The Brevard Fault Zone is a 700-km [1] long and several km-wide thrust fault that extends from the North Carolina-Virginia border, runs through the north metro Atlanta area, and ends near Montgomery, Alabama. It is an important Paleozoic era feature in the uplift of the Appalachian Mountains. [2]
Arthur Keith from the United States Geological Survey first identified an exposed segment of the Brevard Fault in 1905, [3] believing it to be a syncline. In 1932, Anna Jonas Stose’s used local petrology to identify the site as a thrust fault. [4] Stose, the first to trace the fault, is also credited with identifying that the rocks in the area must have been formed through deformation, [5] placing the Brevard Fault in a regional perspective. [3] Using modern methods of seismic reflection and high-resolution profiling, geologists have since discovered that the Brevard Fault Zone has undergone both thrust and strike-slip movement. [6]
The Brevard Fault Zone is a part of a much larger system of faults at the base of the Appalachian thrust sheet [1] that played a key role in uplifting the Appalachian Mountains. The extent of its role remains uncertain because most of the fault is buried beneath Quaternary sediment. [7] Many studies of the fault come from Grandfather Mountain in the Linville Fall Quadrangle, [8] which contains the exposed region that was first discovered by Arthur Keith. This region is only 1–3 km of its 700 km length. [7]
The Brevard Fault experienced multiple phases of deformation and minimal stratigraphic displacement. [3] The Brevard Fault Zone contains diverse lithologies, but it is primarily composed of mylonitic metagraywacke, schist, amphibolite, and gneiss [9] that underwent metamorphism 350–360 million years ago. [1] The Fault Zone is characterized by ductile behavior as indicated by the widespread presence of mylonitic and phyllonitic rocks. [1]
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The Antler orogeny was a tectonic event that began in the early Late Devonian with widespread effects continuing into the Mississippian and early Pennsylvanian. Most of the evidence for this event is in Nevada but the limits of its reach are unknown. A great volume of conglomeratic deposits of mainly Mississippian age in Nevada and adjacent areas testifies to the existence of an important tectonic event, and implies nearby areas of uplift and erosion, but the nature and cause of that event are uncertain and in dispute. Although it is known as an orogeny, some of the classic features of orogeny as commonly defined such as metamorphism, and granitic intrusives have not been linked to it. In spite of this, the event is universally designated as an orogeny and that practice is continued here. This article outlines what is known and unknown about the Antler orogeny and describes three current theories regarding its nature and origin.
The Sevier orogeny was a mountain-building event that affected western North America from northern Canada to the north to Mexico to the south.
John James Stevenson was an American geologist, born in New York City. He graduated from New York University in 1863, became professor of chemistry at West Virginia University for two years (1869–71), then served as professor of geology at New York University until 1909. During 1873–74 and from 1878 to 1880 he was geologist for the United States Geological Survey. He also served on the Pennsylvania Geological Survey from 1875 to 1878 and from 1881 to 1882. He was president of the Geological Society of America in 1898.
Décollement is a gliding plane between two rock masses, also known as a basal detachment fault. Décollements are a deformational structure, resulting in independent styles of deformation in the rocks above and below the fault. They are associated with both compressional settings and extensional settings.
Burrell Clark Burchfiel was an American structural geologist. Born in Stockton, California, he earned his Ph.D. in 1961 at Yale University. His first academic appointment was to the Geology department at Rice University. He was the Schlumberger Professor Emeritus of Geology at MIT. Research interests: Origin, development, and structural evolution of the continental crust. His later work involved study of the geological history and evolution of the Tibetan plateau.
Metamorphic core complexes are exposed areas of deep crust brought to the surface by crustal extension (stretching). They form, and are exhumed, through relatively fast transport of middle and lower continental crust to the Earth's surface in the form of uplifting welts of hot rock and magma. The resulting doming causes the overlying rock to gravitationally collapse, sliding down and usually away from the uplift along low-angle detachment faults. Brittle, faulted cover rock above the detachment surface lies in direct contact with the ductile middle-lower crust below.
The Walker Lane is a geologic trough roughly aligned with the California/Nevada border southward to where Death Valley intersects the Garlock Fault, a major left lateral, or sinistral, strike-slip fault. The north-northwest end of the Walker Lane is between Pyramid Lake in Nevada and California's Lassen Peak where the Honey Lake Fault Zone, the Warm Springs Valley Fault, and the Pyramid Lake Fault Zone meet the transverse tectonic zone forming the southern boundary of the Modoc Plateau and Columbia Plateau provinces. The Walker Lane takes up 15 to 25 percent of the boundary motion between the Pacific Plate and the North American Plate, the other 75 percent being taken up by the San Andreas Fault system to the west. The Walker Lane may represent an incipient major transform fault zone which could replace the San Andreas as the plate boundary in the future.
