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Background: Ameloblastic carcinoma is a rare and malignant odontogenic tumour possibly arising de-novo from pre-existing ameloblastoma. It is aggressive and locally destructive. Ameloblastoma is the most common benign odontogenic tumour of the mandible. It originates from the tooth-forming epithelium, where its aetiology remains unknown. Ameloblastoma usually grows slowly, is asymptomatic, and destroys the surrounding bone tissue. Malignant transformation of ameloblastomas may occur spontaneously. Resection is the primary therapy for ameloblastic carcinoma with extensive bone destruction. Mandibular resection causes instability due to the missing parts of bone, so reconstruction is needed. Purpose: This study will report on an individual case of ameloblastic carcinoma that underwent a bilateral ramus mandibulectomy with reconstruction using the plate technique. Case: Bilateral ramus mandibulectomy with plate and reconstruction in an ameloblastic carcinoma patient. Case Management: Two months after surgery, the patient could open her mouth functionally and aesthetically. Conclusion: Plate reconstruction is an option for reconstructing bilateral ramus mandibulectomy of a large ameloblastic carcinoma of the mandible.

Insight into the evolution of Philippine Sea‐South China Sea (SCS) plate motions helps reveal the driving mechanisms of the long‐term tectonic complexity in Southeast Asia. Here, based on the integration of the most recent geological and seismic data, we present a new plate reconstruction model for this region characterized by back‐arc extension and subduction since the Eocene. We suggest that the western boundary of the Philippine Sea Plate was a constant sinistral strike‐slip fault at 55–22 Ma with a clockwise self‐rotation. The connection between the SCS and Shikoku Ridges possibly initiates at 30 Ma, when their spreading times overlapped indicating an affinitive origin and magma source. Regional‐scale geodynamic simulations interfaced with our reconstructed plate motion indicate that the seismic high‐velocity body under the SCS is likely to be the leading edge of the Pacific Slab. Plain Language Summary: Since 55 million years ago, East Asia has been going through a complex plate recombination. Several quantitative plate motion models have been published, but there remain several irrationalities, for example, a footwall plate was moving away from the trench. We established a new model for the Philippine Sea‐South China Sea (SCS) region as an improvement. Our model provides a smooth movement of the Philippine Sea Plate (PSP) from the equatorial zone to its present position, with a clockwise rotation. Based on it, we deduce: (a) the western boundary of the PSP was a sinistral strike‐slip fault; (b) the spreading ridges in SCS and Shikoku Basin were connected at 30 Ma; (c) the stagnant slab under the SCS is a part of the subducting Pacific Slab. Key Points: A new plate reconstruction model of Philippine Sea‐South China Sea (SCS) region since 55 Ma by integrating the latest geological geophysical dataThe western boundary of the Philippine Sea Plate was a constant sinistral strike‐slip fault at 55–22 MaThe geodynamic model indicates the seismic high‐velocity body under the SCS likely to be the leading edge of the Pacific Slab [ABSTRACT FROM AUTHOR]

In this study, we summarized paleomagnetic data from West Antarctica and reconstructed the paleoposition of different crustal blocks of West Antarctica. Plate reconstructions identified two widely influenced tectonic events in West Antarctica due to the subduction of the Pacific Plate, including the rapid southward drift of Thurston Island-Eights Coast and Eastern Marie Byrd Land during the eruption of Ontong Java-Manihiki-Hikurangi Large Igneous Provinces and related peak global ocean crust production rate at 120~100 Ma; The lithospheric extension in the Ross Sea region and rapid separation of Thurston Island-Eights Coast and Marie Byrd Land from East Antarctica, as well as the southward drift and clockwise rotation of the Antarctic Peninsula due to the subduction of Pacific-Phoenix Ridge under the Ross sea region at~100 Ma. This supports a co-evolution of the tectonic process between the Pacific Plate subduction and the plate motion in West Antarctica. In the future, we need more reliable paleomagnetic data with precise age constraints to make a more detailed reconstruction of different tectonic processes of West Antarctica. This will help us in understanding the geological evolution of Antarctica, and the geodynamics mechanism of plate growth and plate separation.

[Display omitted] • We present a full-plate tectonic model for the last 1.8 Gyr. • The model is constrained by geological and geophysical data. • It spans three supercontinents and forms the basis for future Earth system studies. Understanding the intricate relationships between the solid Earth and its surface systems in deep time necessitates comprehensive full-plate tectonic reconstructions that include evolving plate boundaries and oceanic plates. In particular, a tectonic reconstruction that spans multiple supercontinent cycles is important to understand the long-term evolution of Earth's interior, surface environments and mineral resources. Here, we present a new full-plate tectonic reconstruction from 1.8 Ga to present that combines and refines three published models: one full-plate tectonic model spanning 1 Ga to present and two continental-drift models focused on the late Paleoproterozoic to Mesoproterozoic eras. Our model is constrained by geological and geophysical data, and presented as a relative plate motion model in a paleomagnetic reference frame. The model encompasses three supercontinents, Nuna (Columbia), Rodinia, and Gondwana/Pangea, and more than two complete supercontinent cycles, covering ∼40% of the Earth's history. Our refinements to the base models are focused on times before 1.0 Ga, with minor changes for the Neoproterozoic. For times between 1.8 Ga and 1.0 Ga, the root mean square speeds for all plates generally range between 4 cm/yr and 7 cm/yr (despite short-term fast motion around 1.1 Ga), which are kinematically consistent with post-Pangean plate tectonic constraints. The time span of the existence of Nuna is updated to between 1.6 Ga (1.65 Ga in the base model) and 1.46 Ga based on geological and paleomagnetic data. We follow the base models to leave Amazonia/West Africa separate from Nuna (as well as Western Australia, which only collides with the remnants of Nuna after initial break-up), and South China/India separate from Rodinia. Contrary to the concept of a "boring billion", our model reveals a dynamic geological history between 1.8 Ga and 0.8 Ga, characterized by supercontinent assembly and breakup, and continuous accretion events. The model is publicly accessible, providing a framework for future refinements and facilitating deep time studies of Earth's system. We suggest that the model can serve as a valuable working hypothesis, laying the groundwork for future hypothesis testing. [ABSTRACT FROM AUTHOR]

