Earth’s Physical History (Tectonics, Orogenies, Transgressions, Paleoclimate)

What were the major tectonic events in Earth’s history?

Breakup of Rodinia; Formation and breakup of Pangaea; Major orogenies like Taconic, Acadian, Alleghanian, Antler, Nevadan, Sevier, Laramide, and Sonoma; Plate collisions and mountain building.

What are major transgressions (epeiric seas) in Earth’s history?

Sauk Sea (Cambrian) – Flooded most of N. America; Tippecanoe Sea (Ordovician) – Deep marine carbonates; Kaskaskia Sea (Devonian) – Reefs and evaporites; Absaroka Sea (Pennsylvanian) – Cyclothems; Zuni Sea (Cretaceous) – Warm widespread marine flooding.

What was the breakup of Pangaea?

Started in the Triassic with rifting, volcanism, and basin formation; driven by heat buildup under the supercontinent.

What is CAMP?

Central Atlantic Magmatic Province—massive lava flows tied to Pangaea breakup and end-Triassic extinction.

What was the Sonoma Orogeny?

Mid-Triassic mountain-building event from accretion of exotic terranes to western North America (e.g., parts of Nevada).

What are general characteristics of the Triassic craton?

Terrestrial, low-lying, red beds, swamps, and forest deposits; Newark Supergroup formed here.

What are the characteristics of the Zuni sequence?

Cretaceous-age marine transgression covering a third of North America; represented by chalk, shale, and sandstone layers.

What is the Morrison Formation?

Nonmarine clastic wedge with colorful mudstones and sandstones; famous for dinosaur fossils.

What are characteristics of the Jurassic and Cretaceous craton?

Quartz-rich sands, pre-Jurassic unconformities, erosion of older rocks, and epicontinental seas.

What is an accretionary prism?

Chaotic wedge of sediments and ocean crust scraped off a subducting plate.

What is mélange?

Jumbled rock mix within an accretionary prism, often near subduction zones.

What is blueschist?

Metamorphic rock formed under high pressure, low temperature in subduction zones.

What defines a subduction zone?

Oceanic crust sinks under continental crust; features include trenches, volcanic arcs, and accretionary prisms.

What are the characteristics of the Nevadan Orogeny?

Mid-Jurassic; initiated west coast subduction and early magmatism.

What defines the Sevier/Sierra-Sevier Orogeny?

Late Jurassic–Cretaceous; shallow-angle subduction, thrust faulting, volcanic arc shifts.

What defines the Laramide Orogeny?

Late Cretaceous–Eocene; basement uplift, inland mountain building.

What is a magmatic null?

Shutdown of volcanism due to shallow-angle subduction during the Cretaceous.

What is the Tejas Transgression?

Paleogene marine transgression that flooded parts of North America after the K-Pg extinction.

What are characteristics of the Early Cenozoic North American craton?

Warm, shallow marine environments with recovery from extinction; lush vegetation.

What is the PETM?

Paleocene-Eocene Thermal Maximum: rapid global warming event ~56 mya.

What ecological changes occurred during the PETM?

Temp rose 5–8°C, dwarfism in mammals, tropical forests expanded, deep ocean anoxia.

What is the Columbia River Plateau Basalt?

Huge Miocene lava flows in Washington, Oregon, and Idaho.

What is the Colorado Plateau?

Stable, uplifted region in the southwestern U.S. with horizontal sedimentary layers.

What is the Basin and Range Province?

Region of crustal extension with tilted fault blocks in Nevada, Utah, and surroundings.

What are horsts and grabens?

Horsts are uplifted blocks; grabens are down-dropped blocks from crustal stretching.

How did the Grand Canyon form?

Erosion by the Colorado River through uplifted rock over the last ~6 million years.

What is the San Andreas Fault?

Transform boundary between Pacific and North American plates; causes major earthquakes.

What are generalizations about orogenic belts?

Form at convergent boundaries with folded, faulted rocks and crustal thickening.

What are superplumes?

Massive mantle upwellings that cause crustal uplift, rapid spreading, and warm climates.

What was the nature of the Cretaceous paleoclimate?

Hot, humid, ice-free poles, high sea levels.

What caused the warm Cretaceous climate?

Rapid seafloor spreading and volcanic CO₂ release from superplumes