paleozoic 2: laurentian orogenies - university of south alabama

Quiz Nine (9:30-9:35 AM)

GY 112: Earth History

Lecture 25: Paleozoic 2: More Laurentia!

Instructor: Dr. Douglas W. Haywick

UNIVERSITY OF SOUTH ALABAMA

Last Time

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: 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.

Equator:

Laurentia (Paleozoic North America)

The Humber zone is a region of undeformed, passive continental margin rocks

http://iz.carnegiemnh.org/crayfish/country_pages/newfoundland.htm

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

B

Thrust Faulting

Cratonic Sequences

Middle Ordovician Early Devonian

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…

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

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). •Basins have thick sequences (shorter disconformities)

•Arches/domes have thin sequences (longer disconformities)

Cratonic Sequences

Today’s Agenda

The Paleozoic Part 2

1) Back to Newfoundland 2) Eastern Laurentian Orogenies (Appalachians) 3) Other Laurentian Orogenies (Antler, Ouachita)

(web notes 25)

Laurentia (Paleozoic North America)

The Humber zone is a region of undeformed, passive continental margin rocks

http://iz.carnegiemnh.org/crayfish/country_pages/newfoundland.htm

Laurentia (Paleozoic North America)

Thrust faulting…

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)

Middle Ordovician

Laurentia

Baltica

Island arc A

B

A

B

The resulting Taconic Orogeny first depressed the seafloor (localized transgression) and then pushed previously deposited passive continental margin sediments up into thrust fault mountains. There was only minimal metamorphism and igneous intrusions.

Laurentia (Paleozoic North America)

Laurentia

Baltica

Middle Ordovician

Laurentia (Paleozoic North America)

Laurentia

Baltica

Middle Ordovician

Laurentia (Paleozoic North America)

Late Ordovician

Laurentia

Baltica

A

B

A

B

The next tectonic event (the Acadian Orogeny) was caused by the approach of Baltica

Baltica

Baltica

Laurentia (Paleozoic North America)

Early Devonian

A

B

The Acadian Orogeny was more extensive and more intense (metamorphism and lots of igneous intrusions)

A

B

Laurentia (Paleozoic North America)

Early Devonian

The Acadian Orogeny was more extensive and more intense (metamorphism and lots of igneous intrusions)

Laurentia (Paleozoic North America)

Mississippian

B

Lastly, along comes Gondwanna and…. …well you get the idea. A

B A

B

Laurentia (Paleozoic North America)

Pennsylvannian

B

Lastly, along comes Gondwanna and…. …well you get the idea. A

B A

B

Suture zone

Laurentia (Paleozoic North America)

Pennsylvanian

B

Lastly, along comes Gondwanna and…. …well you get the idea.

Other Laurentian Orogenies

Period North America

Permian Alleghenian Orogeny* (SE)

Pensylvannian

Mississippian Ouachita Orogeny (S)

Devonian Acadian Orogeny* (E) Antler Orogeny (W)

Silurian

Ordovician Taconic Orogeny* (NE)

Cambrian

Other Laurentian Orogenies

Antler Orogeny

Period North America

Permian Alleghenian Orogeny* (SE)

Pensylvannian

Mississippian Ouachita Orogeny (S)

Devonian Acadian Orogeny* (E) Antler Orogeny (W)

Silurian

Ordovician Taconic Orogeny* (NE)

Cambrian

Other Laurentian Orogenies

Period North America

Permian Alleghenian Orogeny* (SE)

Pensylvannian

Mississippian Ouachita Orogeny (S)

Devonian Acadian Orogeny* (E) Antler Orogeny (W)

Silurian

Ordovician Taconic Orogeny* (NE)

Cambrian

Other Laurentian Orogenies

Period North America

Permian Alleghenian Orogeny* (SE)

Pensylvannian

Mississippian Ouachita Orogeny (S)

Devonian Acadian Orogeny* (E) Antler Orogeny (W)

Silurian

Ordovician Taconic Orogeny* (NE)

Cambrian

Other Laurentian Orogenies

Ouachita Orogeny

Period North America

Permian Alleghenian Orogeny* (SE)

Pensylvannian

Mississippian Ouachita Orogeny (S)

Devonian Acadian Orogeny* (E) Antler Orogeny (W)

Silurian

Ordovician Taconic Orogeny* (NE)

Cambrian

Today’s Homework 1. Catch up on your sleep!

Next Time 1. Paleozoic Geology of Alabama