GY 112 lecture notes
D. Haywick (2006)
1
GY 112 Lecture Notes
Paleozoic Overview
Lecture Goals:
A) World Paleogeography (Preceded by a series of videos)
B) Key Tectonic Events
Textbook reference: Levin 7th edition (2003), Chapters 8-10; Levin 8th edition (2006), Chapters 10-12
A) World Paleogeography
We have a tremendous amount of paleogeographic data for the Paleozoic thanks to
dedicated geologists like Chris Scotese. The plate tectonic/paleogeography video that you
will see in class (or have already seen in class depending upon when you read these
notes) is largely a result of Scotese’s efforts to sort through countless pieces of
paleomagnetic, radiometric, paleontological and sedimentological data. In class, we will
discuss the paleogeography of North America (then known as Laurentia) in some detail,
but it is also necessary to discuss the word as a whole.
Two diagrams scanned
directly out of a standard text
book appear on the next pages
(refer to Scotese’s web site
(http://www.scotese.com/) for
high quality images). You will
note that in the early part of
the Paleozoic (see Scotese’s
map to left), several continents
(sub continents really) were
scattered across the equator.
North America (Laurentia)
Siberia and Europe (Baltica)
were surrounded by passive continental margins. Beach sediments (quartz arenite sand)
and shallow marine limestones were deposited all around the shoreline. Because they lie
in warm water, the paleoclimate was tropical, so oolites and reef limestones abounded.
As the Paleozoic progressed, the continents all slowly drifted toward one another. Plate
tectonic collisions began in the early Ordovician, but it wasn’t until the end of the
Paleozoic (the Permian) when almost all of the continents had come together. The
assembly of Pangaea brought with it tremendous changes in world climate. In the early
Paleozoic (Cambrian to Devonian), shallow epeiric seaways were common (including
impressive ones in North America). But as we approached the Mississippian, those
seaways began to vanish. Instead much of the world’s landmasses were covered in
temperate to tropical forests. By the Permian (and well into the Mesozoic Era), the world
became a much dried place. Deserts and dry alluvial basins were very common. Against
this backdrop of paleoclimate change, life had to adopt or it would die off. The evolution
of plants and land animals was strongly controlled by the distribution of water on the
land. As water became more rare, plants and animals had to adapt or else.
GY 112 lecture notes
D. Haywick (2006)
2
Early Paleozoic Paleogeography cartoons
From Scotese, C. 1995. Phanerozoic Plate Tectonic Reconstructions, PALEOMAP Progress Report #36, Department of Geology,
University of Texas, Arlington.
One other thing to note about Paleozoic paleogeography, especially for the latter part of
the era, is the change in ocean distribution. When Pangaea was assembled (see the next
Scotese map a couple of pages up), a large equatorial ocean called the Tethys Sea (or
seaway) developed. Oceans today are dominated by north-south orientations (e.g., the
Atlantic, or Indian Oceans), but back in the end of the Paleozoic, east-west was the way
to go. The Tethys Sea was gradually closed throughout the Mesozoic and Cenozoic. In
fact it is still closing today. All that is left of it is the Mediterranean Sea and for one brief
time not that long ago, it vanished entirely. Put that’s a story for another day.
GY 112 lecture notes
D. Haywick (2006)
3
Late Paleozoic Paleogeography cartoons
From Scotese, C. 1995. Phanerozoic Plate Tectonic Reconstructions, PALEOMAP Progress Report #36, Department of Geology,
University of Texas, Arlington.
C) Key Tectonic Events
This will not be an intensive component for today’s lecture as we will spend considerable
time discussing the origin of the Appalachian Mountains (the key tectonic event in North
America during the Paleozoic). But there was also a lot happening in the rest of the
world. The major orogenies that occurred during the Paleozoic are shown in the table on
the next page. My interpretation of Gondwanna events (Australia, South America, India
Africa, and Antarctica) is intentionally sketchy. Unfortunately, we do not have time to go
over everything that happened in this part of the world.
GY 112 lecture notes
D. Haywick (2006)
4
Major Orogenic Events During the Paleozoic (know the ones in blue!)
Period
North America
Europe
Asia/Gondwanna
Permian
Alleghenian Orogeny*
Hercynian Orogeny
Ural Orogeny
(SE)
Pensylvannian
Mississippian
Acadian Orogeny* (E)
Caledonian Orogeny
Ouachita equivalent
Devonian
Ouachita Orogeny (S)
Silurian
Ordovician
Cambrian
(South America)
Taconic Orogeny* (NE)
Broad deformation
(Southern Gondwanna)
For North America, letters in parentheses show the portion of the continent affected by the specified
orogenic event. E – east; SE-southeast, NE- northeast. Orogenies indicated with * were responsible for the
formation of the Appalachian Mountain in eastern North America
Important terms/concepts from today’s lecture
(Google any terms that you are not familiar with)
Permian (Age of Amphibians)
Paleozoic Era
Laurentia
Cambrian (Age of Marine Invertebrates)
Baltica
Ordovician (Age of Marine
Invertebrates)
Pangaea
Silurian (Age of Fishes)
Tethys Sea
Devonian (Age of Fishes)
Taconic Orogeny
Mississippian (Age of Trees)
Ouachita Orogeny
Pensylvannian (Age of Ferns)
Acadian Orogeny
Carboniferous (Age of Coal)
Alleghenian Orogeny