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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. Three Periods.
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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
Three Periods Triassic – first dinosaurs Mesozoic – first birds Cretaceous – first flowers & great extinction
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
Breakup of Pangaea – Stage 2 Stage 2 Narrow ocean opening between Africa and Antarctica An extension of this rift separates India from Africa
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
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!
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.
Gulf of Mexico Gulf of Mexico – one of world’s great depositional basins. >1000 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.
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.
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.
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.
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.
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
