3):217–277) 12
DEVONIAN PALEOGEOGRAPHY
There is an extensive sedimentary record for Devonian.
Note that North America sat on the equator, with warm, tropical climatic conditions.
(After C. R. Scotese, et al., 1979, Jour. Geol. 83(3):217–277)
DEVONIAN PALEOGEOGRAPHY
A large continental landmass named Gondwana (composed of South America,
Africa, India, Antarctica, and Australia) was present in the southern hemisphere, on
or near the South Pole.
(After C. R. Scotese, et al., 1979, Jour. Geol. 83(3):217–277)
DEVONIAN PALEOGEOGRAPHY
Laurentia and Baltica collided to form Laurasia in the Caledonian orogeny affecting
northeastern Canada, Greenland, and Europe).
(After C. R. Scotese, et al., 1979, Jour. Geol. 83(3):217–277)
DEVONIAN PALEOGEOGRAPHY
A volcanic island arc or exotic terrane, called the Avalon terrane (or Carolina
terrane), collided with Eastern North America in the Acadian orogeny. A thick
sequences of sedimentary rocks are interbedded with rhyolitic volcanic rocks and
granitic intrusions.
(After C. R. Scotese, et al., 1979, Jour. Geol. 83(3):217–277)
DEVONIAN PALEOGEOGRAPHY
The Acadian highlands in eastern North America (orange), form a continuous belt
with the Caledonian Mountains adjacent to Greenland and Europe.
Erosion of these mountains resulted in the deposition of the Catskill Red beds in
the Appalachian area, and the Old Red Sandstone in Europe.
DEVONIAN PALEOGEOGRAPHY
Sea levels were high worldwide during Devonian (indicating that there were no
glaciers).
Much of the North American continent was flooded by shallow seas.
DEVONIAN SEDIMENTARY DEPOSITS
The seas regressed from the continents at the end of Early Paleozoic as a result of
the Ordovician-Silurian glaciation.
Gradual flooding of the North American craton occurred during Late Paleozoic,
reaching its maximum extent during Mississippian Period. This new inland sea was
called the Kaskaskia sea.
DEVONIAN SEDIMENTARY DEPOSITS
In eastern North America, initial deposits of the Kaskaskia sea were clean quartz
sands, such as the Devonian Oriskany Sandstone, used for glass making because of
its purity.
As the sea continued to transgress, shales, and then limestones with reef-forming
coral were deposited over the sands.
In areas where water circulation was more restricted, evaporites were deposited.
Reefs and carbonates indicate a warm climate.
Evaporites suggest dry conditions.
DEVONIAN SEDIMENTARY DEPOSITS
After the Acadian orogeny, carbonate sedimentation was followed by deposition of
clastic sediments.
Clastic sediments are thicker and coarser to the east, nearer their source area in
the Acadian highlands.
Primarily continental red beds (stream deposits).
Wedge-shaped deposit called the Catskill clastic wedge or Catskill delta (although
these are not deltaic deposits).
DEVONIAN SEDIMENTARY DEPOSITS
Similar Devonian red beds are also present in Europe, such as the Old Red
Sandstone.
The red color of the sandstone indicates deposition under oxidizing conditions in
continental or non-marine environments.
FIGURE 11-20 Upper Devonian sedimentary rocks in the northeastern U.S.;
Catskill clastic wedge in New York.
FIGURE 11-21 Panorama of the Catskill clastic wedge viewed from a point
above southcentral
Pennsylvania.
Isopach (sediment thickness) and lithofacies map of Upper Devonian in the eastern
U.S.
The Catskill clastic wedge sediments are thicker and coarser in the east.
The sediments become finer-grained westward, away from the Acadian highland
source area.
Catskill clastic wedge deposits
DEVONIAN SEDIMENTARY DEPOSITS
CHATTANOOGA SHALE
Farther west, black shales were deposited in a thin unit (less than about 10-20 m
thick) over a wide area (Chattanooga Shale) during Late Devonian and Early
Mississippian.
Offshore equivalent of the 3000 m thick Catskill clastic wedge.
An important marker bed for regional correlation.
High organic carbon content, along with finely disseminated pyrite, and uranium.
