Introduction to Oceanic Lithosphere

What is/are Oceanic Lithosphere?

Oceanic Lithosphere - The Mesozoic Karoo-Maud and Kerguelen plumes had a significant influence on Gondwana and the oceanic lithosphere. ^[1] Ocean Plate Stratigraphy (OPS) is the travelogue of the oceanic lithosphere from its birth at the Mid Ocean Ridge to its demise at the subduction zone in convergent plate margins. ^[2] Based on the petrological, geochemical, and isotopic data, we suggest that the El-Shadli bimodal suite and the intermediate rocks were produced by reworking of MORB-like and arc-like oceanic lithosphere, respectively, most likely driven by a mantle plume during the break-up of Rodinia. ^[3] To the south, oceanic lithosphere (e. ^[4] The head of a mantle plume can weaken the oceanic lithosphere through the combined action of its buoyancy forces and excess temperature, which eventually induces intra-oceanic subductions. ^[5] The broken-off piece of oceanic lithosphere is then transported on top of the continent along a flat thrust segment and becomes a far-travelled ophiolite sheet separated from its root by the extruded continental crust. ^[6] Subduction of oceanic lithosphere is a diagnostic characteristic of plate tectonics. ^[7] The characteristics of the metamorphism indicate an arc−back-arc environment with ongoing subduction of oceanic lithosphere at ca. ^[8] The plate model is described by a simple analytical formula, and it is widely adapted as a reference model to represent averaged global depth We present a new reference model for the evolution of oceanic lithosphere, which incorporates the effects of incomplete viscous relaxation, radiogenic heating, and secular cooling. ^[9] Conjugated Diamantin and Labuan structures located in the southeastern part of the Indian Ocean were formed as a result of the split of a single Australian-Antarctic continent and the continental rift movement towards the oceanic lithosphere of the Indian Ocean. ^[10] Carbon presence has been discussed in a variety of magmatic contexts, under the oceanic lithosphere (hotspots, petit spots, and fossil ridges). ^[11] One key component in understanding the amount of exposed landmasses in the early Earth is the evolution of the oceanic lithosphere. ^[12] Elastic units in the model include the subducting slab, continental and oceanic lithospheres. ^[13] A model is suggested for their formation during various stages of a single evolutionary cycle of the oceanic lithosphere, in relation to the geochemical and dynamic features of an ascending flow of mantle material, which produces the oceanic lithosphere at mid-oceanic ridges. ^[14] Cracks that develop during brittle deformation easily modify rocks' physical properties; therefore, understanding of seismic properties of oceanic rocks during deformation is essential for interpretation of the seismic observations of the oceanic lithosphere. ^[15] In the next stage, shear localization through the formation of a decollement within the ductile passive margin crust favors underthrusting of the oceanic lithosphere, leading to a reduction of the area affected by deformation. ^[16] According to the theory of thrust tectonics of the Binalood region, the oceanic lithosphere of the Palo-Tethys has subducted under the Turan microplate. ^[17] The broken-off piece of oceanic lithosphere is then transported on top of the continent along a flat thrust segment and becomes a far-travelled ophiolite sheet separated from its root by the extruded continental crust. ^[18] While the central margin depicts a typical thick- and thin-skinned tectonic style with frontal propagation of crustal thrust ramps, the central-eastern margin (Jijel segment) reveals a higher strain focusing at the margin toe together with the largest flexural response of the oceanic lithosphere. ^[19] Our data suggest that no oceanic crust is presently subducting below the Bradano Basin, although we cannot exclude that a narrow sliver of oceanic lithosphere was subducted before and/or during Pliocene times. ^[20] Vertical magnetic transfer functions (tippers) estimated at island observatories can constrain