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53-784: It is also believed to be closely connected with the Paraná and Etendeka flood basalt provinces, which formed over the hotspot during the opening of the South Atlantic Ocean. The Tristan and Gough hotspots are widely spaced end-members of the volcanic system that generated the Walvis Ridge on the African plate and the Rio Grande Rise on the South American plate beginning at 129 to 133 Ma when

106-665: A chain of islands across the South Atlantic during the Maastrichtian and Palaeocene 70 to 65 Ma allowing the primates to disperse across the ocean. Other researchers dismiss the hypothesis of Arnason et al. instead favouring a less spectacular rafting event . Other hints of transoceanic island hopping in the fossil record is Lavocatavis , a flightless terror bird found in Eocene layers in Algeria,

159-449: A consequence of the initial hot-spot activity in ocean basins as well as on continents. It is possible to track the hot spot back to the flood basalts of a large igneous province; the table below correlates large igneous provinces with the track of a specific hot spot. Eruptions or emplacements of LIPs appear to have, in some cases, occurred simultaneously with oceanic anoxic events and extinction events . The most important examples are

212-423: A high proportion of dykes relative to country rocks, particularly when the width of the linear field is less than 100 km. The dykes have a typical width of 20–100 m, although ultramafic dykes with widths greater than 1 km have been reported. Dykes are typically sub-vertical to vertical. When upward flowing (dyke-forming) magma encounters horizontal boundaries or weaknesses, such as between layers in

265-517: A large proportion (>75%) of the total igneous volume has been emplaced. They are dominantly mafic, but also can have significant ultramafic and silicic components, and some are dominated by silicic magmatism." This definition places emphasis on the high magma emplacement rate characteristics of the LIP event and excludes seamounts, seamount groups, submarine ridges and anomalous seafloor crust. The definition has since been expanded and refined, and remains

318-653: A product of multiple eruptions. Moreover, units of each province are not the exact correlatives of the same eruptive event but may share the same magmatic system . In contrast, Chapecó and Palmas volcanics in Paraná are not unambiguously identified as the eastward extensions of ash-flows. Most studies have characterized Chapecó and Palmas as stacks of local lava flows and lava domes produced by effusive eruptions , and were emitted from nearby silicic conduits and feeder dikes . The extremely large volume estimations and explosive style of them, therefore, are questioned. On

371-543: A result of these periodic stress releases along the Mid-Atlantic Ridge. O'Connor et al. 2012 found that the hotspot trails in the eastern South Atlantic (Tristan, Gough, Discovery, Shona , and possibly Bouvet ) started forming synchronously 44 to 41 Ma . Older seamounts east of these hotspot trails formed at the edge of the African swell where the oceanic crust was spreading apart and are not

424-441: A sedimentary deposit, the magma can flow horizontally creating a sill. Some sill provinces have areal extents >1000 km. A series of related sills that were formed essentially contemporaneously (within several million years) from related dikes comprise a LIP if their area is sufficiently large. Examples include: Volcanic rifted margins are found on the boundary of large igneous provinces. Volcanic margins form when rifting

477-500: A solid convective mantle above a liquid core . The mantle's flow is driven by the descent of cold tectonic plates during subduction and the complementary ascent of mantle plumes of hot material from lower levels. The surface of the Earth reflects stretching, thickening and bending of the tectonic plates as they interact. Ocean-plate creation at upwellings, spreading and subduction are well accepted fundamentals of plate tectonics, with

530-627: A volcanic province), and volcanic rifted margins . Mafic basalt sea floors and other geological products of 'normal' plate tectonics were not included in the definition. Most of these LIPs consist of basalt, but some contain large volumes of associated rhyolite (e.g. the Columbia River Basalt Group in the western United States); the rhyolite is typically very dry compared to island arc rhyolites, with much higher eruption temperatures (850 °C to 1000 °C) than normal rhyolites. Some LIPs are geographically intact, such as

583-554: A work in progress. Some new definitions of LIP include large granitic provinces such as those found in the Andes Mountains of South America and in western North America. Comprehensive taxonomies have been developed to focus technical discussions. Sub-categorization of LIPs into large volcanic provinces (LVP) and large plutonic provinces (LPP), and including rocks produced by normal plate tectonic processes, have been proposed, but these modifications are not generally accepted. LIP

