Subduction

Last updated
Diagram of the geological process of subduction Subduction-en.svg
Diagram of the geological process of subduction

Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. [1] Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year. [2]

Contents

Subduction is possible because the cold oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle underlying the cold, rigid lithosphere. Once initiated, stable subduction is driven mostly by the negative buoyancy of the dense subducting lithosphere. The slab sinks into the mantle largely under its weight. [3]

Earthquakes are common along the subduction zone, and fluids released by the subducting plate trigger volcanism in the overriding plate. If the subducting plate sinks at a shallow angle, the overriding plate develops a belt of deformation characterized by crustal thickening, mountain building, and metamorphism. Subduction at a steeper angle is characterized by the formation of back-arc basins. [4]

Subduction and plate tectonics

The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone JuandeFucasubduction.jpg
The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone
The simplified model of mantle convection: Oceanic plates are subducted creating oceanic trenches. Oceanic spreading.svg
The simplified model of mantle convection: Oceanic plates are subducted creating oceanic trenches.

According to the theory of plate tectonics, the Earth's lithosphere, its rigid outer shell, is broken into sixteen larger tectonic plates and several smaller plates. These plates are in slow motion, due mostly to the pull force of subducting lithosphere. Sinking lithosphere at subduction zones are a part of convection cells in the underlying ductile mantle. This process of convection allows heat generated by radioactive decay to escape from the Earth's interior. [6]

The lithosphere consists of the outermost light crust plus the uppermost rigid portion of the mantle. Oceanic lithosphere ranges in thickness from just a few km for young lithosphere created at mid-ocean ridges to around 100 km (62 mi) for the oldest oceanic lithosphere. [7] Continental lithosphere is up to 200 km (120 mi) thick. [8] The lithosphere is relatively cold and rigid compared with the underlying asthenosphere, and so tectonic plates move as solid bodies atop the asthenosphere. Individual plates often include both regions of the oceanic lithosphere and continental lithosphere.

Subduction zones are where the cold oceanic lithosphere sinks back into the mantle and is recycled. [4] [9] They are found at convergent plate boundaries, where the oceanic lithosphere of one plate converges with the less dense lithosphere of another plate. The heavier oceanic lithosphere is overridden by the leading edge of the other plate. [7] The overridden plate (the slab ) sinks at an angle of approximately 25 to 75 degrees to Earth's surface. [10] This sinking is driven by the temperature difference between the slab and the surrounding asthenosphere, as the colder oceanic lithosphere has, on average, a greater density. [7] Sediments and some trapped water are carried downwards by the slab and recycled into the deep mantle. [11]

Earth is so far the only planet where subduction is known to occur, and subduction zones are its most important tectonic feature. Subduction is the driving force behind plate tectonics, and without it, plate tectonics could not occur. [12] Oceanic subduction zones are located along 55,000 km (34,000 mi) convergent plate margins, [13] almost equal to the cumulative plate formation rate 60,000 km (37,000 mi) of mid-ocean ridges. [14]

Sea water seeps into oceanic lithosphere through fractures and pores, and reacts with minerals in the crust and mantle to form hydrous minerals (such as serpentine) that store water in their crystal structures. [15] Water is transported into the deep mantle via hydrous minerals in subducting slabs. During subduction, a series of minerals in these slabs such as serpentine can be stable at different pressures within the slab geotherms, and may transport significant amount of water into the Earth's interior. [16] As plates sink and heat up, released fluids can trigger seismicity and induce melting within the subducted plate and in the overlying mantle wedge. This type of melting selectively concentrates volatiles and transports them into the overlying plate. If an eruption occurs, the cycle then returns the volatiles into the oceans and atmosphere [17]

Structure of subduction zones

Arc-trench complex

The surface expressions of subduction zones are arc-trench complexes. On the ocean side of the complex, where the subducting plate first approaches the subduction zone, there is often an outer trench high or outer trench swell. Here the plate shallows slightly before plunging downwards, as a consequence of the rigidity of the plate. [18] The point where the slab begins to plunge downwards is marked by an oceanic trench . Oceanic trenches are the deepest parts of the ocean floor.

Beyond the trench is the forearc portion of the overriding plate. Depending on sedimentation rates, the forearc may include an accretionary wedge of sediments scraped off the subducting slab and accreted to the overriding plate. However, not all arc-trench complexes have an accretionary wedge. Accretionary arcs have a well-developed forearc basin behind the accretionary wedge, while the forearc basin is poorly developed in non-accretionary arcs. [19]

Beyond the forearc basin, volcanoes are found in long chains called volcanic arcs . The subducting basalt and sediment are normally rich in hydrous minerals and clays. Additionally, large quantities of water are introduced into cracks and fractures created as the subducting slab bends downward. [20] During the transition from basalt to eclogite, these hydrous materials break down, producing copious quantities of water, which at such great pressure and temperature exists as a supercritical fluid. [21] The supercritical water, which is hot and more buoyant than the surrounding rock, rises into the overlying mantle, where it lowers the melting temperature of the mantle rock, generating magma via flux melting. [22] The magmas, in turn, rise as diapirs because they are less dense than the rocks of the mantle. [23] The mantle-derived magmas (which are initially basaltic in composition) can ultimately reach the Earth's surface, resulting in volcanic eruptions. The chemical composition of the erupting lava depends upon the degree to which the mantle-derived basalt interacts with (melts) Earth's crust or undergoes fractional crystallization. Arc volcanoes tend to produce dangerous eruptions because they are rich in water (from the slab and sediments) and tend to be extremely explosive. [24] Krakatoa, Nevado del Ruiz, and Mount Vesuvius are all examples of arc volcanoes. Arcs are also associated with most ore deposits. [23]

Beyond the volcanic arc is a back-arc region whose character depends strongly on the angle of subduction of the subducting slab. Where this angle is shallow, the subducting slab drags the overlying continental crust partially with it, which produces a zone of shortening and crustal thickening in which there may be extensive folding and thrust faulting. If the angle of subduction steepens or rolls back, the upper plate lithosphere will be put in tension instead, often producing a back-arc basin. [25]

Deep structure

The arc-trench complex is the surface expression of a much deeper structure. Though not directly accessible, the deeper portions can be studied using geophysics and geochemistry. Subduction zones are defined by an inclined zone of earthquakes, the Wadati–Benioff zone, that dips away from the trench and extends down below the volcanic arc to the 660-kilometer discontinuity. Subduction zone earthquakes occur at greater depths (up to 600 km (370 mi)) than elsewhere on Earth (typically less than 20 km (12 mi) depth); such deep earthquakes may be driven by deep phase transformations, thermal runaway, or dehydration embrittlement. [26] [27] Seismic tomography shows that some slabs can penetrate the lower mantle [28] [29] and sink clear to the core–mantle boundary. [30] Here the residue of the slabs may eventually heat enough to rise back to the surface as mantle plumes. [31] [32]

Subduction angle

Subduction typically occurs at a moderately steep angle by the time it is beneath the volcanic arc. However, anomalous shallower angles of subduction are known to exist as well as some that are extremely steep. [33]

Flat-slab subduction is ongoing beneath part of the Andes, causing segmentation of the Andean Volcanic Belt into four zones. The flat-slab subduction in northern Peru and the Norte Chico region of Chile is believed to be the result of the subduction of two buoyant aseismic ridges, the Nazca Ridge and the Juan Fernández Ridge, respectively. Around Taitao Peninsula flat-slab subduction is attributed to the subduction of the Chile Rise, a spreading ridge. [36] [37]

