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

UNIVERSITY OF SOUTH ALAAMA GY 112: Earth History Lecture 25: Paleozoic 2: More Laurentia! Instructor: Dr. Douglas W. Haywick

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)

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.

http://iz.carnegiemnh.org/crayfish/country_pages/newfoundland.htm The Humber zone is a region of undeformed, passive continental margin rocks

Classic Paleozoic reef rocks (stromatolites, rugose and tabulate corals), quartz arenite sandstone, shallow marine dolostone, even some evaporites

A sudden (localized) deepening occurred (transgression) and above that.

Thrust faulting A Thrust Faulting A

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) ack to Newfoundland 2) Eastern Laurentian Orogenies (Appalachians) 3) Other Laurentian Orogenies (Antler, Ouachita) (web notes 25)

http://iz.carnegiemnh.org/crayfish/country_pages/newfoundland.htm The Humber zone is a region of undeformed, passive continental margin rocks

Thrust faulting

A Even though this coastline of Laurentia was a passive continental margin, a plate tectonic boundary was rapidly approaching A

Laurentia A Island arc altica A 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. Middle Ordovician

Laurentia altica Middle Ordovician

Laurentia A The next tectonic event (the Acadian Orogeny) was caused by the approach of altica altica A altica altica Late Ordovician

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

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

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

Lastly, along comes Gondwanna and. A well you get the idea. A Pennsylvannian Suture zone

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

Other Laurentian Orogenies Period Permian Pensylvannian Mississippian Devonian Silurian North America Alleghenian Orogeny* (SE) Ouachita Orogeny (S) Acadian Orogeny* (E) Antler Orogeny (W) Ordovician Cambrian Taconic Orogeny* (NE)

Today s Homework 1. Catch up on your sleep! Next Time 1. Paleozoic Geology of Alabama