UNIVERSITY OF SOUTH ALABAMA
GY 112: Earth History
Lectures 30 and 31:
Extinctions and Mesozoic Geology Part 1
Instructor: Dr. Douglas W. Haywick
Last time we covered….
Chordates
A) Fish to Amphibians
B) Amphibians to Reptiles
C) Reptiles to Mammals
Vertebrate
Evolution
Vertebrate
Evolution
Mammals
Reptiles
Reptile
Evolution
Mammal
Evolution
Today’s Agenda
Mesozoic Overview
A) The end of the Paleozoic
B) Mesozoic time frame and evolutionary developments
C) Paleogeography and key tectonic events
(web notes 30)
Mesozoic Tectonics
A) The Triassic
B) The Jurassic
C) The Cretaceous
(web notes 31)
Geological Time Boundaries…
Were defined primarily on the basis of paleontological changes.
Geological Time Boundaries…
Were defined primarily on the basis of paleontological changes.
Periods: significant changes
Geological Time Boundaries…
Were defined primarily on the basis of paleontological changes.
Periods: significant changes
Eras: really significant changes (i.e., Mass extinctions)
Mass Extinctions
Cenozoic
Phanerozoic
Phanerozoic
Era
Years
(0 to 65 MA)
Major Extinction
Mesozoic
(65 to 245 MA)
Paleozoic
(245 to 550 MA)
Major Extinction
Mass Extinctions
Extinctions have
always been a part of
the rock record
Mass Extinctions
Extinctions have
always been a part of
the rock record
Mass Extinctions
The K-T extinction
event is widely
believed to have been
the result of an
asteroid impact in the
Yucatan Peninsula
Mass Extinctions
The K-T extinction
event is widely
believed to have been
the result of an
asteroid impact in the
Yucatan Peninsula
(Chicxulub)
Mass Extinctions
The K-T extinction
event is widely
believed to have been
the result of an
asteroid impact in the
Yucatan Peninsula
(Chicxulub)
Mass Extinctions
The impact was
suspected in the early
1980’s because of the
presence of high
quantities of iridium (a
metal found in
asteroids) in clay
layers right at the K-T
boundary.
http://www.palaeos.com/Mesozoic/Triassic/Images/iridium-fern-spike.jpg
Mass Extinctions
The Yucatan site was
found when geologists
examined seismic
lines run for petroleum
exploration.
Mass Extinctions
The crater is
approximately 180 km
wide. The asteroid
impacted in a shallow
marine, tropical
environment.
Moscow Landing
Stratigraphy
T
K
Beasties from ZoomDinosaurs.com
Section from Smith (1997)
Mass Extinctions
New studies are suggesting
that the Yucatan impact
might not have been the
only cause of the K-T mass
extinction. It might have
occurred 300 KA before
the end of the Cretaceous.
Multiple hits?
Mass Extinctions
New studies are suggesting
that the Yucatan impact
might not have been the
only cause of the K-T mass
extinction. It might have
occurred 300 KA before
the end of the Cretaceous.
Including one in India (named
Shiva) which is 500 km wide
Multiple hits?
Mass Extinctions
New studies are suggesting
that the Yucatan impact
might not have been the
only cause of the K-T mass
extinction. It might have
occurred 300 KA before
the end of the Cretaceous.
Including one in the Indian
Ocean that 65 million years ago
would have impacted near what
is today India. The crater is
named Shiva and is 500 km
wide
Multiple hits?
Mass Extinctions
The cause(s) of the
Permian-Triassic
extinction remain
uncertain….
… but whatever it
was, it caused
unprecedented
changes
Mass Extinctions
The cause(s) of the
Permian-Triassic
extinction remain
uncertain.
Mass Extinctions
The cause(s) of the
Permian-Triassic
extinction remain
uncertain.
•Asteroid strike
Mass Extinctions
The cause(s) of the
Permian-Triassic
extinction remain
uncertain.
•Asteroid strike
•Cosmic radiation
Mass Extinctions
The cause(s) of the
Permian-Triassic
extinction remain
uncertain.
•Asteroid strike
•Cosmic radiation
•Climate change
Mass Extinctions
The cause(s) of the
Permian-Triassic
extinction remain
uncertain.
•Asteroid strike
•Cosmic radiation
•Climate change
•Plate tectonics
Mass Extinctions
The cause(s) of the
Permian-Triassic
extinction remain
uncertain.
•Asteroid strike
•Cosmic radiation
•Climate change
•Plate tectonics
•“Nemesis”
Mass Extinctions
The cause(s) of the
Permian-Triassic
extinction remain
uncertain.
•Asteroid strike
•Cosmic radiation
•Climate change
•Plate tectonics
•“Nemesis”
•Flood basalts
Mass Extinctions
Deccan traps
in India (K-T
boundary)
At the end of the
Permian and the end
of the Cretaceous,
extensive basalt lava
flows covered a good
chunk of the surface
up to 1000’s of feet
thick.