The paradigm of plate tectonics has aided in the identification of the journey of continents on the globe, their assembly into supercontinents, disruption, and re‐assembly. Here, we use meteorite impact craters as proxies for tracking the voyage of lithospheric plates. Employing the provisions in GPlates, an interactive geographic information system‐based plate tectonic reconstruction model, we were able to identify the palaeo‐position, and velocity of the 174 terrestrial impact craters, formed after 1,100 Ma, across the globe. These parameters of craters were evaluated for independent tectonic plates and were correlated with global tectonic events. For example, the similarity in the velocity of Beaverhead (900 Ma) and Holleford (550 Ma) craters since 550 Ma is traced to the connection between the Eastern Basin and North America Craton commencing 1,100 Ma, and through the South Basin and Range. Likewise, the drastic reduction in the velocity of Spider Crater (700 Ma) in Australia after 600 Ma can be attributed to the subduction between east and west Gondwana. The accelerated motion of the Indian Plate at 63 Ma, when the lithosphere was hovering over the Réunion hotspot, is also explained. With the advent of more improved plate tectonic models and the discovery of more impact craters, improvised interpretations will be possible. [ABSTRACT FROM AUTHOR]

Lithospheric net rotation (LNR) is the movement of the lithosphere as a solid body with respect to the mantle. Separating the signal of LNR from plate tectonic motion is therefore an important factor in producing absolute plate motion models. Net rotation is difficult to constrain because of uncertainties in geological data and outstanding questions about the stability of the mantle plumes used as a reference frame. We use mantle convection simulations to investigate the controlling factors for the magnitude of LNR and to find the statistical predictability of LNR in a fully self‐consistent convective system. We find that high lateral viscosity variations are required to produce Earth‐like values of LNR. When the temperature dependence of viscosity is lower, and therefore slabs are softer, other factors such as the presence of continents and a viscosity gradient at the transition zone are also important for determining the magnitude of net rotation. We find that, as an emergent property of the chaotic mantle convection system, the evolution of LNR is too complicated to predict in our models. However, we find that the range of LNR within the simulations follows a Gaussian distribution, with a correlation time of 5 Myr. The LNR from the models needs to be sampled for around 50 Myr to produce a fully Gaussian distribution. This implies, that within the time frames considered for absolute plate motion reconstructions, LNR can be treated as a Gaussian variable. This provides a new geodynamic constraint for absolute plate motion reconstructions. Plain Language Summary: The Earth's surface is constantly moving with respect to its interior. Some of the movement is due to plate tectonic processes, where parts of the surface move with respect to each other. The surface also moves as one rigid body, termed net rotation. In order to reconstruct the plate tectonic motion, we need to be able to separate these two processes. However, records of motion are imperfect, due to a lack of data in the geological record. In this work, we use computational models of Earth to investigate what the expected range of values should be for net rotation. We find that it is not possible to predict net rotation based on the structure of the Earth's mantle or tectonic configuration. However, the range of net rotation values falls in a predictable distribution. We can therefore constrain the maximum likely values of net rotation. This means that we have a maximum value of how much surface motion can be caused by net rotation, and how much is plate tectonic motion. Key Points: Net rotation is an emergent property of a chaotic system and is difficult to predict, but the range and distribution can be constrainedLarge lateral viscosity contrasts are required for an Earth‐like magnitude of net rotation in geodynamic modelsNet rotation follows a Gaussian distribution over timescales greater than 50 Myr with a correlation time of 5 Myr [ABSTRACT FROM AUTHOR]

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The late Mesozoic closure of the Mongol‐Okhotsk Ocean (MOO) is critical for understanding the tectonics of East Asia. There is a considerable mismatch (~40 million years) between the timing of MOO closure based on paleomagnetic data and geological evidence. We review paleomagnetic data from Mongolia, Siberia, and North China and argue that previously published apparent polar wander paths (APWPs) for North China and Siberia are insufficient to constrain the timing of MOO closure. Our new analysis incorporates newly published paleomagnetic data from North China and a refined geochronology for the key Siberian poles. We combine this with an updated global APWP incorporating large‐scale Jurassic true polar wander and argue that the MOO was closed by the Middle Jurassic. This temporal shift is compatible with geology‐based models. The Middle Jurassic reconstruction of Eurasia suggests that the East Asian blocks had become a quasi‐rigid part of Pangea prior to breakup. Plain Language Summary: A wide, eastward‐opening ocean, known as the Mongol‐Okhotsk Ocean (MOO), lay between Siberia and Mongolia during Paleozoic and Mesozoic time (~250–130 Ma). Geological data and tectonic models posit that the MOO was nearly closed by the Middle Jurassic (~174 Ma), whereas paleogeographic interpretations based on paleomagnetic data indicate a large gap of 1,000–3,000 km between Siberia and Mongolia in the Late Jurassic (~164–145 Ma). In general, the paleomagnetic data obtained from North China, Mongolia, and Siberia lack proper age control needed to resolve this conundrum. Based on newly published paleomagnetic data from North China and a critical selection of data from Siberia, this work argues that the MOO was closed by the Middle Jurassic and brings harmony to these previously conflicting data sets. Key Points: Paleomagnetic data from the North China‐Amuria block and Siberia are reviewed and analyzedPaleomagnetic analysis suggests a closure of the Mongol‐Okhotsk Ocean by the Middle Jurassic that is compatible with geological evidenceEast Asian blocks formed a quasi‐rigid part of Pangea by the Middle Jurassic [ABSTRACT FROM AUTHOR]