The Laramide Orogeny in the Rocky Mountains of the United States is attributed to flat-slab subduction. [38] During this orogeny, a broad volcanic gap appeared at the southwestern margin of North America, and deformation occurred much farther inland; it was during this time that the basement-cored mountain ranges of Colorado, Utah, Wyoming, South Dakota, and New Mexico came into being. The most massive subduction zone earthquakes, so-called "megaquakes", have been found to occur in flat-slab subduction zones. [39]

Life cycle of subduction zones

Initiation of subduction

Although stable subduction is fairly well understood, the process by which subduction is initiated remains a matter of discussion and continuing study. Subduction can begin spontaneously if the denser oceanic lithosphere can founder and sink beneath the adjacent oceanic or continental lithosphere through vertical forcing only; alternatively, existing plate motions can induce new subduction zones by horizontally forcing the oceanic lithosphere to rupture and sink into the asthenosphere. [41] [42] Both models can eventually yield self-sustaining subduction zones, as the oceanic crust is metamorphosed at great depth and becomes denser than the surrounding mantle rocks. The compilation of subduction zone initiation events back to 100 Ma suggests horizontally-forced subduction zone initiation for most modern subduction zones, [42] which is supported by results from numerical models [43] [44] and geologic studies. [45] [46] Some analogue modeling shows, however, the possibility of spontaneous subduction from inherent density differences between two plates at specific locations like passive margins and along transform faults. [47] [48] There is evidence this has taken place in the Izu-Bonin-Mariana subduction system. [49] [50] Earlier in Earth's history, subduction is likely to have initiated without horizontal forcing due to the lack of relative plate motion, though a proposal by A. Yin suggests that meteorite impacts may have contributed to subduction initiation on early Earth. [51]

Though the idea of subduction initiation at passive margins is popular, there is no modern day example for this type of subduction nucleation. [52] This is likely due to the strength of the oceanic or transitional crust at the continental passive margins, suggesting that if the crust did not break in its first 20 million years of life, it is unlikely to break in the future under normal sedimentation loads. Only with additional weaking of the crust, through hotspot magmatism or extensional rifting, would the crust be able to break from its continent and begin subduction.

End of subduction

Subduction can continue as long as the oceanic lithosphere moves into the subduction zone. However, the arrival of buoyant continental lithosphere at a subduction zone can result in increased coupling at the trench and cause plate boundary reorganization. The arrival of continental crust results in continental collision or terrane accretion that may disrupt subduction. [53] Continental crust can subduct to depths of 250 km (160 mi) where it can reach a point of no return. [54] [32] Sections of crustal or intraoceanic arc crust greater than 15 km (9.3 mi) in thickness or oceanic plateau greater than 30 km (19 mi) in thickness can disrupt subduction. However, island arcs subducted end-on may cause only local disruption, while an arc arriving parallel to the zone can shut it down. [53] This has happened with the Ontong Java Plateau and the Vitiaz Trench. [55]

Characteristics and Effects

Metamorphism

Subduction zones host a unique variety of rock types created by the high-pressure, low-temperature conditions a subducting slab encounters during its descent. [56] The metamorphic conditions the slab passes through in this process create and destroy water bearing (hydrous) mineral phases, releasing water into the mantle. This water lowers the melting point of mantle rock, initiating melting. [57] Understanding the timing and conditions in which these dehydration reactions occur is key to interpreting mantle melting, volcanic arc magmatism, and the formation of continental crust. [58]

A metamorphic facies is characterized by a stable mineral assemblage specific to a pressure-temperature range and specific starting material. Subduction zone metamorphism is characterized by a low temperature, high-ultrahigh pressure metamorphic path through the zeolite, prehnite-pumpellyite, blueschist, and eclogite facies stability zones of subducted oceanic crust. [59] Zeolite and prehnite-pumpellyite facies assemblages may or may not be present, thus the onset of metamorphism may only be marked by blueschist facies conditions. [60] Subducting slabs are composed of basaltic crust topped with pelagic sediments; [61] however, the pelagic sediments may be accreted onto the forearc-hanging wall and not subducted. [62] Most metamorphic phase transitions that occur within the subducting slab are prompted by the dehydration of hydrous mineral phases. The breakdown of hydrous mineral phases typically occurs at depths greater than 10 km. [63] Each of these metamorphic facies is marked by the presence of a specific stable mineral assemblage, recording the metamorphic conditions undergone but the subducting slab. Transitions between facies cause hydrous minerals to dehydrate at certain pressure-temperature conditions and can therefore be tracked to melting events in the mantle beneath a volcanic arc.

Arc magmatism

Two kinds of arcs are generally observed on Earth: island arcs that form on the oceanic lithosphere (for example, the Mariana and the Tonga island arcs), and continental arcs such as the Cascade Volcanic Arc, that form along the coast of continents. Island arcs (intraoceanic or primitive arcs) are produced by the subduction of oceanic lithosphere beneath another oceanic lithosphere (ocean-ocean subduction) while continental arcs (Andean arcs) form during the subduction of oceanic lithosphere beneath a continental lithosphere (ocean-continent subduction). [64] An example of a volcanic arc having both island and continental arc sections is found behind the Aleutian Trench subduction zone in Alaska.

Volcanoes that occur above subduction zones, such as Mount St. Helens, Mount Etna, and Mount Fuji, lie approximately one hundred kilometers from the trench in arcuate chains called volcanic arcs. Plutons, like Half Dome in Yosemite National Park, generally form 10–50 km [65] below the volcanoes within the volcanic arcs and are only visible on the surface once the volcanoes have weathered away. The volcanism and plutonism occur as a consequence of the subducting oceanic slab dehydrating as it reaches higher pressures and temperatures. Once the oceanic slab reaches about 100 km in depth, [65] hydrous minerals become unstable and release fluids into the asthenosphere. The fluids act as a flux for the rock within the asthenosphere and cause it to partially melt. The partially melted material is more buoyant and as a result will rise into the lithosphere, where it forms large magma chambers called diapirs. Some of the magma will make it to the surface of the crust where it will form volcanoes and, if eruptive on earth's surface, will produce andesitic lava. Magma that remains in the lithosphere long enough will cool and form plutonic rocks such as diorite, granodiorite, and sometimes granite.

The arc magmatism occurs one hundred to two hundred kilometers from the trench and approximately one hundred kilometers above the subducting slab. [66] Arcs produce about 10% of the total volume of magma produced each year on Earth (approximately 0.75 cubic kilometers), much less than the volume produced at mid-ocean ridges, [67] but they have formed most continental crust. [4] Arc volcanism has the greatest impact on humans because many arc volcanoes lie above sea level and erupt violently. Aerosols injected into the stratosphere during violent eruptions can cause rapid cooling of Earth's climate and affect air travel. [68]

Arc-magmatism plays a role in Earth's Carbon cycle by releasing subducted carbon through volcanic processes. Older theory states that the carbon from the subducting plate is made available in overlying magmatic systems via decarbonation, where CO2 is released through silicate-carbonate metamorphism. [69] However, evidence from thermodynamic modeling has shown that the pressures and temperatures necessary for this type of metamorphism are much higher than what is observed in most subduction zones. [69] Frezzoti et al. (2011) propose a different mechanism for carbon transport into the overriding plate via dissolution (release of carbon from carbon-bearing minerals into an aqueous solution) instead of decarbonation. Their evidence comes from the close examination of mineral and fluid inclusions in low-temperature (<600 °C) diamonds and garnets found in an eclogite facies in the Alps. The chemistry of the inclusions supports the existence of a carbon-rich fluid in that environment, and additional chemical measurements of lower pressure and temperature facies in the same tectonic complex support a model for carbon dissolution (rather than decarbonation) as a means of carbon transport. [69]

Earthquakes and tsunamis

Global map of subduction zones, with subducted slabs contoured by depth Global subducted slabs USGS.png
Global map of subduction zones, with subducted slabs contoured by depth

Elastic strain caused by plate convergence in subduction zones produces at least three types of earthquakes. These are deep earthquakes, megathrust earthquakes, and outer rise earthquakes. Deep earthquakes happen within the crust, megathrust earthquakes on the subduction interface near the trench, and outer rise earthquakes on the subducting lower plate as it bends near the trench.

