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Earth History GEOL 2110. The Mesozoic Era Cretaceous 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
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Earth History GEOL 2110 The Mesozoic Era Cretaceous 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
Alluvial Fan Conglomerate Cretaceous Seaway Rock Types Deltaic SS and Coal Chalk Carbonate Deltaic SS and Marine Shale Black Shale
Calcareous ooze Cretaceous Chalk DepositsAccumulation of Carbonate Micro-organism White Cliffs of Dover Carbonate Ooze Niobrara Chalk of Nebraska Carbonate Microfossils
Deposits along the Eastern Shore of the Cretaceous Seaway Lignite and Fine Sandstone Weathered Archean Gneiss
Cretaceous Paleoclimate Unlike the Permian, globe seemed uniformly warm Humid (rare evaporites) No glacial deposits Extensive 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
Cretaceous Volcanism Deccan Flood Basalts Ontang–Java Oceanic Plateau
Mesozoic Marine Life After the Permo-Triassic Extinction Bryozoans, 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 Life Bivalves Dominate Rudistid clams Inoceramids
Mesozoic Marine LifeAmmonites – the index fossil of the Mesozoic
Mesozoic Marine LifeMicro-organisms Siliceous Diatoms CalcereousForaminfera Coccoliths
Mesozoic Marine Life Mososaurs, plesiosaurs, teleost fish, ammonites, turtles ----
Mesozoic Land Life The 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 Impact Volcanic Glass Spherules Shocked Quartz
