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Los Rastros Formation
The Los Rastros Formation is a Ladinian to Carnian fossiliferous formation of the Agua de la Peña Group in the Ischigualasto-Villa Unión Basin in northwestern Argentina. Fossil theropod tracks,Weishampel et al., 2004, pp. 517-607 as well as many insects, fossil fish of '' Myriolepis'',Leonardi, 1994, p.20 bivalves and crustaceans and flora have been reported from the formation. Description The formation overlies the Chañares Formation (and/or the Ischicuca Formation), and is overlain by the Ischigualasto Formation.Aceituno Cieri, 2015, p.60 The formation belongs to the Agua de la Peña Group of the Ischigualasto-Villa Unión Basin, where it is exposed in the Ischigualasto Provincial Park, a World Heritage Site in Argentina.Kent et al, 2014, p.7959 The up to thick formation of claystones, mudstones and sandstones was deposited in a deltaic to lacustrine environment during the first post-rift sequence in the basin. A CA-TIMS U-Pb zircon age of 234.47 ± 0.44 Ma from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ischigualasto-Villa Unión Basin
The Ischigualasto-Villa Unión Basin ( es, Cuenca de Ischigualasto-Villa Unión) is a small sedimentary basin located in the Argentine Northwest, Argentina. It is located in the southwestern part of La Rioja Province and the northeastern part of San Juan Province. The basin borders the Sierras Pampeanas in the east, the western boundary of the basin is formed by the Valle Fértil Fault, bordering the Precordillera, and it is bound in the southeast by the El Alto Fault, separating the basin from the Marayes-El Carrizal Basin. The basin started forming in the Late Permian, with the break-up of Pangea, when extensional tectonics, including rifting, formed several basins in Gondwana; present-day South America, Africa, Antarctica, India and Australia. The accommodation space in the Ischigualasto-Villa Unión Basin was filled by an approximately thick succession of volcaniclastic, eolian, alluvial, fluvial and lacustrine deposits in various geologic formations. The Cenozoic ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnian Pluvial Event
The Carnian pluvial episode (CPE), often called the Carnian pluvial event, was an interval of major change in global climate synchronous with significant changes in Earth's biota both in the sea and on land. It occurred during the latter part of the Carnian Stage of the late Triassic period over an interval of perhaps 1-2 million years (approximately 234-232 million years ago), across the boundary between the Julian and Tuvalian substages of the Carnian. It represents a significant episode in the evolution and diversification of many taxa that are important today, among them some of the earliest dinosaurs (which include the ancestors of birds), lepidosaurs (ancestors of modern-day snakes and lizards), pterosaurs and true mammals. In the marine realm it saw the first appearance among the microplankton of coccoliths and dinoflagellates , with the latter linked to the rapid diversification of scleractinian corals through the establishment of symbiotic zooxanthellae. The CPE also saw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depositional Environment
In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record. In most cases, the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the further back in geological time sediments were deposited, the more likely that direct modern analogues are not available (e.g. banded iron formations). Types of depositional environments Continental * – type of Fluvial deposit. Caused by moving water in a fan shape (Alluvial Fan) and containing mostly impermeable and nonporous sediments well sorted. * . Often in deserts and coastal regions and well sorted, large scale cross-beds * – processes due to moving water, mainly streams. Common sediments are grav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacustrine
A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger oceans, they do form part of the Earth's water cycle. Lakes are distinct from lagoons, which are generally coastal parts of the ocean. Lakes are typically larger and deeper than ponds, which also lie on land, though there are no official or scientific definitions. Lakes can be contrasted with rivers or streams, which usually flow in a channel on land. Most lakes are fed and drained by rivers and streams. Natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers, where a river channel has widened into a basin. Some parts of the world have many lakes formed by the chaotic drainage patterns left over from the last ice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
River Delta
A river delta is a landform shaped like a triangle, created by deposition (geology), deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot carry away the supplied sediment. It is so named because its triangle shape resembles the Greek letter Delta. The size and shape of a delta is controlled by the balance between watershed processes that supply sediment, and receiving basin processes that redistribute, sequester, and export that sediment. The size, geometry, and location of the receiving basin also plays an important role in delta evolution. River deltas are important in human civilization, as they are major agricultural production centers and population centers. They can provide Coast, coastline defense and can impact drinking water supply. They are also Ecology, ecologically important, with different species' assemblages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, W. H. Freeman, 2nd ed, 529 pp. The term ''mudstone'' is also used to describe carbonate rocks (limestone or dolomite) that are composed predominantly of carbonate mud. However, in most contexts, the term refers to siliciclastic mudstone, composed mostly of silicate minerals. The NASA Curiosity rover has found deposits of mudstone on Mars that contain organic substances such as propane, benzene and toluene. Definition There is not a single definition of mudstone that has gained general acceptance,Boggs 2006, p.143 though there is wide agreement that mudstones are fine-grained sedimentary rocks, composed mostly of silicate grains with a grain size less than . Individual grains this size are too small to be disting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Claystone
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 sedimen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Heritage Site
A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for having cultural, historical, scientific or other form of significance. The sites are judged to contain " cultural and natural heritage around the world considered to be of outstanding value to humanity". To be selected, a World Heritage Site must be a somehow unique landmark which is geographically and historically identifiable and has special cultural or physical significance. For example, World Heritage Sites might be ancient ruins or historical structures, buildings, cities, deserts, forests, islands, lakes, monuments, mountains, or wilderness areas. A World Heritage Site may signify a remarkable accomplishment of humanity, and serve as evidence of our intellectual history on the planet, or it might be a place of great natural beauty. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ischigualasto Provincial Park
Ischigualasto Provincial Park ( es, Parque Provincial Ischigualasto), also called ''Valle de la Luna'' ("Valley of the Moon" or "Moon Valley"), due to its moon like appearance, is a provincial protected area in the north-east of San Juan Province, north-western Argentina, limiting to the north with the Talampaya National Park, in La Rioja Province. Both areas belong to the same geological formation, the Ischigualasto Formation (sometimes called the Ischigualasto-Talampaya Formation). Established on 3 November 1971, the park has an area of . In 2000, UNESCO included Ischigualasto and Talampaya National Park among its World Heritage Sites. History The name Ischigualasto is derived from the extinct Cacán language, spoken by an indigenous group referred to as the Diaguita by the Spanish conquistadors and means "place where the moon alights". Another hypothesis gives the name "Ischigualasto" a Quechua origin, meaning "dead land", although some scholars have proposed Huarpe root ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
