Lebu Group | |
---|---|
Stratigraphic range: Paleocene–Eocene | |
Type | Stratigraphic group |
Sub-units | Millongue Formation Trihueco Formation Boca Lebu Formation Curanilahue Formation |
Underlies | Ranquil Formation |
Overlies | Quiriquina Formation |
Lithology | |
Primary | Shale, sandstone, siltstone, mudstone |
Other | Coal |
Location | |
Coordinates | 37°36′S73°42′W / 37.6°S 73.7°W |
Approximate paleocoordinates | 40°06′S64°12′W / 40.1°S 64.2°W |
Region | Bío Bío Region |
Country | Chile |
Extent | Arauco Basin |
Type section | |
Named for | Lebu |
Lebu Group is stratigraphic unit of Arauco Basin in south-central Chile. The group consists of a sequence of four formations, of both marine and nonmarine origin, deposited between the Early Paleocene and Middle Eocene. [1]
The group is made up of four formations, from youngest to oldest these are: Millongue Formation, [note 1] Trihueco Formation, Boca Lebu Formation and Curanilahue Formation. [1]
The Eocene Millongue Formation is composed of shale and siltstone of both marine and continental origin. Its top is marked by an unconformity, the so-called “main unconformity” of Arauco Basin, which is thought to have formed by erosion during a period of tectonic inversion. [1] [3]
Cañete is a city and commune in Chile, located in the Arauco Province of the Biobío Region. It is located 135 km to the south of Concepción. Cañete is known as a "Historic City" as it is one of the oldest cities in the country. The Battle of Tucapel and Pedro de Valdivia's death happened near the city's current location. Cañete was also an important location in the Arauco War.
The Biobío River is the second largest river in Chile. It originates from Icalma and Galletué lakes in the Andes and flows 380 km to the Gulf of Arauco on the Pacific Ocean.
The Arauco War was a long-running conflict between colonial Spaniards and the Mapuche people, mostly fought in the Araucanía region of Chile. The conflict began at first as a reaction to the Spanish conquerors attempting to establish cities and force Mapuches into servitude. It subsequently evolved over time into phases comprising drawn-out sieges, slave-hunting expeditions, pillaging raids, punitive expeditions, and renewed Spanish attempts to secure lost territories. Abduction of women and war rape was common on both sides.
Lebu is a port city and commune in central Chile administered by the Municipality of Lebu. Lebu is also the capital of Arauco Province in Bío Bío Region. It lies on the south bank of the mouth of the Lebu River.
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 Tremp Formation, alternatively described as Tremp Group, is a geological formation in the comarca Pallars Jussà, Lleida, Spain. The formation is restricted to the Tremp or Tremp-Graus Basin, a piggyback foreland basin in the Catalonian Pre-Pyrenees. The formation dates to the Maastrichtian to Thanetian, thus the formation includes the Cretaceous-Paleogene boundary that has been well studied in the area, using paleomagnetism and carbon and oxygen isotopes. The formation comprises several lithologies, from sandstone, conglomerates and shales to marls, siltstones, limestones and lignite and gypsum beds and ranges between 250 and 800 metres in thickness. The Tremp Formation was deposited in a continental to marginally marine fluvial-lacustrine environment characterized by estuarine to deltaic settings.
Neuquén Basin is a sedimentary basin covering most of Neuquén Province in Argentina. The basin originated in the Jurassic and developed through alternating continental and marine conditions well into the Tertiary. The basin bounds to the west with the Andean Volcanic Belt, to the southeast with the North Patagonian Massif and to the northeast with the San Rafael Block and to the east with the Sierra Pintada System. The basin covers an area of approximately 120,000 square kilometres (46,000 sq mi). One age of the SALMA classification, the Colloncuran, is defined in the basin, based on the Collón Curá Formation, named after the Collón Curá River, a tributary of the Limay River.
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.