The puzzling <7 Ma old "postsubduction" arc magmatism of New Guinea contains geochemical subduction‐type signatures yet did not occur above an active subduction zone. Here we show that these arc magmas formed at the North Australian continental lithospheric edge when it plowed northward through mantle above the detached Arafura slab remnant. This mantle preserved its subduction signature and the edge plowing process generated new melts that ascended via an active transform fault. Arafura slab subduction occurred at an intraoceanic subduction zone that ended ~30–25 Ma ago, when the Australian continental edge was still ~1,000 km to the south. Our absolute plate tectonic reconstruction of continental‐edge plowing suggests that ancient mantle wedges remain semistationary in the upper mantle and can preserve their geochemical signature for tens of Ma, explaining previously enigmatic "postsubduction" arc magmatism. Plain Language Summary: During subduction, downgoing plate lithosphere ("slab") releases water to the overlying mantle causing so‐called "arc volcanism." A puzzling class of "postsubduction" arc magmatism bears geochemical signatures of subduction but occurs in a setting without subduction. Here we show that this magmatism is the result of remelting of mantle portions that were previously enriched by ancient subduction zones, slab relics of which are now found with seismological techniques below these enriched portions. From famous postarc magmatic rocks on New Guinea we identify that the "plowing" of the edge of a thick, continental lithosphere through a previously enriched mantle portion may provide a cause of melting, producing arc‐like magmatism. We also identify that pathways for the melts to rise to (close to) the surface, provided by major faults, are essential. The "New Guinea recipe" also explains magmatism on the Fiji Islands, California, and Colombia. A major implication of our work is that asthenospheric upper mantle rocks appear to move much slower than plates, such that lithosphere may have undergone a very different geological history than the currently underlying mantle. Key Points: "Postsubduction" arc magmatism on New Guinea results from the Australian cratonic margin plowing through a previously enriched mantle wedgeMantle wedges may appear to remain semistationary in the mantle for tens of million years or even longer times and produce subduction signatures if remeltedAbsolute plate motions juxtapose mantle and crustal rocks with very different geological histories [ABSTRACT FROM AUTHOR]

We studied long‐term evolution of nontransform discontinuities (NTDs) on the Mid‐Atlantic Ridge from 0‐ to ~20‐ to 25‐Ma crust using plate reconstructions of multibeam bathymetry, long‐range HMR1 sidescan sonar, residual mantle Bouguer gravity anomaly (RMBA), and gravity‐derived crustal thickness. NTDs have propagated north and south with respect to flowlines of relative plate motion and both rapidly and slowly compared to the half spreading rate; at times they have been quasi‐stable. Fast, short‐term (<2 Myr) propagation is driven by reduced magma supply (increased tectonic extension) in the propagating ridge tip when NTD ridge‐axis offsets are small (≲5 km). Propagation at larger offsets generally is slower and longer term. These NTDs can show classic structures of rift propagation including inner and outer pseudofaults and crustal blocks transferred between ridge flanks by discontinuous jumps of the propagating ridge tip. In all cases crustal transfer occurs within the NTD valley. Aside from ridge‐axis offset, the evolution of NTDs appears to be controlled by three factors: (1) gross volume and distribution of magma supplied to ridge segments as controlled by 3‐D heterogeneities in mantle fertility and/or dynamic upwelling; this controls fundamental ridge segmentation. (2) The lithospheric plumbing system through which magma is delivered to the crust. (3) The consequent focusing of tectonic extension in magma‐poor parts of spreading segments, typically at segment ends, which can drive propagation. We also observe long‐wavelength (5‐10 Myr) RMBA asymmetry between the conjugate ridge flanks, and we attribute this to asymmetric distribution of density anomalies in the upper mantle. Key Points: Propagation of non‐transform discontinuities on the Mid‐Atlantic Ridge was analyzed in reconstructions of bathymetric and gravity dataRapid and slow propagation occurs and is controlled by magma distribution within the mantle and crust of spreading segmentsWe attribute long‐wavelength cross‐axis asymmetry in gravity anomalies to asymmetric distribution of density anomalies in the upper mantle [ABSTRACT FROM AUTHOR]

We present ten new ID-TIMS U-Pb baddeleyite ages for late Neoarchean to Paleoproterozoic dyke swarms cutting Archean gneisses of the Hopedale block (North Atlantic craton, NAC). An age of 2505 ± 4 Ma for a NNE-trending pyroxenite dyke represents the first date for extension-related mafic magmatism of this antiquity in the Labrador portion of the NAC. Four samples of N-S to NNE-trending Kikkertavak dykes yield ages between 2238 ± 6 Ma and 2216 ± 2 Ma, defining a minimum age range and distribution for this extensive swarm. A single NNE-trending dyke is dated at 2169 ± 13 Ma, representing a new magmatic event at this age in Nain Province, but is equivalent in timing to the well-known Biscotasing dykes in the southern Superior craton. Three NW-trending dykes (termed Ellen Island dykes) yield ages of 2051 ± 6 Ma, 2051 ± 1 Ma and 2050 ± 2 Ma, and represent part of a newly-recognized but important swarm in southern Nain craton. The 2.05 Ga dykes better define a vast radiating fan of dykes that include Kangâmiut and MD3 dykes of southern West and South-West Greenland, respectively. A U-Pb baddeleyite age of 1800 ± 4 Ma has been obtained for a fourth, NW-trending ("Ussiranniak Lake") dyke, which also represents a newly-revealed mafic magmatic event, both in the Labrador and Greenland portions of the NAC. The results presented here are unique for Labrador, but invite comparison with other Neoarchean and Paleoproterozoic mafic dykes elsewhere in the North Atlantic craton and other Archean cratons (e.g., Superior, Kola-Karelia, Zimbabwe). Multiple precise age matches, dyke geochemistry, and dyke geometries for several swarms allow a preliminary level testing of possible reconstructions involving the North Atlantic and eastern Superior cratons. [ABSTRACT FROM AUTHOR]

