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Chichinales Formation
The Chichinales Formation is a geological formation in Río Negro Province, Argentina which dates from the Late Oligocene to the Early Miocene, around 23 to 17.5 million years ago. It predominantly consists of pyroclastic deposits, which were deposited in a semi-arid environment. It is divided up into a number of members. The diverse fauna of the Chichinales Formation, including a variety of turtles and birds, also includes many mammals such as South American native ungulates (notoungulates and litopterns) as well as armadillos, and caviomorph rodents. It is named after the type locality and extends over a large part of the province of Río Negro. It outcrops in the valle de Río Negro, in the towns of General Roca, Río Negro and Villa Regina, bordering the southern bank of the Río Negro. Part of the most important outcrops are located within the Paso Córdova Natural Protected Area. The Chichinales Formation, broadly speaking, is made up of grayish sandstones, whitish tuf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colhuehuapian
The Colhuehuapian age is a period of geologic time (21.0–17.5 Ma) within the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Deseadan and precedes the Santacrucian age. Etymology The age is named after the Colhué Huapí Member of the Sarmiento Formation in the Golfo San Jorge Basin, Patagonia, Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th .... Formations Fossils References Bibliography ;Colhué Huapí Member * * ;Abanico Formation * * * * * * ;Biblián Formation * ;Castillo Formation * * * * * ;Cerro Bandera Formation * * ;Chichinales Formation * * ;Chilcatay Formation * * * * * * * * * * ;Cura-Mallín Group * * * ;Gaiman Formation * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuquén Basin
Neuquén Basin ( es, Cuenca Neuquina) 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 .Howell et al., 2005 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. Description Jurassic and Cretaceous marine transgressions from the Pacific are recorded in the sediments of Neuquén Basin. These marine sediments belong to Cuyo Group, Tordillo Formation, Auquilco Formation and Vaca Muerta. In the Late Cretaceous, conditions in the neighboring Andean orogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chattian
The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage of the Miocene). Stratigraphic definition The Chattian was introduced by Austrian palaeontologist Theodor Fuchs in 1894. Fuchs named the stage after the Chatti, a Germanic tribe.Berry, Edward W"The Mayence Basin, a Chapter of Geologic History" ''The Scientific Monthly'', Vol. 16, No. 2, February 1923. pp. 114. Retrieved March 18, 2020. The original type locality was near the German city of Kassel. The base of the Chattian is at the extinction of the foram genus ''Chiloguembelina'' (which is also the base of foram biozone P21b). An official GSSP for the Chattian Stage was ratified in October of 2016. The top of the Chattian Stage (which is the base of the Aquitanian Stage, Miocene Series and Neogene System) is at the first appearance o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Litopterna
Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of South American ungulates that were endemic to the continent, until the Great American Biotic Interchange brought new ungulate species. Like other endemic South American mammals, their relationship to other mammal groups had long been unclear, but recent genetic and proteomic evidence indicates that their closest living relatives are Perissodactyls (odd-toed ungulates) including horses, rhinoceros, and tapirs, and that litopterns are closely related to notoungulates, another widespread group of South American ungulates. There were two major groups of litopterns: Proterotheriidae and Macraucheniidae. Proterotheriids were medium to large animals that evolved adaptations for fast running, and occupied a variety of niches that elsewhere were filled by animals such as goats and antelopes, mouse deer, and horses. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross-bedding
In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The original depositional layering is tilted, such tilting not being the result of post-depositional deformation. Cross-beds or "sets" are the groups of inclined layers, which are known as cross-strata. Cross-bedding forms during deposition on the inclined surfaces of bedforms such as ripples and dunes; it indicates that the depositional environment contained a flowing medium (typically water or wind). Examples of these bedforms are ripples, dunes, anti-dunes, sand waves, hummocks, bars, and delta slopes.Collinson, J.D., Thompson, D.B., 1989, Sedimentary Structures (2nd ed): Academic Division of Unwin Hyman Ltd, Winchester, MA, XXX p. Environments in which water movement is fast enough and deep enough to develop large-scale bed forms fall into thre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Claystones
Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too small to study readily in the field. At first sight, the rock types appear quite similar; however, there are important differences in composition and nomenclature. There has been a great deal of disagreement involving the classification of mudrocks. A few important hurdles to their classification include the following: # Mudrocks are the least understood and among the most understudied sedimentary rocks to date. # Studying mudrock constituents is difficult due to their diminutive size and susceptibility to weathering on outcrops. # And most importantly, scientists accept more than one classification scheme. Mudrocks make up 50% of the sedimentary rocks in the geologic record and are easily the most widespread deposits on Earth. Fine sediment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, pp.381-382 Although its permeability and porosity is relatively low, siltstone is sometimes a tight gas reservoir rock, an unconventional reservoir for natural gas that requires hydraulic fracturing for economic gas production. Siltstone was prized in ancient Egypt for manufacturing statuary and cosmetic palettes. The siltstone quarried at Wadi Hammamat was a hard, fine-grained siltstone that resisted flaking and was almost ideal for such uses. Description There is not complete agreement on the definition of siltstone. One definition is that siltstone is mudrock ( clastic sedimentary rock containing at least 50% clay and silt) in which at least 2/3 of the clay and silt fraction is composed of silt-sized particles. Silt is defined a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous (for example, ''tuffaceous sandstone''). Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. Tuff is a relatively soft rock, so it has been used for construction since ancient times. Because it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the ''moai'' statues on Easter Island. Tuff can be classified as either igneous or sedimentary rock. It is usually studied in the context of igneous petrology, although it is sometimes described using sedimentological terms. Tuff is often erroneously called tufa in guidebooks and in television programmes. Volcanic ash The material that is expelled in a volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstones
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-bearing sandstone can be changed into quartzite through metamorphism, usually related to te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paso Córdoba
Paso Córdova is a village of General Roca municipality in Río Negro Province in Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th .... References Populated places in Río Negro Province {{RíoNegroAR-geo-stub ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Río Negro (Argentina)
Río Negro (; ''Black River'') is the main river of Patagonia in terms of the size of its drainage basin, its associated agricultural produce and population living at its shores. In eastern Patagonia it is also the largest by flow rate. The river flows through the Argentine province of Río Negro which is named after it. Its name comes from the literal translation of the Mapuche term ''Curu Leuvu'', although the water is more green than black. Formerly, it was also known as "river of the willows" because of the big number of weeping willows that grow along the bank. It is 635 km in length. It originates from the junction of the Limay River and Neuquén River at the border with the Neuquén Province, and flows southeast incised through steppes to the Atlantic Ocean at , near El Cóndor beach resort some downstream from Viedma, Río Negro province's capital. The river allows the Río Negro province to produce 70% of the pears and 72% the apples of Argentina. The main area o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Villa Regina
Villa Regina is a city in the General Roca Department of the . The city is connected to the rest of the towns in the Upper Río Negro Valley via National Route 22. The city was built by the Italian-Argentine Colonization Company ( es, Compañía Italo-Argentina de Colonización), which purchased 5,000 hectares for urban development from the estate of Manuel Zorrilla. The lands were divided into four zones of 1,300 hectares, 1,200 hectares, 1,300 hectares, and 1,200 hectares. These zones were then subdivided into lots, which were sold to families that immigrated to Argentina from Italy. The settlement was established on November 7, 1924. It was originally named Colonia Regina de Alvear, after the wife of then-president Marcelo T. de Alvear, who had approved the project. The company developed the town with the help of Italian investors. In 1930, the government of Rio Negro created the municipality of Villa Regina, dissolving the Italian-Argentine Colonization Company. By 1939, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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