earth history geol 2110 the mesozoic era cretaceous trangression and mesozoic life
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Earth History GEOL 2110
The Mesozoic EraCretaceous Trangression
And Mesozoic Life
Major Concepts• A major transgression in the Cretaceous created a Great
Interior Seaway where great accumulation of marine and non-marine sediment were deposited in the Great Plains
• Climate in the Cretaceous was uniformly warm due to a lack of polar ice caps, an abundance of water surface, large volcanic eruptions
• After the Permo-Triassic extinction, radiation of marine life was driven by reactions of species to predatation.
• Synapsid reptiles of the Triassic gave way to dinosaurs during the Jurassic and Cretaceous
• Flowering plants (angiosperms) bloomed in the mid-Cretaceous and supplied a rapidly reproducing supply of food to the dinosaurs
• The mass extinction at the end of the Cretaceous was not as abrupt as first described, suggesting a non-impact cause
Events of the Mesozoic Era
Great Inland SeawayThe Last Epicontinental Sea
Cretaceous Seaway Rock Types
Alluvial Fan Conglomerate
Deltaic SS and Coal
Deltaic SS and Marine Shale
Black Shale
Chalk Carbonate
Cretaceous Chalk DepositsAccumulation of Carbonate Micro-organism
Calcareous ooze
White Cliffs of Dover Carbonate Ooze
Carb
onat
e M
icro
foss
ils
NiobraraChalk of Nebraska
Deposits along the Eastern Shore of the Cretaceous Seaway
Lignite and Fine Sandstone
Weathered Archean Gneiss
Cretaceous PaleoclimateUnlike the Permian, globe
seemed uniformly warmHumid (rare evaporites)No glacial depositsExtensive water coverage promoted solar heating
Cretaceous Black ShalesEvidence of Uniformly Warm Ocean Waters
Organic –rich muds due to : - Rapid deposition of C- Rapid mud deposition- O-poor deep waters* * Oxygen is more soluble in cold water leading to vigorous circulation of cold, dense oxygenated water in the deep ocean when temperature is strongly zoned. Not the case when oceans are uniformly warm
Pierre Shale
Mesozoic Marine Life
After the Permo-Triassic ExtinctionBryozoans, Brachiopods, Rugose and Tabulate Coral, and Crinoids give way to: Bivalves, Gastropods, Mollusks, Modern Coral Crustaceans, Cephlapods, Echoniderms, Diverse Fish and Swimming Reptiles
PREDATOR-PREY RELATIONS RULE THE SEAS
Mesozoic Marine LifeBivalves Dominate
Rudistid clams
Inoceramids
Mesozoic Marine LifeAmmonites – the index fossil of the Mesozoic
Mesozoic Marine LifeMicro-organisms
Calcereous ForaminferaSiliceous Diatoms
Coccoliths
Mesozoic Marine LifeMososaurs, plesiosaurs, teleost fish, ammonites, turtles ----
Mesozoic Land LifeThe Land Before Time
Flowering Plants Evolve
Rapid regeneration provided ample food supply for dinosaurs
Pollinating insects (moths and bees) become important partners
The Cretaceous-Tertiary Extinction~ half of life is exterminated
Evidence for a Meteor ImpactVolcanic Glass Spherules
Shocked Quartz
Cretaceous Volcanism
Ontang–Java Oceanic Plateau
Deccan Flood Basalts
Summary of the Mesozoic
Next Lecture
The Cenozoic Era
The Modern World EmergesTectonics
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