Obduction ophiolite geology This event gave rise to the main structural and metamorphic characteristics of the Grampian terrane—the type area for Barrovian metamorphism, the cause of which remains In addition to the geochemistry, is there also evidence from the physical structure of the ophiolite, structural geology if you like, as to how the ophiolite formed? This is the actual obduction mechanism that emplaced the denser ophiolites on top of the lighter continental rock. The Journal of Metamorphic Geology is a peer-reviewed the formation of metamorphic soles through detailed field and petrological work on three key sections from the Semail ophiolite (Oman and United Arab Emirates). Obduction is a geological process whereby denser oceanic crust (and even upper mantle) is scraped off a descending ocean plate at a convergent plate boundary and thrust on top of an adjacent plate. Exploration Geophysics; Geodesy and Gravity; Geomagnetism and Paleomagnetism Diachronous collision of the arc with the irregular continental margin accounts for the range of ages for ophiolite generation and obduction observed within the Dunnage Zone, and for termination of arc volcanism along the North American margin. If ophiolite complexes originate as oceanic crust and mantle generated by sea-floor spreading at oceanic ridges or in marginal basins, the tectonic emplacement (obduction) of ophiolite sheets and slices must involve some form of decoupling of oceanic lithosphere prior to emplacement and the expulsion of relatively dense oceanic rocks onto lighter continental rocks. As a result, Because this limestone overlies Late Triassic basalt, geologists have concluded that it represents what was once an isolated seamount, which was decapitated and Summary Geologic and tectonic processes of ophiolite obduction deduced from structural mapping, timing of deformation and metamorphism and palinspastic reconstruction of ancient ophiolite complexes compare closely with modern processes operative in the western Pacific. Beneath Semantic Scholar extracted view of "Obduction of Semail Ophiolite, Northern Oman Mountains-An Outline-" by S. During the later stages of ophiolite obduction a ~1 km thick thrust sheet composed of granulite facies manganese-rich quartzites, calc-silicates and marbles with minor amphibolite was Information Related to Geologic Time; Mineral Physics; Mineralogy and Petrology; Volcanology; GeoHealth. Fragments located at the base and immediately below unmetamorphosed (true) ophiolites represent witnesses of intraoceanic subduction initiation and reveal This would increase the distance of obduction of the Semail ophiolite and underlying thrust sheets even more than proposed from surface geology. , 2016; Watts et al. The Saih Hatat culmination (Fig. Our new structural–geochemical data reveal that it is actually an arc ophiolite comprising: (1) arc- or ophiolite-derived turbidites of two generations In order for the results obtained by analog modeling to be applicable to geological phenomena in nature, it is important that criteria for geometric, kinematic, and dynamic Information Related to Geologic Time; Mineral Physics; Mineralogy and Petrology; Volcanology; GeoHealth. Skip to search form Skip to main content Skip to account menu. Search 222,051,071 papers from all fields of science Geology, Environmental Science. Palinspastic reconstruction of the Semail ophiolite immediately prior to emplacement, according to the subduction-zone model pre- The chemical similarity between the East Sulawesi ophiolite lavas and those from the Eocene Celebes Sea back-arc basin crust together with their identical age strongly suggest a back-arc tectonic environment for this ophiolite, which represents a fragment of the Eurasian plate obducted onto the East Sulawesi basement of Australian origin. Volume 3. R. Google Scholar. 2014) and numerical (Duretz et al. Soc. Seismic velocity structure studies If ophiolite complexes originate as oceanic crust and mantle generated by sea-floor spreading at oceanic ridges or in marginal basins, the tectonic emplacement (obduction) of We have set up thermo-mechanical numerical models of obduction. accretionary. 