Chattanooga Shale was deposited in stagnant, oxygen-deficient water.
WILLISTON BASIN
In the Williston Basin area (South Dakota, Montana, and adjacent Canada),
extensive reefs formed.
Restricted circulation within the reef-encircled basin led to the deposition of thick
evaporite deposits.
The reefs of the Williston Basin provided permeable structures into which
petroleum migrated, forming rich oil fields.
CARBONIFEROUS
In North America, Carboniferous consists of two periods: Mississippian and
Pennsylvanian.
Mississippian is Early Carboniferous.
Pennsylvanian is Late Carboniferous.
MISSISSIPPIAN
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.
PENNSYLVANIAN
Pennsylvanian rocks are dominated by coal-rich sediments that were deposited in
swamps and deltas.
Coal deposits are particularly well developed in Pennsylvania.
MISSISSIPPIAN PALEOGEOGRAPHY Landmass in eastern North America and
Europe (yellow), formed as the mountains (orange) eroded after Caledonian and
Acadian orogenies.
Although a large mountain range was present in the Appalachian area, another
orogeny was soon to occur, as indicated by the arrows and the words "Africa
approaching" along the right side of the map.
MISSISSIPPIAN PALEOGEOGRAPHY
Much of North America was covered by a shallow epicontinental sea.
North America sat on the equator, so temperatures were warm.
Note the Antler highlands in the western U.S.
MISSISSIPPIAN PALEOGEOGRAPHY
MISSISSIPPIAN SEDIMENTARY DEPOSITS
By Mississippian, the Acadian highlands were reduced in size by erosion, and were
no longer releasing large quantities of sediment.
In the east, near the remaining highlands, non-marine shales, sandstones, and
conglomerates were deposited.
These sediments belong to the Pocono Group.
MISSISSIPPIAN SEDIMENTARY DEPOSITS
As muddy sediment from the eroding highlands decreased, carbonate deposition
became widespread in the warm, shallow Kaskaskia sea.
Mississippian limestones contain abundant crinoids, blastoids, bryozoans, and
fusulinid foraminifera.
The widespread blanket of carbonate rocks deposited during this time is called the
great Mississippian lime bank.
In places, Mississippian limestones are more than 700 m thick.
CRINOIDS (top) National Museum of Natural History/ Smithsonian Institution; (right) )
35 MISSISSIPPIAN SEDIMENTARY DEPOSITS
Sands, clays, and thin layers of carbonates were deposited during Late
Mississippian time as the Kaskaskia sea regressed.
These rocks are a source of petroleum in Illinois.
They appear to have been deposited in stream valleys developed on the former
seafloor.
Farther west, the Williston basin (South Dakota, Montana, and part of Canada)
continued to have extensive reefs developed around.
MISSISSIPPIAN SEDIMENTARY DEPOSITS
In the Gulf Coast area, slow deposition continued from Early Devonian to Late
Mississippian.
Carbonates predominated in the more northerly shelf zone.
Cherty rocks called novaculites were deposited in deeper waters to the south.
Novaculites are composed of microcrystalline quartz, which has been subjected to
heat and pressure.
Arkansas novaculite is used as a whetstone to sharpen steel knives and tools.
MISSISSIPPIAN SEDIMENTARY DEPOSITS
Graywackes and shales spread into the depositional basin near the end of
Mississippian, forming a clastic wedge more than 8000 m thick, that thickened and
coarsened to the south, where a new mountain range had formed and was eroding.
The remnants of this mountain range are the Ouachita Mountains of Arkansas and
Oklahoma, and the Marathon Mountains of southwestern Texas.
MISSISSIPPIAN SEDIMENTARY DEPOSITS
The Kaskaskia sea retreated from the craton at the end of Mississippian.
This event is marked by one of the most widespread unconformities in the world.
This unconformity separates Mississippian from Pennsylvanian.
The overlying Pennsylvanian rocks were deposited under very different conditions.
ALLEGHANIAN OROGENY
During Late Paleozoic, northwestern Africa collided with southeastern North
America, causing the Alleghanian orogeny, and building the Appalachian mountains.