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636-400: Is a common geochemical proxy used to detect massive volcanism in the geologic record, although its foolproofness has been called into question. Jameson Land Thulean Plateau Brazilian Highlands These LIPs are composed dominantly of felsic materials. Examples include: These LIPs are comprised dominantly of andesitic materials. Examples include: This subcategory includes most of

689-462: Is accompanied by significant mantle melting, with volcanism occurring before and/or during continental breakup. Volcanic rifted margins are characterized by: a transitional crust composed of basaltic igneous rocks, including lava flows, sills, dikes, and gabbros , high volume basalt flows, seaward-dipping reflector sequences of basalt flows that were rotated during the early stages of breakup, limited passive-margin subsidence during and after breakup, and

742-740: 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. In 1992, Coffin and Eldholm initially defined

795-561: Is associated with subduction zones or mid-oceanic ridges, there are significant regions of long-lived, extensive volcanism, known as hotspots , which are only indirectly related to plate tectonics. The Hawaiian–Emperor seamount chain , located on the Pacific Plate , is one example, tracing millions of years of relative motion as the plate moves over the Hawaii hotspot . Numerous hotspots of varying size and age have been identified across

848-481: Is composed of six members : Naudé, Sarusas, Elliott, Khoraseb, and Ventura. The low-Ti suite is composed of eight members: Fria, Beacon, Grootberg, Wereldsend, Hoanib, Springbok, Goboboseb, and Terrace. In particular, Goboboseb consists of four eruptive units, labeled Goboboseb-I to -IV. On the basis of trans-Atlantic chemostratigraphy , the low-Ti suite in Etendeka is equivalent to Palmas volcanics in Paraná, and

901-618: Is not now observable. The upper basalt layers of older LIPs may have been removed by erosion or deformed by tectonic plate collisions occurring after the layer is formed. This is especially likely for earlier periods such as the Paleozoic and Proterozoic . Giant dyke swarms having lengths over 300 km are a common record of severely eroded LIPs. Both radial and linear dyke swarm configurations exist. Radial swarms with an areal extent over 2,000 km and linear swarms extending over 1,000 km are known. The linear dyke swarms often have

954-652: Is now frequently used to also describe voluminous areas of, not just mafic, but all types of igneous rocks. Further, the minimum threshold to be included as a LIP has been lowered to 50,000 km . The working taxonomy, focused heavily on geochemistry, is: Because large igneous provinces are created during short-lived igneous events resulting in relatively rapid and high-volume accumulations of volcanic and intrusive igneous rock, they warrant study. LIPs present possible links to mass extinctions and global environmental and climatic changes. Michael Rampino and Richard Stothers cite 11 distinct flood basalt episodes—occurring in

1007-671: The Homo – Pan divergence occurred 13 to 10.5 Ma (in contrast to earlier estimates that suggested around 5 Ma). Arnason et al. also estimated the Platyrrhini – Catarrhini divergence to have occurred around 70 Ma and found that the latter evolved in South America before their dispersal into Africa. Arnason et al. hypothesised that the Rio Grande–Walvis Ridge system was exposed above sea level and formed

1060-756: The Baffin Island flood basalt about 60 million years ago. Basalts from the Ontong Java Plateau show similar isotopic and trace element signatures proposed for the early-Earth reservoir. Seven pairs of hotspots and LIPs located on opposite sides of the earth have been noted; analyses indicate this coincident antipodal location is highly unlikely to be random. The hotspot pairs include a large igneous province with continental volcanism opposite an oceanic hotspot. Oceanic impacts of large meteorites are expected to have high efficiency in converting energy into seismic waves. These waves would propagate around

1113-574: The Deccan Traps of India were not antipodal to (and began erupting several Myr before) the Chicxulub impact in Mexico. In addition, no clear example of impact-induced volcanism, unrelated to melt sheets, has been confirmed at any known terrestrial crater. Aerally extensive dike swarms , sill provinces, and large layered ultramafic intrusions are indicators of LIPs, even when other evidence

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1166-758: The Valanginian stage of the Early Cretaceous . Indirectly, the rifting and extension are probably the origin of the Paraná and Etendeka traps and it could be the origin of the Gough and Tristan da Cunha Islands as well, as they are connected by the Walvis Ridge (Gough/ Tristan hotspot ). The seamounts of the Rio Grande Rise (25°S to 35°S) that go eastwards from the Paraná side are part of this traps system. Interpretations of geochemistry, including isotopes , have led geologists to conclude that