• The Semail ophiolite formed along a NNE–SSW striking ridge above a parallel, incipient subduction zone. • The nascent Semail subduction zone formed orthogonal and close to the Arabian passive margin. • Subduction initiation likely occurred along an ancient, Permian Neotethyan fracture zone. The archetypal Semail ophiolite of Oman has inspired much thought on the dynamics of initiation of intra-oceanic subduction zones. Current models invoke subduction initiation at a mid-oceanic ridge located sufficiently close to the Arabian passive margin to allow initiation of continental subduction below the ophiolite within ∼10–15 Myr after the 96–95 Ma age of formation of supra-subduction zone crust. Here, we perform an extensive paleomagnetic analysis of sheeted dyke sections across the Semail ophiolite to restore the orientation of the supra-subduction zone ridge during spreading. Our results consistently indicate that the ridge was oriented NNE–SSW, and we infer that the associated trench, close to the modern obduction front, had the same orientation. Our data are consistent with a previously documented ∼150° clockwise rotation of the ophiolite, and we reconstruct that the original subduction zone was WNW-ward dipping and NNE–SSW striking. Initial subduction likely occurred in the ocean adjacent and parallel to a transform margin of the part of the Arabian continent now underthrust below Iran that originally underpinned the nappes of the Zagros fold-thrust belt. Subduction thus likely initiated along an ancient, continental margin-parallel fracture zone, as also recently inferred from near-coeval ophiolites from the eastern Mediterranean and NW Arabian regions. Subduction initiation was therefore likely induced by (WN)W–(ES)E contraction and this constraint may help the future identification of the dynamic triggers of Neotethyan subduction initiation in the Late Cretaceous. [ABSTRACT FROM AUTHOR]

The absolute motion of tectonic plates since Pangea can be derived from observations of hotspot trails, paleomagnetism, or seismic tomography. However, fitting observations is typically carried out in isolation without consideration for the fit to unused data or whether the resulting plate motions are geodynamically plausible. Through the joint evaluation of global hotspot track observations (for times <80 Ma), first‐order estimates of net lithospheric rotation (NLR), and parameter estimation for paleo–trench migration (TM), we present a suite of geodynamically consistent, data‐optimized global absolute reference frames from 220 Ma to the present. Each absolute plate motion (APM) model was evaluated against six published APM models, together incorporating the full range of primary data constraints. Model performance for published and new models was quantified through a standard statistical analyses using three key diagnostic global metrics: root‐mean square plate velocities, NLR characteristics, and TM behavior. Additionally, models were assessed for consistency with published global paleomagnetic data and for ages <80 Ma for predicted relative hotspot motion, track geometry, and time dependence. Optimized APM models demonstrated significantly improved global fit with geological and geophysical observations while performing consistently with geodynamic constraints. Critically, APM models derived by limiting average rates of NLR to ~0.05°/Myr and absolute TM velocities to ~27‐mm/year fit geological observations including hotspot tracks. This suggests that this range of NLR and TM estimates may be appropriate for Earth over the last 220 Myr, providing a key step toward the practical integration of numerical geodynamics into plate tectonic reconstructions. Key Points: New global absolute plate motion models integrating geodynamic principles and geological observations for the last 220 million yearsModels derived by constraining trench migration and net lithospheric rotation produce optimum plate motion characteristicsNew models of absolute motion for nine hotspots from the Pacific, Indian, and Atlantic Oceans [ABSTRACT FROM AUTHOR]

The Central Indian Ocean, namely the Central Indian, Crozet, and Madagascar basins, formed by rifting and subsequent drifting of India (now Capricorn), Antarctica, and Africa (now Somalia). We gathered a comprehensive set of sea surface magnetic anomaly profiles over these basins and revisited location and identification of magnetic isochrons between C34ny (83.0 Ma) and C20ny (42.536 Ma) using the objective analytic signal technique. We present high‐resolution magnetic isochrons for 29 periods based on ~1,400 magnetic anomaly picks. From the conjugate sets of picks, we derive two‐plate finite rotation parameters for both the Capricorn‐Antarctica and Capricorn‐Somalia motions. These finite rotations are compared to three‐plate reconstructions of the plate boundaries between the Capricorn, Antarctica, and Somalia plates, constrained by the closure of the Indian Ocean Triple junction. In general, the three‐plate reconstructions slightly overrotate the reconstructed isochrons with respect to the Capricorn‐Antarctica and Capricorn‐Somalia two‐plate reconstructions. Conversely, the two‐plate reconstructions for Somalia‐Antarctica slightly underrotate the isochrons compared to the Capricorn‐Antarctica‐Somalia three‐plate reconstructions. We suspect that the discrepancies between the two‐plate and three‐plate methods result from the recent seafloor deformation in the Capricorn‐India diffuse plate boundary and/or from the contrasted nature and geometry of magnetic isochrons at different spreading rates (i.e., magnetic structure of the three spreading centers). Three‐plate reconstructions better constrain the closure of the triple junction but spread any misfit among all three plate boundaries. When enough quality data are available, two‐plate reconstructions may lead to more realistic plate motion estimates from which additional geological problems can be identified and solved. Key Points: We mapped high‐resolution magnetic isochrons in the Central Indian Ocean between 83.0 and 42.5 MaWe derived two‐plate solutions to the relative motion of Capricorn‐Antarctica and Capricorn‐Somalia plate pairs at higher resolutionTwo‐plate reconstructions may lead to more realistic plate motion estimates when enough quality data are available [ABSTRACT FROM AUTHOR]

We have created a digital age grid of the ocean floor with a grid node interval of 6 arc minutes using a self-consistent set of global isochrons and associated plate reconstruction poles. The age at each grid node was determined by linear interpolation between adjacent isochrons in the direction of spreading. Ages for ocean floor between the oldest identified magnetic anomalies and continental crust were interpolated by estimating the ages of passive continental margin segments from geological data and published plate models.

