Earth History GEOL 2110

The Cenozoic EraThe Modern World Emerges

Tectonics

Major Concepts• The volcanic null that corresponded with the Laramide

Orogeny starting in the late Cretaceous ended in the late Eocene epoch (~40Ma) with the resumption of arc magmatism along the western margin of NA

• Starting in the Miocene (~20Ma), the collision of the East Pacific Rise created a transform boundary between the Pacific and NA plates; this brought on the Basin and Range-style extension tectonics, the uplift of the Colorado Plateau, the creation of the Rio Grande Rift, and shift in the motion of the Pacific plate

• The collision of India and various microcontinents spalled from Gondwana’s break-up closed the Tethy’s Sea and created the Alpine-Himalayan orogenic belt

Summary of the Cenozoic

PEOMPP

Early Cenozoic (66-40 Ma)Paleocene - Mid-Eocene

Laramide Orogeny

Block uplift of the Precambrian basement

Laramide Orogeny Magmatic Null Zone – Shallow Slab Subduction

Sedimentation in Laramide Intermontane Basins

Lacustrine Shales of the Green River Basin, UT

Coal Seams in the Powder River Basin, WY

Lacustrine Shales Marls Bryce Canyon NP, UT

PRBHWR

GR

U

Middle Cenozoic (40-20 Ma)Late Eocene – Oligocene – Mid-Miocene

Resumption of continental volcanic arc magmatism as subduction of the Farallon Plate steepens

Tectonics during the Oligocene (~30 Ma)

Middle Cenozoic (40-20 Ma)San Juan Volcanic Field

La Garita Caldera (28Ma)

San Luis Tuff, Wheeler Geologic Monument

Middle Cenozoic (40-20 Ma)Burial and Exhumation of the Laramide Mountains

66Ma

57 Ma

50 Ma

35 Ma

15 Ma

Lara

mid

e O

roge

ny

Post

- Lar

amid

e O

roge

ny

Laramide Mtns Buried

Laramide Mtns Exhumed

Laramide Mtns Re-Exhumed

Laramide Mtns Re-Buried

Laramide Sediments and Volcanic Ash Spreads across the Great Plains

Eocene – Oligocene fluvial sediments of the White River Group, Badlands, SD

Late Cenozoic (20-0 Ma)Mid-Miocene – Pliocene –Pleistocene - Holocene

Collision of East Pacific Rise with NA plate creates the San Andreas Transform Fault System, Basin and Range Province, Colorado Plateau and Rio Grand Rift

Mid-Miocene (~15 Ma) Pliocene (~5 Ma)

Basin and Range ProvinceExtensional Thinning of the Crust

Listric Normal Faults

Sevier Deformation

Basin and Range ProvinceExtensional Thinning of the Crust

Basin and Range ProvinceExtensional Thinning of the Crust

Extension due to mantle upwelling in area of Slab Gap

Basin and Range Province Extensional Thinning of the Crust

As the SA transform boundary grows, Basin and Range Extension migrates to the North. Establishment of rift zone in the Gulf of California kills extension in the southern Basin and Range.

The Slicing and Dicing of CaliforniaNarrow fault –bound basins

rapidly fill with great thickness of sediment that are simultaneously

deformed (e.g., Ventura Basin)

Pliocene (~5 Ma)

Uplift of the Colorado PlateauRejuvenation of Mature Rivers

Pliocene (~5 Ma)

Mantle Upwelling?

Columbia River Basalts, Snake River Basalts, and the Yellowstone Hotspot

Newberry

YellowstoneNA Drift

Edge of Craton

Mantle Plume-Generated Volcanism

Newberry Rhyolite

Columbia River Basalts

Yellowstone Hydrothermal Field

Present-Day Tectonic Picture

Pacific Plate Tectonics

Passive Margins East and South

Triassic-sourced Halite DepositsPangea Break-up – Shallow Marine Deposits

Erosion of North America – River and Deltaic Deposits

Passive Margins East and SouthRejuvenation of the Appalachians

The Closing of the Tethys Sea

The Closing of the Tethys Sea

25 Ma

5-6 MaMediteranean Dries Up -Evaporites

4 MaStraits of Gibraltar

open up

Tectonics of East Asia

Next Lecture

The CenozoicThe Modern World Emerges

Climate and Life