Major climate change!
http://volcano.und.edu/vwdocs/volc images/southeast asia/india/Mambai.jpg
Mass Extinctions
At the end of the
Permian and the end
of the Cretaceous,
extensive basalt lava
flows covered a good
chunk of the surface
up to 1000’s of feet
thick.
The Siberian Traps are much more
extensive than the Deccan traps
Major climate change!
Mesozoic Overview
Mesozoic Overview
Phanerozoic
Era
Years
Cenozoic
(0 to 65 MA)
Mesozoic
(65 to 245 MA)
Paleozoic
(245 to 550 MA)
Mesozoic Overview
Cretaceous
Late
(65-135 MA)
Middle
Age of the
Angiosperms
Early
Mesozoic
Jurassic
Late
(203-135 MA)
Middle
Age of the
Cycads
Early
Triassic
Late
(245-203 MA)
Middle
Early
Age of the
Reptiles
Mesozoic Overview
Cretaceous
Late
(65-135 MA)
Middle
Age of the
Angiosperms
Early
Mesozoic
Jurassic
Late
(203-135 MA)
Middle
Age of the
Cycads
Early
Triassic
Late
(245-203 MA)
Middle
Early
Age of the
Reptiles
The entire Mesozoic is
also called the Age of
the Reptiles
Mesozoic Overview
Many major evolutionary
changes occurred during
the Mesozoic
Mesozoic Overview
Many major evolutionary
changes occurred during
the Mesozoic
•Rise of the dinosaurs
Mesozoic Overview
Many major evolutionary
changes occurred during
the Mesozoic
•Rise of the dinosaurs
•Rise of the cephalopods
Mesozoic Overview
Many major evolutionary
changes occurred during
the Mesozoic
•Rise of the dinosaurs
•Rise of the cephalopods
•Major microfossils (coccoliths)
Mesozoic Overview
Many major evolutionary
changes occurred during
the Mesozoic
•Rise of the dinosaurs
•Rise of the cephalopods
•Major microfossils (coccoliths)
•Rise of the angiosperms
Mesozoic Paleogeography
Mesozoic Paleogeography
Mesozoic Paleogeography
Mesozoic Paleogeography
Mesozoic Paleogeography
Mesozoic animation
Mesozoic Tectonics (Key Events)
Period
North America
Orogenies
Cretaceous
Jurassic
Separation of India
from Gondwanna
Nevadan Orogeny
(J-K)
Sevier Orogeny
(J-K)
Triassic
Devonian
Other Major Events
Sonoma Orogeny
(Triassic)
Antler Orogeny
(Devonian)
Opening of Atlantic
Ocean
Opening of Gulf of
Mexico
Mesozoic Tectonics
The separation of Gondwanna
and Laurentia began in the
Triassic.
Initial flooding of the “Atlantic
Ocean” began in the Jurassic.
(More on sedimentation next time )
This was the start of a new drift
direction for North America;
WNW
Paleozoic Tectonics
Now we have convergence
along what had been a pretty
stable (passive) continental
margin (except for the Antler
Orogeny) in the Devonian
Paleozoic Tectonics
Speaking of which…
… when the Antler Orogeny
occurred, an island arc stuck
onto the side of Laurentia. This
clump of “new continent” is
called a terrane (specifically the
Antler Terrane)
Paleozoic Tectonics
When terranes hit a continent, they are called docking events. Ultimately,
continents grow bigger by scooping up geo-crap in their drift direction
(Accretionary tectonics)
Mesozoic Tectonics
Into the Triassic, many more
“terranes” (mostly island arcs)
began to be scooped up by North
America as it drifted WNW
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
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
Mesozoic Tectonics
The Sonoman Orogeny in the
Triassic marks the start of the
formation of the Cordilleran
Mountains and the current active
margin
Mid-Triassic Paleogeography
(source http://jan.ucc.nau.edu/~rcb7)
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
The culmination of several
“hits” and docking events
as well as major phases of
felsic intrusions is
collectively called the
Nevadan Orogeny
Mid-Jurassic Paleogeography
(source http://jan.ucc.nau.edu/~rcb7)
Mesozoic Tectonics
In the Cretaceous, more hits and
more intrusions. More uplift
•Wrangellia Terrane docks
Mesozoic Tectonics
The culmination of several
“hits” and docking events
from the Jurassic to the
Cretaceous produced major
phases of thrust faulting
and is collectively called
the Sevier Orogeny
Early Cretaceous Paleogeography
(source http://jan.ucc.nau.edu/~rcb7)
What’s the Point?
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
What’s the Point?
And once we get into the
Cenozoic, deciphering the
tectonic history of the
Cordilleran Mountains gets
really tricky…
… stay tuned for details!
Today’s Homework
1. Bonus quiz this Tuesday (Multiple choice )
Next Time
1. Mesozoic Sedimentation (Lectures 32 and 33)
GY 112: Earth History
Lectures 30 and 31: Mesozoic Geology
Instructor: Dr. Doug Haywick
dhaywick@southalabama.edu
This is a free open access lecture, but not for commercial purposes.
For personal use only.