|Stratigraphic range: Mid-Late Jurassic|
|Sub-units||Basal Clastic Complex|
|Underlies||Zapata, Springhill, Pampa Rincón & Chon Aike Formations|
|Overlies|| Tierra del Fuego Igneous and Metamorphic Complex |
Cordillera Darwin Metamorphic Complex
|Primary||Silicic pyroclastic rocks (including tuff)|
|Other||Black shale, silicic intrusions, conglomerate, sandstone|
|Region|| Santa Cruz Province |
Magallanes y la Antártica Chilena Region
|Country|| Argentina |
|Extent||Rocas Verdes Basin|
Magallanes & Malvinas Basins
|Named for||Spanish for "tuffaceous"|
Tobífera Formation (Spanish : Formación Tobífera) is a volcano-sedimentary formation of Middle to Late Jurassic age. The formation is crops out in the Magallanes Region in southern Patagonia and Tierra del Fuego of Chile, the Santa Cruz Province of southern Argentina, and in the subsurface of the Malvinas Basin offshore Argentina and the Falkland Islands.
The bulk of the formation originates from silicic pyroclastic material during a period of bimodal volcanism in Rocas Verdes Basin, a rift basin.The Tobífera Formation is grouped together with other formations of similar age in Patagonia in the Chon Aike Province an extraordinarily large province of silicic volcanism.
Except for some western and southern exposures most of the formation is buried and known only from boreholes in the Magallanes and Malvinas Basins. The formation is equivalent to El Quemado and Ibañez Formations. 80 metres (260 ft) thick Basal Clastic Complex, a sub-unit made up of conglomerate and sandstone. Tobífera Formation unconformably overlies metamorphic and igneous basement complexes of Cambrian age.Tobífera Formation has an up to
Much of the formation is folded and faulted as consequence of the Andean orogeny.At Última Esperanza Province the formation metamorphosed first under greenschist facies and then under prehnite-pumpellyite facies conditions. Some rhyolites of Tobífera Formation were incorporated into Cordillera Darwin Metamorphic Complex. The incorporation of part of Tobífera Formation in the metamorphic complex was accompanied by deformation and metamorphism and occurred in the context of the Andean orogeny in the Cretaceous.
Tierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla Grande de Tierra del Fuego, with an area of 48,100 km2 (18,572 sq mi), and a group of many islands, including Cape Horn and Diego Ramírez Islands. Tierra del Fuego is divided between Chile and Argentina, with the latter controlling the eastern half of the main island and the former the western half plus the islands south of Beagle Channel and the southernmost islands. The southernmost extent of the archipelago is just north of latitude 56°S.
The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca Plate and Antarctic Plate underneath the South American Plate. The belt is subdivided into four main volcanic zones which are separated by volcanic gaps. The volcanoes of the belt are diverse in terms of activity style, products, and morphology. While some differences can be explained by which volcanic zone a volcano belongs to, there are significant differences within volcanic zones and even between neighboring volcanoes. Despite being a type location for calc-alkalic and subduction volcanism, the Andean Volcanic Belt has a broad range of volcano-tectonic settings, as it has rift systems and extensional zones, transpressional faults, subduction of mid-ocean ridges and seamount chains as well as a large range of crustal thicknesses and magma ascent paths and different amounts of crustal assimilations.
The geology of Chile is a characterized by processes linked to subduction such as volcanism, earthquakes and orogeny. The buildings blocks of Chile's geology assembled during the Paleozoic Era. Chile was by then the southwestern margin of the supercontinent Gondwana. In the Jurassic Gondwana began to split and the ongoing period of crustal deformation and mountain building known as the Andean orogeny began. In the Late Cenozoic Chile definitely separated from Antarctica, the Andes experienced a great rise accomplained by a cooling climate and the onset of glaciations.
The Magallanes–Fagnano Fault is a continental transform fault. The fault marks a transform boundary between the Scotia Plate and the South American Plate, cutting across continental crust. It runs under the Strait of Magellan's western arm, Almirantazgo Sound and Fagnano Lake.
The Magallanes Basin or Austral Basin is a major sedimentary basin in southern Patagonia. The basin covers a surface of about 170,000 to 200,000 square kilometres and has a NNW-SSE oriented shape. The basin is bounded to the west by the Andes mountains and is separated from the Malvinas Basin to the east by the Río Chico-Dungeness High. The basin evolved from being an extensional back-arc basin in the Mesozoic to being a compressional foreland basin in the Cenozoic. Rocks within the basin are Jurassic in age and include the Cerro Toro Formation. Three ages of the SALMA classification are defined in the basin; the Early Miocene Santacrucian from the Santa Cruz Formation and Friasian from the Río Frías Formation and the Pleistocene Ensenadan from the La Ensenada Formation.
