Quiz 12 Bonus 2 (9:30-9:35 AM) UNIVERSITY OF SOUTH ALABAMA

GY 112: Earth History

Lectures 32 and 33: Sedimentation

Instructor: Dr. Douglas W. Haywick Last Time

Mesozoic Tectonics

A) The Triassic B) The C) The Cretaceous

(web notes 31) Mesozoic Tectonics

Tectonics in during the Mesozoic was dominated by docking events involving terranes. Ultimately, continents grow bigger by scooping up geo-crap in their drift direction (Accretionary tectonics)

Sonoman Orogeny Mesozoic Tectonics

Into the Triassic, many more “terranes” (mostly island arcs) began to be scooped up by North America as it drifted WNW

•Brooke Range Terrane (Alaska) •Stikine Terrane (British Columbia) •Sonoma Terrane (Nevada)

Mesozoic Tectonics

In the Jurassic, we start to see terranes with mixed lithologies docking with North America (e.g., Klamath Terrane)

•Major (felsic) intrusions begin Mesozoic Tectonics

In the Cretaceous, more hits and more intrusions. More uplift

•Wrangellia Terrane docks What’s the Point?

The Appalachians and Cordilleran Mountains were both formed via compressional tectonic events.

Appalachians formed through collisions with other continents

Cordilleran Mts. formed via accretionary tectonics Today’s Agenda Mesozoic Sedimentation A) Triassic Sedimentation (Breakup of Pangaea) B) Jurassic Sedimentation (Birth of the Atlantic Ocean) C) Cretaceous Sedimentation (Creation of the Coastal Plain Province) D) Mesozoic-Cenozoic climate (Greenhouse-Icehouse Earth Transition)

(web notes 32) Mesozoic Paleogeography Mesozoic Sedimentation

Triassic •Initial opening of Gulf of Mexico

Mesozoic Sedimentation

Triassic •Initial opening of Gulf of Mexico

Mesozoic Sedimentation

Triassic •Initial opening of Gulf of Mexico

Mesozoic Sedimentation

Triassic Mesozoic Paleogeography Mesozoic Sedimentation

Early Jurassic •Initial flooding of Gulf of Mexico and Northern Atlantic Ocean

Mesozoic Sedimentation

Early Jurassic •Initial flooding of Gulf of Mexico and Northern Atlantic Ocean

Mesozoic Sedimentation

Late-Triassic/Early Jurassic

Mesozoic Sedimentation

Late-Triassic/Early Jurassic

Alabama Mesozoic Stratigraphy Alabama Mesozoic Stratigraphy

Halite (evaporite basin)

Great Salt Lake (evaporite basin)

http://www.americansouthwest.net/utah/photographs700/salt.jpg Alabama Mesozoic Stratigraphy

Quartz Arenite (beach/desert)

Sand dunes in the Gobi Desert Alabama Mesozoic Stratigraphy

Fossil. Limestone & Dolostone (shallow marine with stromatolitic reefs)

The Great Barrier Reef

http://www.anntorrence.com/blog/at-images/gbr_02.jpg Mesozoic Sedimentation

Mid-Late Jurassic •More widespread flooding of Gulf of Mexico and Atlantic Ocean and…

Mesozoic Sedimentation

Late Jurassic …major transgression and flooding of the craton begins

•Sundance Sea

Mesozoic Sedimentation

Late Jurassic …major transgression and flooding of the craton begins

•Sundance Sea •Clastic wedges

Mesozoic Sedimentation

Late Jurassic …major transgression and flooding of the Sundance Sea craton begins

•Sundance Sea •Clastic wedges Mesozoic Paleogeography Mesozoic Sedimentation

Cretaceous •Southern rifting in the Atlantic Ocean

•Gulf of Mexico stops opening

Mesozoic Sedimentation

Cretaceous •Southern rifting in the Atlantic Ocean

•Gulf of Mexico stops opening

•AL Coastal Plain sedimentation

Mesozoic Sedimentation

North South

Only key formations are labeled (those discussed in GY 112) Mesozoic Sedimentation

North South

Only key formations are labeled (those discussed in GY 112) Mesozoic Climate

• High latitudes were warm – 50°F / 10°C – near south pole

Mesozoic Climate

• Period of high sea level – Associated with rapid sea floor spreading – Long period without reversal Long Cretaceous Normal Chron Mesozoic Climate

• Oceans stagnated – Epicontinental black muds when seas spilled over – Normally thin oxygen poor zone expanded

This will change in the early Cenozoic (Late Eocene) Cenozoic Climate

• Oxygen isotopes – Late Eocene cooling • Deep sea foraminifera Cenozoic Climate

• Temperature inferred from leaf margins Cenozoic Climate

Paleocene-Middle Eocene: •No circumpolar current

Late Eocene-today: •Circumpolar current –Permitted development of glaciers on Antarctica Cenozoic Climate Today’s Homework

1. Time Chart 3 due Thursday April 28th 2. Study. Lab Final April 26th 3. Study. Lecture Final May 4th 4. Online class evaluation bonus opportunity soon Next Time

1. Cenozoic overview/tectonics GY 112: Earth History

Lectures 32, 33: Mesozoic Sedimentation

Instructor: Dr. Doug Haywick [email protected]

This is a free open access lecture, but not for commercial purposes. For personal use only.