Sevier orogeny

The Sevier orogeny - was one of the outstanding sections of the mountain-building processes of western North America. Their sphere of influence stretched from Canada in the north to Mexico in the south. Your name conferring type locality is situated in the area of the Sevier River in Utah, its time frame extends from about 140 million years BP ( Lower Cretaceous ) to 50 million years BP (Lower Eocene ). The Sevier orogeny - was preceded by several major orogenic movements, such as the Nevadische orogeny, the Sonomische orogeny and the Antler orogeny. It is very difficult from the subsequent orogenic phase, the Lara mixing orogeny, delineate, with which it overlaps spatially and temporally.

The Sevier mountain formation is an example of the impact of convergent plate boundaries, the causes of the orogenic movements are expected here in the meeting of the oceanic Farallon plate on which also oceanic Kula plate - both forerunners of the Pacific plate - as well as in their subsequent subduction beneath the continental North American Plate to be sought.

Since the Sevier orogeny - is so closely intertwined with the Lara mixing orogeny in space and time, the two phases are often confused. Generalizing, we can say that the Sevier - orogeny represents a compressive tectonic phase, which generally further west unfolded from the Lara mixing orogeny, while the shear webs most mechanically "weak" used layer boundaries in the resting paläozischen and Mesozoic overburden. The narrowing of the crust had the consequence that the resulting compressive stresses were transferred to mechanically weaker sedimentary sequences and thin-layer thrusts generated, who were advancing more and more to the east with time.

This tectonic behavior is strongly influenced by the mixing of Lara orogeny differs. In this there was block-like uplift of the basement, which took place mostly on existing distortions. The weakness zones used therein of the basement were already during the break ( continental rifting ) of the supercontinent Rodinia and the subsequent mountain building process called Ancestral Rocky Mountains, has been the forerunners of the Rocky Mountains created.

The Sevier and also Lara mixer orogeny was extinguished at the time at which the western continental margin of North America subduction takes place came to an end.