The Carolina Terrane, also called the Carolina Superterrane or Carolinia, is an exotic terrane running ~370 miles (600 km) approximately North-South from central Georgia to central Virginia in the United States. It constitutes a major part of the eastern Piedmont Province.
The Karakoram fault is an oblique-slip fault system in the Himalayan region across India and Asia. The slip along the fault accommodates radial expansion of the Himalayan arc, northward indentation of the Pamir Mountains, and eastward lateral extrusion of the Tibetan plateau. Current plate motions suggest that the convergence between the Indian plate and the Eurasian plate is around 44±5 mm per year in the western Himalaya-Pamir region and approximately 50±2 mm per year in the eastern Himalayan region.
The Vinini Formation is a marine, deep-water, sedimentary deposit of Ordovician to Early Silurian age in Nevada, U.S.A. It is notable for its highly varied, mainly siliceous composition, its mineral deposits, and controversies surrounding both its depositional environment and structural history. The formation was named by Merriam and Anderson for an occurrence along Vinini Creek in the Roberts Mountains of central Nevada and that name is now used extensively in the State.
In geology, exhumation is the process by which a parcel of buried rock approaches Earth's surface.
The Waits River Formation (WRF) is a late Silurian to early Devonian limestone containing lesser amounts of phyllite and schist. It is located in the northern Appalachian Mountains of North America. It ranges from Long Island Sound in Connecticut to the Gulf of St. Lawrence in Quebec (about 1,000 km), and its width ranges from 10–50 km. It is part of the Connecticut Valley–Gaspé Trough, which is present in eastern and northeastern Vermont.
Anna Isabel Jonas Stose was a major geological pioneer, who worked for the American Museum of Natural History, Maryland Geological Survey, Pennsylvania Geological Survey, Virginia Geological Survey, and the United States Geological Survey. She is best known for her work mapping the Appalachian Mountain Range, documenting the structure of and exposure to the rock formations, and tracing crystalline rocks. Stose was among the first to implement petrographic and structural techniques to the Appalachian Mountains, which were still in development at the time. This was rare because women at this time didn't do physical work in the fields, and her hard efforts are now noted and appreciated. She contributed largely to the Geologic Map of Virginia and the Geologic Map of the United States.
Project FAMOUS was the first-ever marine scientific exploration by manned submersibles of a diverging tectonic plate boundary on a mid-ocean ridge. It took place between 1971 and 1974, with a multi-national team of scientists concentrating numerous underwater surveys on an area of the Mid-Atlantic Ridge about 700 kilometers west of the Azores. By deploying new methods and specialized equipment, scientists were able to look at the sea floor in far greater detail than ever before. The project succeeded in defining the main mechanisms of creation of the median rift valley on the Mid-Atlantic Ridge, and in locating and mapping the zone of oceanic crustal accretion.
The Superior Craton is a stable crustal block covering Quebec, Ontario, and southeast Manitoba in Canada, and northern Minnesota in the United States. It is the biggest craton among those formed during the Archean period. A craton is a large part of the Earth's crust that has been stable and subjected to very little geological changes over a long time. The size of Superior Craton is about 1,572,000 km2. The craton underwent a series of events from 4.3 to 2.57 Ga. These events included the growth, drifting and deformation of both oceanic and continental crusts.
The Concord Gabbro-Syenite Complex is a paleozoic pluton located in North Carolina.
The Ashe Metamorphic Suite, also referred to as the Ashe Formation, was named after its type locality, Ashe County, North Carolina. The Ashe Metamorphic Suite is located in the Eastern Blue Ridge providence that extends from North Carolina up to South-Western Virginia. It is a collection of metamorphic rocks of both sedimentary and volcanic origin. Zircon dating indicates an age of 470 to 335 Ma for the unit. The protolith of the Ashe Metamorphic Suite was deposited during the Late Proterozoic and reaching its cooling age during the end of the Devonian. The Ashe Metamorphic Suite is overwhelmingly composed of amphibolites and mica schists.
Elizabeth Scott Cochran is a seismologist known for her work on early warning systems for earthquakes and human-induced earthquakes.
Paul Barry Wignall is a British palaeontologist and sedimentologist. He is best known for his research on mass extinctions in the marine realm., particularly via the interpretation of black shales.
Robert Dean Hatcher Jr. is an American structural geologist, known as one of the world's leading experts on the geology of the southern and central Appalachians.