the one-dimensional (1-D) conductivity distribution of the oceanic lithosphere and upper mantle. ^[21] Further data are needed to better constrain the fraction of magmatic CO2 that does not escape the oceanic lithosphere but remains stored as reduced and inorganic carbon. ^[22] Subduction of the oceanic lithosphere, as the engine that drives plate tectonics, has played a key role in the theory. ^[23] Occurrences of diopsidites, rocks made predominantly of gem-like diopside whose composition precludes a purely igneous origin, allow tracking the pathway of high-temperature fluids and fluid-saturated melts in the oceanic lithosphere in vicinity of the mantle-crust transition zone (the Moho) and the adjacent mantle in an oceanic setting. ^[24] To understand how a spherical geometry influences the dynamics of gravity-driven subduction of the oceanic lithosphere on Earth, we study a simple model of a thin and dense axisymmetric shell of thickness $h$ and viscosity $\eta _1$ sinking in a spherical body of fluid with radius $R_0$ and a lower viscosity $\eta _0$. ^[25] Coupling our P-T profiles with thermodynamic models of oceanic lithosphere, we show that dehydrating ultramafic rocks at the slab Moho provide the bulk of hydrous fluid at subarc depths during the earliest phases. ^[26] The break-off of Neo-Tethyan slab and subduction of this slab branch beneath the oceanic lithosphere during cretaceous led to cessation of the Neo-Tethyan subduction beneath the Sanandaj-Sirjan block, and forming arc-back arc basin (second step of subduction) and related rocks in the Kamyaran ophiolite. ^[27] 2106 A robust elemental and isotopic dataset fromNeoproterozoic igneous rocks discloses protracted consumption of oceanic lithosphere in the 3,000 km long orogenic system of southeastern South America. ^[28] The existence of SSC has been proposed to account for observed geophysical data, such as the seafloor depth which reflects the thermal subsidence of the oceanic lithosphere. ^[29] This coupling occurred during the exhumation of the different tectono-metamorphic units belonging to both continental and oceanic lithosphere and under a relatively cold thermal regime, typical for an active oceanic subduction zone, pre-dating Alpine continental collision. ^[30] The transition between continental and oceanic lithosphere in rifted margins can display a wide range of characteristics, which primarily depend on the regional tectonic evolution. ^[31] The initial model setup simulates the scenario at ca 20 Ma, where the oceanic lithosphere of the westward-subducting Adria plate was entirely consumed and some amount of continental subduction also occurred. ^[32] The geology of the Oman Mountains was shaped by the SW-directed obduction of allochthonous deep-sea rocks (Hawasina), trench-facies rocks (Haybi) and oceanic lithosphere (Semail Ophiolite) onto Arabian autochthonous shelf carbonates during the Late Cretaceous. ^[33] The oceanic lithosphere was likely underthrusted within an east-to-northeast-dipping subduction zone, where ophiolitic rocks and metasedimentary sequences were tectonically interleaved at the base of an accretionary wedge. ^[34] Nonetheless, this model still cannot fully reproduce a gradual Moho deepening caused by a conductive cooling and a subsequent isostatic rebalance of the oceanic lithosphere, which can functionally be described by a Moho deepening with the increasing ocean-floor age. ^[35] The Truong Son has Silurian granites and a Late Ordovician to Silurian magmatic arc along its southern and western borders caused by eastward and northward subduction of oceanic lithosphere, the remnants of which are now partially preserved in the Loei and Tamky sutures. ^[36] Serpentinization of mantle peridotites has first order effects on the rheology and tectonic behavior of the oceanic lithosphere, on the global water cycle, and on the biosphere at mid-oceanic ridges. ^[37] The post-Triassic age of all oceanic lithospheres indicates the efficiency and the sustainability of lithospheric subduction, which consumes the basaltic seafloor and recirculates it in the upper mantle. ^[38]

