The Famatinian orogeny (Spanish : Orogenia de Famatina) is an orogeny that predates the rise of the Andes and that took place in what is now western South America [note 1] during the Paleozoic, leading to the formation of the Famatinian orogen also known as the Famatinian belt. The Famatinian orogeny lasted from the Late Cambrian to at least the Late Devonian and possibly the Early Carboniferous, with orogenic activity peaking about 490 to 460 million years ago. [1] The orogeny involved metamorphism and deformation in the crust and the eruption and intrusion of magma along a Famatinian magmatic arc that formed a chain of volcanoes. [2] The igneous rocks of the Famatinian magmatic arc are of calc-alkaline character and include gabbros, tonalites, granodiorites and trondhjemites. [1] [3] The youngest igneous rocks of the arc are granites. [1]
Part of the pegmatite dykes of the Pampean Pegmatite Province formed during the orogeny. [4] These dykes are thought to be derived from S-type granitic melts. [4]
The relationship of the orogeny with the Achala and Cerro Aspero batholiths of central Argentina is not fully understood. These Devonian batholiths are possibly of post-orogenic character. [5] [6]
The Famatinian orogen's main outcrops lie in Sierras Pampeanas in northwestern Argentina. [1] [7] Only the western part of Sierras Pampeanas bears evidence of the Famatinian orogeny; the eastern parts appear to have been largely unaffected. [1] In northern Chile the Belén Metamorphic Complex is thought to have been subject to metamorphism that was "time-equivalent" to the Famatinian orogeny in the early Paleozoic. [7] It can this be considered part of the orogen in a broad sense. [7] To the south in La Pampa Province, outcrops associated with the orogeny are scarce since most of that region has become blanketed by much more recent Quaternary sediments. [8]
In Peru's Cordillera Oriental a "Famatinian" orogeny exists which is coeval with the classical Famatinian orogeny found further south. In the time-span from 480 Ma to 435 Ma (Late Cambrian to Silurian) rocks of Cordillera Oriental were deformed and a magmatic arc developed. [9]
Towards what is now the east of the Famatinian magmatic arc a Precambrian sedimentary basin developed into a back-arc basin during the Ordovician. This basin went from Peru, through Bolivia to northwestern Argentina. The basin collected sediments from the Famatinian orogen and arc and while it did not contain oceanic crust it was a marine basin. [10]
Plutonic rocks cropping out in Cordón de Lila and Sierra de Almeida south of Salar de Atacama in Chile formed in the Cambrian and Ordovician in association with the orogeny. [11] The compositions of the plutonic rocks are granodiorite and monzogranite that are either metaluminous or peraluminous. [11] These rocks are remnants of the magmatism along the western rim of the Famatinian orogeny. [11]
Famatinian arc magmatism was caused by the subduction of Iapetus Ocean lithosphere beneath Gondwana. [8] As subduction went on, the peak of the orogeny resulted from the collision of the Cuyania terrane with Pampia in the Ordovician. [12]
It has been suggested that the coeval Appalachian Taconic orogeny is the "northward" continuation of the Famatinian orogeny. [note 2] This has been explained by adding that the continent Laurentia could have collided with Gondwana (at what is today western South America) in early Paleozoic times due to the closure of the Iapetus Ocean. [13] Supporting this hypothesis is the suggestion that the orogens have "truncated ends" that can be matched and that both share the commonality of having carbonate platform sediments at what is today their western side. [13] [14] Further, in the mentioned sediments both orogens host similar Olenellid trilobite faunas, something that is not expected to be unless both orogens had some sort of contact. [13] This is because trilobites are unable to cross deep ocean basins. [15] According to this view the Cuyania terrane would be an allochthonous block of Laurentian origin that was left in Gondwana after the continents went apart. But such views are not unchallenged since Cuyania is alternatively suggested to have drifted across Iapetus Ocean as a microcontinent starting in Laurentia and accreting then to Gondwana. Further a third model claims Cuyania is para-autochthonous and arrived at its current place by strike-slip fault movements starting not from Laurentia but from another region of Gondwana. [12] The fact that Precordillera terrane has many trilobite genera in common with Laurentia but many species are endemic have led to some differing interpretations on what paleogeographic and tectonic history conditions are plausible explanations for this biogeography. [15]
The Iapetus Ocean existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale. It was in the southern hemisphere, between the paleocontinents of Laurentia, Baltica and Avalonia. The ocean disappeared with the Acadian, Caledonian and Taconic orogenies, when these three continents joined to form one big landmass called Euramerica. The "southern" Iapetus Ocean has been proposed to have closed with the Famatinian and Taconic orogenies, meaning a collision between Western Gondwana and Laurentia.
Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, is more than three billion years old and formed part of the Rodinia supercontinent at c. 1 Ga.
Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent underlie south-west Great Britain, southern Ireland, and the eastern coast of North America. It is the source of many of the older rocks of Western Europe, Atlantic Canada, and parts of the coastal United States. Avalonia is named for the Avalon Peninsula in Newfoundland.
The Acadian orogeny is a long-lasting mountain building event which began in the Middle Devonian, reaching a climax in the Late Devonian. It was active for approximately 50 million years, beginning roughly around 375 million years ago (Ma), with deformational, plutonic, and metamorphic events extending into the early Mississippian. The Acadian orogeny is the third of the four orogenies that formed the Appalachian Mountains and subsequent basin. The preceding orogenies consisted of the Grenville and Taconic orogenies, which followed a rift/drift stage in the Neoproterozoic. The Acadian orogeny involved the collision of a series of Avalonian continental fragments with the Laurasian continent. Geographically, the Acadian orogeny extended from the Canadian Maritime provinces migrating in a southwesterly direction toward Alabama. However, the northern Appalachian region, from New England northeastward into Gaspé region of Canada, was the most greatly affected region by the collision.
