Paleozoic Late Tectonics
Late Paleozoic
410-250 million years ago.
Divided into Devonian, Carboniferous,
Permian.
By the Permian Pangea was assembled.
During this time
Acadian & Caladonian orogenies
Alleghenian & Hercynian orogenies
Late
Paleozoic
Paleozoic climate
Blue-tillite
Red-coal
Greenevaporites
Paleozoic glacial striations
Devonian
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Late Paleozoic
Land areas were small with low relief until this
time.
Calcareous organisms abounded.
Warping of the crust in N.A. was widespread in
the early Devonian.
During this time an immense barrier reef extended
northwest into Canada. These reefs now yield
petroleum reserves in the Canadian Rockies.
Devonian was a time of severe cratonic
deformation due to effects of mountain building in
eastern N.A. ACADIAN MOUNTAINS.
Kaskaskia -the next cratonic
sequence
Kaskaskia Sea
First major transgression of late Paleozoic.
Did not regress until Mississippian.
This produced the Oriskany sandstone.
You may have seen it!
Oriskany sandstone.
Very resistant.
Very mature.
Hawk Mountain, PA
Catskill mountains
The Catskill clastic wedge is named for the
Catskill Mountains in southeastern NY.
Catskill sediments coarsen towards the east
and reect elevation and erosion of
Acadian orogeny -Devonian in age.
Catskills were actually a delta eroding off
the Acadian mountains!
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Catskills
More Catskill info
Tropical world.
Abundant land plants.
Red beds.
Catskills
Catskill clastic wedge
Catskills had a twin
Acadian and Caladonian
The Old Red sandstone of Northern Europe
Same formation, but
Catskills from the erosion of Acadians.
While Old Red SS from erosion of
Caladonian.
Remember, they are only 10my between
them.
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Acadia National park
Catskills
Devonian
Old Red
Standstone
Silurian
Acadian age rocks at Great Falls NP
Chattanooga Shale
This shale was transported from the
mountains into the inland sea to the West.
Contains Uranium dated as 350myr.
Contains pyrite and organic matter
indication of a low oxygen environment.
Putting it together
Devonian
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The late Paleozoic was time of great
changes, during the Carboniferous and
Permian times (362-250myr), the earth was
inuenced by tectonic activities that raised
the craton above sea level.
The Mississippian period (362-322myr) was
characterized by the last widespread
carbonate and aragonite producing an
epeiric sea in N.A. The reefs were smaller
than middle Paleozoic reefs.
Absaroka sequence
At the end of the Mississippian a major
regression drained the entire craton.
Warping & faulting occurred before the sea
returned to the craton in the middle
Pennsylvania.
This is the Absaroka sequence
Absaroka sequence
Pennsylvanian through Triassic.
Continental sandstones, shales, coal beds.
Mississippian
Remember
Mississippian + Pennsylvanian =Carboniferous
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Mississippian
Last inland sea in
Paleozoic.
Crinoids were
dominant.
Enough to produce
crinoid limestones
Mississippian crinoidal limestone
But what is a crinoid?
An echinoderm.
Relative to the
starsh.
Pentameral
symmetry.
At the of end the Mississippian
Carbonate production ceased.
Tectonic events start up again.
Alleghanian orogeny
Hercynian orogeny.
Pennsylvanian
Pennsylvanian
Age of our largest coal deposits
Think change in sea level!
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Coal forest
(Lycopsids and Synopsids)
Pennsylvanian
Beginning in the Late Mississippian and
continuing through early Permian, the strata
deposited over the N.A. craton displays a
repetitive patterns or cyclothems.
The eastern part of the craton has coal bearing non
marine rocks.
The central part of the craton has cyclothems and
marine rocks.
While the western part of the craton was covered
by a huge sand dune desert which was covered
~25 times by a marine limestone environment.
Cyclothems or PACs
cyclothems
This alternation between marine & nonmarine
points to many transgressions & regressions,
possibly 100 of them during this time period!
They represent a short interval in time (~1myr),
because of a eustatic change in sea level.
The land was of very low relief, and thus a small
change in sea level could inundate large areas, or
greatly enlarge the land areas.
Remember that
Trangressive-regressive sequences
Cyclothems=
Trangressive-Regressive sequences=
Punctuated Aggregated Cycles =PACs
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PACs
Final Deformation in Paleozoic
Alleghanian orogeny
Related to Ouachita orogeny
Related to Hercynian orogeny
NOTE: Taconic + Acadian + Alleghanian
= Appalachian
This produced PANGEA
Alleghanian
orogeny
Alleghanian orogeny
The nal deformation of the Appalachian
belt.
Occurred between the Late Pennsylvanian
and Late Triassic periods.
One huge thrust sheet ~10km thick and
includes Cryptozoic basement rock.
This sheet was displaced 260km west!
Appalachian orogenic belt
Cross section of Appalachian
provinces
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Evolution of Appalachians
Meanwhile in the South..
The Ouachita deformation
The southern most part of the Alleghanian
orogenic belt.
While carbonates were found in the north,
novaculites are associated with this region.
Metamorphosed bedded cherts
novaculites
So where are the mountains now?
Since the Permian, these southern
mountains have almost completely eroded
away.
Remnants are the Ouachitas (AR, OK) and
the Marathon (TX) mountain chains.
Now to the West Coast
In early Paleozoic the region was a passive
margin.
In Devonian-beginning of the Antler
Orogeny
Antler orogeny
A volcanic arc
Lasted through Carboniferous.
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Antler orogeny cross section
And in the western U.S. in the
Permian
The Sonoma orogeny.
First of 4 orogenies to affect the west coast.
Well also talk about this is the Mesozoic
and Cenozoic!
PANGEA
TA-DA!!
Meanwhile in Europe
A microcontinent made up of Southern
South America, part of western Antarctica
and New Zealand converged on southern
Gondwana.
The resulting mountain building was named
the Gondwana orogeny
All this produced PANGEA!
Climates of Late Paleozoic
Economic minerals from this
period
Coal
That means trees and swamps were around!
In the next chapter
PACS
Petroleum
Phosphates
Metals
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Coal
Petroleum
Phosphorus
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