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  Considering the whole Pontide – Sredna-Gora Upper Cretaceous magmatic arc, it can be stated that calc-alkaline volcanism developed in relation to northward subduction of the Neo-Tethys oceanic lithosphere during the Turonian, and may have passed into high-K calc alkaline and shoshonitic magmatism as a result of the progressive extentional tectonism during the Campanian. ^[1]  We show that the key drivers of plate-scale processes related to  Alpine orogenic and topographic evolution reflect three main ingredients : 1) a protracted magmatic and tectono-thermal transformation of Africa (Gondwana) and North Europea (Baltica) cratonic mantle lithosphere since the Neoproterozoic, 2) an overall limited Mesozoic Tethyan extension of the weak Variscan lithosphere characterized by the lack of wide, thermally relaxed, oceanic lithosphere, 3) a relatively slow Cenozoic convergence between Africa and Europe, preserving initial stages of distributed tectonic inversion of rifted continental blocks throughout Europe, and partial subduction and delamination in the Mediterranean region of the most evolved lithospheric domains. ^[2]

Tethy Oceanic Lithosphere

As a result, we propose that rapid, cold subduction of continental crust, and its subsequent rapid exhumation, occurred shortly after the closure of the dense and long-lived Paleo-Tethys oceanic lithosphere. ^[1] The 487 ± 7 Ma andesitic lava sample with eHf(t) values clustering 10 to 15 formed during retreating subduction indicates that the northward subduction of the Proto-Tethys oceanic lithosphere initiated prior to 487 ± 7 Ma. ^[2] The Kashan-Ardestan sedimentary basin in Central Iran was initially formed by back-arc extension due to the subduction of Neo-Tethys oceanic lithosphere beneath the Iranian Plate during Eocene time. ^[3] Integrating data from previous studies and this study, we propose that the northward subduction of the Neo-Tethys oceanic lithosphere and formation of arc-type magmas provide a viable model to account for the heavy Mg isotopic compositions through fluid-rock interaction within the subduction channel. ^[4]   Considering the whole Pontide – Sredna-Gora Upper Cretaceous magmatic arc, it can be stated that calc-alkaline volcanism developed in relation to northward subduction of the Neo-Tethys oceanic lithosphere during the Turonian, and may have passed into high-K calc alkaline and shoshonitic magmatism as a result of the progressive extentional tectonism during the Campanian. ^[5] The magmatic arc formed at Early Cretaceous in the Southern Qiangtang subterrane, was products of the Mesozoic magmatism during the long-term subduction of the Bangong-Nujiang Tethys oceanic lithosphere and the subsequent Qiangtang-Lhasa terrane collision. ^[6] A number of studies revealed that the Gangdese magmatic belt of southern Tibet was closely related to the northward subduction of the Neo-Tethys oceanic lithosphere and Indo-Asian collision. ^[7] During the early Eocene continental collision, breakoff of the Neo-Tethys oceanic lithosphere caused the Indian plate to fold back resulting in a major asthenospheric disturbance. ^[8] Geochemical data and the geological setting indicate that Devonian intrusions in the Maxingdawannan area are related to northward subduction of the Proto-Tethys oceanic lithosphere. ^[9]

Subducted Oceanic Lithosphere

Late Cretaceous satellite plutons suggest a continentward migration of the magmatic arc, related to the flattening of the subducted oceanic lithosphere of the proto-Pacific Ocean. ^[1] These results indicate that moderately oxidized, sulfur-rich arc magma associated with porphyry Cu mineralization already existed in the late Paleoproterozoic, probably as a result of recycling of sulfate-rich seawater or sediments from the subducted oceanic lithosphere at that time. ^[2] Integrated studies indicate that Eshtehard HABs were derived from the hydrated, dominantly depleted shallow asthenospheric mantle wedge (and possibly also in the lower lithosphere) overlying subducted oceanic lithosphere. ^[3] This interpretation provides a new perspective with which to investigate the deep recycling of subducted oceanic lithosphere and associated magma petrogenesis. ^[4] 2110 Isotope systematics of the redox sensitive and chalcophile element selenium (Se) were investigated on exhumed parts of subducted oceanic lithosphere to provide new constraints on slab dehydration conditions during subduction. ^[5] In response to dynamic topography, the forebulge probably shifted to a system dominated by long-wavelength propagation developed over a distance of more than 800 km, most likely due to the influence of the subducted oceanic lithosphere of Panthalassa. ^[6] Here, we identify a seismological expression of the iron spin crossover in fast regions associated with cold Fp-rich subducted oceanic lithosphere: the relative abundance of fast velocities in P- and S-wave tomography models diverges in the ~1,400-2,000 km depth range. ^[7] Our analysis focuses on the interpretation of subducted oceanic lithosphere beneath Myanmar to Sulawesi and includes a cross sectional area-based restoration of actively subducting India-Australia plate oceanic lithosphere. ^[8] However, the complex topography of the “410-km discontinuity” is unclear within cold subducted oceanic lithospheres sinking into the lower mantle, partly due to the sparsity of seismic waves sampling the pertaining complex 3-D structures. ^[9]

