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Initial model configurations with three different tectonic settings. (a) Spontaneous subduction initiation (SI) at a transform fault, which is close to continental margins. (b) A short‐lived supra‐subduction zone (SSZ) spreading during slab retreat after SI. (c) A long‐lived SSZ spreading with a spreading center. The contour lines marked with numbers indicate the temperature field in °C. The red arrow denotes the region where convergent velocity is implemented. The red dashed box indicates the location of markers for tracing the P‐T conditions. Colors indicate the rock types, specified by the color grid at the bottom: 1, stick air; 2, seawater; 3 and 4, sediments; 5 and 6, continental upper and lower crust, respectively; 7 and 8, oceanic upper and lower crust, respectively; 9, lithospheric mantle; 10, asthenosphere; 11, hydrated mantle; 12, serpentinized mantle; 13, partially molten sediments; 14, partially molten continental upper crust; 15, partially molten continental lower crust; 16, partially molten oceanic crust; 17, partially molten mantle.
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The understanding of subduction initiation (SI) remains ambiguous due to limited geological records. The metamorphic sole, generally considered to be generated by oceanic crustal metamorphism during SI, is characterized by high temperature condition (∼800°C) at shallow depths (<40 km). However, the exact tectonic setting of the metamorphic sole wit...
Citations
... The soles discovered in the present Earth are mostly generated under a low pressure of 0.5-1 .5 GPa and high temperature of 70 0-90 0°C [5 ]. Such a critical condition generally requires heating from the asthenosphere, by means of asthenospheric upwelling or greatly thinned overriding lithosphere [6 ]. The related numerical models indicate that induced SI beneath a rather thin overriding plate contributes to the generation of pressure-temperature conditions of most metamorphic soles [7 ]. ...
... As a typical example, the tectonic reversal of a spreading ridge may lead to the occurrence of SI. Due to the general buoyancy of the ridge, its SI could be driven by the horizontal compression; but I think such type of SI should be categorized into the hot SI regime, because the incipient subduction channel is hot and can generate the metamorphic sole under high temperature conditions [6 ]. On the other hand, the new cold SI regime favors horizontal driving, but does not exclude the vertical driving cases. ...
Initiation of a new subduction zone could act in two different ways, forming either a hot or cold incipient subduction channel with contrasting geological records.
... Based on their geochemical affinity, the ophiolites from the Indian subcontinent can be classified as 'Supra Subduction Zone (SSZ) with SSZ-type metamorphic soles' and 'Supra Subduction Zone (SSZ) with Mid Ocean Ridge (MORB) type metamorphic soles' (Zhong and Li, 2022;Furnes et al., 2020;Hu and Stern, 2020a,b). The SSZ-SSZ type soles are formed in the back-arc spreading regimes of island arcs over an active subduction zone while the SSZ-MORB type soles originate when transform faults undergo spontaneous Subduction initiation. ...
Geochronological data compiled for 29 major ophiolitic occurrences from the northern margin of the Indian
plate precisely coincide with the three major mantle plume interactions over Indian plate (viz., Kerguelen at
130–110 Ma, Marion at 90–84 Ma, and Reunion at 65–70 Ma). We analysed i) the geological juxtapositions of
these ophiolitic belts, ii) seismic tomographic imaging of the slab breakoffs, iii) equivalent deflections in the marine magnetic anomalies (MMA), iv) stratigraphic records of the Cretaceous formations and v) the paleomagnetic
inclination anomalies; and propose significant influence of plume-driven forces over the subduction and obduction processes in Himalayas. The impingement of Kerguelen plume strongly influenced the ∼ 2500 km long subduction of Neo-Tethys, leading to Indus-Tsangpo-Suture-Zone (ITSZ) ophiolites with their metamorphic soles.
The impact of Marion plume further led to repeated tilting of the Indian plate reinvigorating Tethyan subduction
at 90 ± 5 Ma. The Reunion event at ∼ 65 Ma, led to the mega-obduction along the Tethyan margin of the Indian
subcontinent. The Kerguelen plume thus played a key role in initiating the intraoceanic subductions in equatorial
Neo-Tethys, and the combined slab pull and plume induced rifting separated Greater India microcontinent from
the northern margin of Indian subcontinent at ∼ 120 Ma. The impact of the Reunion plume resulted in the obduction of ITSZ ophiolites at the northern margin and the Pakistan ophiolites at the northwestern margin. The
mantle plume impingements caused plate tilting and triggered the subduction/obduction that is well preserved
by sharp inflexions in MMA and the spreading rates. We therefore infer that the three mantle plumes have a
greater role in the subduction, obduction and tilting of the Indian plate throughout the Late Mesozoic.