Anomalously deep events are a characteristic of subduction zones, which produce the deepest quakes on the planet. Earthquakes are generally restricted to the shallow, brittle parts of the crust, generally at depths of less than twenty kilometers. However, in subduction zones quakes occur at depths as great as 700 km (430 mi). These quakes define inclined zones of seismicity known as Wadati–Benioff zones which trace the descending slab. [70]

Nine of the ten largest earthquakes of the last 100 years were subduction zone megathrust earthquakes. These included the 1960 Great Chilean earthquake which at M 9.5 was the largest earthquake ever recorded, the 2004 Indian Ocean earthquake and tsunami, and the 2011 Tōhoku earthquake and tsunami. The subduction of cold oceanic lithosphere into the mantle depresses the local geothermal gradient and causes a larger portion of Earth's crust to deform in a more brittle fashion than it would in a normal geothermal gradient setting. Because earthquakes can occur only when a rock is deforming in a brittle fashion, subduction zones can cause large earthquakes. If such a quake causes rapid deformation of the sea floor, there is potential for tsunamis. The largest tsunami ever recorded happened due to a mega-thrust earthquake on December 26, 2004. The earthquake was caused by subduction of the Indo-Australian Plate under the Euro-Asian Plate, but the tsunami spread over most of the planet and devastated the areas around the Indian Ocean. Small tremors which cause small, nondamaging tsunamis, also occur frequently. [70]

A study published in 2016 suggested a new parameter to determine a subduction zone's ability to generate mega-earthquakes. [71] By examining subduction zone geometry and comparing the degree of lower plate curvature of the subducting plate in great historical earthquakes such as the 2004 Sumatra-Andaman and the 2011 Tōhoku earthquake, it was determined that the magnitude of earthquakes in subduction zones is inversely proportional to the angle of subduction near the trench, meaning that "the flatter the contact between the two plates, the more likely it is that mega-earthquakes will occur". [72]

Outer rise earthquakes on the lower plate occur when normal faults oceanward of the subduction zone are activated by flexure of the plate as it bends into the subduction zone. [73] The 2009 Samoa earthquake is an example of this type of event. Displacement of the sea floor caused by this event generated a six-meter tsunami in nearby Samoa.

Seismic tomography has helped detect subducted lithospheric slabs deep in the mantle where there are no earthquakes.[ citation needed ] About one hundred slabs have been described in terms of depth and their timing and location of subduction. [74] The great seismic discontinuities in the mantle, at 410 km (250 mi) depth and 670 km (420 mi), are disrupted by the descent of cold slabs in deep subduction zones. Some subducted slabs seem to have difficulty penetrating the major discontinuity that marks the boundary between the upper mantle and lower mantle at a depth of about 670 kilometers. Other subducted oceanic plates have sunk to the core–mantle boundary at 2890 km depth. Generally, slabs decelerate during their descent into the mantle, from typically several cm/yr (up to ~10 cm/yr in some cases) at the subduction zone and in the uppermost mantle, to ~1 cm/yr in the lower mantle. [74] This leads to either folding or stacking of slabs at those depths, visible as thickened slabs in Seismic tomography. Below ~1700 km, there might be a limited acceleration of slabs due to lower viscosity as a result of inferred mineral phase changes until they approach and finally stall at the core–mantle boundary. [74] Here the slabs are heated up by the ambient heat and are not detected anymore ~300 Myr after subduction. [74]

Orogeny

Orogeny is the process of mountain building. Subducting plates can lead to orogeny by bringing oceanic islands, oceanic plateaus, sediments and passive continental margins to convergent margins. The material often does not subduct with the rest of the plate but instead is accreted to (scraped off) the continent, resulting in exotic terranes. The collision of this oceanic material causes crustal thickening and mountain-building. The accreted material is often referred to as an accretionary wedge or prism. These accretionary wedges can be associated with ophiolites (uplifted ocean crust consisting of sediments, pillow basalts, sheeted dykes, gabbro, and peridotite). [75]

Subduction may also cause orogeny without bringing in oceanic material that accretes to the overriding continent. When the lower plate subducts at a shallow angle underneath a continent (something called "flat-slab subduction"), the subducting plate may have enough traction on the bottom of the continental plate to cause the upper plate to contract by folding, faulting, crustal thickening, and mountain building. Flat-slab subduction causes mountain building and volcanism moving into the continent, away from the trench, and has been described in western North America (i.e. Laramide orogeny, and currently in Alaska, South America, and East Asia. [74]

The processes described above allow subduction to continue while mountain building happens concurrently, which is in contrast to continent-continent collision orogeny, which often leads to the termination of subduction.

Subduction of continental lithosphere

Continents are pulled into subduction zones by the sinking oceanic plate they are attached to. Where continents are attached to oceanic plates with no subduction, there is a deep basin that accumulates thick suites of sedimentary and volcanic rocks known as a passive margin. Some passive margins have up to 10 km of sedimentary and volcanic rocks covering the continental crust. As a passive margin is pulled into a subduction zone by the attached and negatively buoyant oceanic lithosphere, the sedimentary and volcanic cover is mostly scraped off to form an orogenic wedge. An orogenic wedge is larger than most accretionary wedges due to the volume of material there is to accrete. The continental basement rocks beneath the weak cover suites are strong and mostly cold, and can be underlain by a >200 km thick layer of dense mantle. After shedding the low density cover units, the continental plate, especially if it is old, goes down the subduction zone. As this happens, metamorphic reactions increase the density of the continental crustal rocks, which leads to less buoyancy.

One study of the active Banda arc-continent collision claims that by unstacking the layers of rock that once covered the continental basement, but are now thrust over one another in the orogenic wedge, and measuring how long they are, can provide a minimum estimate of how far the continent has subducted. [76] The results show at least a minimum of 229 kilometers of subduction of the northern Australian continental plate. Another example may be the continued northward motion of India, which is subducting beneath Asia. The collision between the two continents initiated around 50 my ago, but is still active.

Intra-Oceanic: Ocean/Ocean plate subduction

Oceanic-Oceanic plate subduction zones comprise roughly 40% of all subduction zone margins on the planet. The ocean-ocean plate relationship can lead to subduction zones between oceanic and continental plates, therefore highlighting how important it is to understand this subduction setting. Although it is not fully understood what causes the initiation of subduction of an oceanic plate under another oceanic plate, there are three main models put forth by Baitsch-Ghirardello et.al that explain the different regimes present in this setting. [77]

The models are as follows: 1) Retreating Subduction: Caused by weak coupling between the lower and upper plate which leads to the opening of a back arc basin and the subduction zone being moved by slab rollback, 2) Stable Subduction: caused by intermediate coupling between the lower and upper plate. The subduction zone generally stays in the same place and the subduction plate subducts at a consistent angle, and 3) Advancing Subduction: caused by strong coupling between the upper and lower plate. The subducting sediments thicken causing partially molten plumes to be on top of subducting plate.