The Western Carpathians are an arc-shaped mountain range, the northern branch of the Alpine-Himalayan fold and thrust system called the Alpide belt, which evolved during the Alpine orogeny. In particular, their pre-Cenozoic evolution is very similar to that of the Eastern Alps, and they constitute a transition between the Eastern Alps and the Eastern Carpathians.
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. Locally the details of the nature of the orogeny varies depending on the segment and the geological period considered.
The geology of Uruguay combines areas of Precambrian-aged shield units with a region of volcanic rock erupted during the Cretaceous and copious sedimentary facies the oldest of which date from the Devonian. Big events that have shaped the geology of Uruguay include the Transamazonian orogeny, the breakup of Rodinia and the opening of the South Atlantic.
The Famatinian orogeny is an orogeny that predates the rise of the Andes and that took place in what is now western South America 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. 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. The igneous rocks of the Famatinian magmatic arc are of calc-alkaline character and include gabbros, tonalites and granodiorites. The youngest igneous rocks of the arc are granites.
Salta Basin or Salta Rift Basin is a sedimentary basin located in the Argentine Northwest. The basin started to accumulate sediments in the Early Cretaceous (Neocomian) and at present it has sedimentary deposits reaching thicknesses of 5,000 metres (16,000 ft). The basin contains seven sub-basins: Tres Cruces, Lomas de Olmedo, Metán, Alemanía, Salfity, El Rey, Sey and Brealito. The basin environment has variously been described as a "foreland rift" and an "intra-continental rift". The basin developed under conditions of extensional tectonics and rift-associated volcanism.
Abanico Formation is a 3 kilometres (9,800 ft) thick sedimentary formation exposed in the Andes of Central Chile. The formation has been deposited in a timespan from the Eocene to the Miocene. Abanico Formation's contact with the overlying Miocene Farellones Formation has been the subject of differing interpretations since the 1960s. A small part of the formation crops out in the Mendoza Province of western Argentina.
The Eastern Andes Metamorphic Complex is a large coherent but varied group of metamorphic and sedimentary rocks –in other words a geologic complex– that crops out in the eastern Patagonian Andes in Chile and Argentina. The metamorphic grade of rocks varies but does not exceed greenschist facies, the only exception to this are rocks near plutons affected by contact metamorphism. The sedimentary protoliths sedimented in the Late Paleozoic. The pressures and temperatures of metamorphism of the Eastern Andes Metamorphic Complex are different those usually expected from accretionary complexes. The sedimentary protoliths of the Eastern Andes Metamorphic Complex were likely deposited in a passive continental margin.
The Cordillera Darwin Metamorphic Complex is a geologic complex composed chiefly of metamorphic rocks located in southern Tierra del Fuego. It has been suggested that the Cordillera Darwin Metamorphic Complex is analogous to the Eastern Andes Metamorphic Complex. The Cordillera Darwin Metamorphic Complex is the only metamorphic complex in the southern Andes known to have amphibolite facies rocks containing kyanite and sillimanite which evidences high-grade metamorphism. High-grade metamorphism took place during the Cretaceous purportedly in association with the closure of the Rocas Verdes Basin.
Tierra del Fuego Igneous and Metamorphic Complex is a geological basement complex known from boreholes in northern Tierra del Fuego. The complex is made up of foliated igneous rocks of Cambrian age including orthogneiss. It underlies unconformably the Jurassic Tobífera Formation. The protoliths of Cordillera Darwin Metamorphic Complex are unrelated to Tierra del Fuego Igneous and Metamorphic Complex despite present-day proximity.
Zapata Formation is a sedimentary formation of Lower Cretaceous age in the Magallanes or Austral Basin of Argentina and Chile. Much of the formation is folded and faulted as consequence of the Andean orogeny. In outcrops of the Zapata Formation near Torres del Paine, the southernmost fossil of the ichthyosaur genus Platypterygius has been found.
The Chon Aike Formation is an extensive geological formation, present in the Deseado Massif in north-central Santa Cruz Province, Patagonia, Argentina. It covers an area of approximately 100,000 square kilometres (39,000 sq mi) and consists of rhyolitic volcanic rocks, particularly ignimbrites and lavas, with smaller amounts of agglomerates and tuffs. Within dacitic rocks, plant fossils have been found.
Fueguino is a volcanic field in Chile. The southernmost volcano in the Andes, it lies on Tierra del Fuego's Cook Island and also extends over nearby Londonderry Island. The field is formed by lava domes, pyroclastic cones, and a crater lake.
Patagonia comprises the southernmost region of South America, portions of which lie 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 their vast earthquakes and the damage.
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.