Tethyan Oceanic Lithosphere

The Mawat ophiolite is a fragment from the Neo-Tethyan oceanic lithosphere and is considered as the largest and best-exposed ophiolite within the Zagros Suture Zone, northeast Iraq. ^[1] The Gangdese magmatic belt, which formed by Mesozoic northward subduction of Neo-Tethyan oceanic lithosphere and Early Mesozoic India-Asia collision, is an excellent natural laboratory for study of subducting slabs, crustal growth, the reworking of convergent continental margins and interaction of crust-mantle in general. ^[2] At the base of both belts, crop out ophiolitic mélange – accretionary complex generated during the northward subduction of the Neo-Tethyan Oceanic lithosphere from the Late Cretaceous until the end of middle Eocene. ^[3] The Tertiary magmatism in the study area originated in an arc-related setting induced by slab roll-back of northward Neo-Tethyan oceanic lithosphere subduction beneath central Iranian micro continent and resulted in lithospheric extensional regime and subsequently asthenosphere upwelling. ^[4] We emphasize the similarity between the Dazhuqu and Oman ophiolites, both representing Neo-Tethyan oceanic lithosphere and implying ridge–trench collision. ^[5] During 120–75 Ma, Gangdese Batholith magmatism migrated from south to north, arguing against rollback of the downgoing, north-dipping Neo-Tethyan oceanic lithosphere for the generation of the 90 ± 5 Ma magmatic pulse. ^[6]

Neotethyan Oceanic Lithosphere

The suture zone provides a record of the subduction of Neotethyan oceanic lithosphere beneath the Lhasa Block, creating the Gangdese magmatic belt, prior to the India–Asia collision. ^[1] The Ladakh Arc was formed by subduction of Neotethyan oceanic lithosphere along the southern Eurasian margin before magmatic activity ceased upon the continental collision between India and Eurasia. ^[2] We infer that the Middle Jurassic mafic and felsic magmatism was the principal heat source for the metamorphism and partial melting of the Boroujerd migmatites in response to the subduction of Neotethyan oceanic lithosphere. ^[3] A major SI event is recorded in the Late Cretaceous forearc ophiolites of Iran, related to the subduction of Neotethyan oceanic lithosphere beneath Eurasia. ^[4] All the sedimentological properties, combined with the regional data, suggest that the member was deposited at the shore of the back-arc Black Sea basin during the northward subduction of Neotethyan Oceanic Lithosphere and affected by the outcrop of the subduction-related magmatic products. ^[5]

Hot Oceanic Lithosphere

The typical adakites are considered the result of partial melting of young and hot oceanic lithosphere under moderate to high pressures in which garnet was an important stable residue. ^[1] We conclude that the studied rocks from north West Junggar record the initiation of ridge subduction related to a transition from normal subduction to subduction of young and hot oceanic lithosphere between the early and late Carboniferous. ^[2] Contrarily, transitional sub-alkaline to alkaline rocks (Suite 2) were formed during the approaching of the Chile spreading ridge and the subduction of hot oceanic lithosphere (prior to the development of a slab window), where metasomatism encompassed a broader region of the mantle wedge, resulting in lower degrees of partial melting (. ^[3] The P-T-t history of these metamorphic units argues for a rapid tectonic process featuring intra-oceanic subduction below a relatively hot oceanic lithosphere, slicing of the overriding oceanic domain, underplating of this subducted material along the hanging wall of the subduction zone and formation of a metamorphic sole as part of an ‘obduction channel’. ^[4]

Ancient Oceanic Lithosphere

The Texenna ophiolites show analogies with many other ophiolites in the Western Mediterranean region, indicating that they represent remnants of the ancient oceanic lithosphere of the western Tethys (i. ^[1] Ophiolites, found in orogenic belts, are slices of ancient oceanic lithosphere obducted on land during continental collision and ocean closure. ^[2] The retrograded eclogites and serpentinized peridotites of the Hongqiyingzi Group, exposed as tectonic lenses within the amphibole plagioclase gneisses, are interpreted as parts of an ancient oceanic lithosphere, whereas the amphibole plagioclase gneisses represent meta-volcano-sedimentary units. ^[3]

Pacific Oceanic Lithosphere

The Zhaiping Ag–Pb–Zn vein deposit in the Coastal Volcanic Belt of southeastern China, which resulted from subduction of the paleo-Pacific oceanic lithosphere beneath the South China Block, is hosted by Early Cretaceous sub-volcanic rocks (rhyolite porphyry) and younger granite porphyry and quartz porphyry. ^[1] Subduction of the Pacific oceanic lithosphere beneath the continental margin developed after Late Jurassic volcanism in Alexander Island that was related to extension of the continental margin. ^[2] The weak correlation between D″ topography and velocity variations indicate chemical heterogeneities must be present beneath the northern Pacific, which might come from north-westward subducted Pacific oceanic lithosphere. ^[3]

