Geology of the Rocky Mountains
The geology of the Rocky Mountains include a rather heterogeneous array of mountain ranges, all of which have undergone an independent geological development. Together, these sub-chains of the Rocky Mountains - a majestic towering rock barrier that extends from Canada to the central New Mexico.
The Rocky Mountains owe their origin to an intense section of plate tectonic movements - ultimate cause of the wild and rugged landscapes of western North America. Three major orogenic phases designed over a period of about 130 million years ago the western North America fundamentally about. The movements began about 170 million years ago in the Middle Jurassic and sounded in front of around 40 million years ago in the Middle Eocene again. The Lara mixer orogeny, which dragged on for the period of 70 to 40 million years BP, was the last of these three phases. She is responsible for the strong lifting of the Rocky Mountains (on the order of about 2 km ).
Precursor - the " Ancestral Rocky Mountains " ( 300 million years ago )
The so-called " Ancestral Rockies " were an ancient Paleozoic mountain range of western North America, they were roughly on the site of what is now southern Rocky Mountains in Colorado. This mountain range was formed about 300 million years ago during the Upper Carboniferous - in about the same time the processes taking place in Europe, Eurasia and western North Africa Variscan orogeny. At that time the uplift area of today's Colorado was mostly covered at the time by a shallow sea. It arose in the course of two island-like movements orogenetischen high areas, which are referred to by geologists as Frontrangia and Uncompahgria - roughly equal to today's Front Range and the San Juan Mountains. They consisted mainly of Precambrian metamorphic rocks that had pioneered as a result of tectonic movements their way through the auflagernde sedimentary cover. The sedimentary cover consisted mainly of carbonate sediments that were deposited in shallow seas during the Paleozoic.
Development to Lara mixing orogeny (before 170-70 million years ago)
From the onset of tectonic movements in the second half of the Mesozoic, the age of dinosaurs, large parts of the current California, British Columbia, Oregon and Washington were drifting on the North American continent. The western North America learned in this context, the effects of repeated collisions, whereas oceanic crustal sections gradually pushed under the continental margin. Shear chips continental crust of the subducting oceanic plates were brought up with, came into the area of the subduction zone and were eventually "docked " to the continental margin of North America. These non-local Terrane come from a variety of different tectonic areas. Among them are island arcs ( roughly comparable to Japan, Indonesia and the Aleutian Islands ), fragments of oceanic crust that have been pushed onto the continental margin, and small ocean islands.
The resulting during Subduktionsprozesses above the subducting oceanic crust magma penetrated the continental crust of the North American continent inland to a distance of 300 to 500 kilometers. There was a large arc-shaped volcanic mountain range, the Sierra Nevada, began to promote it as dozens of volcanoes lava and ash. In deeper areas were injected huge amounts of molten rock, which then slowly cooled down and solidified.
The during the Mesozoic sediments deposited in the Rockies were mariner, of transitional and continental nature, seen regionally and temporally they changed according to the prevailing conditions crustal their character. Until the beginning of the mix lara movements between 3,000 to 4,500 meters had been deposited on sediment that were distributed among 15 geological formations. The maximum sediment originated during the Cretaceous period, when the estuary of the Western Interior Seaway penetrated into the Rockies. Areas of origin of the deposited sediments are both the area of the estuary and the volcanic arc of the Sierra Nevada.
More than 100 million years, the effects of plate collisions remained essentially limited only to the edge of the North American plate, far to the west of the actual Rocky Mountains. Only 70 million years ago, they then made itself felt in the Rockies.
Emergence of the Rocky Mountains (before 70-40 million years ago)
The emergence of the Rocky Mountains is one of the most complex geological mystery. Mountains usually occur 200 to 400 miles behind a subduction zone, but the Rockies were formed much further inland. The answer for this discrepancy may be to look into an anomaly of the subducting oceanic plate.
On a typical subduction zone, the oceanic plate dips usually at a relatively steep angle back into the mantle and there is a volcanic island arc above the subducting plate. Perhaps this Abtauchwinkel was much flatter during the formation of the Rocky Mountains, so that the zone of Magmenbildung and its accompanying orogenic movements and was significantly restored to normal as usual into the hinterland. It can be assumed that the flat Abtauchwinkel the subducting plate increased the friction forces and other interactions with the thick continental crust overlying mass. Thrusts of giant proportions stacked sheared crustal layers to each other - resulting isostatic Auftauchbewegungen in turn caused the Rocky Mountains then rise to an exceptionally wide and high mountain range.
The current Rockies were pressed at her rise through the remnants of the former sedimentary cover ( Upper Carboniferous and Permian ) of the " Ancestral Rocky Mountains ". But the younger sediments of the outer layers were spectacularly deformed part, especially at the edges of the individual mountain ranges, where they were placed steep. An example of this is the Dakota Hogback, a sandstone formation from the Lower Cretaceous, which accompanies the entire east side of the Rockies with modern high angles of incidence.