Arc-continent collision and global climate

In their 2019 study, Macdonald et al. proposed that arc-continent collision zones and the subsequent obduction of oceanic lithosphere was at least partially responsible for controlling global climate. Their model relies on arc-continent collision in tropical zones, where exposed ophiolites composed mainly of mafic material increase "global weatherability" and result in the storage of carbon through silicate weathering processes. This storage represents a carbon sink, removing carbon from the atmosphere and resulting in global cooling. Their study correlates several Phanerozoic ophiolite complexes, including active arc-continent subduction, with known global cooling and glaciation periods. [78] This study does not discuss Milankovitch cycles as a driver of global climate cyclicity.

Beginnings of subduction on Earth

Modern-style subduction is characterized by low geothermal gradients and the associated formation of high-pressure low-temperature rocks such as eclogite and blueschist. [79] [80] Likewise, rock assemblages called ophiolites, associated with modern-style subduction, also indicate such conditions. [79] Eclogite xenoliths found in the North China Craton provide evidence that modern-style subduction occurred at least as early as 1.8  Ga ago in the Paleoproterozoic Era. [79] The eclogite itself was produced by oceanic subduction during the assembly of supercontinents at about 1.9–2.0 Ga.

Blueschist is a rock typical for present-day subduction settings. The absence of blueschist older than Neoproterozoic reflects more magnesium-rich compositions of Earth's oceanic crust during that period. [81] These more magnesium-rich rocks metamorphose into greenschist at conditions when modern oceanic crust rocks metamorphose into blueschist. [81] The ancient magnesium-rich rocks mean that Earth's mantle was once hotter, but not that subduction conditions were hotter. Previously, the lack of pre-Neoproterozoic blueschist was thought to indicate a different type of subduction. [81] Both lines of evidence refute previous conceptions of modern-style subduction having been initiated in the Neoproterozoic Era 1.0 Ga ago. [79] [81]

History of investigation

Harry Hammond Hess, who during World War II served in the United States Navy Reserve and became fascinated in the ocean floor, studied the Mid-Atlantic Ridge and proposed that hot molten rock was added to the crust at the ridge and expanded the seafloor outward. This theory was to become known as seafloor spreading. Since the Earth's circumference has not changed over geologic time, Hess concluded that older seafloor has to be consumed somewhere else, and suggested that this process takes place at oceanic trenches, where the crust would be melted and recycled into the Earth's mantle. [82]

In 1964, George Plafker researched the Good Friday earthquake in Alaska. He concluded that the cause of the earthquake was a megathrust reaction in the Aleutian Trench, a result of the Alaskan continental crust overlapping the Pacific oceanic crust. This meant that the Pacific crust was being forced downward, or subducted, beneath the Alaskan crust. The concept of subduction would play a role in the development of the plate tectonics theory. [83]

First geologic attestations of the "subduct" words date to 1970, [84] In ordinary English to subduct, or to subduce (from Latin subducere, "to lead away") [85] are transitive verbs requiring a subject to perform an action on an object not itself, here the lower plate, which has then been subducted ("removed"). The geological term is "consumed", which happens the geological moment the lower plate slips under, even though it may persist for some time until its remelting and dissipation. In this conceptual model, plate is continually being used up. [86] The identity of the subject, the consumer, or agent of consumption, is left unstated. Some sources accept this subject-object construct.

Geology makes to subduct into an intransitive verb and a reflexive verb. The lower plate itself is the subject. It subducts, in the sense of retreat, or removes itself, and while doing so, is the "subducting plate". Moreover, the word slab is specifically attached to the "subducting plate", even though in English the upper plate is just as much of a slab. [87] The upper plate is left hanging, so to speak. To express it geology must switch to a different verb, typically to override. The upper plate, the subject, performs the action of overriding the object, the lower plate, which is overridden. [88]

Importance

Subduction zones are important for several reasons:

Subduction zones have also been considered as possible disposal sites for nuclear waste in which the action of subduction itself would carry the material into the planetary mantle, safely away from any possible influence on humanity or the surface environment. However, that method of disposal is currently banned by international agreement. [91] [92] [93] [94] Furthermore, plate subduction zones are associated with very large megathrust earthquakes, making the effects of using any specific site for disposal unpredictable and possibly adverse to the safety of long-term disposal. [92]

See also

Related Research Articles

<span class="mw-page-title-main">Plate tectonics</span> Movement of Earths lithosphere

Plate tectonics is the scientific theory that Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since about 3.4 billion years ago. The model builds on the concept of continental drift, an idea developed during the first decades of the 20th century. Plate tectonics came to be accepted by geoscientists after seafloor spreading was validated in the mid-to-late 1960s.

<span class="mw-page-title-main">Oceanic trench</span> Long and narrow depressions of the sea floor

Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically 50 to 100 kilometers wide and 3 to 4 km below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about 50,000 km (31,000 mi) of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of 10,920 m (35,830 ft) below sea level.

<span class="mw-page-title-main">Lithosphere</span> Outermost shell of a terrestrial-type planet or natural satellite

A lithosphere is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time scales of up to thousands of years or more. The crust and upper mantle are distinguished on the basis of chemistry and mineralogy.

Obduction is a geological process whereby denser oceanic crust is scraped off a descending ocean plate at a convergent plate boundary and thrust on top of an adjacent plate. When oceanic and continental plates converge, normally the denser oceanic crust sinks under the continental crust in the process of subduction. Obduction, which is less common, normally occurs in plate collisions at orogenic belts or back-arc basins.

<span class="mw-page-title-main">Convergent boundary</span> Region of active deformation between colliding tectonic plates

A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.

<span class="mw-page-title-main">Island arc</span> Arc-shaped archipelago formed by intense seismic activity of long chains of active volcanoes

Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle along the subduction zone. They are the principal way by which continental growth is achieved.

<span class="mw-page-title-main">Forearc</span> The region between an oceanic trench and the associated volcanic arc

Forearc is a plate tectonic term referring to a region in a subduction zone between an oceanic trench and the associated volcanic arc. Forearc regions are present along convergent margins and eponymously form 'in front of' the volcanic arcs that are characteristic of convergent plate margins. A back-arc region is the companion region behind the volcanic arc.

<span class="mw-page-title-main">Volcanic arc</span> Chain of volcanoes formed above a subducting plate

A volcanic arc is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc located further from the subducting plate than the trench. The oceanic plate is saturated with water, mostly in the form of hydrous minerals such as micas, amphiboles, and serpentines. As the oceanic plate is subducted, it is subjected to increasing pressure and temperature with increasing depth. The heat and pressure break down the hydrous minerals in the plate, releasing water into the overlying mantle. Volatiles such as water drastically lower the melting point of the mantle, causing some of the mantle to melt and form magma at depth under the overriding plate. The magma ascends to form an arc of volcanoes parallel to the subduction zone.

<span class="mw-page-title-main">Continental collision</span> Phenomenon in which mountains can be produced on the boundaries of converging tectonic plates

In geology, continental collision is a phenomenon of plate tectonics that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together. Continental collision is only known to occur on Earth.

<span class="mw-page-title-main">Mendocino Triple Junction</span> Point where the Gorda plate, the North American plate, and the Pacific plate meet

The Mendocino Triple Junction (MTJ) is the point where the Gorda plate, the North American plate, and the Pacific plate meet, in the Pacific Ocean near Cape Mendocino in northern California. This triple junction is the location of a change in the broad plate motions which dominate the west coast of North America, linking convergence of the northern Cascadia subduction zone and translation of the southern San Andreas Fault system. This region can be characterized by transform fault movement, the San Andreas also by transform strike slip movement, and the Cascadia subduction zone by a convergent plate boundary subduction movement. The Gorda plate is subducting, towards N50ºE, under the North American plate at 2.5 – 3 cm/yr, and is simultaneously converging obliquely against the Pacific plate at a rate of 5 cm/yr in the direction N115ºE. The accommodation of this plate configuration results in a transform boundary along the Mendocino Fracture Zone, and a divergent boundary at the Gorda Ridge. This area is tectonically active historically and today. The Cascadia subduction zone is known to be capable of producing megathrust earthquakes on the order of MW 9.0.

