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14-597: Geologically, the South Mountains are thought to be a metamorphic core complex : evidence of movement of the North American tectonic plates from southwest to northeast and northeast to southwest, pushing up a series of mountain ranges including South Mountain. Other ridges with parallel orientation lie within the basin covered by basin fill sediments. The structural basin forms the Phoenix metro area, which appears flat like

28-467: A complex structure, which is usually the result of folding and faulting accompanied by volcanic activity . In South America, the ranges include numerous volcanic peaks . The Andes cordillera has Ojos del Salado , the highest active volcano in the world and second-highest point in the Western Hemisphere (though not itself a volcano, Argentina's Aconcagua , at 6,960 m or 22,830 ft,

42-528: A lake around mountains that rise over it like islands. The buried ridges are in the same orientation as the South Mountains, about one km high, and about one km apart from peak to peak, perhaps about 15 of them underneath the basin fill. The mountain, along with the nearby Sierra Estrella , is considered sacred by the Akimel O'odham and the Kwevkepaya band of Yavapai . This had become a point of contention prior to

56-496: Is a decollement and/or steep metamorphic gradient with much brecciation and kinematic structural relationships indicating sliding or detachment. The decollement is also called a detachment fault. Metamorphic core complexes form as the result of major continental extension, when the middle and lower continental crust is dragged out from beneath the fracturing, extending upper crust. Movement zones capable of producing such effects evolve in space as well as with time. Deforming rocks in

70-514: 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. High-grade metamorphic rocks ( eclogite -, granulite - to amphibolite - facies ) are exposed below

84-556: The Salt River Mountains. One of the notable tree species here is the elephant tree , Bursera microphylla . 33°20′0″N 112°3′45″W  /  33.33333°N 112.06250°W  / 33.33333; -112.06250 Metamorphic core complex 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

98-701: The construction of Arizona State Route 202 through the range's southwestern corner. The construction of the highway ultimately left a gash in the range at the border of the Gila River Indian Community within the City of Phoenix and South Mountain Preserve. The South Mountain Preserve is part of the Phoenix Parks System and is the second largest municipal park in Arizona, and the 13th largest municipal park in

112-470: The detachment faults (and mylonitic shear zones). Amphibolite - to greenschist -facies, syndeformational metamorphism , and ductile-brittle to brittle deformation are shown on the upper-side (hanging-wall), with tilted geometries. They range from several miles to over 50 miles across, and usually exhibit several miles of vertical uplift. They are common in areas of localized crustal extension in otherwise thickened fold-thrust belts . The origin of

126-492: The footwall are uplifted through a progression of different metamorphic and deformational environments, producing a characteristic sequence of (overprinted) meso- and microstructures. The core complex model was first developed in the cordillera of western North America , with older cores found in the north ( Eocene ), and younger to the south. The structures were first described by Peter Misch and his students in 1960. They were formerly called "cordilleran core complexes" after

140-465: The largest metamorphic core complex in the solar system. Cordillera A cordillera is a small chain and/or network system of mountain ranges , such as those in the west coast of the Americas . The term is borrowed from Spanish , where the word comes from cordilla , a diminutive of cuerda ('rope'). The term is most commonly used in physical geography and is particularly applied to

154-417: The low angles of the detachment faults were a subject of debate as of 2022. are characterized by a generally heterogeneous, older metamorphic-plutonic basement terrane overprinted by low-dipping lineated and foliated mylonitic and gneissic fabrics . An unmetamorphosed cover terrane is typically attenuated and sliced by numerous subhorizontal younger-on-older faults . Between the basement and cover terranes

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168-493: The region in which they were discovered. Globally, core complexes are thought to be found in the Aegean Sea , Anatolia , Iran , Tibet , north China , Slovakia , Venezuela - Trinidad ( Miocene ), New Zealand and West Antarctica . Core complexes are currently continuing to form in eastern New Guinea . A feature at the center of Artemis Corona on Venus has been suggested as a metamorphic core complex. This could be

182-683: The various large mountain systems of the American Cordillera , such as the Andes of South America , and less frequently to other mountain ranges in the " ridge " that rims the Pacific Ocean . In Colombia and Venezuela , cordilleras are named according to their position: Cordillera Occidental , Central , and Oriental . Various local names are used for the cordilleras in Ecuador , Peru , Bolivia , Chile and Argentina . Such mountain systems have

196-451: The world. The preserve features recreational facilities such as ramadas , hiking and mountain biking trails, and equestrian facilities. The major peaks of the South Mountains are (from West to East): A spur plateau of the Salt River Mountains was described by an early survey of the area as the dividing feature of the Salt River valley. There are a variety of flora and fauna within

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