Chapter 13 – Mesozoic Events

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Chapter 13 Mesozoic Events
Important events Breakup of Pangaea Begins
200 million years ago Formation of rift
valleys Oceans widen Gulf of Mexico
formation Cretaceous epicontinental
seas Accretionary tectonics add to
continents
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Three Periods
Triassic first dinosaurs Mesozoic first
birds Cretaceous first flowers great
extinction
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Breakup of Pangaea
Stage 1 Rifting and volcanism along normal
faults North America separates from
Gondwana Mexico separates from South
America Eastern border of N.A. separates from
Moroccan bulge of Africa
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Breakup of Pangaea Stage 2
Stage 2 Narrow ocean opening between Africa and
Antarctica An extension of this rift separates
India from Africa
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Breakup of Pangaea Stage 3
Stage 3 Atlantic Ocean begins to unzip from the
south towards the north Starts to rift
Greenland from North America but shifts to
separate Greenland from Baltica
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Breakup of Pangaea Stage 4
Stage 4 North Atlantic rift separates Laurentia
from Baltica Occurred 45 million years
ago Complete breakup took 150 million years!
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Breakup of Pangaea Model
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The Mesozoic in Eastern North America
Appalachian Mountains are eroding and shedding
massive amounts of sediment. Begins to fill in
non-marine continental rifts. Much basaltic
volcanism. Fall Line boundary between
igenous and metamorphic rocks of Appalachian
Mountains and more easily eroded sedimentary
rocks. Location of many water wheels for textile
and grain mills. Philadelphia, Baltimore,
Washington, Richmond, and Augusta.
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Gulf of Mexico
Gulf of Mexico one of worlds great
depositional basins. gt1000 m of rock salt
(halite). Salt Domes low density causes them
to rise producing folded and faulted petroleum
traps. Salt, sulfur and other chemicals also
produced.
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Salt Dome Geology
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Cretaceous (The Chalk Period)
Cretaceous is a period of high sea level.
Why? Continental flooding. The rock chalk is
composed of calcite shells that formerly were
occupied by golden-brown algae.
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Chalk Electron Microscope Picture
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White Cliffs of Dover
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Chunnel
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The Mesozoic in Western North America
North America is overriding the Pacific
Plate Accretionary Tectonics add to western
N.A. Exotic terranes Alien, displaced
landmasses added to continent. Area 51.
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Area 51 Resident
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Abducted Terranes
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Abducted Terranes
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Western United States
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Triassic
Much western volcanism with stream
deposits. Chinle Kayenta formations of
Painted desert. Petrified Forest of Triassic
age. Conifers Uranium deposits of Mt. Taylor
stream channels.
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Triassic
Much western volcanism with stream
deposits. Chinle Kayenta formations of
Painted desert. Petrified Forest of Triassic
age. Conifers Uranium deposits of Mt. Taylor
stream channels.
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Jurassic
Navajo Sandstone (Late Triassic-Early
Jurassic) Cross-bedded sandstone coastal
dunes, windblown sand. Source of sand
Alberta. Sundance Sea (Formation) Marine
reptiles Morrison Formation Floodplain
deposits contain 70 dinosaur species
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Navajo Sandstone
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Sundance Sea
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Morrison Formation
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Seafloor Spreading and Epicontinental Seas
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Mesozoic Volcanism
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Mesozoic Plutonism - Yosemite
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Mesozoic Subduction Complex Franciscan Formation
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Grand StaircaseEscalante National Monument
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Grand StaircaseEscalante Statigraphy
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Deccan Traps Volcanic Eruption