Abstract The origin of the Rio Grande Rise and Walvis Ridge within the central South Atlantic and its implications for the separation of South America and Africa during the Cretaceous are controversial. The recent report of the discovery from submersible sampling of continental material of Proterozoic age on the Rio Grande Rise suggests that the existing explanation involving ocean ridge – mantle plume interaction or simply excess 'on-ridge' magmatism for the formation of the Rio Grande Rise and Walvis Ridge needs to be re-examined. We use gravity anomaly inversion to map crustal thickness for the central South Atlantic area encompassing the Rio Grande Rise, Walvis Ridge and adjacent South American and African rifted continental margins. We show that the Rio Grande Rise consists of three distinct bodies of anomalously thick crust (Western, Central and Eastern) separated by normal thickness oceanic crust. The Central Rio Grande Rise forms a large elliptical body with maximum crustal thickness of 25 km. The Walvis Ridge also has a maximum crustal thickness of 25 km but has a narrower and more linear geometry. We use plate reconstructions to restore maps of crustal thickness and magnetic anomaly to Early Cretaceous times to examine the development of the Rio Grande Rise and Walvis Ridge. These restorations together with ages of magmatic addition suggest that the Central Rio Grande Rise and Walvis Ridge formed a single body between 90 and 80 Ma located on the ocean ridge plate boundary similar to Iceland today. On the basis of crustal thickness mapping, the plate restorations and the magmatic ages, we propose that the Rio Grande Rise was fragmented into its 3 parts and separated from Walvis Ridge by at least 4 ocean ridge jumps during the opening of the South Atlantic Ocean between approximately 90 and 50 Ma. Plate reconstructions of crustal thickness showing rotated structural lineaments imply that the separation of Eastern Rio Grande Rise and Walvis Ridge was highly complex involving simultaneous crustal extension and magmatic addition. We propose that the continental material reported on the Rio Grande Rise, if not drop-stones, was isolated from the main continental land-mass and transported into the ocean by these ridge jumps during the Cretaceous formation of the South Atlantic. Highlights • Central RGR and the WR have maximum crustal thicknesses of 25 km. • RGR is composed of 3 units with thick crust and high amplitude magnetic anomalies. • Ocean ridge jumps present in RGR-WR evolution post Western Gondwana break-up. [ABSTRACT FROM AUTHOR]

A half-century has passed since the dawning of the plate tectonic revolution, and yet, with rare exception, palaeogeographic models of pre-Jurassic time are still constructed in a way more akin to Wegener's paradigm of continental drift. Historically, this was due to a series of problems – the near-complete absence of in situ oceanic lithosphere older than 200 Ma, a fragmentary history of the latitudinal drift of continents, unconstrained longitudes, unsettled geodynamic concepts and a lack of efficient plate modelling tools – which together precluded the construction of plate tectonic models. But over the course of the last five decades strategies have been developed to overcome these problems, and the first plate model for pre-Jurassic time was presented in 2002. Following on that pioneering work, but with a number of significant improvements (most notably longitude control), we here provide a recipe for the construction of full-plate models (including oceanic lithosphere) for pre-Jurassic time. In brief, our workflow begins with the erection of a traditional (or 'Wegenerian') continental rotation model, but then employs basic plate tectonic principles and continental geology to enable reconstruction of former plate boundaries, and thus the resurrection of lost oceanic lithosphere. Full-plate models can yield a range of testable predictions that can be used to critically evaluate them, but also novel information regarding long-term processes that we have few (or no) alternative means of investigating, thus providing exceptionally fertile ground for new exploration and discovery. [ABSTRACT FROM AUTHOR]

Abstract The Central Atlantic, North Atlantic and Maghrebian Tethys formed a triple junction during the Mesozoic break-up of Pangea. Plate reconstructions of this triple junction have concentrated on the Atlantic branches, for which there are abundant geophysical data over their conjugate margins and associated oceanic domains. This is not the case for the Maghrebian Tethys, where both the Mesozoic Iberian and African margins and the intervening ocean are mostly overthrust by the Betic-Rif-Tell orogenic systems. The resulting lack of constraints on the evolution of the Africa-Iberia system has led most authors to treat the evolution of this system as a secondary problem in the more global Atlantic and Tethys systems. In this paper the evolution of the basins of Iberia and Northwest Africa is discussed and geological constraints are used to propose a new Late Triassic fit of Iberia with North America and Africa. This Late Triassic fit and its implications for Jurassic evolution are compared with the evolution of the sedimentary basins of the Atlantic-Tethys triple junction, and in particular those of the Africa-Iberia margins. The geological evidence and the resulting plate reconstructions are consistent with a Jurassic evolution of the Africa-Iberia system that is dominated by three major events: 1) the Early to Middle Jurassic transition, in which oblique rifting gives way to transtensional rifting; 2) the Middle to Late Jurassic transition, marking the termination of most rifting in the system and interpreted to coincide with exhumation of sub-continental mantle and formation of oceanic crust in a setting dominated by transcurrence between Africa and Iberia; and 3) the Late Jurassic to Early Cretaceous transition, in which the rate of relative motion between and Iberia and Africa decreased significantly as rifting in the North Atlantic gained momentum. [ABSTRACT FROM AUTHOR]