<span class="mw-page-title-main">Adakite</span> Volcanic rock type

Adakites are volcanic rocks of intermediate to felsic composition that have geochemical characteristics of magma originally thought to have formed by partial melting of altered basalt that is subducted below volcanic arcs. Most magmas derived in subduction zones come from the mantle above the subducting plate when hydrous fluids are released from minerals that break down in the metamorphosed basalt, rise into the mantle, and initiate partial melting. However, Defant and Drummond recognized that when young oceanic crust is subducted, adakites are typically produced in the arc. They postulated that when young oceanic crust is subducted it is "warmer" than crust that is typically subducted. The warmer crust enables melting of the metamorphosed subducted basalt rather than the mantle above. Experimental work by several researchers has verified the geochemical characteristics of "slab melts" and the contention that melts can form from young and therefore warmer crust in subduction zones.

<span class="mw-page-title-main">Izu–Bonin–Mariana Arc</span> Convergent boundary in Micronesia

The Izu–Bonin–Mariana (IBM) arc system is a tectonic plate convergent boundary in Micronesia. The IBM arc system extends over 2800 km south from Tokyo, Japan, to beyond Guam, and includes the Izu Islands, the Bonin Islands, and the Mariana Islands; much more of the IBM arc system is submerged below sealevel. The IBM arc system lies along the eastern margin of the Philippine Sea Plate in the Western Pacific Ocean. It is the site of the deepest gash in Earth's solid surface, the Challenger Deep in the Mariana Trench.

<span class="mw-page-title-main">Back-arc region</span>

The back-arc region is the area behind a volcanic arc. In island volcanic arcs, it consists of back-arc basins of oceanic crust with abyssal depths, which may be separated by remnant arcs, similar to island arcs. In continental arcs, the back-arc region is part of continental platform, either dry land (subaerial) or forming shallow marine basins.

<span class="mw-page-title-main">Slab (geology)</span> The portion of a tectonic plate that is being subducted

In geology, the slab is a significant constituent of subduction zones.

Ultra-high-pressure metamorphism refers to metamorphic processes at pressures high enough to stabilize coesite, the high-pressure polymorph of SiO2. It is important because the processes that form and exhume ultra-high-pressure (UHP) metamorphic rocks may strongly affect plate tectonics, the composition and evolution of Earth's crust. The discovery of UHP metamorphic rocks in 1984 revolutionized our understanding of plate tectonics. Prior to 1984 there was little suspicion that continental rocks could reach such high pressures.

<span class="mw-page-title-main">Banda Arc</span> Set of island arcs in eastern Indonesia

The Banda Arc is a dual chain of islands in eastern Indonesia that is around 2,300 km long. It is the result of the collision of a continent and an intra-oceanic island arc.

<span class="mw-page-title-main">Subduction zone metamorphism</span> Changes of rock due to pressure and heat near a subduction zone

A subduction zone is a region of the Earth's crust where one tectonic plate moves under another tectonic plate; oceanic crust gets recycled back into the mantle and continental crust gets created by the formation of arc magmas. Arc magmas account for more than 20% of terrestrially produced magmas and are produced by the dehydration of minerals within the subducting slab as it descends into the mantle and are accreted onto the base of the overriding continental plate. Subduction zones host a unique variety of rock types created by the high-pressure, low-temperature conditions a subducting slab encounters during its descent. The metamorphic conditions the slab passes through in this process creates and destroys water bearing (hydrous) mineral phases, releasing water into the mantle. This water lowers the melting point of mantle rock, initiating melting. Understanding the timing and conditions in which these dehydration reactions occur, is key to interpreting mantle melting, volcanic arc magmatism, and the formation of continental crust.

A continental arc is a type of volcanic arc occurring as an "arc-shape" topographic high region along a continental margin. The continental arc is formed at an active continental margin where two tectonic plates meet, and where one plate has continental crust and the other oceanic crust along the line of plate convergence, and a subduction zone develops. The magmatism and petrogenesis of continental crust are complicated: in essence, continental arcs reflect a mixture of oceanic crust materials, mantle wedge and continental crust materials.

<span class="mw-page-title-main">Flat slab subduction</span> Subduction characterized by a low subduction angle

Flat slab subduction is characterized by a low subduction angle beyond the seismogenic layer and a resumption of normal subduction far from the trench. A slab refers to the subducting lower plate. A broader definition of flat slab subduction includes any shallowly dipping lower plate, as in western Mexico. Flat slab subduction is associated with the pinching out of the asthenosphere, an inland migration of arc magmatism, and an eventual cessation of arc magmatism. The coupling of the flat slab to the upper plate is thought to change the style of deformation occurring on the upper plate's surface and form basement-cored uplifts like the Rocky Mountains. The flat slab also may hydrate the lower continental lithosphere and be involved in the formation of economically important ore deposits. During the subduction, a flat slab itself may deform or buckle, causing sedimentary hiatus in marine sediments on the slab. The failure of a flat slab is associated with ignimbritic volcanism and the reverse migration of arc volcanism. Multiple working hypotheses about the cause of flat slabs are subduction of thick, buoyant oceanic crust (15–20 km) and trench rollback accompanying a rapidly overriding upper plate and enhanced trench suction. The west coast of South America has two of the largest flat slab subduction zones. Flat slab subduction is occurring at 10% of subduction zones.

<span class="mw-page-title-main">Aleutian subduction zone</span> Convergence boundary between the North American Plate and the Pacific Plate

The Aleutian subduction zone is a 2,500 mi (4,000 km) long convergent boundary between the North American Plate and the Pacific Plate, that extends from the Alaska Range to the Kamchatka Peninsula. Here, the Pacific Plate is being subducted underneath the North American Plate and the rate of subduction changes from west to east from 7.5 to 5.1 cm per year. The Aleutian subduction zone includes two prominent features, the Aleutian Arc and the Aleutian Trench. The Aleutian Arc was created via volcanic eruptions from dehydration of the subducting slab at ~100 km depth. The Aleutian Trench is a narrow and deep morphology that occurs between the two converging plates as the subducting slab dives beneath the overriding plate.