The orogeny began during Mississippian and continued through Pennsylvanian and
Permian.
ALLEGHANIAN OROGENY
•South America collided with the Gulf Coast region of North America, forming the
Ouachita Mountains, a southwestern continuation of the Alleghanian orogenic
belt.
The Alleghanian orogeny produced folds in the Appalachian Valley and Ridge
province, and large thrust faults in the southern Appalachians.
Many folds are asymmetrically overturned to the northwest, and surfaces of thrust
faults dip to the southeast.
THE ALLEGHANIAN OROGENY
Blue Ridge and Piedmont metamorphic and igneous rocks form a sheet ranging from
6-15 km thick, overlying relatively flat-lying lower Paleozoic sedimentary rocks. This
type of tectonic deformation is called "thin-skinned tectonics."
THE ALLEGHANIAN OROGENY
PLATE TECTONICS MODEL FOR THE CONTINENTAL COLLISIONS DURING LATE
PALEOZOIC PANGEA
By Late Carboniferous, a large continental landmass called Pangea, had formed by
the collision of Laurasia (North America plus Europe) with Gondwana (the southern
continents of Africa, South America, Australia, Antarctica, and India).
LATE PALEOZOIC OROGENIES OF WESTERN NORTH AMERICA
In the western part of North America, the Antler orogeny began during Devonian
with the subduction of oceanic lithosphere beneath the western margin of the
continent.
The Antler Orogeny continued into Mississippian and Pennsylvanian.
LATE PALEOZOIC OROGENIES OF WESTERN NORTH AMERICA
A volcanic island arc collided with the western margin of North America, crushing
sediments and causing thrust faulting (Roberts Mountains Thrust Fault of Nevada).
Continental rise and slope deposits were thrust as much as 80 km over shallow
water sediments of the former continental shelf.
47
FIGURE 11-32 Interpretation of the Cordilleran orogenic belt shortly after the
Antler orogeny.
PANGEA ON THE SOUTH POLE
The supercontinent, Pangea, sat over the South Pole. When a continent is over a
pole, conditions are right for a glaciation, if the climate is cold and if sufficient
moisture is present.
IAPETUS OCEAN CLOSED
The Iapetus Ocean (or Proto-Atlantic), completely closed by Late Carboniferous.
Closure of the Iapetus Ocean disrupted global ocean circulation and caused
currents to be diverted from the tropics to more polar areas, contributing to
glaciation.
LATE PALEOZOIC EVAPORITES
The presence of evaporites (E) indicates that the climate was at least locally dry.
This was probably due in part to changes in global oceanic and atmospheric
circulation induced by the closure of the Iapetus, as well as by orogeny.
LATE PALEOZOIC GLACIAL DEPOSITS
Glacial deposits are present in the southern hemisphere, indicating that a
glaciation occurred during Carboniferous and Permian.
PENNSYLVANIAN PALEOGEOGRAPHY
Large landmass in the east, with extensive lowlands (yellow).
Appalachian Mountains (orange) have formed as a result of the Alleghanian
orogeny.
PENNSYLVANIAN PALEOGEOGRAPHY
Sediment eroding from the Appalachian Mountains was transported to the west
into the epicontinental sea that covered much of North America during Mississippian.
These sedimentary deposits have built a broad plain to the west, with alternating
non-marine and marine deposits, as the sea transgressed and regressed.
PENNSYLVANIAN PALEOGEOGRAPHY
Coal swamps formed along the western edge of the Appalachian Mountains, in
what was basically a tropical rainforest setting.
PENNSYLVANIAN PALEOGEOGRAPHY
Uplifts in the southern and southwestern North America (Uncompahgre mountains
or ancestral Rockies, and others), and the Antler Mountains in the western U.S.
The erosion of the Antler Mountains provided detrital sediment that was
transported into adjacent basins.
Thick sequences of Pennsylvanian and Permian shelf sediments accumulated in
the area now occupied by the Wasatch and Oquirrh Mountains in Utah.
PENNSYLVANIAN SEDIMENTARY DEPOSITS
PENNSYLVANIAN SEDIMENTARY DEPOSITS
The Absaroka sea began to transgress upon the North American craton near the
beginning of Middle Pennsylvanian.