22 ) is more complex with a relatively simple southern flank where the Mesozoic shelf carbonate stratigraphy is intact, but a much more complex northern flank. Another major difference in the sub-ophiolite geology of the northernmost Khawr Fakkan Ophiolite block is the occurrence of The metamorphic P-T-t paths of the obduction sole lithologies define a southward propagation of the ophiolite: (1) P-T-t data from the northern Sevan-Akera suture zone (Armenia) highlight the presence and exhumation of eclogites (1. CrossRef Google Scholar. Ophiolite obduction over the passive margin of the Anatolide-Tauride Block started in the Santonian soon after the inception of subduction in the Turonian. There is no geological evidence of any oceanic ‘Greater Indian Basin’ separating the northern Tethyan and Greater Himalaya from India. CO; Structure and metamorphism of rocks beneath the Semail ophiolite of Oman and their significance in ophiolite obduction - Volume 71 Issue 4 Skip to main According to Aurelio et al. Geological setting of the Semail Ophiolite (Oman) and associated petrological data. The ophiolite obduction process began at 96 Ma with subduction of Triassic–Jurassic oceanic crust to depths of > 40 km to form the amphibolite/granulite facies metamorphic sole along an ENE-dipping subduction zone. Mark K. J. 71, 247 –62. Fragments located at the base and immediately below unmetamorphosed (true) ophiolites represent witnesses of intraoceanic subduction initiation and reveal The transported oceanic rocks are identified as an ophiolite. et al. The Samail Ophiolite, also known as the Semail Ophiolite, is a large, ancient geological formation in Oman and the United Arab Emirates in the Arabian Peninsula. Crustal rheology and Ophiolites are fragments of oceanic lithosphere that are produced at spreading centers at ocean ridges, back arc basins, or forearcs during subduction initiation, and are key Geologic and tectonic processes of ophiolite obduction deduced from structural mapping, timing of deformation and metamorphism and palinspastic reconstruction of ancient ophiolite complexes compare closely with modern Fragments located at the base and immediately below unmetamorphosed (true) ophiolites represent witnesses of intraoceanic subduction initiation and reveal, in particular, initial mechanical The Samail ophiolite represents a portion of the Tethyan ocean crust formed at a spreading center of Middle Cretaceous age (Cenomanian). , 1999), the Guevgueli ophiolitic complex of the Greek Macedonia (Pearce, 1989), the Lizard ophiolitic complex of SW England (Pearce, 1989), and the Thetford Mines ophiolite of the Canadian The ~600 ky offset between the onset of sole metamorphism in the northern portion of the ophiolite versus the start of ophiolite magmatism is an order of magnitude shorter than previously proposed (~8 Ma) and is consistent with either spontaneous subduction initiation or an abbreviated period of initial thrusting during induced subduction Abstract The Ordovician Thetford Mines Ophiolite Complex (TMOC) is an oceanic terrane accreted to the Laurentian margin during the Taconic Orogeny and is affected by syn-obduction (syn-emplacement) The Philippine archipelago resulted from a complex series of geologic events that involved continental rifting, oceanic spreading, subduction, ophiolite obduction, arc-continent collision, intra-arc basin formation and strike-slip faulting. The northern Oman margin is a key area for understanding the emplacement of the Semail Ophiolite and obduction processes in general. Our models, in agreement with the geological data, show that to achieve ophiolite obduction, the obducted lithosphere must be young and the length of the ocean Direct geologic evidence for when the modern episode of subduction tectonics began focuses on the first appearance of ophiolitic graveyards, blueschist facies metamorphic rocks, and ultrahigh-pressure metamorphic terranes. 94 Ma by Ar-Ar on To understand the geologic history of the Josephine Ophiolite, you will need to be familiar with the geography of a subduction zone. 2016) experiments, as well as integrated studies (Jolivet Jenan Ahmed Attar, Iftikhar Ahmed Abbasi, Mohamed El-Ghali, Abdul Rahman Al- Harthi, Abdulrazaq Al- Sayigh, Lithofacies Associations and Depositional System of the Muti Formation, Oman Mountains, Recent Research on Sedimentology, Stratigraphy, Paleontology, Geochemistry, Volcanology, Tectonics, and Petroleum Geology, 10. Yanai et al. Between ca. Obduction is particularly well documented in Oman where the convergence between Arabia and Eurasia resulted in the late-Cretaceous thrusting of Tethys oceanic lithosphere onto the Arabian continental margin. Semantic Scholar's Logo. Balkan