1219-409: The largest known explosive eruptions on Earth. Notably, the largest Guarapuava-Tamarana/Sarusas is estimated to have a volume of 8,600 km (2,100 cubic miles), which dwarfs other extremely large eruptions such as 30 million year old Wah Wah Springs and 28 million year old Fish Canyon Tuff . This interpretation, however, is disputed. Sarusas member is known to consist of 10 eruptive units hence

1272-726: The Deccan Traps ( Cretaceous–Paleogene extinction event ), the Karoo-Ferrar ( Pliensbachian-Toarcian extinction ), the Central Atlantic magmatic province ( Triassic-Jurassic extinction event ), and the Siberian Traps ( Permian-Triassic extinction event ). Several mechanisms are proposed to explain the association of LIPs with extinction events. The eruption of basaltic LIPs onto the earth's surface releases large volumes of sulfate gas, which forms sulfuric acid in

1325-522: The LIP-triggered changes may be used as cases to understand current and future environmental changes. Plate tectonic theory explains topography using interactions between the tectonic plates, as influenced by viscous stresses created by flow within the underlying mantle . Since the mantle is extremely viscous, the mantle flow rate varies in pulses which are reflected in the lithosphere by small amplitude, long wavelength undulations. Understanding how

1378-518: The Paraná and Etendeka traps formed. Whether or not Tristan and Gough represent two distinct volcanic centers is still debated. Fairhead & Wilson 2005 argued that the Walvis Ridge is not the product of a deep mantle plume or the Tristan hotspot, but that changes in the internal stress in the spreading African and South American plates trigger changes in the magmatic processes in the Mid-Atlantic Ridge. The Walvis Ridge should then have developed as

1431-552: The atmosphere; this absorbs heat and causes substantial cooling (e.g., the Laki eruption in Iceland, 1783). Oceanic LIPs can reduce oxygen in seawater by either direct oxidation reactions with metals in hydrothermal fluids or by causing algal blooms that consume large amounts of oxygen. Large igneous provinces are associated with a handful of ore deposit types including: Enrichment in mercury relative to total organic carbon (Hg/TOC)

1484-794: The basaltic Deccan Traps in India, while others have been fragmented and separated by plate movements, like the Central Atlantic magmatic province —parts of which are found in Brazil, eastern North America, and northwestern Africa. In 2008, Bryan and Ernst refined the definition to narrow it somewhat: "Large Igneous Provinces are magmatic provinces with areal extents > 1 × 10  km , igneous volumes > 1 × 10  km and maximum lifespans of ~50 Myr that have intraplate tectonic settings or geochemical affinities, and are characterised by igneous pulse(s) of short duration (~1–5 Myr), during which

1537-471: The core; roughly 15–20% have characteristics such as presence of a linear chain of sea mounts with increasing ages, LIPs at the point of origin of the track, low shear wave velocity indicating high temperatures below the current location of the track, and ratios of He to He which are judged consistent with a deep origin. Others such as the Pitcairn , Samoan and Tahitian hotspots appear to originate at

1590-423: The eruptions has been recognized. A 18 km (11 miles) diameter, circular structure, called Messum igneous complex , is identified to be the eruptive centre for Goboboseb-I to -IV and Springbok. It was postulated that Chapecó and Palmas volcanics in Paraná are the eastward extensions of Etendeka ash-flows, so each correlation represents a huge ignimbrite eruption. The volumes of these eruptions would make them

1643-497: The high-Ti suite is equivalent to Chapecó volcanics. At a finer scale, geochemical affinities have made tentative correlations in these pairs: PAV-G of Anita Garibaldi and Beacon, PAV-B of Caxias do Sul and Springbok, PAV-A of Jacuí and Goboboseb-II, Guarapuava and Ventura, Ourinhos and Khoraseb, BRA-21 and Wereldsend, PAV-F of Caxias do Sul and Grootberg. Sarusas may correlate either to Guarapuava or Tamarana, and Fria may correlate either to Santa Maria or Clevelândia. In Etendeka,

