User:Olumideadedeji/Laramide orogeny
The Laramide orogeny was a time 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[1]. The exact duration and ages of beginning and end of the orogeny are in dispute[2][3]. The Laramide orogeny occurred in a series of pulses, with quiescent phases intervening[4]. The major feature that was created by this orogeny was deep-seated, thick-skinned deformation, with evidence of this orogeny found from Canada to northern Mexico[5], with the easternmost extent of the mountain-building represented by the Black Hills of South Dakota. The phenomenon is named for the Laramie Mountains of eastern Wyoming. The Laramide orogeny is sometimes confused with the Sevier orogeny, which partially overlapped in time and space.[6]
The orogeny is commonly attributed to events off the west coast of North America, where the Kula and Farallon Plates were sliding under the North American plate[1][7]. Most hypotheses propose that oceanic crust was undergoing flat-slab subduction,[8] i.e., with a shallow subduction angle, and as a consequence, no magmatism occurred in the central west of the continent, and the underlying oceanic lithosphere actually caused drag on the root of the overlying continental lithosphere. One cause for shallow subduction may have been an increased rate of plate convergence[7]. Another proposed cause was subduction of thickened oceanic crust.
Magmatism associated with subduction occurred away from the plate edges, far to the east, now known as the Coast Range Arc. Geologists call such a lack of volcanic activity near a subduction zone a magmatic gap. This particular gap may have occurred because the subducted slab was in contact with relatively cool continental lithosphere, not hotter asthenosphere.[9] One result of shallow angle of subduction and the drag that it caused was a broad belt of mountains, some of which were the progenitors of the Rocky Mountains. Part of the proto-Rocky Mountains would be later modified by extension to become the Basin and Range Province.
- ^ a b English, Joseph M.; Johnston, Stephen T. (2004-09-01). "The Laramide Orogeny: What Were the Driving Forces?". International Geology Review. 46 (9): 833–838. doi:10.2747/0020-6814.46.9.833. ISSN 0020-6814.
- ^ Curtis, Bruce F. (1975-01-01). "Cenozoic History of the Southern Rocky Mountains". doi:10.1130/MEM144.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Copeland, Peter; Currie, Claire A.; Lawton, Timothy F.; Murphy, Michael A. (2017-03-01). "Location, location, location: The variable lifespan of the Laramide orogeny". Geology. 45 (3): 223–226. doi:10.1130/G38810.1. ISSN 0091-7613.
- ^ Bird, Peter (1998). "Kinematic history of the Laramide orogeny in latitudes 35°–49°N, western United States". Tectonics. 17 (5): 780–801. doi:10.1029/98TC02698. ISSN 1944-9194.
- ^ Dickinson, W. R., Snyder, W. S., & Matthews, V. (1978). Plate tectonics of the Laramide orogeny (Vol. 3, pp. 355-366).
- ^ Willis 2000
- ^ a b Murphy, J. Brendan; Hynes, Andrew J.; Johnston, Stephen T.; Keppie, J. Duncan (2003-04-24). "Reconstructing the ancestral Yellowstone plume from accreted seamounts and its relationship to flat-slab subduction". Tectonophysics. Collisional Orogenesis in the Geological Record and Modern Analogues. 365 (1): 185–194. doi:10.1016/S0040-1951(03)00022-2. ISSN 0040-1951.
- ^ Coney, Peter J.; Reynolds, Stephen J. (1977-12). "Cordilleran Benioff zones". Nature. 270 (5636): 403–406. doi:10.1038/270403a0. ISSN 1476-4687.
{{cite journal}}: Check date values in:|date=(help) - ^ Dumitru 1991