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Geology Of Guyana
Guyana occurs within the northern part of the Guiana Shield. The Guiana Shield forms the northern part of the Amazonian Craton, the core of the South American continent. Most of the geology of northern Guyana consists of Palaeoproterozoic Orosirian greenstone belts (Barama-Mazaruni Supergroup) intruded by granites. These are overlain unconformably by the Statherian Burro-Burro Group, which consist of the Muruwa Formation sandstones and Iwokrama Formation felsic volcanics. Both are intruded by granites associated with the Iwokrama Formation. Some folding occurred before these were overlain by the locally unconformable almost flat lying Roraima Group.Gibbs, A.K & Barron, C.N (1993). ''The Geology of the Guiana Shield''. Oxford University Press. Major mafic sills and dykes of the Avanavero Suite intrude all of the older rocks, and are part of a Large Igneous Province (LIP). Numerous mafic dykes intruded the basement in the late Permian and Early Jurassic, associated with the start of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guiana Shield
The Guiana Shield (french: Plateau des Guyanes, Bouclier guyanais; nl, Hoogland van Guyana, Guianaschild; pt, Planalto das Guianas, Escudo das Guianas; es, Escudo guayanés) is one of the three cratons of the South American Plate. It is a 1.7 billion-year-old Precambrian geological formation in northeast South America that forms a portion of the northern coast. The higher elevations on the shield are called the Guiana Highlands, which is where the table-like mountains called tepuis are found. The Guiana Highlands are also the source of some of the world's most well-known waterfalls such as Angel Falls, Kaieteur Falls and Cuquenan Falls. The Guiana Shield underlies Guyana (previously British Guiana), Suriname (previously Dutch Guiana) and French Guiana (or Guyane), much of southern Venezuela, as well as parts of Colombia and Brazil. The rocks of the Guiana Shield consist of metasediments and metavolcanics ( greenstones) overlain by sub-horizontal layers of sandstones, quartz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amazonian Craton
The Amazonian Craton is a geologic province located in South America. It occupies a large portion of the central, north and eastern part of the continent and represents one of Earth's largest cratonic regions. The Guiana Shield and Central Brazil Shield (Guaporé Shield) constitute respectively the northern and southern exhumed parts of the craton. Between the two shields lies the Amazon Rift, a zone of weakness within the craton. Smaller cratons of Precambrian rocks south of the Amazonian Shield are the Río de la Plata Craton and the São Francisco Craton, which lies to the east. The Río Apa Craton at the Paraguay-Brazil border is considered be likely just the southern part of the Amazonian Craton. The rocks of Río Apa were deformed during the Sunsás orogeny. It has been suggested that the Late Mesoproterozoic– Early Neoproterozoic aged Sveconorwegian Orogen in Fennoscandia could have been caused by a continent–continent collision between the Amazonia and Balti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleoproterozoic
The Paleoproterozoic Era (;, also spelled Palaeoproterozoic), spanning the time period from (2.5–1.6 Ga), is the first of the three sub-divisions (eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's geological history. It was during this era that the continents first stabilized. Paleontological evidence suggests that the Earth's rotational rate ~1.8 billion years ago equated to 20-hour days, implying a total of ~450 days per year. Atmosphere Before the enormous increase in atmospheric oxygen, almost all existing lifeforms were anaerobic organisms whose metabolism was based on a form of cellular respiration that did not require oxygen. Free oxygen in large amounts is toxic to most anaerobic organisms. Consequently, most died when the atmospheric free oxygen levels soared in an extinction event called the Great Oxidation Event, which brought atmospheric oxygen levels to up to 10% of their current level. The only creatures that survi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orosirian
The Orosirian Period (; grc, ὀροσειρά, translit=oroseirá, meaning "mountain range") is the third geologic period in the Paleoproterozoic era (geology), Era and lasted from annum, Mya to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined Absolute dating, chronometrically. The later half of the period was an episode of intensive orogeny on virtually all continents. Two of the largest known impact events on Earth occurred during the Orosirian. Early in the period, 2023 Mya, a large asteroid collision created the Vredefort impact structure. The event that created the Sudbury Basin structure occurred near the end of the period, 1850 Mya. For the time period from about 2060 to 1780 Mya, an alternative period based on stratigraphy rather than chronometry, named the Columbian, was suggested in the geological timescale review 2012 edited by Gradstein et al., but , this has not yet been officially adopted by the IUGS. Paleogeography T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statherian
The Statherian Period (; grc, σταθερός, statherós, meaning "stable, firm") is the final geologic period in the Paleoproterozoic Era and lasted from Mya to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. The period was characterized on most continents by either new platforms or final cratonization of fold belts. Oxygen levels were 10% to 20% of current values. ''Rafatazmia'', controversially claimed to be present in Statherian beds in India, may be the oldest known confirmably eukaryotic fossil organism. By the beginning of the Statherian, the supercontinent Columbia had assembled. At roughly 1.7 billion years before present a series of natural nuclear fission reactors was operational in what is now Oklo Oklo is a region near the town of Franceville, in the Haut-Ogooué province of the Central African country of Gabon. Several natural nuclear fission reactors were discovered in the uranium mines in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Large Igneous Province