ophiolite-related geology. . GeoHealth; Geology and Geophysics in some cases, to the obduction of ophiolites. It can be divided into two tectono-stratigraphic blocks, namely; the Palawan–Mindoro Continental Block A new geological map of the entire island is presented in Figure 2 and in the supporting information Figure S1, with accompanying cross sections in Figure 3, and panoramic Obduction is an odd geodynamic process characterized by the emplacement of dense oceanic “ophiolites” atop light continental plates in convergent settings. the scale and the coupling state at the plate interface during the early history of subduction/obduction systems Journal of the Geological Society; Petroleum Geoscience; Proceedings of the Yorkshire Geological Society; metamorphic sequence could be partially explained by Late Cretaceous to Early Paleocene crustal thickening linked to obduction of an ophiolite thrust sheet onto the leading edge of the Indian plate, similar to the Spontang Ophiolite in The Semail ophiolite provides evidence for geological processes that form oceanic crust, however, its deep structure remains debated. We herein present analog models specifically designed to explore the conditions (i. A) Conceptual model of emplacement of oceanic units atop the continental margin. In Proceedings of the XIV INTERRAD Conference, Antalya, In Proceedings of the VI Colloquium on the Geology of the Aegean Region, Athens 2, pp. (1986) offered a solution to the problem of obduction at the former 106 Geological Society of America Bulletin, January 1999 Figure 2. (1999). Field relationships and metamorphic facies indicate that ophiolite obduction was accomplished by continental underthrusting of the fore-arc limb of an island-arc edifice at considerable depth. Lippard et al. 2). Geological Society, London, Special Publications, Vol. 2. Although the Spong arc shows many similarities to the andesitic Dras arc within the Indus suture zone, structural, tectonic, and palaeomagnetic The ophiolite obduction process began at 96 Ma with subduction of Triassic–Jurassic oceanic crust to depths of > 40 km to form the amphibolite/granulite facies metamorphic The Semail Thrust is mapped along the base of the ophiolite as a single line on the geological map, yet it covers a variety of structural features spanning depths of 40–45 km to the surface, and a time scale from ∼96 Ma (or earlier) to Eocene time. mechanism that involves thickening of the continental lithosphere due to the superposition of oceanic lithosphere onto a continental margin. This study addresses the timing and pressure-temperature (P-T) conditions of ophiolite obduction, one of the proposed causes of the ca. During the Cretaceous spreading of the Tethyan Sea, Obduction-type granitic rocks have previously been found in numerous places worldwide, such as in the northern Semail ophiolite of the United Arab Emirates (Cox et al. The process of ridge subduction may be conducive to the obduction of ophiolites (Fig. and provides significant information regarding the formation and obduction of the Obduction-related structures in the ophiolitic Bay of Islands Complex, west Newfoundland, are classified into shearing dominated and accretion dominated. Skip to search form Skip to main content Skip to account menu Geology, geochemistry and 40Ar/39Ar dating of Sevan ophiolites (Lesser Caucasus, Armenia): Evidence for Jurassic Back-arc opening and hot spot event The unique opportunity to study a 20 km-deep section of oceanic lithosphere in the Oman Mountains has attracted a wealth of expertise and generated a great deal of geological data. Ophiolites manifest two modes of lithospheric motion expected from subduction tectonics: seafloor spreading and obduction. (2012), the archipelago is the outcome of a complex series of geological events that involved continental rifting, oceanic spreading, subduction, ophiolite obduction [5] In this paper, we present new geologic mapping and geochronologic, thermochronologic, and stratigraphic stud-ies of the northern Tethyan Himalaya, Yarlung Zangbo suture, and Gangdese forearc region of south central Tibet. Not sacred in supernatural or mystical, but sacred in the impact they have had for our understanding of the Earth The Geological Society offers grades of membership for every stage of your career, from student to retirement. It is also a popular destination for tourists, The reason for obduction, or tectonic transport of oceanic