Quiz 12 Bonus 2 (9:30-9:35 AM) UNIVERSITY OF SOUTH ALABAMA
GY 112: Earth History
Lectures 32 and 33: Mesozoic Sedimentation
Instructor: Dr. Douglas W. Haywick Last Time
Mesozoic Tectonics
A) The Triassic B) The Jurassic C) The Cretaceous
(web notes 31) Mesozoic Tectonics
Tectonics in North America 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 – Dinosaurs 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.