Laramide orogeny
The Lara mixer orogeny, also lara lara shuffle shuffle orogeny or folding phase was a major portion of the mountain-building processes of western North America. As Laramide revolution, the term was introduced in 1901 for the first time by George Mercer Dawson in the literature and adopted in 1924 by Hans silence. Your name conferring type locality is in the Laramie Mountains in the U.S. state of Wyoming.
The orogeny began in the late Upper Cretaceous period about 80 Mya and ended in the Eocene, about 40 Mya. The exact length of time is just as controversial as the root cause.
The lara mix orogeny was not continuous but occurred in bursts with intervening rest periods. Were affected by it in the main, the Rocky Mountains, but their impact was felt even more in Alaska and northern Mexico; in the Black Hills of South Dakota it reached its easternmost area of effect.
The mountain formation is usually associated with events in compound off the North American west coast played out - so here slid the oceanic Farallon plate gradually beneath the continental North American plate. In most explanatory hypotheses is assumed that the Abtauchwinkel the subducted Farallon plate was quite flat and therefore it was no magmatism in the western central part of the North American plate. In addition, the submerged oceanic lithosphere induced shear stresses in the lower portion of the overlying continental lithosphere. One reason for the flat Abtauchwinkel may accelerate the convergence of the two plates; but also a thickened oceanic crust might as well come into question this.
The code associated with a subduction magmatism usually occurs near the plate edges on ( a good example here is the volcanic belt of the Andes), in the case of lara mix orogeny he was, however, far to the east. One explanation for the non-existent magmatism at subduction zones ( known in English as magmatic null referred ) is possibly due to the fact that the subducting oceanic crust met in this particular case on relatively cool continental lithosphere, rather than as usual on warmer asthenosphere.
The flat Abtauchwinkel together with the induced shear stresses gave rise to a very broad mountain belt - precursor to the actual Rocky Mountains (proto -Rocky Mountains ). As the Farallon plate was completely melted down to fragments accounted for the lateral pressure and the rocks relaxed. As a counter movement was followed by an extensional tectonics that made the Basin -and- Range Province arise.
It is useful to refer to comparative in this context, the previous - Sevier orogeny and the even earlier was Nevadische orogeny.