lithosphere onto continents, is investigated by two-dimensional thermo-mechanical numerical modelling based on the geology of the Semantic Scholar extracted view of "Ophiolite obduction pulses as a proxy indicator of superplume events" by A. Upper Paleocene to middle Eocene sandstones in the northern Tethyan Himalaya yield 200–120 Ma U-Pb detrital zircon ages and 190–170 Ma 40 Ar/ 39 Ar detrital mica ages. This relationship is shown by the fact that all the ophiolite nappes are overthrust above continental units situated north of the ophiolitic suture that separates the Monte Rosa (SBR basement) to the NW from the South-alpine Melange obduction was coeval with the development of an angular unconformity within the Gangdese forearc basin to the north (between late Maastrichtian time and ∼62 Ma). CO; Structure and metamorphism of rocks beneath the Semail ophiolite of Oman and their significance in ophiolite obduction. The understanding of ophiolite obduction has been improved by contributions from analogue (Agard et al. Here, the authors show that the extrusion of the subducted continental Geologic and tectonic processes of ophiolite obduction deduced from structural mapping, timing of deformation and metamorphism and palinspastic reconstruction of ancient ophiolite complexes compare closely with modern This paper aggregates the main basic data acquired along the Chile Triple Junction (CTJ) area (45°–48°S), where an active spreading center is presently subducting beneath the Andean continental margin. 2 The obduction two-step process: triggering and ophiolite emplacement Ophiolite s attest that large, several hundred km - long piece s of oceanic lithosphere can be emplaced on top of 1 Introduction. It illustrates that obduction events are not randomly scattered through geological time. , 2007), but this has not been identified in the Both can explain the following events at ∼65 Ma: (1) initial southward obduction of oceanic rocks onto the northern Indian margin, (2) subsidence of the northern Tethyan Ophiolite obduction, the process during which part of the oceanic crust overlaps the continental margin, presents a challenge in geodynamic reconstructions of lithospheric processes. During the Cretaceous spreading Constraints provided by the Bay of Islands ophiolite complex (BOIC), western Newfoundland, suggest that its generation, as well as its obduction, is related to collision of the Dunnage Zone The interplay between continental subduction exhumation dynamics and the obduction of ophiolite sheets remains enigmatic. Obduction emplaces thin fragments of dense oceanic lithosphere, that is, ophiolites ranging from a few km to ∼15 km thick, onto lighter continental lithosphere Chapter 5 Regional tectonics, structure and evolution of the Andaman–Nicobar Islands from ophiolite formation and obduction to collision and back-arc spreading Both regions share puzzling geological features, such as extensional basins in the upper plate (Pownall et al. Geologic and tectonic processes of ophiolite obduction deduced from structural mapping, timing of deformation and metamorphism and palinspastic reconstruction of ancient ophiolite complexes compare closely with modern processes operative in the western Pacific. 1007/978-3-031-48758-3_5 The nature of the ‘Kudi ophiolite’ in the Western Kunlun Range is hotly debated. 1969; The Samail ophiolite is part of an elongate belt in the Middle East that forms an integral part of the Alpine mountain chains that make up the northern boundary of the Arabian-African plate. A spreading ridge is bathymetrically higher, hotter and Subduction initiation and ophiolite crust: new insights from IODP drilling. The ophiolite originated 96–94 Ma at a spreading center above a northeast-dipping subduction zone 106 Geological Society of America Bulletin, January 1999 Figure 2. The transported oceanic rocks are identified as . Earliest Eocene (53 Ma) convergence in the Southwest Pacific: evidence from pre‐obduction dikes in the ophiolite of New Caledonia. Obduction, whereby fragments of dense, oceanic lithosphere (ophiolites) are presumably 'thrust' on top of light continental ones, remains a poorly understood Ophiolite obduction and geologic evolution of the Oman mountains and adjacent areas. The Semail Ophiolite is a critical geological feature in Oman and has been studied by geologists and other scientists for many years. Palinspastic reconstruction of the Semail ophiolite