Abstract Hotspots are generated by partial melting due to hot plumes rising within the Earth's mantle, and when tectonic plates move relative to the plume source, hotspot tracks form. Off South America, the oceanic Nazca Plate hosts a large population of hotspot tracks. Examples include seamounts formed far from the Pacific-Nazca spreading center (" off-ridge " seamounts), such as the Juan Fernández Ridge (Juan Fernández hotspot), the Taltal Ridge (San Félix hotspot), and the Copiapó Ridge (Caldera hotspot). These hotspot tracks are characterized by a rough and discontinuous topography. Other examples include seamounts formed near the East Pacific Rise (EPR) (" on-ridge " seamounts), such as the Nazca Ridge (Salas y Gómez hotspot) and Easter Seamount Chain (Easter hotspot), and the Iquique Ridge (Foundation hotspot). These oceanic ridges developed a relatively smooth and broad morphology. Here, we present a plate reconstruction of these six oceanic hotspot tracks since the Paleocene, providing a kinematic model of ridge-continental margin collision. For the " off-ridge " seamount group, the plate kinematic reconstruction indicates that the collision point remained quasi-stationary from 40 to 30–25 Ma. Eventually, the southward migration of the collision point of this seamount group accelerated from 23 to 15 Ma (reaching a maxima speed of 300 km/Ma along the trench). From 15 Ma to present the collision point has remained quasi-stationary. The predicted location of the subducted portion of the Taltal, Copiapó and Juan Fernández Ridges coincides with the southward migrating (relative to South America) flat slab segment. For the " on-ridge " seamount group, the kinematic plate reconstruction indicates a continuous southward migration of the collision point from ~23 Ma, which is related to the fragmentation of the Farallon Plate. The southward migration accelerated until 15 Ma, reaching approximately 150 km/Ma. From 15 Ma to present, the southward migration has been decelerating except an increment of the migration velocity during the Chron 4 due to an increase of the convergence velocity. The migration velocity differences between the on-ridge and off-ridge hotspot tracks are mainly result from the hotspot track azimuth and the margin azimuth on the collision point. Convergence velocity varies along the trench, but it is a minor factor comparing different hotspot tracks migration velocity. Due to the EPR-plume interactions, our reconstruction suggests that the eastern Tuamotu Island Plateau formation occurred 48–27 Ma on the Easter Hotspot, which was located near to the EPR segment between the Marquesas and Austral Fracture Zones. Our model also predicts that the Iquique Ridge seamounts track is consistent with the position of the Foundation hotspot. The Foundation hotspot jumped to the Challenger (Resolution) Fracture Zone from the Farallon plate to the Pacific plate. This process triggered the cessation of the Iquique Ridge volcanic formation, and initiated volcanism at Foundation Chain in the Pacific Plate at ~25 Ma. Graphical abstract Unlabelled Image Highlights • We present a plate reconstruction model for the Hotspot tracks in the Nazca Plate. • We show a paleo-bathymetric reconstruction from 60 Ma to present off South America. • We provide a kinematic model of ridge-trench collision off South America. [ABSTRACT FROM AUTHOR]

Continental rifted margins show variations between a few hundred to almost a thousand kilometres in their conjugated widths from the relatively undisturbed continent to the oceanic crust. Analogue and numerical modelling results suggest that the conjugated width of rifted margins may have a relationship to their obliquity of divergence, with narrower margins occurring for higher obliquity. We here test this prediction by analysing the obliquity and rift width for 26 segments of transtensional conjugate rifted margins in the Atlantic and Indian Oceans. We use the plate reconstruction software GPlates ( www.gplates.org ) for different plate rotation models to estimate the direction and magnitude of rifting from the initial phases of continental rifting until breakup. Our rift width corresponds to the distance between the onshore maximum topography and the last identified continental crust. We find a weak positive correlation between the obliquity of rifting and rift width. Highly oblique margins are narrower than orthogonal margins, as expected from analogue and numerical models. We find no relationships between rift obliquities and rift duration nor the presence or absence of Large Igneous Provinces (LIPs). [ABSTRACT FROM AUTHOR]

The tectonic evolution of the Southeast Indian Ridge (SEIR), and in particular of its easternmost edge, has not been constrained by high-resolution shipboard data and therefore the kinematic details of its behavior are uncertain. Using new shipboard magnetic data obtained by R/VIB Araon and M/V L'Astrolabe along the easternmost SEIR and available archived magnetic data, we estimated the finite rotation parameters of the Macquarie–Antarctic and Australian–Antarctic motions for eight anomalies (1o, 2, 2Ay, 2Ao, 3y, 3o, 3Ay, and 3Ao). These new finite rotations indicate that the Macquarie Plate since its creation ∼6.24 million years ago behaved as an independent and rigid plate, confirming previous estimates. The change in the Australian–Antarctic spreading direction from N–S to NW–SE appears to coincide with the formation of the Macquarie Plate at ∼6.24 Ma. Analysis of the estimated plate motions indicates that the initiation and growth stages of the Macquarie Plate resemble the kinematic evolution of other microplates and continental breakup, whereby a rapid acceleration in angular velocity took place after its initial formation, followed by a slow decay, suggesting that a decrease in the resistive strength force might have played a significant role in the kinematic evolution of the microplate. The motions of the Macquarie Plate during its growth stages may have been further enhanced by the increased subducting rates along the Hjort Trench, while the Macquarie Plate has exhibited constant growth by seafloor spreading. [ABSTRACT FROM AUTHOR]