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1696-401: The interaction between mantle flow and lithosphere elevation influences formation of LIPs is important to gaining insights into past mantle dynamics. LIPs have played a major role in the cycles of continental breakup, continental formation, new crustal additions from the upper mantle , and supercontinent cycles . Earth has an outer shell made of discrete, moving tectonic plates floating on

1749-411: The large-scale plate tectonic circulation in which they are imbedded. Images reveal continuous but convoluted vertical paths with varying quantities of hotter material, even at depths where crystallographic transformations are predicted to occur. A major alternative to the plume model is a model in which ruptures are caused by plate-related stresses that fractured the lithosphere, allowing melt to reach

1802-457: The lower efficiency of kinetic energy conversion into seismic energy is not expected to create an antipodal hotspot. A second impact-related model of hotspot and LIP formation has been suggested in which minor hotspot volcanism was generated at large-body impact sites and flood basalt volcanism was triggered antipodally by focused seismic energy. This model has been challenged because impacts are generally considered seismically too inefficient, and

1855-403: The magmas forming the traps and associated igneous rocks originated by melting of asthenosphic mantle due to the arrival of a mantle plume to the base of Earth's lithosphere . Then much of the magma was contaminated with crustal materials prior to their eruption. Some plutonic rocks related to the traps escaped crustal contamination reflecting more directly the source of the magmas in

1908-642: The mantle. In Paraná, the silicic rocks are divided into two compositional groups, the Palmas volcanics and Chapecó volcanics. Palmas is recognized as composed of the five geochemical subtypes Santa Maria, Caxias do Sul, Anita Garibaldi, Clevelândia and Jacuí, while Chapecó is composed of the three geochemical subtypes Ourinhos, Tamarana and Guarapuav. Eight major eruptive units, labeled PAV-A to -G and BRA-21, are recognized within Palmas volcanics. In Etendeka, individual eruptive units of quartz latite are grouped into high- Ti and low-Ti suites . The high-Ti suit

1961-490: The only one found outside South America. 37°S 12°W  /  37°S 12°W  / -37; -12 Paran%C3%A1 and Etendeka traps The Paraná-Etendeka Large Igneous Province (PE-LIP) (or Paraná and Etendeka Plateau ; or Paraná and Etendeka Province ) is a large igneous province that includes both the main Paraná traps (in Paraná Basin , a South American geological basin ) as well as

2014-564: The order of 1 million cubic kilometers. In most cases, the majority of a basaltic LIP's volume is emplaced in less than 1 million years. One of the conundra of such LIPs' origins is to understand how enormous volumes of basaltic magma are formed and erupted over such short time scales, with effusion rates up to an order of magnitude greater than mid-ocean ridge basalts. The source of many or all LIPs are variously attributed to mantle plumes, to processes associated with plate tectonics or to meteorite impacts. Although most volcanic activity on Earth

2067-580: The other hand, a study has found pyroclastic -like textures in Chapecó and Palmas volcanics that are indicative of explosive eruptions. Guarapuava and Clevelândia subtypes are interpreted to be entirely of ignimbrites, while Jacuí, Anita Garibaldi, Caxias do Sul, and Santa Maria are multiple ignimbrite units intercalated with lava domes. These ignimbrites were characterzied by low-explosivity, high eruptive mass-flux, and low-column fountains . Large igneous province A large igneous province ( LIP )

2120-603: The past 250 million years—which created volcanic provinces and oceanic plateaus and coincided with mass extinctions. This theme has developed into a broad field of research, bridging geoscience disciplines such as biostratigraphy , volcanology , metamorphic petrology , and Earth System Modelling . The study of LIPs has economic implications. Some workers associate them with trapped hydrocarbons. They are associated with economic concentrations of copper–nickel and iron. They are also associated with formation of major mineral provinces including platinum group element deposits and, in

2173-534: The plume generation zones. All major African LIPs ( Karoo , Paraná-Etendeka , and Agulhas ) formed at the plume generation zones of the African LLSVP but 132 to 100 Ma the Tristan-Gough hotspot was the only hotspot located at a spreading boundary and therefore the only African hotspot that started to form a volcanic trail. Based on molecular estimates, Arnason et al. 2000 found that