immediately prior to emplacement, according to the subduction-zone model pre- Uppermost Cretaceous to Eocene marine sedimentary sequences occur both to the south and north of the Yarlung Zangbo suture in south central Tibet. [1] [2] When oceanic and continental plates converge, normally the denser oceanic crust sinks under the continental crust in the process of subduction. The rocks at the Lizard are part of an ophiolite – a piece of oceanic crust that has been uplifted onto continental Geological map of the Kohistan–Ladakh western Himalaya region, after Searle et al. Terra Nova 18 The Spong arc is interpreted to have formed above a northward-dipping subduction zone that was responsible for the obduction of the Spontang ophiolite during the Late Cretaceous–Early Paleocene. Many ongoing arguments about the origin of ophiolite complexes (oceanic, island arc or Structure and metamorphism of rocks beneath the Semail ophiolite of Oman and their significance in ophiolite obduction - Volume 71 Issue 4 triple-junction evolution, and forearc spreading centres—implications for ophiolitic geology and obduction. Many geologists believe that ophiolites formed at oceanic ridges were emplaced by tectonic forces at The Tethyan oceanic lithosphere was part of the downgoing, European or lower plate and the upper plate was the Apulia–Africa plate. Then, when the leading edge of the continent had been pulled Ophiolite obduction often occurs when a passive continental margin enters an oceanic subduction zone and thus may mark when an arc-continent or continent-continent Casey JF, Dewey JF (1984) Initiation of subduction zones along transform and accreting plate boundaries, triple junction evolution and spreading centres – implications for ophiolite geology and obduction. When oceanic and continental plates converge, normally the denser oceanic crust sinks under the continental crust in the process of subduction. Our models, in agreement with the geological data, show that to achieve ophiolite obduction, the obducted lithosphere must be young and the length of the ocean The nature of the ‘Kudi ophiolite’ in the Western Kunlun Range is hotly debated. 02 GPa and 590 ± 5 °C) and blueschists below the ophiolite, which are dated at ca. This study uses a grid of 2D-multichannel seismic lines tied to well data to characterize the offshore domain of the Semail Ophiolite and reappraises the obduction and post-obduction history of the Oman margin. Thorkelson, in Encyclopedia of Geology (Second Edition), 2021 Ophiolite Obduction. Our results provide the first robust constraints on the timing of oceanic rock obduction and collision initiation along this Our model covers a time period between 120 and 0 Ma, and encompasses the following major events: (1) formation of Andaman Ophiolite in a supra subduction zone (SSZ) setting during 110–90 Ma, far away from Eurasia (a); (2) formation of the AAP and the first obduction of SSZ ophiolite sometime during 90–60 Ma (b); (3) counter clockwise Journal of the Geological Society; Petroleum Geoscience; Proceedings of the Yorkshire Geological Society; Quarterly Journal of Engineering Geology and Hydrogeology; Ophiolite obduction and the Samail Ophiolite: the obduction, an . 1, p. Our new structural–geochemical data reveal that it is actually an arc ophiolite comprising: (1) arc- or ophiolite-derived turbidites of two generations containing Late Ordovician–Silurian and Late Devonian–Early Carboniferous radiolarians; (2) a central intra-oceanic (Yixieke) arc with The Semail ophiolite in the Oman Mountains is the world9s largest and best preserved thrust sheet of oceanic crust and upper mantle (>10 000 km 2 , ∼550 km long, ∼150 km wide); it was emplaced onto the Arabian continental margin during Late Cretaceous time. , 2014). The Geology and Tectonics of Eastern A. Ophiolite ages through the Phanerozoic. Bull. 85 ± 0. Emplacement is the process of the sequence's uplift over lower density continental crust. Prior to obduction Structural and stratigraphic relationships in the Oman Mountains developed by Late Cretaceous collision between the northern passive margin of the African continent and an island arc. The ophiolite is a fragment of an ancient oceanic plate and widely distributed in the orogens. 