Nevadan orogeny

Nevadan orogeny

      mountain-building event in western North America that started in the Late Jurassic (Jurassic Period) Epoch about 156 million years ago. This event is generally considered to be the first significant phase of Cordilleran (cordillera) mountain building, which continued into the Early Cretaceous (Cretaceous Period) Epoch. The name is derived from the changes that occurred in the Sierra Nevada range of eastern California, although the effects of the Nevadan orogeny extended through a larger area of western North America.

      Evidence for the Nevadan orogeny includes the formation of vast Late Jurassic and Early Cretaceous batholiths (batholith) (large bodies of igneous rock that formed underground) in southern California, the Sierra Nevada, the Coast Ranges, Idaho, and British Columbia. Folding and thrust faulting took place on the western slope of the Sierra Nevada and in the Klamath Mountains of northern California.

      The uplift that occurred during the Nevadan orogeny in California, Nevada, western Utah, and Idaho is believed to have caused major depositional changes on the eastern side of these new mountain ranges. As the mountains rose, the sea level in the western interior of North America dropped, and the region filled with sediment eroded from the new mountains. Thick sequences of coarse siliciclastic (sedimentary rock) strata were deposited in eastern Utah, Colorado, Wyoming, and other western states; these deposits include the Morrison Formation, which is famous for its dinosaur fossils.

      The Nevadan orogeny is considered to have been a result of the westward movement of the North American plate, causing the thrusting of oceanic crust under the North American continent along a subduction trench (subduction zone). During this time, the Franciscan Sequence (consisting of metamorphosed (metamorphic rock) rocks from an accretionary wedge (ocean)) and the Great Valley sequence (consisting of deep-sea sedimentary rocks from a forearc basin) were accreted onto the North American continent. They are now exposed in northern and central California.

Carol Marie Tang
 

* * *


Universalium. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Nevadan orogeny — The Nevadan Orogeny was a major mountain building event that took place along the western edge of ancient North America between the Mid to Late Jurassic (between about 180 and 140 million years ago).[1] The Nevadan orogeny was the first of three… …   Wikipedia

  • Laramide orogeny — The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the… …   Wikipedia

  • Sevier orogeny — The Sevier orogeny was a mountain building event that affected western North America from Canada to the north to Mexico to the south. This orogeny was the result of convergent boundary tectonism between approximately 140 million years (Ma) ago,… …   Wikipedia

  • Laramide orogeny — Series of mountain building events that affected much of western North America in Late Cretaceous and Early Tertiary time (с 65 million years ago). The Laramide orogeny originally was believed to mark the Cretaceous Tertiary boundary. It is now… …   Universalium

  • North American Cordillera — The North American Cordillera is the North American portion of the American Cordillera which is a cordillera extending up and down the western side of the Americas. The North American Cordillera covers an extensive area of mountain ranges,… …   Wikipedia

  • Geology of the Yosemite area — The exposed geology of the Yosemite area includes primarily granitic rocks with some older metamorphic rock. The first rocks were laid down in Precambrian times, when the area around Yosemite National Park was on the edge of a very young North… …   Wikipedia

  • Geological history of Earth — impacting the Earth in a glancing blow. [cite journal | last = R. Canup and E. Asphaug | title = Origin of the Moon in a giant impact near the end of the Earth s formation | journal = Nature | volume = 412 | pages = 708–712 | date = 2001 | url =… …   Wikipedia

  • Geologic time scale — This clock representation shows some of the major units of geological time and definitive events of Earth history. The Hadean eon represents the time before fossil record of life on Earth; its upper boundary is now regarded as 4.0 Ga.[1] Other… …   Wikipedia

  • Sierra Nevada (U.S.) — Geobox|Range name=Sierra Nevada image size=300 image caption=Little Lakes Valley: typical eastside terrain country=United States state=California| state1=Nevada parent= | border= length imperial=400 length orientation=North South highest=Mount… …   Wikipedia

  • Yosemite National Park — Infobox Protected area name = Yosemite National Park iucn category = Ib caption = locator x = 20 locator y = 84 location = Tuolumne, Mariposa, Madera Counties, California, USA nearest city = Mariposa lat degrees = 37 lat minutes = 50 lat seconds …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”