The rocks in the eastern half of the U.S. are predominantly interbedded marine and
nonmarine sediments, indicating the advance and retreat of the sea.
Each nonmarine-marine sequence is called a cyclothem.
PENNSYLVANIAN CYCLOTHEM
A typical Pennsylvanian cyclothem contains 10 units.
The lower half consist of nonmarine sediments, topped by a coal deposit.
The coal is overlain by marine deposits, indicating the advance of the sea into the
swampy, vegetated area.
MARINE AND NON-MARINE DEPOSITS
The repetitious interbedding of non-marine and marine sedimentary deposits
indicates either:



OR
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.
SOUTHWESTERN NORTH AMERICA
SW part of the North American craton experienced mountain building during
Pennsylvanian.
The highlands are called the Uncompahgre Mountains (or ancestral Rockies) in
southwestern Colorado, and the Oklahoma Mountains of western Oklahoma.
These mountains and related uplifts resulted from movement along large, nearly
vertical faults.
COLORADO FRONT RANGE
The Colorado Front Range-Pedernal uplifts extending north-south through central
Colorado formed at this time.
Precambrian igneous and metamorphic rocks are now exposed in the cores of
these eroded mountain ranges.
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
OTHER UPLIFTS
Other uplifts also formed, including the Zuni-Fort Defiance uplift, the Amarillo
mountains, and the Oklahoma mountains (represented today by the Arbuckle and
Wichita mountains).
The origin of these mountains may be related to the collision of Gondwana along
the southern edge of the North American craton in the Ouachita orogenic belt.
Crustal adjustments to relieve stress may have resulted in the deformation that
produced the highlands and associated basins (such as the Early Pennsylvanian
Paradox basin, which contains evaporites and petroleum deposits).
OTHER UPLIFTS
The Paradox basin lies southwest of the Uncompahgre mountains.
Clastic sediments from the mountains were deposited along the northeastern side
of the basin.
PARADOX BASIN
•The Paradox basin was flooded by the Absaroka sea during Early
Pennsylvanian.
•Shales were deposited over Mississippian limestone.
•The basin became restricted and thick beds of evaporites (salt, gypsum and
anhydrite) were deposited.
•Reef-like algal mounds, associated with fossiliferous and oolitic limestones,
developed along the western rim of the basin.
•The reefs serve as petroleum reservoirs.
•Near the end of Pennsylvanian, the basin filled with arkosic sediments eroded
from the Uncompahgre highlands.
REGRESSION OF THE ABSAROKA SEA
The Absaroka sea, which began its transgression at the beginning of
Pennsylvanian, began a slow and irregular regression before the end of
Pennsylvanian, which continued into Permian.
PERMIAN PALEOGEOGRAPHY
During Permian, the continents collided 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.
PERMIAN PALEOGEOGRAPHY
Continental collision was accompanied by orogeny, and the Appalachian mountain
chain reached its peak during the Alleghanian orogeny.
PERMIAN PALEOGEOGRAPHY
Late Permian was a time of widespread regression of the seas.
The global map above indicates that sea levels were low worldwide.
The vast epicontinental seas that once covered North America and parts of other
continents were gone.
PERMIAN PALEOGEOGRAPHY
The Gondwana part of Pangea continued to sit atop the South Pole, and glaciation
continued into Permian.
PERMIAN PALEOCLIMATIC INDICATORS
Red circles are coal deposits (humid climates during interglacial periods, possibly
associated with glacial meltwaters). Blue triangles are glacial tillites. Irregular green
areas are evaporites (arid climates). 74
PERMIAN EVAPORITES
Cold air holds less moisture than warm air, and the climate became arid during
Permian.
Evaporite deposits (gypsum and salt) accumulated in the green areas on the map.
There are more Permian salt deposits than any other age.
END OF THE COAL SWAMPS
Drying of climates at low latitudes led to contraction of coal swamps and
extinctions among spore-bearing plants and amphibians that required moist
conditions.
Because of the drying, gymnosperms (seed plants, including conifers) replaced
many spore-bearing plants, which require moist conditions.