... Whether all SI occurs under such hot geological settings is still a controversial issue. In this case, an extremely young overriding plate is needed to achieve such high temperature during SI (Zhong and Li, 2022a), which is, however, not a favorable condition for the Tethys tectonic system with an overriding continental plate. By comparing the numerical models with global data of ophiolites and metamorphic soles, Zhong and Li (2022a) proposed that the high-temperature condition may not be necessary for all of the SI but only represents the end-member case of SI in high-temperature conditions. ...
... In this case, an extremely young overriding plate is needed to achieve such high temperature during SI (Zhong and Li, 2022a), which is, however, not a favorable condition for the Tethys tectonic system with an overriding continental plate. By comparing the numerical models with global data of ophiolites and metamorphic soles, Zhong and Li (2022a) proposed that the high-temperature condition may not be necessary for all of the SI but only represents the end-member case of SI in high-temperature conditions. Alternatively, the far-field convergence-induced SI may result in a subduction channel with low temperature; consequently, the "detachment-exhumation-emplacement" processes for the formation of natural rock records do not occur. ...
... The most important characteristic of the Palawan SI is that the ages of ophiolites emplaced on the overriding plate and the metamorphic soles from the subducting plate are consistent with the time of SI. This finding indicates that a spreading oceanic ridge changes rapidly into a subduction zone; thus, the young oceanic crust on both sides of the MOR forms the rock assemblage of ophiolites and metamorphic soles of the same age, which is a rare case on Earth (Zhong and Li, 2022a). The key geodynamic condition for SI at the MOR is the rapid transition from plate divergence to convergence. ...
Tethys tectonic system has experienced a long-term evolution history, including multiple Wilson cycles; thus, it is an ideal target for analyzing plate tectonics and geodynamics. Tethyan evolution is typically characterized by a series of continental blocks that separated from the Gondwana in the Southern Hemisphere, drifted northward, and collided and accreted with Laurasia in the Northern Hemisphere. During this process, the successive opening and closing of multistage Tethys oceans (e.g., Proto-Tethys, Paleo-Tethys, and Neo-Tethys) are considered core parts of the Tethyan evolution. Herein, focusing on the life cycle of an oceanic plate, four key geodynamic processes during the Tethyan evolution, namely, continental margin breakup, subduction initiation (SI), Mid-Ocean Ridge (MOR) subduction, and continental collision, were highlighted and dynamically analyzed to gather the following insights. (1) Breakup of the narrow continental margin terranes from the northern Gondwana is probably controlled by plate subduction, particularly the subduction-induced far-field stretching. The breakup of the Indian continent and the subsequent spreading of the Indian Ocean can be attributed to the interactions between multiple mantle plumes and slab drag-induced far-field stretching. (2) Continental margin terrane collision-induced subduction transference/jump is a key factor in progressive Tethyan evolution, which is driven by the combined forces of collision-induced reverse push, far-field ridge push, and mantle flow traction. Moreover, lithospheric weakening plays an important role in the occurrence of SI. (3) MOR subduction is generally accompanied by slab break-off. In case of the considerably reduced or temporary absence of slab pull, mantle flow traction may contribute to the progression of plate subduction. MOR subduction can dynamically influence the overriding and downgoing plates by producing important and diagnostic geological records. (4) The large gravitational potential energy of the Tibetan Plateau indicates that the long-lasting India-Asia continental collision requires other driving forces beyond the far-field ridge push. Further, the mantle flow traction is a good candidate that may considerably contribute to the continuous collision. The possible future SI in the northern Indian Ocean will release the sustained convergent force and cause the collapse of the Tibetan Plateau. Based on the integration of these four geodynamic processes and their driving forces, a “multiengine-driving” model is proposed for the dynamics of Tethyan evolution, indicating that the multiple stages of Tethys oceanic subduction provide the main driving force for the northward drifting of continental margin terranes. However, the subducting slab pull may be considerably reduced or even lost during tectonic transitional processes, such as terrane collision or MOR subduction. In such stages, the far-field ridge push and mantle flow traction will induce the initiation of new subduction zones, driving the continuous northward convergence of the Tethys tectonic system.
... In Güira de Jauco, highly foliated amphibolites of mafic protolith with a back-arc signature record metamorphic peak conditions of ~ 660°C and 8.6 kbar, which correspond to a metamorphic gradient of 23°C/km. Metamorphic soles form at anomalously high geothermal gradients, which in intra-oceanic subduction zones are only reached during subduction initiation (Wakabayashi and Dilek 2000;Maffione et al. 2015;Stern and Gerya 2018;Zhong and Li 2022). The metamorphic age of the Güira de Jauco metamorphic sole thus points to Turonian-Coniacian inception of a new subduction zone in the back-arc of the Greater Antilles ( Figure 5). ...