Hydrated Oceanic Lithosphere

In order to keep this water cycle in balance, an efficient rock dehydration mechanism at depth is needed to keep pace with loss of ocean water due to subduction of hydrated oceanic lithosphere. ^[1] Subduction of hydrated oceanic lithosphere can carry water deep into the Earth, with important consequences for a range of tectonic and magmatic processes. ^[2] Subduction of hydrated oceanic lithosphere represents a profound coupling of the Earth’s surface and its interior, with significant implications for both the internal dynamics and chemistry, as well as the surface habitability of our planet. ^[3]

Asian Oceanic Lithosphere

Based on the detrital zircon age populations and trace element contents, we conclude that the western Khanka Massif experienced a change from a stable to an active margin setting during the late Paleozoic, which was caused by subduction of the Paleo-Asian oceanic lithosphere. ^[1] The Chinese Altai is considered to have formed through accretion of volcanic arcs associated with subduction of the Paleo-Asian oceanic lithosphere. ^[2]

Plate Oceanic Lithosphere

During evolution of the South Sandwich subduction zone, which has consumed South American Plate oceanic lithosphere, somehow continental crust of both the South American and Antarctic plates have become incorporated into its upper plate. ^[1] During evolution of the South Sandwich subduction zone, which has consumed South American Plate oceanic lithosphere, somehow continental crust of both the South American and Antarctic plates have become incorporated into its upper plate. ^[2]

Subducting Oceanic Lithosphere

Hydrous fluids released from subducting oceanic lithosphere fuel arc magmatism and associated hydrothermal mineralization, including formation of porphyry copper deposits. ^[1] Fluid release from subducting oceanic lithosphere is a key process for subduction zone geodynamics, from controlling arc volcanism to seismicity and tectonic exhumation. ^[2]

Moving Oceanic Lithosphere

In the case of subduction initiation of older moving oceanic lithosphere, asymmetrical cylindrical subduction is promoted instead of more symmetrical stagnant lid subduction. ^[1] In present study we investigate the response of moving oceanic lithosphere to the arrival of a rising mantle plume head including the effect of magmatic lithospheric weakening. ^[2]

Strong Oceanic Lithosphere

Initiation of Mariana-type oceanic subduction zones requires rheologically strong oceanic lithosphere, which developed through secular cooling of Earth’s mantle. ^[1] Initiation of stable Mariana type one-sided oceanic subduction zones requires rheologically strong oceanic lithosphere, which developed through secular cooling of Earth mantle. ^[2]

Nujiang Oceanic Lithosphere

Tectonic compression and crustal thickening of the western Tibetan Plateau during the Early Cretaceous occurred when the Bangong–Nujiang oceanic lithosphere was subducted northward at a low angle beneath the western Qiangtang Terrane before ca. ^[1] Based on previously published data and the regional geology, we also suggest that these magnesian andesites were generated in a back-arc setting caused by the southward subduction of the Bangong–Nujiang oceanic lithosphere during the Late Jurassic. ^[2]

Formed Oceanic Lithosphere

We also show that the final stage of Jurassic magmatism (~157–145 Ma) was coincident with rifting that formed oceanic lithosphere of the Weddell Sea and back-arc extension of the Rocas Verdes Basin, potentially revealing the presence of a triple junction located between southern Patagonia and the northern Antarctic Peninsula that led to the disassembly of southern Gondwana. ^[1] On the other hand, rift jump occurs in models with multiple extensional phases resulting in more complex morphologies that go from a hyperextend margin, to microcontinent formation, to spreading centre jumps within the newly formed oceanic lithosphere. ^[2]