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2226-558: The presence of a lower crust with anomalously high seismic P-wave velocities in lower crustal bodies, indicative of lower temperature, dense media. The early volcanic activity of major hotspots, postulated to result from deep mantle plumes, is frequently accompanied by flood basalts. These flood basalt eruptions have resulted in large accumulations of basaltic lavas emplaced at a rate greatly exceeding that seen in contemporary volcanic processes. Continental rifting commonly follows flood basalt volcanism. Flood basalt provinces may also occur as

2279-488: The product of hotspot volcanism. The Tristan-Gough trail switched from forming a series of aseismic ridges to a broader line of guyots and smaller volcanic ridges at about the same time. The hotspots of the eastern South Atlantic formed along the plume generation zones of the African large low seismic velocity province (LLSVP). LLSVPs are dense and stable structures, and most of the plumes , kimberlites , and large igneous provinces (LIPs) on Earth can be rotated back to

2332-461: The quartz latite units are interpreted to be rheomorphic ignimbrites , which are emplaced by explosive eruptions of high-temperature ash-flows . Each eruption produced voluminous and widespread pyroclastic sheet with thickness between 40–300 m (130–980 feet). Individual unit, within Etendeka, has a volume between 400–2,600 km (96–624 cubic miles) and covers an area up to 8,800 km (3,400 square miles). No air-fall layer associated with

2385-407: The silicic LIPs, silver and gold deposits. Titanium and vanadium deposits are also found in association with LIPs. LIPs in the geological record have marked major changes in the hydrosphere and atmosphere , leading to major climate shifts and maybe mass extinctions of species. Some of these changes were related to rapid release of greenhouse gases from the lithosphere to the atmosphere. Thus

2438-440: The smaller severed portions of the flood basalts at the Etendeka traps (in northwest Namibia and southwest Angola ). The original basalt flows occurred 136 to 132 million years ago. The province had a post-flow surface area of 1,000,000 square kilometres (390,000 sq mi) and an original volume projected to be in excess of 2.3 x 10 km . The basalt samples at Paraná and Etendeka have an age of about 132 Ma, during

2491-465: The surface from shallow heterogeneous sources. The high volumes of molten material that form the LIPs is postulated to be caused by convection in the upper mantle, which is secondary to the convection driving tectonic plate motion. It has been proposed that geochemical evidence supports an early-formed reservoir that survived in the Earth's mantle for about 4.5 billion years. Molten material is postulated to have originated from this reservoir, contributing

2544-432: The surface topography. The convective circulation drives up-wellings and down-wellings in Earth's mantle that are reflected in local surface levels. Hot mantle materials rising up in a plume can spread out radially beneath the tectonic plate causing regions of uplift. These ascending plumes play an important role in LIP formation. When created, LIPs often have an areal extent of a few million square kilometers and volumes on

2597-458: The term "large igneous province" as representing a variety of mafic igneous provinces with areal extent greater than 100,000 km that represented "massive crustal emplacements of predominantly mafic (magnesium- and iron-rich) extrusive and intrusive rock, and originated via processes other than 'normal' seafloor spreading." That original definition included continental flood basalts , oceanic plateaus , large dike swarms (the eroded roots of

2650-472: The top of large, transient, hot lava domes (termed superswells) in the mantle. The remainder appear to originate in the upper mantle and have been suggested to result from the breakup of subducting lithosphere. Recent imaging of the region below known hotspots (for example, Yellowstone and Hawaii) using seismic-wave tomography has produced mounting evidence that supports relatively narrow, deep-origin, convective plumes that are limited in region compared to

2703-399: The upwelling of hot mantle materials and the sinking of the cooler ocean plates driving the mantle convection. In this model, tectonic plates diverge at mid-ocean ridges , where hot mantle rock flows upward to fill the space. Plate-tectonic processes account for the vast majority of Earth's volcanism . Beyond the effects of convectively driven motion, deep processes have other influences on

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2756-399: The world and reconverge close to the antipodal position; small variations are expected as the seismic velocity varies depending upon the route characteristics along which the waves propagate. As the waves focus on the antipodal position, they put the crust at the focal point under significant stress and are proposed to rupture it, creating antipodal pairs. When the meteorite impacts a continent,

2809-415: The world. These hotspots move slowly with respect to one another but move an order of magnitude more quickly with respect to tectonic plates, providing evidence that they are not directly linked to tectonic plates. The origin of hotspots remains controversial. Hotspots that reach the Earth's surface may have three distinct origins. The deepest probably originate from the boundary between the lower mantle and

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