A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics. The formation of some of the LIPs in the past 500 million years coincide in time with mass extinctions and rapid climatic changes, which has led to numerous hypotheses about causal relationships. LIPs are fundamentally different from any other currently active volcanoes or volcanic systems. Definition In 1992 researchers first used the term ''large igneous province'' to describe very large accumulations—areas greater than 100,000 square kilometers (approximately the area of Iceland)—of mafic igneous rocks that were erupted or emplaced at depth within an extremely short geological time interval: a few million years or less. Maf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lopingian
The Lopingian is the uppermost series/last epoch of the Permian. It is the last epoch of the Paleozoic. The Lopingian was preceded by the Guadalupian and followed by the Early Triassic. The Lopingian is often synonymous with the informal terms late Permian or upper Permian. The name was introduced by Amadeus William Grabau in 1931 and derives from Leping, Jiangxi in China. It consists of two stages/ ages. The earlier is the Wuchiapingian and the later is the Changhsingian. The International Chronostratigraphic Chart (v2018/07) provides a numerical age of 259.1 ±0.5 Ma. If a Global Boundary Stratotype Section and Point (GSSP) has been approved, the lower boundary of the earliest stage determines numerical age of an epoch. The GSSP for the Wuchiapingian has a numerical age of 259.8 ± 0.4 Ma. Evidence from Milankovitch cycles suggests that the length of an Earth day during this epoch was approximately 22 hours. The Lopingian ended with the Permian–Triassic extinction event. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Atlantic Magmatic Province
The Central Atlantic magmatic province (CAMP) is the Earth's largest continental large igneous province, covering an area of roughly 11 million km2. It is composed mainly of basalt that formed before Pangaea broke up in the Mesozoic Era, near the end of the Triassic and the beginning of the Jurassic periods. The subsequent breakup of Pangaea created the Atlantic Ocean, but the massive igneous upwelling provided a legacy of basaltic dikes, sills, and lavas now spread over a vast area around the present central North Atlantic Ocean, including large deposits in northwest Africa, southwest Europe, as well as northeast South and southeast North America (found as continental tholeiitic basalts in subaerial flows and intrusive bodies). The name and CAMP acronym were proposed by Andrea Marzoli (Marzoli et al. 1999) and adopted at a symposium held at the 1999 Spring Meeting of the American Geophysical Union. The CAMP volcanic eruptions occurred about 201 million years ago and split into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rupununi
The Rupununi is a region in the south-west of Guyana, bordering the Brazilian Amazon. The Rupununi river, also known by the local indigenous peoples as ''Raponani'', flows through the Rupununi region. The name Rupununi originates from the word ''rapon'' in the Makushi language, in which it means the black-bellied whistling duck found along the river. Geography The Rupununi River is one of the main tributaries of the Essequibo River and is located in southern Guyana. The river originates in the Kanuku Mountains, which are located in the Upper Takutu-Essequibo region. The Rupununi River flows near the Guyana-Brazil border, and eventually leads into the Essequibo River. Throughout the flood season, the river shares a watershed with the Amazon. During the rainy season it is connected to the Takutu River by the flooded Pirara Creek, draining the vast swamps of the Parima or Amaku Lake. The region surrounding the Rupununi river is composed of mainly savannah, wetlands, forest, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petroleum Exploration In Guyana
Guyana is one of the newest petroleum producing regions in the world, making the first commercial grade crude oil draw in December 2019. Crude oil is sent abroad for refining. Early Explorations Historically, Guyana is a net importer of fuel. Guyana's offshore Guyana Basin and the inland Takatu Basin have attracted foreign companies such as Shell, Total and Mobil since the 1940s, who completed much geological surveyance of the area and drilled a number of wells. In the Takatu Basin, 3 wells were dug between 1981 and 1993, however they were dry or not found to be commercially viable. Offshore oil exploration began in the 1950's, and 9 wells were drilled between 1965 and 1970, only one of which struck oil, Abary-1 well in the Kanuku license area. In the late 1980's, Mobil, Total, Guyana Exploration and BHP continued exploration in the region. In the mid-2000s, CGX Energy attempted to spud a well but the rig was deterred by Surinamese gunboats claiming they were in Surinamese wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orinoco River
The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the world by discharge volume of water. The Orinoco River and its tributaries are the major transportation system for eastern and interior Venezuela and the Llanos of Colombia. The environment and wildlife in the Orinoco's basin are extremely diverse. Etymology The river's name is derived from the Warao term for "a place to paddle", itself derived from the terms ''güiri'' (paddle) and ''noko'' (place) i.e. a navigable place. History The mouth of the Orinoco River at the Atlantic Ocean was documented by Christopher Columbus on 1 August 1498, during his third voyage. Its source at the Cerro Delgado–Chalbaud, in the Parima range, was not explored until 453 years later, in 1951. The source, near the Venezuelan–Brazilian border, at ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branco River
The Branco River ( pt, Rio Branco; Engl: ''White River'') is the principal affluent of the Rio Negro from the north. Basin The river drains the Guayanan Highlands moist forests ecoregion. It is enriched by many streams from the Tepui highlands which separate Venezuela and Guyana from Brazil. Its two upper main tributaries are the Uraricoera and the Takutu. The latter almost links its sources with those of the Essequibo; during floods headwaters of the Branco and those of the Essequibo are connected, allowing a level of exchange in the aquatic fauna (such as fish) between the two systems. The Branco flows nearly south, and finds its way into the Negro through several channels and a chain of lagoons similar to those of the latter river. It is long, up to its Uraricoera confluence. It has numerous islands, and, above its mouth, it is broken by a bad series of rapids. Water chemistry As suggested by its name, the Branco (literally "white" in Portuguese) has whitish water that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.JPG "Click for more on -> Guiana Shield")