References

  1. ↑ Stern, Robert J. (2002), "Subduction zones", Reviews of Geophysics, 40 (4): 1012, Bibcode:2002RvGeo..40.1012S, doi: 10.1029/2001RG000108 , S2CID   247695067
  2. ↑ Defant, M. J. (1998). Voyage of Discovery: From the Big Bang to the Ice Age. Mancorp. p. 325. ISBN   978-0-931541-61-2.
  3. ↑ Stern 2002, p. 3.
  4. 1 2 3 Stern 2002.
  5. ↑ Carlo Doglioni, Giuliano Panza: Polarized Plate Tectonics . Advances in Geophysics, Volume 56, 2015.
  6. ↑ Schmincke, Hans-Ulrich (2003). Volcanism. Berlin: Springer. pp. 13–20. ISBN   9783540436508.
  7. 1 2 3 Stern 2002, p. 5.
  8. ↑ Rudnick, Roberta L.; McDonough, William F.; O'Connell, Richard J. (April 1998). "Thermal structure, thickness and composition of continental lithosphere". Chemical Geology. 145 (3–4): 395–411. Bibcode:1998ChGeo.145..395R. doi:10.1016/S0009-2541(97)00151-4.
  9. ↑ Zheng, YF; Chen, YX (2016). "Continental versus oceanic subduction zones". National Science Review. 3 (4): 495–519. doi: 10.1093/nsr/nww049 .
  10. ↑ Tovish, Aaron; Schubert, Gerald; Luyendyk, Bruce P. (10 December 1978). "Mantle flow pressure and the angle of subduction: Non-Newtonian corner flows". Journal of Geophysical Research: Solid Earth. 83 (B12): 5892–5898. Bibcode:1978JGR....83.5892T. doi:10.1029/JB083iB12p05892.
  11. ↑ Stern 2002, p. 15.
  12. ↑ Stern 2002, pp. 1–4.
  13. ↑ Lallemand, S (1999). La Subduction Oceanique (in French). Newark, New Jersey: Gordon and Breach.
  14. ↑ Stern 2002, p. 4.
  15. ↑ Frost, Daniel J. (2006-12-31), Keppler, Hans; Smyth, Joseph R (eds.), "11. The Stability of Hydrous Mantle Phases", Water in Nominally Anhydrous Minerals, Berlin, Boston: De Gruyter, pp. 243–272, doi:10.1515/9781501509476-015, ISBN   978-1-5015-0947-6 , retrieved 2021-02-27
  16. ↑ Ohtani, Eiji (2015-12-15). "Hydrous minerals and the storage of water in the deep mantle". Chemical Geology. 418: 6–15. Bibcode:2015ChGeo.418....6O. doi:10.1016/j.chemgeo.2015.05.005. ISSN   0009-2541.
  17. ↑ Goes, Saskia; Collier, Jenny; Blundy, Jon; Davidson, Jon; Harmon, Nick; Henstock, Tim; Kendall, J.; MacPherson, Colin; Rietbrock, Andreas; Rychert, Kate; Prytulak, Julie; Van Hunen, Jeroen; Wilkinson, Jamie; Wilson, Marjorie (2019). "Project VoiLA: Volatile Recycling in the Lesser Antilles". Eos. 100. doi:10.1029/2019eo117309. hdl: 10044/1/69387 . S2CID   134704781 . Retrieved 2021-02-27.
  18. ↑ Whitman, Dean (May 1999). "The Isostatic Residual Gravity Anomaly of the Central Andes, 12° to 29° S: A Guide to Interpreting Crustal Structure and Deeper Lithospheric Processes". International Geology Review. 41 (5): 457–475. Bibcode:1999IGRv...41..457W. doi:10.1080/00206819909465152. S2CID   129797807.
  19. ↑ Stern 2002, pp. 25–26.
  20. ↑ Fujie, Gou; et al. (2013). "Systematic changes in the incoming plate structure at the Kuril trench". Geophysical Research Letters. 40 (1): 88–93. Bibcode:2013GeoRL..40...88F. doi: 10.1029/2012GL054340 .
  21. ↑ Stern 2002, pp. 6–10.
  22. ↑ Schmincke 2003, pp. 18, 113–126.
  23. 1 2 Stern 2002, pp. 19–22.
  24. ↑ Stern 2002, p. 27-28.
  25. ↑ Stern 2002, p. 31.
  26. ↑ Frolich, C. (1989). "The Nature of Deep Focus Earthquakes". Annual Review of Earth and Planetary Sciences. 17: 227–254. Bibcode:1989AREPS..17..227F. doi:10.1146/annurev.ea.17.050189.001303.
  27. ↑ Hacker, B.; et al. (2003). "Subduction factory 2. Are intermediate-depth earthquakes in subducting slabs linked to metamorphic dehydration reactions?" (PDF). Journal of Geophysical Research. 108 (B1): 2030. Bibcode:2003JGRB..108.2030H. doi:10.1029/2001JB001129.
  28. ↑ Domeier, Mathew; Doubrovine, Pavel V.; Torsvik, Trond H.; Spakman, Wim; Bull, Abigail L. (28 May 2016). "Global correlation of lower mantle structure and past subduction". Geophysical Research Letters. 43 (10): 4945–4953. Bibcode:2016GeoRL..43.4945D. doi: 10.1002/2016GL068827 . PMC   6686211 . PMID   31413424.
  29. ↑ Faccenna, Claudio; Oncken, Onno; Holt, Adam F.; Becker, Thorsten W. (2017). "Initiation of the Andean orogeny by lower mantle subduction". Earth and Planetary Science Letters. 463: 189–201. Bibcode:2017E&PSL.463..189F. doi:10.1016/j.epsl.2017.01.041. hdl: 11590/315613 .
  30. ↑ Hutko, Alexander R.; Lay, Thorne; Garnero, Edward J.; Revenaugh, Justin (2006). "Seismic detection of folded, subducted lithosphere at the core–mantle boundary". Nature. 441 (7091): 333–336. Bibcode:2006Natur.441..333H. doi:10.1038/nature04757. PMID   16710418. S2CID   4408681.
  31. ↑ Li, Mingming; McNamara, Allen K. (2013). "The difficulty for subducted oceanic crust to accumulate at the Earth's core-mantle boundary". Journal of Geophysical Research: Solid Earth. 118 (4): 1807–1816. Bibcode:2013JGRB..118.1807L. doi: 10.1002/jgrb.50156 .
  32. 1 2 Stern 2002, p. 1.
  33. ↑ Zheng, YF; Chen, RX; Xu, Z; Zhang, SB (2016). "The transport of water in subduction zones". Science China Earth Sciences. 59 (4): 651–682. Bibcode:2016ScChD..59..651Z. doi:10.1007/s11430-015-5258-4. S2CID   130912355.
  34. ↑ Schellart WP (2020) Control of Subduction Zone Age and Size on Flat Slab Subduction. Front. Earth Sci. 8:26. doi : 10.3389/feart.2020.00026
  35. ↑ Hu, J., & Gurnis, M. (2020). Subduction duration and slab dip. Geochemistry, Geophysics, Geosystems, 21, e2019GC008862. https://doi.org/ 10.1029/2019GC008862
  36. ↑ Sillitoe, Richard H. (August 1974). "Tectonic segmentation of the Andes: implications for magmatism and metallogeny". Nature. 250 (5467): 542–545. Bibcode:1974Natur.250..542S. doi:10.1038/250542a0. S2CID   4173349.
  37. ↑ Jordan, Teresa E.; Isacks, Bryan L.; Allmendinger, Richard W.; Brewer, Jon A.; Ramos, Victor A.; Ando, Clifford J. (1 March 1983). "Andean tectonics related to geometry of subducted Nazca plate". GSA Bulletin. 94 (3): 341–361. Bibcode:1983GSAB...94..341J. doi:10.1130/0016-7606(1983)94<341:ATRTGO>2.0.CO;2.
  38. ↑ W. P. Schellart; D. R. Stegman; R. J. Farrington; J. Freeman & L. Moresi (16 July 2010). "Cenozoic Tectonics of Western North America Controlled by Evolving Width of Farallon Slab". Science. 329 (5989): 316–319. Bibcode:2010Sci...329..316S. doi:10.1126/science.1190366. PMID   20647465. S2CID   12044269.