High quality paleomagnetic poles (a.k.a. paleopoles) are essential for quantitative lithospheric plate reconstruction. However, the current paleomagnetic database of the major Chinese blocks, including the North China Block (NCB), the South China Block (SCB), and the Tarim Block (TB), since the Late Paleozoic Era contain outdated and low quality data. Here, we update the database by adding recently published high quality paleopoles and rejecting low quality outdated ones. The database includes 288 paleopoles published 1980–2014, 90 of them published after 2000. Following the Van der Voo selection criteria, 75 paleopoles, each with a quality factor Q smaller than 4, were rejected in the first round of selection. We then removed another 59 paleopoles that have been locally rotated or shallowed since the acquisition of stable remanence. Eventually, 154 paleopoles were selected and adopted to calculate the new apparent polar wander paths (APWPs) for the major Chinese blocks. We found comparable clastic and igneous paleopoles at intervals when a quantitative comparison was available. As such comparison was not possible during most periods/epochs, our conclusions reflect an unclear extent of inclination errors in Chinese clastic paleopoles. New models of the Chinese APWPs, with and without inclination error corrections, were computed from carefully selected paleopoles: version 1 running mean (V1RM) paths were calculated at the period/epoch level; version 2 running mean (V2RM) paths were computed in a set sliding time window of 20 or 30 Myr; spline paths were calculated with the same time windows along with a smoothing parameter of 50. Using a recent global reconstruction model and up-to-date geological observations, new models of the Chinese APWPs allowed us to re-evaluate the coalescence history of East Eurasia since the Late Paleozoic Era. Four major tectonic events were confirmed: (1) the TB accreted with the Kazakhstan orocline during amalgamation of the West Altaids during the Middle–Late Permian Period (ca. 265–250 Ma); (2) the suturing of the NCB and the SCB likely occurred in a scissor-like pattern and had been accomplished no later than the Middle Jurassic Period (ca. 180–160 Ma); (3) the amalgamation between the NCB and the TB along with the microblocks between the two might have been achieved during the Late Jurassic–Early Cretaceous Periods (ca. 160–140 Ma); (4) the Mongol-Okhotsk Ocean should have been closed no later than the Early Cretaceous Period (ca. 140–120 Ma). [ABSTRACT FROM AUTHOR]

Study of the deep structure of conjugate passive continental margins combined with detailed plate kinematic reconstructions can provide constraints on the mechanisms of rifting and formation of initial oceanic crust. In this study the central Atlantic conjugate margins are compared based on compilation of wide-angle seismic profiles from NW Africa Nova Scotian and U.S. passive margins. The patterns of volcanism, crustal thickness, geometry, and seismic velocities in the transition zone suggest symmetric rifting followed by asymmetric oceanic crustal accretion. Conjugate profiles in the southern central Atlantic image differences in the continental crustal thickness. While profiles on the eastern U.S. margin are characterized by thick layers of magmatic underplating, no such underplate was imaged along the African continental margin. In the north, two wide-angle seismic profiles acquired in exactly conjugate positions show that the crustal geometry of the unthinned continental crust and the necking zone are nearly symmetric. A region including seismic velocities too high to be explained by either continental or oceanic crust is imaged along the Canadian side, corresponding on the African side to an oceanic crust with slightly elevated velocities. These might result from asymmetric spreading creating seafloor by faulting the existing lithosphere on the Canadian side and the emplacement of magmatic oceanic crust including pockets of serpentinite on the Moroccan margin. After isochron M25, a large-scale plate reorganization might then have led to an increase in spreading velocity and the production of thin magmatic crust on both sides. [ABSTRACT FROM AUTHOR]

Reconstructions of Earth's past surface kinematics are traditionally based on a combination of relative plate motions inferred mostly from preserved seafloor information and an assumed absolute reference frame using data from hotspots and/or true polar wander. Recently, plate reconstructions progressively introduced constraints from deep mantle structures like those imaged through seismic tomography. This additional information is utilized through either implicit or explicit fashion, where the lateral location of an imaged mantle slab represents that of its paleo-trench with the age of initial subduction estimated from geological proxies and slab depth. Here we quantitatively evaluated the geodynamic and tectonic implications of three recent global plate reconstructions (Müller et al., 2016, 2019 ; and Clennett et al., 2020) by focusing on subduction beneath North America. These reconstructions imply different amounts of trench retreat, plate motion and subduction zones, due to their varying dependence on the tomotectonic constraints. We simulated their respective subduction histories since 200 Ma using a sequential data-assimilation methodology. The resulting present-day slab structures based on these reconstructions show clearly diagnostic differences, among which the model based on Müller et al., 2016 best matches seismic tomography and Mesozoic paleotopography constraints within North America, supporting the tomography-implied differential lithosphere motion relative to the mantle. In contrast, modeled results based on the explicit tomotectonic reconstruction of Clennett et al., 2020 match both slab structure/evolution and associated paleotopographic constraints to the least. Consequently, the presented data-assimilation geodynamic modeling exercise, through reproducing the associated subduction history and continental tectonics, could quantify the tectonic implications of different plate reconstructions. We propose that further implementing this exercise through an iterative geodynamic-tomographic-tectonic workflow could serve to improve the tomotectonic reconstruction. [ABSTRACT FROM AUTHOR]

