Geological Development of Western North America (Timeline)

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This chronological table tries to show in a condensed form the striking events in the geological development of western North America . The age information is approximate.

date Period / epoch event
350 million years of BP Devon Antler orogeny . An as yet unnamed terran collides with the North American Plate and docks on the continent along the state border between Nevada and Utah. This suture is expressed as discordance and is called Carlin discordance .
250 million years of BP Turn Permian / Triassic Sonomic mountain formation . The Sonomia-Terranes encounters the North American plate and welded to North America then along the Golconda Thrust - a large thrust in the central Nevada. This process is also known as the Golconda event.
200 million years of BP Turn Triassic / Jurassic First-time intrusions form the original Sierra Nevada batholith .
180 - 140 million years BP law Nevadian mountain formation caused by subduction on the western edge of the North American Plate.
165 million years BP law The Smartville Block , an island arc terran, meets the North American plate and is deposited along the Mother Lode lineament from California to the continent.
140 million years of BP Lower Cretaceous A second series of plutons intrudes the Sierra Nevada batholith.
140 - 50 million years BP Lower Cretaceous - Eocene Sevier orogeny
90 million years of BP Upper Chalk A third and final wave of plutons invades the Sierra Nevada batholith.
80-40 million years of BP Upper Cretaceous - Eocene Laramian orogeny . When this is completed, the change from narrowing tectonics to expansion tectonics takes place .
46-45 million years BP Eocene In the northern section of the Cordillera, the stretching process begins at flat faults.
43 million years of BP Eocene The Pacific Plate changes direction from north to northwest.
43 - 20 million years BP Eocene - Oligocene An intermediate to acidic calcareous igneous magmatism starts from northwestern Mexico ( Sierra Madre Occidental ) New Mexico and Colorado and then shifts over Arizona to Nevada. At the same time, a second magmatic front is moving from the north (Idaho, Oregon) to Nevada.
36 million years of BP Eocene The stretch now also includes the southwest. The crust thickened by the Laramian mountain formation is also pulled apart here by means of flat faults. The so-called metamorphic core complexes (bulges of the metamorphic lower crust) are formed.
35 million years of BP Eocene The rift system of the Rio Grande Rift begins to collapse.
20 million years of BP Miocene The large lateral displacement of the San Andreas Fault occurs, the North American plate crosses the Farallon plate , two partial plates remain.
16 million years of BP example Beginning of the expansion process in the Basin and Range Province .
8 million years of BP Upper Miocene The second stage in the development process of the Basin and Range Province ( horst and grave tectonics ) begins.
5 million years of BP Miocene- Pliocene The East Pacific Ridge penetrates north into the North American Plate and causes the Baja California Peninsula to emerge and drift away .
4 million years BP Pliocene The Sierra Nevada is gradually pushing up.
3.5 million years BP Pliocene The Pacific Plate changes direction again by 11 degrees - this time from northwest to the current north-northwest.

Web links

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  • WS Baldridge: Geology of the American Southwest. Cambridge University Press, 2004. ISBN 0-521-01666-5