  39. ↑ Bletery, Quentin; Thomas, Amanda M.; Rempel, Alan W.; Karlstrom, Leif; Sladen, Anthony; De Barros, Louis (2016-11-24). "Fault curvature may control where big quakes occur, Eurekalert 24-NOV-2016". Science. 354 (6315): 1027–1031. Bibcode:2016Sci...354.1027B. doi: 10.1126/science.aag0482 . PMID   27885027 . Retrieved 2018-06-05.
  40. ↑ Lallemand, Serge; Heuret, Arnauld; Boutelier, David (8 September 2005). "On the relationships between slab dip, back-arc stress, upper plate absolute motion, and crustal nature in subduction zones" (PDF). Geochemistry, Geophysics, Geosystems. 6 (9): Q09006. Bibcode:2005GGG.....6.9006L. doi: 10.1029/2005GC000917 .
  41. ↑ Stern, R.J. (2004). "Subduction initiation: spontaneous and induced". Earth and Planetary Science Letters. 226 (3–4): 275–292. Bibcode:2004E&PSL.226..275S. doi:10.1016/j.epsl.2004.08.007.
  42. 1 2 Crameri, Fabio; Magni, Valentina; Domeier, Mathew; Shephard, Grace E.; Chotalia, Kiran; Cooper, George; Eakin, Caroline M.; Grima, Antoniette Greta; Gürer, Derya; Király, Ágnes; Mulyukova, Elvira (2020-07-27). "A transdisciplinary and community-driven database to unravel subduction zone initiation". Nature Communications. 11 (1): 3750. Bibcode:2020NatCo..11.3750C. doi:10.1038/s41467-020-17522-9. ISSN   2041-1723. PMC   7385650 . PMID   32719322.
  43. ↑ Hall, C.E.; et al. (2003). "Catastrophic initiation of subduction following forced convergence across fracture zones". Earth and Planetary Science Letters. 212 (1–2): 15–30. Bibcode:2003E&PSL.212...15H. doi:10.1016/S0012-821X(03)00242-5.
  44. ↑ Gurnis, M.; et al. (2004). "Evolving force balance during incipient subduction". Geochemistry, Geophysics, Geosystems. 5 (7): Q07001. Bibcode:2004GGG.....5.7001G. doi:10.1029/2003GC000681. S2CID   18412472. Archived from the original on 2022-02-10. Retrieved 2016-07-22.
  45. ↑ Keenan, Timothy E.; Encarnación, John; Buchwaldt, Robert; Fernandez, Dan; Mattinson, James; Rasoazanamparany, Christine; Luetkemeyer, P. Benjamin (2016). "Rapid conversion of an oceanic spreading center to a subduction zone inferred from high-precision geochronology". PNAS. 113 (47): E7359–E7366. Bibcode:2016PNAS..113E7359K. doi: 10.1073/pnas.1609999113 . PMC   5127376 . PMID   27821756.
  46. ↑ House, M. A.; Gurnis, M.; Kamp, P. J. J.; Sutherland, R. (September 2002). "Uplift in the Fiordland Region, New Zealand: Implications for Incipient Subduction" (PDF). Science. 297 (5589): 2038–2041. Bibcode:2002Sci...297.2038H. doi:10.1126/science.1075328. PMID   12242439. S2CID   31707224.
  47. ↑ Mart, Y., Aharonov, E., Mulugeta, G., Ryan, W.B.F., Tentler, T., Goren, L. (2005). "Analog modeling of the initiation of subduction". Geophys. J. Int. 160 (3): 1081–1091. Bibcode:2005GeoJI.160.1081M. doi: 10.1111/j.1365-246X.2005.02544.x .{{cite journal}}: CS1 maint: multiple names: authors list (link)
  48. ↑ Goren, L.; E. Aharonov; G. Mulugeta; H. A. Koyi; Y. Mart (2008). "Ductile Deformation of Passive Margins: A New Mechanism for Subduction Initiation". J. Geophys. Res. 113 (B8): B08411. Bibcode:2008JGRB..113.8411G. doi: 10.1029/2005JB004179 . S2CID   130779676.
  49. ↑ Stern, R.J.; Bloomer, S.H. (1992). "Subduction zone infancy: examples from the Eocene Izu-Bonin-Mariana and Jurassic California arcs". Geological Society of America Bulletin. 104 (12): 1621–1636. Bibcode:1992GSAB..104.1621S. doi:10.1130/0016-7606(1992)104<1621:SZIEFT>2.3.CO;2.
  50. ↑ Arculus, R.J.; et al. (2015). "A record of spontaneous subduction initiation in the Izu–Bonin–Mariana arc" (PDF). Nature Geoscience. 8 (9): 728–733. Bibcode:2015NatGe...8..728A. doi:10.1038/ngeo2515. S2CID   29775269.
  51. ↑ Yin, A. (2012). "An episodic slab-rollback model for the origin of the Tharsis rise on Mars: Implications for initiation of local plate subduction and final unification of a kinematically linked global plate-tectonic network on Earth". Lithosphere. 4 (6): 553–593. Bibcode:2012Lsphe...4..553Y. doi: 10.1130/L195.1 .
  52. ↑ Stern, Robert J.; Gerya, Taras (October 2018). "Subduction initiation in nature and models: A review". Tectonophysics. 746: 173–198. Bibcode:2018Tectp.746..173S. doi:10.1016/j.tecto.2017.10.014. S2CID   53970781.
  53. 1 2 Stern 2002, pp. 6–7.
  54. ↑ Ernst, W. G. (June 1999). "Metamorphism, partial preservation, and exhumation of ultrahigh-pressure belts". Island Arc. 8 (2): 125–153. Bibcode:1999IsArc...8..125E. doi:10.1046/j.1440-1738.1999.00227.x. S2CID   128908164.
  55. ↑ Cooper, P. A.; Taylor, B. (1985). "Polarity reversal in the Solomon Islands arc" (PDF). Nature. 314 (6010): 428–430. Bibcode:1985Natur.314..428C. doi:10.1038/314428a0. S2CID   4341305 . Retrieved 4 December 2020.
  56. ↑ Zheng, Y.-F., Chen, Y.-X., 2016. Continental versus oceanic subduction zones. National Science Review 3, 495-519.
  57. ↑ "How Volcanoes work – Subduction Zone Volcanism". San Diego State University Department of Geological Science. Archived from the original on 2018-12-29. Retrieved 2021-04-11.
  58. ↑ Mibe, Kenji; et al. (2011). "Slab melting versus slab dehydration in subduction zones". Proceedings of the National Academy of Sciences. 108 (20): 8177–8182. doi: 10.1073/pnas.1010968108 . PMC   3100975 . PMID   21536910.
  59. ↑ Zheng, Y.-F., Chen, R.-X., 2017. Regional metamorphism at extreme conditions: Implications for orogeny at convergent plate margins. Journal of Asian Earth Sciences 145, 46-73.
  60. ↑ Winter, John D. (2010). Principles of Igneous and Metamorphic Petrology. Prentice Hall. pp. 541–548. ISBN   978-0-321-59257-6.
  61. ↑ Reynolds, Stephen (2012-01-09). Exploring Geology. McGraw-Hill. p. 124. ISBN   978-0073524122.
  62. ↑ Bebout, Grey E. (May 31, 2007). "Metamorphic Chemical Geodynamics of Subduction". Earth and Planetary Science Letters. 260 (3–4): 375. Bibcode:2007E&PSL.260..373B. doi:10.1016/j.epsl.2007.05.050.
  63. ↑ Peacock, Simon M. (1 January 2004). "Thermal Structure and Metamorphic Evolution of Subducting Slabs". In Eiler, John (ed.). Inside the subduction factory. Geophysical Monograph Series. Vol. 138. American Geophysical Union. pp. 12–15. ISBN   9781118668573.
