Mesozoic Earth History Study Notes

Mesozoic Earth History Overview

Introduction to the Mesozoic Era

  • The Mesozoic Era is a significant geological time period, comprising the Triassic, Jurassic, and Cretaceous periods.

  • Timeline of Major Geologic and Biologic Events:

    • Formation and breakup of Pangaea, the supercontinent.

    • Major evolutionary milestones, including the emergence of dinosaurs, mammals, and birds.

    • Notable geological events such as mountain formations and climatic changes.

Mesozoic Timeline

  • ## Phanerozoic Eon

    • ### Paleozoic Era

    • ### Periods and Events:

      • Cambrian: First fish (488 million years ago)

      • Ordovician: First land plants (444 million years ago)

      • Silurian: First amphibians (416 million years ago)

      • Devonian: First reptiles (359 million years ago)

      • Carboniferous: Abundant coal-forming swamps (299 million years ago)

    • ### Mesozoic Era (251-66 million years ago)

    • #### Triassic (251-201 million years ago)

      • First dinosaurs, first mammals, formation of Sierra Nevada.

    • #### Jurassic (201-145 million years ago)

      • First birds, significant geological formations.

    • #### Cretaceous (145-66 million years ago)

      • Extinction of dinosaurs (66 million years ago), major geological transitions.

    • ### Cenozoic Era (66 million years ago to present)

    • Epochs include Paleogene, Neogene (Miocene, Oligocene, Pliocene) and Quaternary (Holocene, Pleistocene).

Major Geologic Events of the Mesozoic

  • Several important geologic events during this era include:

    • Breakup of Pangaea into Laurasia and Gondwana.

    • Formation of the Atlantic Ocean.

    • Uplift and formation of the Rocky Mountains.

    • Accumulation of vast amounts of petroleum and mineral deposits.

Breakup of Pangaea

  • ### Triassic Period

    • The Triassic marks the beginning of Pangaea's breakup:

    • Geographic Changes: North America began separating from Eurasia and Gondwana.

    • Signs of shallow seas and evolving landscapes including mountains and deserts.

  • ### Jurassic Period

    • Further separation led to:

    • Development of significant oceanic expanses such as the Tethys Ocean.

    • Positioning of landmasses that includes Africa, India, and Australia.

  • ### Cretaceous Period

    • The breakup continued with:

    • Expansion of the Cretaceous seaway, influencing the aquatic environments.

    • Formation of lowlands and continued development of major geological features.

Mesozoic Evaporite Deposits

  • Evaporite deposits were significant:

    • Occurred around North America and included several marine layers due to evaporation in coastal regions.

Oceanic Circulation Patterns

  • The Mesozoic influenced oceanic circulation patterns:

    • Changes in currents due to tectonic shifts and climate variations during this era.

Mesozoic History of North America

  • ### Triassic History

    • Features included:

    • Formation of fault-block basins and volcanic activity.

    • Presence of an epeiric sea that formed conducive environments for fossil development.

  • ### Jurassic History

    • Characterized by:

    • The Cordilleran mobile belt and volcanic island arcs, contributing to landform diversity.

    • Formation of the Sundance Sea.

  • ### Cretaceous History

    • Distinguished by:

    • Rising mountain ranges from continued tectonic activity.

    • Significant deposition of sedimentary layers leading to complex stratigraphy in regions like the Appalachian Mountains.

Mesozoic Sedimentary Formations

  • Important rock formations include:

    • Kayenta Formation

    • Wingate Sandstone

    • Chinle Formation

    • Shinarump Conglomerate

    • Moenkopi Formation

The Newark Group

  • The Newark Group represents a significant sedimentary deposit from the Late Triassic to Early Jurassic:

    • Defined by non-marine detrital sediments due to erosion and subsidence events.

Mesozoic Terranes and Tectonic Activity

  • Terranes are defined as:

    • Small, exogenous lithospheric blocks that accrete onto larger continental masses, contributing to geological complexity.

    • These blocks vary in fossil content, stratigraphy, and paleomagnetic properties, playing crucial roles in the geological history.

Resource Formation During the Mesozoic

  • The Mesozoic era produced vital resources:

    • Coal, petroleum, uranium, gold, iron, and copper were formed from various geological processes.

    • Notably, rich uranium deposits occur in Mesozoic sandstones of the Colorado Plateau.