Both of this mountain are mountain belts - one is a folded mountain belt the other is a Igneous mountain belt. I need to know more facts about this two mountains. What make them alike and what make them different.© BrainMass Inc. brainmass.com October 24, 2018, 7:47 pm ad1c9bdddf
Question:What is the different in Sierra Nevada (CA) vs. Mount Mitchell (NC) Both of this mountain are mountain belts - one is a folded mountain belt the other is a Igneous mountain belt. I need to know more facts about this two mountains. What make them alike and what make them different.
Actually, both are volcanic to some degree. However, the Blue Ridge range in NC (part of the Appalachian orogeny) is primarily metamorphic rocks associated with the tectonic folding forces. These folding events are associated with the accretion of an island arc / exotic terrane along the subduction zone that did exist on the eastern side of the pre-N American continent. The majority of the mountain range is comprised of metamorphics (slates, schists, gneisses) While the Sierra Nevadas were formed from a passive margin that became a subduction zone later and is composed mostly of volcanic rocks...see below for details
Sierra Nevada Range
Passive to active margin
The area of the park was astride a passive continental margin (similar to the east coast of present-day United States) during the Precambrian and early Paleozoic. Sediment was derived from continental sources and was deposited in shallow water. The limestones, sandstones, and shales thus created have since been metamorphosed into marble, quartzite, and slate. These rocks are now exposed on isolated pendants in the northern and central parts of the park (Snow Lake Pendant in the Emigrant Wilderness is a good example).
Starting in the mid-Paleozoic and lasting into the early Mesozoic, a convergent plate boundary transported many of the above-mentioned seabed sediments into the area of the park (possibly during the Antler orogeny). Heat generated from the subduction led to the creation of an island arc of volcanoes on the west coast of Laurentia (proto-North America) between the late Devonian and Permian periods. These rocks were incorporated into proto-North America by the middle of the Triassic, some of them finding their way to the area of the park. Most of these igneous and sedimentary rocks have since been heavily metamorphosed, uplifted and eroded away. Outcrops of the resulting Shoo Fly Complex (made of schists and gneisses) and younger Calaveras Complex (a mélange of shale, siltstone, and chert with mafic inclusions) are now found in the western side of the park.
Later volcanism in the Jurassic intruded and covered these rocks in what may have been magmatic activity associated with the early stages of the creation of the Sierra Nevada Batholith. 95% of these rocks were eventually removed by uplifted-accelerated erosion. Most of the remaining rocks are exposed as 'roof pendents' in the eastern metamorphic zone. Mount Dana and Mount Gibbs are made of these metavolcanic rocks. Only 5% of the rocks exposed in Yosemite National Park are metamorphic. (Geology of U.S. Parklands, page 218)
The first phase of regional plutonism started 210 million years ago in the late Triassic and continued throughout the Jurassic to about 150 million years BP. Also starting 150 million years ago was an increase in the westward drift rate of the North American Plate. The resulting orogeny (mountain-building event) is called the Nevadan orogeny by geologists. The resulting Nevadan mountain range (also called the Ancestral Sierra Nevada) was 15,000 feet (4500 m) high and was made of sections of seafloor and mélange.
These rocks were later metamorphosed and today can be seen in the gold-bearing metamorphic belt of California's Mother Lode country. In the area of the park these rocks are exposed along the Merced River and California State Route 140. This was directly part of the creation of the Sierra Nevada Batholith, and the resulting rocks were mostly granitic in composition and emplaced about 6 miles (10 km) below the surface.
The second, major pluton emplacement phase lasted from about 120 million to 80 million years ago during the Cretaceous. This was part of the Sevier orogeny. All told there have been ...
A detailed discussion of metamophic and tectonic mountain forming systems using two specific US mountains as examples