The Taconic orogeny was a mountain building period that ended 440 million years ago (Ma) and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the east coast of the United States. As the mountain chain eroded in the Silurian and Devonian periods, sediment spread throughout the present-day Appalachians and midcontinental North America.
The Caledonian orogeny was a mountain-building cycle recorded in the northern parts of the British Isles, the Scandinavian Caledonides, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occurred from the Ordovician to Early Devonian, roughly 490–390 million years ago (Ma). It was caused by the closure of the Iapetus Ocean when the Laurentia and Baltica continents and the Avalonia microcontinent collided.
The Rheic Ocean was an ocean which separated two major paleocontinents, Gondwana and Laurussia (Laurentia-Baltica-Avalonia). One of the principal oceans of the Paleozoic, its sutures today stretch 10,000 km (6,200 mi) from Mexico to Turkey and its closure resulted in the assembly of the supercontinent Pangaea and the formation of the Variscan–Alleghenian–Ouachita orogenies.
Gondwana was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia, Zealandia, Arabia, and the Indian Subcontinent.
Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and the Hebridean Terrane in northwest Scotland. During other times in its past, Laurentia has been part of larger continents and supercontinents and consists of many smaller terranes assembled on a network of early Proterozoic orogenic belts. Small microcontinents and oceanic islands collided with and sutured onto the ever-growing Laurentia, and together formed the stable Precambrian craton seen today.
The Precordillera Terrane or Cuyania was an ancient microcontinent or terrane whose history affected many of the older rocks of Cuyo in Argentina. It was separated by oceanic crust from the Chilenia terrane which accreted into it at ~420-390 Ma when Cuyania was already amalgamated with Gondwana. The hypothesized Mejillonia Terrane in the coast of northern Chile is considered by some geologists to be a single block with Cuyania.
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 Sierras Pampeanas is a geographical region of Argentina.
The Andean orogeny is an ongoing process of orogeny that began in the Early Jurassic and is responsible for the rise of the Andes mountains. The orogeny is driven by a reactivation of a long-lived subduction system along the western margin of South America. On a continental scale the Cretaceous and Oligocene were periods of re-arrangements in the orogeny. The details of the orogeny vary depending on the segment and the geological period considered.
The Terra Australis Orogen (TAO) was a late Neoproterozoic- to Paleozoic-age accretionary orogen that ringed the ancient, active southern margin of the supercontinents Rodinia and later Pannotia. This vast orogenic belt stretched for c. 18,000 km (11,000 mi) along-strike and involved, from west to east, landmasses belonging to the modern-day Andean margin of South America, the South African Cape, West Antarctica, Victoria Land in East Antarctica, Eastern Australia, Tasmania, and New Zealand. The formation of the Terra Australis Orogen is associated with the breakup of Rodinia at the end of the Neoproterozoic Era and the creation of Panthalassa, the paleo-Pacific Ocean, and it was succeeded by the Gondwanide orogeny with the formation of the supercontinent Pangea in the middle Paleozoic Era.
The Pampean orogeny was an orogeny active in the Cambrian in the western margin of the ancient landmass of Gondwana. The orogen's remains can now be observed in central Argentina, in particular at the Sierras de Córdoba and other parts of the eastern Sierras Pampeanas. It is uncertain if the orogeny involved at some point a continental collision. The Pampean orogen can be considered both part of the larger Terra Australis orogen and of the Brasiliano orogeny. The Pampean orogeny was succeeded by the Famatinian orogeny further west.
Puncoviscana Formation is a formation of sedimentary and metasedimentary rocks Late Ediacaran and Lower Cambrian age, estimated at between 700 and 535 Ma, that crop out in the Argentine Northwest. Most of the formation lies in Jujuy, Salta and Tucumán Province albeit some authors extend the formation further south to the Sierras Pampeanas near Córdoba.
The Precordillera terrane of western Argentina is a large mountain range located southeast of the main Andes mountain range. The evolution of the Precordillera is noted for its unique formation history compared to the region nearby. The Cambrian-Ordovian sedimentology in the Precordillera terrane has its source neither from old Andes nor nearby country rock, but shares similar characteristics with the Grenville orogeny of eastern North America. This indicates a rift-drift history of the Precordillera in the early Paleozoic. The Precordillera is a moving micro-continent which started from the southeast part of the ancient continent Laurentia. The separation of the Precordillera started around the early Cambrian. The mass collided with Gondwana around Late Ordovician period. Different models and thinking of rift-drift process and the time of occurrence have been proposed. This page focuses on the evidence of drifting found in the stratigraphical record of the Precordillera, as well as exhibiting models of how the Precordillera drifted to Gondwana.
Patagonia comprises the southernmost region of South America, portions of which lie on either side of the Argentina-Chile border. It has traditionally been described as the region south of the Rio, Colorado, although the physiographic border has more recently been moved southward to the Huincul fault. The region's geologic border to the north is composed of the Rio de la Plata craton and several accreted terranes comprising the La Pampa province. The underlying basement rocks of the Patagonian region can be subdivided into two large massifs: the North Patagonian Massif and the Deseado Massif. These massifs are surrounded by sedimentary basins formed in the Mesozoic that underwent subsequent deformation during the Andean orogeny. Patagonia is known for its vast earthquakes and the damage they cause.
The geology of Argentina includes ancient Precambrian basement rock affected by the Grenville orogeny, sediment filled basins from the Mesozoic and Cenozoic as well as newly uplifted areas in the Andes.
The geology of Peru includes ancient Proterozoic rocks, Paleozoic and Mesozoic volcanic and sedimentary rocks, and numerous basins and the Andes Mountains formed in the Cenozoic.