Uplift and unroofing of Jurassic-Cretaceous, mantle and crust, arc-and plume-related rock units in the Median Belt of the Dominican Republic exposed basement rocks with a protracted record of tectono-thermal events delineating the evolution of the northern edge of the Caribbean plate. In this article we focus on crustal rock units in the northeastern half of the Median Belt. First 40 Ar/ 39 Ar dating of metamorphic ferri-winchite (86.4 ± 2.5 Ma; crystallization date) and albite (82.3 ± 5.8 and 79.8 ± 1.6 Ma; cooling dates) in metabasites of boninitic photolith from the Aptian-Albian Maimón Formation in the Ozama shear zone points to a tectono-metamorphic event in the Upper Cretaceous. Beltwide, this event caused syn-metamorphic N-to NNE-directed, simple-shear dominated , mylonitic and phyllonitic deformation of the Maimón Formation at peak metamorphic conditions of 8.2 kbar and 380°C. Such conditions are consistent with subduction of a coherent portion of forearc (represented by the Maimón Formation) to depths of ~25-29 km. The tectono-metamorphic event dated here overlaps with the inception of Turonian-Coniacian SW-dipping subduction and metamorphic sole formation in a back-arc position recorded in the Moa-Baracoa ophiolite complex in neighboring Eastern Cuba. Contemporaneity between the subduction inception of forearc and back-arc portions of the Caribbean arc and the main pulse of plume activity recorded in the Caribbean Large Igneous Province (CLIP) suggests that plume activity promoted general plate instability leading to a regional-scale plate reorganization. This mantle-plume-induced plate margin reorganization was coeval with the inception of the NE-dipping subduction of the Farallón plate beneath Central America leading to the definition of the Caribbean Plate by double-verging subduction zones along its northern and southwestern margins. ARTICLE HISTORY
... Therefore, studying on SSZ ophiolites and associated metamorphic soles may get more comprehensive insights into the subduction initiation ( Fig. 1 and Fig. 2; Agard et al., 2020;Yang et al., 2022a;Xin et al., 2022). In particular, both can provide key constraints on the timing of the subduction initiation, because they are rock records of upper plate extension and lower plate burial, respectively , although the occurrence and formation of both the ophiolites and metamorphic soles together require strict tectonic and dynamic conditions Zhong and Li, 2022). ...
... The ongoing subduction initiation processes preserve magmatic and stratigraphic records, but it is distant from continents, and difficult and expensive to directly study the records. The ophiolites that tectonically emplaced on land along with the metamorphic soles are thus a good window for studying subduction initiation processes and dynamics (Wakabayashi and Dilek, 2003;Whattam and Stern, 2011;Stern et al., 2012;Agard et al., 2016;Guilmette et al., 2018;Yang et al., 2020aYang et al., , 2022aZhong and Li, 2022). For the further study of mechanisms of the subduction initiation, the scholars should conduct detailed research on previous ophiolites and metamorphic soles. ...
Subduction initiation is one of the main unsolved issues in plate tectonics theory with different proposed mechanisms. In the arc (plateau, terrane)-continent collision models, a new subduction zone can be induced by subduction polarity reversal or subduction transference. In this study, I have reviewed the typical natural examples and numerical models for the subduction initiation of polarity reversal and subduction transference, and then summarized the key characteristics, geological records, and future directions of the subduction initiation. The subduction polarity reversal usually occurs at intraoceanic arc settings, but the subduction transference often happens at active continental margins as well as intraoceanic arc settings. Natural examples of subduction polarity reversal and subduction transference have representative geological records of supra-subduction zones (SSZ) ophiolites (ophiolitic mélanges) and metamorphic soles, which have long been recognized as the key to understanding the subduction initiation and geodynamic processes, because both are rock records of upper plate extension and lower plate burial, respectively. Weak zones and driving forces are required for the collision-induced subduction polarity reversal and subduction transference, which generally occurs about 10 Myr after collision both in natural observations and numerical models. However, subduction transference happens about 10–30 Myr after the collision in the Proto-, Paleo-, and Neo-Tethys oceans. Numerical models of the subduction initiation moving from 2D to 3D will break through the constraints of the 2D geometric model and better simulate the subduction initiation processes. However, the parameters used in the numerical modelling are not yet able to fully describe the various controlling factors of the subduction initiation. Moreover, the mechanism of weak rheology and its effect on the subduction initiation are still ambiguous and need further study by natural observations and numerical modelling.