In Chile, coal mining is restricted to a few places located in its southern half. Energy originating from coal stands for 11,6% of Chile's electricity consumption. Currently the country is not considered a major producer of coal.
The Altiplano Basin is a sedimentary basin within the Andes in Bolivia and Peru. The basin is located on the Altiplano plateau between the Cordillera Occidental and the Cordillera Oriental. Over-all the basin has evolved through time in a context of horizontal shortening of Earth's crust. The great thickness of the sediments accumulated in the basin is mostly the result of the erosion of Cordillera Oriental.
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 Ranquil Formation is a Miocene and Pliocene sedimentary formation located in Arauco Province in south–central Chile, including outcrops in Mocha Island. The formation has its greatest thicknesses in the south-west, where its sediments were largely deposited in marine conditions. It overlies unconformably sedimentary formations of the Paleocene-Eocene Lebu Group. The formation is part of the fill of Arauco Basin which is a sedimentary basin that extends south of Concepción.
The Arauco Basin is a sediment-filled depression –a sedimentary basin– in south-central Chile. In the context of plate tectonics it is classified as a forearc basin. The basin has an approximate area of 8,000 square kilometres (3,100 sq mi) and at its deeper parts the surface of its sedimentary fill reaches 200 metres (660 ft) below sea-level. The basin is interpreted as being part of an uplifted part of the continental shelf. To the west it bounds an active accretionary prism that lies next to the Chile trench and to the east it bounds metamorphic basement representing a fossil Paleozoic accretionary complex that has been intruded by the Coastal Batholith of central Chile.
Tubul Formation is an Early Pleistocene sedimentary formation located in Arauco Province in south–central Chile. Its sediments were deposited in marine conditions. It overlies unconformably the folded sedimentary formations of Ranquil (Miocene–Pliocene), Quiriquina and the Lebu Group (Paleocene-Eocene).
Farellones Formation is a geological formation of Miocene age in the Andes of Central Chile made up almost entirely of volcanic and volcaniclastic rocks. At some location reaches thicknesses in excess of 3,000 metres (9,800 ft). It overlies the Oligo–Miocene Abanico Formation across a diachronous unconformity. The best exposure of the formation is said to be at the ski resort of Farellones east of Santiago.
Nacientes del Biobío Formation is a geological formation that crops out near the uppermost reaches of Bío Bío River, in south-central Chile, and nearby areas of Argentina. The formation is made up of basalt and pyroclastic rocks and marine sedimentary rocks, such as sandstone and mudstone. Some less abundant sedimentary lithologies are conglomerate, volcaniclastic sedimentary rock. The formation is intruded by Grupo Plutónico Galletué which is of Late Jurassic to Late Cretaceous age. Further north in Chile the formation is similar to Nacientes del Teno Formation while in Argentina it is similar to Los Molles Formation and Lotena Formation.
Cheuquemó Formation is a geological formation of sedimentary rock in south-central Chile. The sediments of the formation were deposited during the Late Oligocene and Early Miocene epochs. The formations lower sections are made up of conglomerate, then successions of sandstone, tuff and mudstone rich in organic material follows. The formation indicates that sedimentation occurred in an estuarine (paralic) and other non-marine (continental) environments. It contains fossils of the following genera: Mytilus, Cardium and Turritella. Stratigraphically it overlies the Bahía Mansa Metamorphic Complex and underlies the Miocene Santo Domingo Formation.
Cholchol Formation is a geological formation composed of sediments that were deposited during the Miocene in the Temuco Basin of south–central Chile. The sediments were deposited in a marine environment.
Mulpún is a coal mine and locality in Los Ríos Region, Chile. Mulpún lies in the commune of Máfil a few kilometers to the west of the Chile Route 5 and north of the Calle-Calle and San Pedro River.
The Agua de la Piedra Formation is a Late Oligocene geologic formation of the Malargüe Group that crops out in the southernmost Precordillera and northernmost Neuquén Basin in southern Mendoza Province, Argentina.