UNIVERSITY OF SOUTH ALABAMA
GY 112: Earth History
Laurentia Part 2
Instructor: Dr. Douglas W. Haywick
Last Time (before the exam)
The Paleozoic of North America
1) Laurentian passive continental margin
sedimentation
2) Central North America
3) The Grand Canyon (geology)
(web notes 24)
Laurentia (Paleozoic North America)
Consider:
Equator:
1) passive continental margin
2) shallow marine water (shelf)
3) tropical climate
All the way from Labrador to
Alabama
1+2+3= Fossil. Limestone,
oolite, quartz arenite etc.
Laurentia (Paleozoic North America)
http://iz.carnegiemnh.org/crayfish/country_pages/newfoundland.htm
The Humber zone is a region
of undeformed, passive
continental margin rocks
Laurentia (Paleozoic North America)
Classic Paleozoic reef rocks
(stromatolites, rugose and tabulate
corals), quartz arenite sandstone,
shallow marine dolostone, even
some evaporites
Laurentia (Paleozoic North America)
A sudden (localized) deepening
occurred (transgression) and
above that….
Laurentia (Paleozoic North America)
Thrust faulting…
A
B
A
Thrust Faulting
B
Cratonic Sequences
Ignoring tectonics for a moment and you’ll see that sea water covers much of
the craton in these 2 paleogeographic images, but not always to the same
extent…
Middle Ordovician
Early Devonian
Cratonic Sequences
When continents flood during
transgressions, sediment is deposited.
When regressions occur, erosion takes
place producing unconformities
(disconformities)
Thick sedimentary packages between
disconformities are called cratonic
(depositional) sequences.
Cratonic Sequences
Today’s Agenda
The Paleozoic Part 2
1) Eastern Laurentian Orogenies (Appalachians)
2) Other Laurentian Orogenies (Antler, Ouachita)
3) Alabama in the Paleozoic
(web notes 25, 26)
Laurentia (Paleozoic North America)
Even though this coastline of
Laurentia was a passive
continental margin, a plate
tectonic boundary was rapidly
approaching…
A
B
A
B
Laurentia (Paleozoic North America)
The resulting Taconic Orogeny
first depressed the seafloor
(localized transgression) and
then pushed previously
deposited passive continental
margin sediments up into
thrust fault mountains.
Laurentia
A
Island arc
B
Baltica
A
Middle Ordovician
There was only minimal
metamorphism and igneous
intrusions.
B
Laurentia (Paleozoic North America)
Laurentia
Baltica
Middle Ordovician
Laurentia (Paleozoic North America)
Laurentia
Baltica
Middle Ordovician
Laurentia (Paleozoic North America)
The next tectonic event (the
Acadian Orogeny) was caused
by the approach of Baltica
Laurentia
A
B
Baltica
B
A
Baltica
Baltica
Late Ordovician
Laurentia (Paleozoic North America)
The Acadian Orogeny was
more extensive and more
intense (metamorphism and
lots of igneous intrusions)
A
B
A
Early Devonian
B
Laurentia (Paleozoic North America)
The Acadian Orogeny was
more extensive and more
intense (metamorphism and
lots of igneous intrusions)
Early Devonian
Laurentia (Paleozoic North America)
Lastly, along comes Gondwanna
and….
…well you get the idea.
A
B
B
Mississippian
A
B
Laurentia (Paleozoic North America)
Lastly, along comes Gondwanna
and….
…well you get the idea.
A
B
B
A
Pennsylvannian
Suture zone
B
Laurentia (Paleozoic North America)
Lastly, along comes Gondwanna
and….
…well you get the idea.
B
Pennsylvanian
Appalachian Provinces
4 Tectonic provinces are identified
1) Plateaus (undeformed)
2) Valley and ridge (folded/faulted)
3) Piedmont (Highly metamorphosed)
4) Blue Ridge (igneous intrusions)
Appalachian Provinces
We only see the first 3 in Alabama
1) Plateaus (undeformed)
2) Valley and ridge (folded/faulted)
3) Piedmont (Highly metamorphosed)
Appalachian Provinces
We only see the first 3 in Alabama
1) Plateaus (undeformed)
2) Valley and ridge (folded/faulted)
3) Piedmont (Highly metamorphosed)
Appalachian Provinces
Other Laurentian Orogenies
Period
Permian
North America
Alleghenian Orogeny*
(SE)
Pensylvannian
Mississippian
Devonian
Ouachita Orogeny (S)
Acadian Orogeny* (E)
Antler Orogeny (W)
Silurian
Ordovician
Cambrian
Taconic Orogeny* (NE)
Other Laurentian Orogenies
Period
Permian
North America
Alleghenian Orogeny*
(SE)
Pensylvannian
Mississippian
Devonian
Ouachita Orogeny (S)
Acadian Orogeny* (E)
Antler Orogeny (W)
Silurian
Ordovician
Taconic Orogeny* (NE)
Cambrian
Antler Orogeny
Other Laurentian Orogenies
Period
Permian
North America
Alleghenian Orogeny*
(SE)
Pensylvannian
Mississippian
Devonian
Acadian Orogeny* (E)
Ouachita Orogeny (S)
Antler Orogeny (W)
Silurian
Ordovician
Cambrian
Taconic Orogeny* (NE)
Other Laurentian Orogenies
Period
Permian
North America
Alleghenian Orogeny*
(SE)
Pensylvannian
Mississippian
Devonian
Ouachita Orogeny (S)
Acadian Orogeny* (E)
Antler Orogeny (W)
Silurian
Ordovician
Cambrian
Taconic Orogeny* (NE)
Other Laurentian Orogenies
Period
Permian
North America
Alleghenian Orogeny*
(SE)
Pensylvannian
Mississippian
Devonian
Ouachita Orogeny (S)
Acadian Orogeny* (E)
Antler Orogeny (W)
Silurian
Ordovician
Taconic Orogeny* (NE)
Cambrian
Ouachita Orogeny
Appalachian Provinces
We only see 3 tectonic provinces
in Alabama
1) Plateaus (undeformed)
2) Valley and ridge (folded/faulted)
3) Piedmont (Highly metamorphosed)
Appalachian Provinces
We only see the first 3 in Alabama
1) Plateaus (undeformed)
2) Valley and ridge (folded/faulted)
3) Piedmont (Highly metamorphosed)
Appalachian Provinces
We only see the first 3 in Alabama
1) Plateaus (undeformed)
2) Valley and ridge (folded/faulted)
3) Piedmont (Highly metamorphosed)
Appalachian Provinces
Alabama Stratigraphy
(Paleozoic)
Alabama
(Early Paleozoic)
B
Cambro-Ordovician
Alabama
(Mississippian)
B
Alabama
(Pennsylvanian )
Today’s Homework
1. Quiz Thursday (Multiple Choice)
2. Time Chart part 2 due Thursday
(Hadean to end of Proterozoic)
Next Time
Evolution of Plants
Note: Last day to drop 4:59 PM Friday
GY 112: Earth History
Lectures 25, 26: Paleozoic Geology
Instructor: Dr. Doug Haywick
dhaywick@southalabama.edu
This is a free open access lecture, but not for commercial purposes.
For personal use only.