Neotethy Oceanic Lithosphere

The East Anatolian Accretionary Complex formed as a result of the natural process of collision between the Arabian and Eurasian plates and the subduction of the Neotethys oceanic lithosphere located between them, covers a broad area, largely east of Lake Van. ^[1] The subsequent Late Jurassic–Paleogene closure of the Vardar Ocean led to the E-ward subduction of the Neotethys oceanic lithosphere beneath the upper European plate (i. ^[2]

oceanic lithosphere beneath

The Zhaiping Ag–Pb–Zn vein deposit in the Coastal Volcanic Belt of southeastern China, which resulted from subduction of the paleo-Pacific oceanic lithosphere beneath the South China Block, is hosted by Early Cretaceous sub-volcanic rocks (rhyolite porphyry) and younger granite porphyry and quartz porphyry. ^[1] The suture zone provides a record of the subduction of Neotethyan oceanic lithosphere beneath the Lhasa Block, creating the Gangdese magmatic belt, prior to the India–Asia collision. ^[2] Subduction of the Pacific oceanic lithosphere beneath the continental margin developed after Late Jurassic volcanism in Alexander Island that was related to extension of the continental margin. ^[3] Our results provide a scenario for the tectono-magmatic evolution of the oceanic lithosphere beneath the Neo-Tethys in the South Tibet. ^[4] The Kashan-Ardestan sedimentary basin in Central Iran was initially formed by back-arc extension due to the subduction of Neo-Tethys oceanic lithosphere beneath the Iranian Plate during Eocene time. ^[5] A major SI event is recorded in the Late Cretaceous forearc ophiolites of Iran, related to the subduction of Neotethyan oceanic lithosphere beneath Eurasia. ^[6] Our analysis focuses on the interpretation of subducted oceanic lithosphere beneath Myanmar to Sulawesi and includes a cross sectional area-based restoration of actively subducting India-Australia plate oceanic lithosphere. ^[7] The subsequent Late Jurassic–Paleogene closure of the Vardar Ocean led to the E-ward subduction of the Neotethys oceanic lithosphere beneath the upper European plate (i. ^[8] Much of the crust of Iran and Anatolia, including their oldest exposed rocks, formed during an episode of intense convergent margin (arc) magmatism as a result of subduction of oceanic lithosphere beneath northern Gondwana from ca 620 Ma to ca 500 Ma, the Cadomian crust-forming event. ^[9] Oceanic-continental convergence indicates subduction of oceanic lithosphere beneath the continental boundary of the North China Craton, whereas post-orogenic extension implies a thickened continental lithosphere experienced a drip-like gravitational instability. ^[10]

oceanic lithosphere subduction

The source rocks for the younger detritus were arc magmatic rocks in the Qinling block, which formed in a continental arc by oceanic lithosphere subduction during the assembly of Rodinia. ^[1] The Tertiary magmatism in the study area originated in an arc-related setting induced by slab roll-back of northward Neo-Tethyan oceanic lithosphere subduction beneath central Iranian micro continent and resulted in lithospheric extensional regime and subsequently asthenosphere upwelling. ^[2] New results of this study reveal that the initial oceanic lithosphere subduction operated since ∼2. ^[3] In the Western Alps, the ophiolitic Zermatt–Saas Zone (ZSZ) and the Lago di Cignana Unit (LCU) record oceanic lithosphere subduction to high (540°C, 2·3GPa) and ultra-high pressure (600°C, 3·2GPa), respectively. ^[4]

oceanic lithosphere worldwide

But to what extent is the Alpine record representative of the subduction of oceanic lithosphere worldwide? What is its significance, merits and limits for understanding subduction (and exhumation) dynamics? This contribution shows that this record is neither exceptional nor atypical but rather exemplifies the fate of relatively short-lived and small, slow-spreading and slowly closing North Atlantic-type oceans (in this case a ~ 400–700 km-wide domain closed over 60 Ma, at ~ 1 cm/a), whose subducting slabs do not reach below the Mantle Transition Zone. ^[1] Fluid inclusions in Alpine metasediments show salinities and gas contents comparable with other subducted fragments of oceanic lithosphere worldwide, whereas fluid salinities of Alpine metagabbros are higher than salinities recorded elsewhere, either due to (1) higher-temperature hydrothermal alteration and brine formation in Alpine metagabbros (compared to metavolcanics) or (2) more restricted infiltration by sediment-derived fluids compared to block-in-melange subduction complexes. ^[2]

oceanic lithosphere obducted

Ophiolites, which represent segments of oceanic lithosphere obducted onto the continental crust, provide an important window into processes such as continental rifting, mantle melting, asthenospheric upwelling and cooling of oceanic lithosphere. ^[1] Ophiolites, found in orogenic belts, are slices of ancient oceanic lithosphere obducted on land during continental collision and ocean closure. ^[2]