OROGENY AND CLIMATE
Orogenies probably also affected the climate.
Locations of mountains can affect climate and control precipitation (rain-shadow
effect).
Deserts form on the downwind side of mountain ranges.
PERMIAN PALEOGEOGRAPHY
The eastern 2/3 of North America consisted of lowlands, undergoing erosion.
Continental red beds were deposited locally.
PERMIAN PALEOGEOGRAPHY
Appalachian mountains in the east.
Ouachita mountains in the southeast.
Farther west are the "Ancestral Rockies."
Antler Mountains have been eroded, and are called uplands.
Subduction and volcanism continue in the far west.
PERMIAN SEDIMENTARY DEPOSITS
The Absaroka sea continued its regression during Permian.
Fossiliferous limestones were deposited in the Absaroka sea, overlain in places by
shales, red beds, and evaporites.
The Kaibab Limestone, which forms the cliffs along the rim of the Grand Canyon, is
a Permian carbonate deposit.
PHOSPHATE DEPOSITS IN NW U.S.
Deep marine basin in the Wyoming, Montana, and Idaho area filled with cherts,
sandstones, and mudstones of the Phosphoria Formation.
Formation named for layers of dark phosphatic sediments and phosphorites.
Phosphorite = dark gray variety of calcium phosphate. May have formed by
upwelling of phosphorus-rich sea water from deeper parts of basin.
Phosphate is mined for fertilizers and other products.
PERMIAN BASINS IN WEST TEXAS AND NEW MEXICO
Several irregularly subsiding basins (such as the Delaware basin) developed
between shallow submerged carbonate platforms.
PERMIAN BASINS IN WEST TEXAS AND NEW MEXICO
Reefs formed along the basin edges (Capitan Limestone).
The ancient reef forms the steep El Capitan promontory in the Guadalupe
Mountains.
PERMIAN BASINS IN WEST TEXAS AND NEW MEXICO
In the shallow water lagoons behind the reefs, thin limestones, evaporites, and red
beds were deposited.
•FIGURE 11-27 Eastern U.S. physiographic provinces. Source: After F. A. Cook
et al., 1979, Geology 7:563–567.
• FIGURE 11-4 Devonian Period paleography. Source:
• FIGURE 11-20 Upper Devonian sedimentary rocks in the northeastern U.S.;
Catskill clastic wedge in New York. Source: (A) After W. D. Sevon, 1985, Geol.
Soc. Amer. Special Paper ZOI: 71–90, and W.G. Ayrton, 1963, Pennsylvania
Geol. Survey Report. 39(4):3–6. (B) Based on Classic Studies by G. H. Chadwick
and G. A. Cooper Completed between 1924 and 1942.
• FIGURE 11-21 Panorama of the Catskill clastic wedge viewed from a point
above southcentral Pennsylvania. Modified from Woodrow, D.L. and Sevon,
W.D., eds., The Catskill Delta: Geological Society of America Special Paper
201:51-63.
• FIGURE 11-8 Mississippian Period paleogeography. Source: .
• FIGURE 11-26 Plate tectonic model for late Paleozoic continental collisions.
Source: After P. E. Socks and D. T. Secor Jr. 1990, Science 25:1702–1705.
• FIGURE 11-32 Interpretation of the Cordilleran orogenic belt shortly after the
Antler orogeny. Source: .
• FIGURE 11-9 Pennsylvanian Period paleogeography. Source: .
• FIGURE 11-11 Coal-bearing cyclothems. Source: .
• FIGURE 11-12 Principal highland areas, southwestern part of the craton,
Pennsylvanian time. Source: .
• FIGURE 11-13 The Pennsylvanian Period across eastern Colorado and New
Mexico. Source: .
• FIGURE 11-15 Generalized cross-section through the Paradox basin in
Utah/Colorado. Source: After D.L. Baars et al., 1988, Basins of the Rocky
Mountain region, in Sloss, L.L., ed., Sedimentary Cover of North American
Craton. Geological Society of America.
• FIGURE 11-16 Division of the Permian Period into four stages in North
America. Source: After P. B. King, 1948, U.S. Geol. Survey, Professional Paper
215.