  64. ↑ Stern 2002, pp. 24–25.
  65. 1 2 Stern 2002, pp. 1–38.
  66. ↑ "Volcanic arcs form by deep melting of rock mixtures: Study changes our understanding of processes inside subduction zones". ScienceDaily. Retrieved 2017-06-21.
  67. ↑ Fisher, Richard V.; Schmincke, H.-U. (1984). Pyroclastic rocks. Berlin: Springer-Verlag. p. 5. ISBN   3540127569.
  68. ↑ Stern 2002, pp. 27–31.
  69. 1 2 3 Frezzotti, M. L.; Selverstone, J.; Sharp, Z. D.; Compagnoni, R. (2011). "Carbonate dissolution during subduction revealed by diamond-bearing rocks from the Alps". Nature Geoscience. 4 (10): 703–706. Bibcode:2011NatGe...4..703F. doi:10.1038/ngeo1246. ISSN   1752-0894.
  70. 1 2 Stern 2002, pp. 17–18.
  71. ↑ Bletery, Quentin; Thomas, Amanda M.; Rempel, Alan W.; Karlstrom, Leif; Sladen, Anthony; Barros, Louis De (2016-11-25). "Mega-earthquakes rupture flat megathrusts". Science. 354 (6315): 1027–1031. Bibcode:2016Sci...354.1027B. doi: 10.1126/science.aag0482 . ISSN   0036-8075. PMID   27885027.
  72. ↑ "Subduction zone geometry: Mega-earthquake risk indicator". ScienceDaily. Retrieved 2017-06-21.
  73. ↑ Garcia-Castellanos, D.; M. Torné; M. Fernàndez (2000). "Slab pull effects from a flexural analysis of the Tonga and Kermadec Trenches (Pacific Plate)". Geophys. J. Int. 141 (2): 479–485. Bibcode:2000GeoJI.141..479G. doi: 10.1046/j.1365-246x.2000.00096.x . hdl: 10261/237992 .
  74. 1 2 3 4 5 "Atlas of the Underworld | Van der Meer, D.G., van Hinsbergen, D.J.J., and Spakman, W., 2017, Atlas of the Underworld: slab remnants in the mantle, their sinking history, and a new outlook on lower mantle viscosity, Tectonophysics". www.atlas-of-the-underworld.org. Retrieved 2017-12-02.
  75. ↑ Matthews, John A., ed. (2014). Encyclopedia of Environmental Change. Vol. 1. Los Angeles: SAGE Reference.
  76. ↑ Garrett W. Tate; Nadine McQuarrie; Douwe J.J. van Hinsbergen; Richard R. Bakker; Ron Harris; Haishui Jiang (2015). "Australia going down under: Quantifying continental subduction during arc-continent accretion in Timor-Leste". Geosphere. 11 (6): 1860–1883. Bibcode:2015Geosp..11.1860T. doi: 10.1130/GES01144.1 .
  77. ↑ Baitsch-Ghirardello, Gerya, Burg, Bettina, Taras, Jean-Pierre (March 2014). "Geodynamic regimes of intra-oceanic subduction: Implications for arc extension vs. shortening processes". Gondwana Research. 25 (2): 546–560. Bibcode:2014GondR..25..546B. doi:10.1016/j.gr.2012.11.003.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  78. ↑ Macdonald, Francis A.; Swanson-Hysell, Nicholas L.; Park, Yuem; Lisiecki, Lorraine; Jagoutz, Oliver (2019). "Arc-continent collisions in the tropics set Earth's climate state". Science. 364 (6436): 181–184. Bibcode:2019Sci...364..181M. doi: 10.1126/science.aav5300 . ISSN   0036-8075. PMID   30872536. S2CID   78094267.
  79. 1 2 3 4 Xu, Cheng; Kynický, Jindřich; Song, Wenlei; Tao, Renbiao; Lü, Zeng; Li, Yunxiu; Yang, Yueheng; Miroslav, Pohanka; Galiova, Michaela V.; Zhang, Lifei; Fei, Yingwei (2018). "Cold deep subduction recorded by remnants of a Paleoproterozoic carbonated slab". Nature Communications. 9 (1): 2790. Bibcode:2018NatCo...9.2790X. doi:10.1038/s41467-018-05140-5. PMC   6050299 . PMID   30018373.
  80. ↑ Stern, Robert J. (2005). "Evidence from ophiolites, blueschists, and ultrahigh-pressure metamorphic terranes that the modern episode of subduction tectonics began in Neoproterozoic time". Geology. 33 (7): 557–560. Bibcode:2005Geo....33..557S. doi:10.1130/G21365.1. S2CID   907243.
  81. 1 2 3 4 Palin, Richard M.; White, Richard W. (2016). "Emergence of blueschists on Earth linked to secular changes in oceanic crust composition". Nature Geoscience. 9 (1): 60. Bibcode:2016NatGe...9...60P. doi:10.1038/ngeo2605. S2CID   130847333.
  82. ↑ Wilson, J. Tuzo (December 1968). "A Revolution in Earth Science". Geotimes. Washington DC. 13 (10): 10–16.
  83. ↑ Geological Society of America (July 6, 2017). "Geological Society of America honors Excellence in Geoscience for 2017" (Press release). Eurekalert!.
  84. ↑ "subduction". Online Etymology Dictionary. Retrieved 31 December 2020.
  85. ↑ John Ogilvie; Charles Annandale (1883). "Subduce, Subduct". Imperial Dictionary of the English Language. Vol. IV Scream-Zythus (New Edition Carefully Reviewed and Greatly Augmented ed.). London: Blackie & Son.
  86. ↑ "What is a tectonic plate?". U.S. Geological Survey (USGS). 1999.
  87. ↑ "Subduction Zone". Database of Individual Seismogenic Sources (DISS). Istituto Nazionale di Geofisica e Vulcanologia (INGV). Archived from the original on 23 April 2021. Retrieved 4 January 2021.
  88. ↑ Schultz, C. (2015). "Overriding plate's properties affect subduction". Eos. 96. doi: 10.1029/2015EO026911 .
  89. ↑ Tsang, Man-Yin; Bowden, Stephen A.; Wang, Zhibin; Mohammed, Abdalla; Tonai, Satoshi; Muirhead, David; Yang, Kiho; Yamamoto, Yuzuru; Kamiya, Nana; Okutsu, Natsumi; Hirose, Takehiro (2020-02-01). "Hot fluids, burial metamorphism and thermal histories in the underthrust sediments at IODP 370 site C0023, Nankai Accretionary Complex". Marine and Petroleum Geology. 112: 104080. Bibcode:2020MarPG.11204080T. doi: 10.1016/j.marpetgeo.2019.104080 . hdl: 2164/13157 . ISSN   0264-8172.
  90. ↑ "USGS publishes a new blueprint that can help make subduction zone areas more resilient". www.usgs.gov. Retrieved 2017-06-21.
  91. ↑ Hafemeister, David W. (2007). Physics of societal issues: calculations on national security, environment, and energy. Berlin: Springer Science & Business Media. p. 187. ISBN   978-0-387-95560-5.
  92. 1 2 Kingsley, Marvin G.; Rogers, Kenneth H. (2007). Calculated risks: highly radioactive waste and homeland security. Aldershot, Hants, England: Ashgate. pp. 75–76. ISBN   978-0-7546-7133-6.
  93. ↑ "Dumping and Loss overview". Oceans in the Nuclear Age. Archived from the original on June 5, 2011. Retrieved 18 September 2010.
  94. ↑ "Storage and Disposal Options. World Nuclear Organization (date unknown)". Archived from the original on July 19, 2011. Retrieved February 8, 2012.

Additional reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.