... The subduction of seamounts induces some pronounced geological effects on the dynamics of subduction zone systems. For example, seamount subduction can increase tectonic erosion in subduction zone (Lallemand et al., 1989;Ranero and von Huene, 2000;Bangs et al., 2006;Morgan and Bangs, 2017;Festa et al., 5 / 46 2022), impact on the magmatism of the volcanic arc (Patino et al., 2000;Regelous et al., 2010;Chiaradia et al., 2020), and can potentially trigger large-scale earthquakes (Scholz and Small, 1997;Mochizuki et al., 2008;Singh et al., 2011;Martínez-Loriente et al., 2019;Chow et al., 2022) and subduction initiation (e.g., Stern and Gerya, 2018;Plunder et al., 2020;Tao et al., 2020;Zhou et al., 2020;Lallemand and Arcay, 2021;Almeida et al., 2022;Zhong and Li, 2022). ...
Seamounts are prominent seafloor features that make inhomogeneous oceanic crust, carried by some moving plates and eventually accreted or subducted at convergent margins. These seamounts contribute to subduction dynamics, continental crustal growth, and chemical mantle heterogeneities. We present a review of seamount subduction and accretion in the West Junggar based on available geological, geochronological, and geochemical data of the ophiolitic mélanges. Several ophiolitic mélanges with ages ranging from 572 Ma to 332 Ma developed in West Junggar, including the Mayile, Tangbale, Chagantaolegai, Barleik, Hebukesaier, Kujibai, Emin, Hongguleleng, Karamay, and Durbut ophiolitic mélanges, and displayed some typical block-in-matrix structures. The mafic rocks from these ophiolitic mélanges can be divided into MORB and OIB types. The MORB type likely to have formed in arc related setting were derived from a depleted mantle source that had been metasomatized by slab-derived fluids. However, the OIB type was formed in seamounts/oceanic plateaus related to mantle plume activities. Many seamounts with different ages developed in the Junggar Ocean as well as the Paleo-Asian Ocean, and had three different destinations: accretion in the accretionary prism, underplating to the overriding plate, and collision, resulting in different geological effects. The subducting and accreting seamounts in West Junggar are mainly involved in deformation of the overriding plate, magmatism of the volcanic arc and plate tectonics. Particularly, seamounts/oceanic plateaus accretion probably induced subduction initiation in West Junggar, namely subduction polarity-reversal and/or subduction transference. This will provide new insights into understanding the tectonic evolution of the West Junggar as well as the CAOB.
In this study, we make a review of the recent developments on the metamorphic and tectonic evolution of the Nagaland-Manipur Ophiolite Belt (NMOB) in the Indo-Myanmar Ranges. We collate key metamorphic findings and chronological constraints in the NMOB to demonstrate an exceptional record of the full life cycle of the thermal and dynamic history of the Early Mesozoic intra-oceanic subduction system within the eastern arm of the Neo-Tethys from its infancy to its cold-mature stage. The earliest stage of an Early Jurassic-aged oceanic subduction under warm thermal conditions (apparent peak thermal gradient of ~ 20 °C/km), and within the first 1–2 Myrs since subduction initiation is recorded in the newly discovered high- and low-temperature metamorphic sole rocks of the Tusom CV area in the Manipur segment of the ophiolite belt. The metamorphic sole sequence, comprising a package of ultra-high temperature mafic granulites → high-temperature mafic granulite → garnet + clinopyroxene-bearing amphibolite → garnetiferous amphibolite → non-garnetiferous amphibolite → epidote amphibolite and low greenschist facies metasediments, and structurally downward, constitutes an inverted metamorphic sequence. Tectonic slices of hornblende eclogite facies metasediments and metabasites from diffrrent locations in the Nagaland segment of the Ophiolite Belt, on the other hand, reveal an apparent peak thermal gradient of ~ 12–15 ℃/km, indicating an intermediate subduction cooling stage. The structurally upward metamorphic sequence of greenschist facies → pumpellyite-diopside facies → lawsonite blueschist facies and epidote eclogite facies, the latter locally reaching ultra-high pressure metamorphic conditions in metabasalts of the structurally lowermost unit of the Nagaland ophiolite mélange together record a cooler apparent peak thermal gradient of ~ 7–8 ℃/km. We relate this metamorphism with the end stage of the Early Jurassic-aged intra-oceanic subduction, when the Neo-Tethys evolved into a cold-mature stage of subduction.