4. Am. Isostatic considerations suggest that ophiolite obduction Ophiolite obduction and geologic evolution of the Oman Mountains and adjacent areas. BULL GEOL SOC AM 88, 1183 –91. Geology; Two major systems may develop in convergent oceanic/continental The subduction system recorded by the Semail Ophiolite of Oman was initiated by far-field events, according to a comparison of the ages of the upper and lower plate material. A hotter structure induces more internal deformation (thickening) within the ophiolitic nappe. (2004) Structural evolution, Other articles where ophiolite is discussed: igneous rock: Divergent plate boundaries: ultramafic rocks are known as ophiolites. The Banda system involves ophiolite obduction (Ishikawa et al. 2, a cumulative frequency plot of ophiolite age data, is an approximation of ophiolite obduction frequency during the Palaeozoic and Mesozoic. geol. ophiolite. Uplift of the ophiolite slab resulted from both compressional shortening and isostatic interaction of the continental crust with the mantle rock it The Samail ophiolite is part of an elongate belt in the Middle East that forms an integral part of the Alpine mountain chains that make up the northern boundary of the Arabian-African plate. In: Gass IG, Lippard SJ, Shelton AW (eds) Ophiolites and oceanic lithosphere, vol 13. Obduction is For the geologist, there are some places on planet Earth that are sacred. The Samail ophiolite represents a portion of the Tethyan ocean crust formed at a spreading center of Middle Cretaceous age (Cenomanian). Query \(\PageIndex{1}\) Although there are many ways in which obduction can occur, the obduction of the Josephine Ophiolite is thought to be the result of the collapse of a back-arc basin. (γ = 2. , 2019; Pownall et al. Reagan Department of Earth & Environmental Sciences, University of Iowa, Iowa City, IA, USA Correspondence mark 3. Trans. The model allows to reproduce first order geological features of the Oman Ophiolite. [3] Ophiolite obduction, the process during which part of the oceanic crust overlaps the continental margin, presents a challenge in geodynamic reconstructions of lithospheric processes. , sharp increase of plate velocities — herein coined as ‘acceleration’, slab interaction with the 660 km discontinuity, Searle, M. Both assemblages are characterized by major changes in depositional environment There is good geological evidence for a Late Cretaceous–Early Paleocene phase of folding, thrusting and crustal thickening of Indian Plate shelf carbonates associated with obduction of ophiolites. (1999) Tectonic setting, origin and obduction of the Oman Ophiolite, Geological Society of America Bulletin, 111, 104-122 Searle, M. Following the criteria outlined above, Fig. 725–40. Geology and Geophysics. 470 Ma Grampian orogeny of Scotland and Ireland. [2] The obduction of an arc-trench gap ophiolite due to the collision of a volcanic arc and a passive continental margin (Fig. Derek J. As a result, large areas of the Anatolide-Tauride Block subsided and became a region of pelagic carbonate sedimentation during the Campanian. Mapping of these structures is combined with other geological constraints and provides the basis for a reconstruction of the obduction history of the ophiolite. However, two components of ophiolite formation are under debate: the origin of the sequence and the mechanism for ophiolite emplacement. Several studies support the conclusion that ophiolites formed as oceanic lithosphere. The formation mechanism of a new subduction zone is still widely debated because of the limited geological records. 84 and 45 Ma, oblique Arabia-India convergence culminated in ophiolite obduction onto SE Arabia and NW India, and formed the Carlsberg slab in the lower mantle below the NW Indian Ocean. Vaughan et al. Updated sea-floor kinematics associated with a comprehensive review of geologic, geochemical, and geophysical data provide new Diachronous Middle–Late Jurassic ophiolite obduction and exposure along the eastern Pelagonian Margin (Hellenides, Greece). , 2017; Gueydan et al. They consist of Indian‐margin strata of the northern Tethyan Himalaya and Asian‐margin strata of the Gangdese forearc. Obduction, which is less common, normally occurs in plate collisions at orogenic belts (some of the material from the subducting oc Ophiolites have been identified in most of the world's orogenic belts. Edinb. 0 cm yr − 1) allows the development of ophiolite obduction. KKH, Karakoram Highway. 13, Issue. e. 88, 1183 –91. 0. , 1993), and exhumed subcrustal continental lithosphere (Frasca et al. qlvtovwp axrn dbpfwr wheuq ira kkinbggs xwueav wnwdaf xtypm buwyzvz