Many aspects of deep-time Earth System models, including mantle convection, paleoclimatology, paleobiogeography and the deep Earth carbon cycle, require high-resolution plate motion models that include the evolution of the mosaic of plate boundaries through time. We present the first continuous late Paleozoic to present-day global plate model with evolving plate boundaries, building on and extending two previously published models for the late Paleozoic (410–250 Ma) and Mesozoic-Cenozoic (230–0 Ma). We ensure continuity during the 250–230 Ma transition period between the two models, update the absolute reference frame of the Mesozoic-Cenozoic model and add a new Paleozoic reconstruction for the Baltica-derived Alexander Terrane, now accreted to western North America. This 410–0 Ma open access model provides a framework for deep-time whole Earth modelling and acts as a base for future extensions and refinement. We analyse the model in terms of the number of plates, predicted plate size distribution, plate and continental root mean square (RMS) speeds, plate velocities and trench migration through time. Overall model trends share many similarities to those for recent times, which we use as a first order benchmark against which to compare the model and identify targets for future model refinement. Except for during the period ~ 260–160 Ma, the number of plates (16–46) and ratio of “large” plates (≥ 10 7.5 km 2 ) to smaller plates (~ 2.7–6.6) are fairly similar to present-day values (46 and 6.6, respectively), with lower values occurring during late Paleozoic assembly and growth of Pangea. This temporal pattern may also reflect difficulties in reconstructing small, now subducted oceanic plates further back in time, as well as whether a supercontinent is assembling or breaking up. During the ~ 260–160 Ma timeframe the model reaches a minima in the number of plates, in contrast to what we would expect during initial Pangea breakup and thus highlighting the need for refinement of the relative plate motion model. Continental and plate RMS speeds show an overall increase backwards through time from ~ 200 to 365 Ma, reaching a peak at 365 Ma of > 14 and > 16 cm/yr, respectively, compared to ~ 3 and ~ 5 cm/yr, respectively, at present-day. The median value of trench motion remains close to, yet above 0 cm/yr for most of the model timeframe, with a dominance in positive values reflecting a prevalence of trench retreat over advance. Trench advance speeds are excessive during the 370–160 Ma period, reaching more than four times that observed at present-day. Extended periods of trench advance and global continental and plate RMS speeds that far exceed present-day values warrant further investigation. Future work should test whether alternative absolute reference frames or relative motions would mitigate these high speeds, while still being consistent with geologic and geophysical observations, or alternatively focus on identifying potential driving mechanisms to account for such rapid motions. [ABSTRACT FROM AUTHOR]

Transform faults in back-arc basins are the key to revealing the evolution of marginal seas. Four marginal basins in the Western Pacific, i.e. the South China Sea (SCS), Okinawa Trough (OT), West Philippine Basin (WPB) and Shikoku-Parece Vela Basin (SPVB), were studied to redefine the strikes and spatial distribution of transform faults or fracture zones. Based on high-resolution tectonomorphology, gravity and magnetic anomalies, pattern of magnetic lineations, seismic profiles, geometry of basins and palaeomagnetic data, together with analyses of regional geological setting, plate reconstruction and geodynamic analysis, this paper suggests that all the transform faults in the four marginal basins are in general NNE-trending. Moreover, by comparing with the contemporary structural framework of the East Asian Continental Margin, we propose new models concerning marginal seas spreading and have revised the previous Cenozoic plate reconstruction models related to the East Asian Continental Margin and the Western Pacific marginal seas. There are three possible origins of these NNE-trending transform faults. 1. Inheriting the orientation of the strike-slip faults at the rifting continental margin (e.g. the SCS and OT). The real strike of transform faults should not be NW but NNE. The large-scale NNE-trending dextral strike-slip faults distributed in the continental shelf of the SCS control a series of pull-apart basins of the SCS. Due to a higher degree of pull-apart, oceanic crust began to open. Then they evolved into the NNE-trending transform faults in the SCS and could also be regarded as a natural extension of the NNE-trending strike-slip faults in the South China Block (SCB). The geodynamic mechanism of the OT is similar to that of the SCS. Consequently, transform faults of the OT should also be NNE-trending, which is not perpendicular to the spreading axis but instead displays oblique spreading. 2. Izu-Bonin-Mariana (IBM) Trench retreat to the NNE and NE. Subduction rollback to the NE and NNE produced the NE- and NNE-striking horizontal tensile stress, resulting in the rifting of the Kyushu-Palau Ridge (KPR), controlling the spreading of the SPVB and forming the NE- and NNE-trending transform faults. This also involves oblique spreading. 3. The later overall rotation of the Philippine Sea Plate (PSP). Since 25 Ma, the WPB has rotated clockwise about 40°. Therefore the NW- and NNW-trending transform faults that formed at the later spreading stage have rotated to be the near-N-S- or NNE-striking faults. These transform faults are almost perpendicular to the spreading axis. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Currently, there are several published end-member plate models that describe the evolution of Iberia during the Mesozoic. We review key geological and geophysical data sets previously used as constraints on these models including (1) geological interpretations of Pyrenean geology; (2) end-member interpretations of magnetic anomalies along the West Iberian and Newfoundland margins and Bay of Biscay; (3) the paleomagnetic data set of Iberia; and (4) seismic tomography models, which have previously been used to support Cretaceous subduction between Iberia and Eurasia. From this review we identify key constraints and argue that a reasonable plate kinematic model of Iberia should satisfy all of these. Instead, we determine inconsistencies between these key constraints and several published end-member plate models through a kinematic analysis using the GPlates software. We also analyze published seismic tomography models, not previously considered, across northern Africa and Iberia, and identify no slab preserved within the mantle supposedly linked to Cretaceous subduction between Iberia and Eurasia. A lack of published geological evidence along the Pyrenees supporting this subduction history also casts doubt on this scenario. Our kinematic analysis highlights that, first, the cessation in transtensional motion between Iberia and Eurasia by the Albian cannot be kinematically reconciled with the concurrent breakup between Iberia and Newfoundland in the Atlantic when reconstructing existing continent-ocean boundary interpretations along their respective margins. Second, either fit of the contentious end-member M0 interpretations (~120.6 Ma) between Iberia and Newfoundland implies plate velocities of Iberia that results in its undocumented transpressional or compressional motion relative to Eurasia until C34. [ABSTRACT FROM AUTHOR]

Deep seismic data represent a key to understand the geometry and mechanism of continental rifting. The passive continental margin of NW-Africa is one of the oldest on earth, formed during the Upper Triassic–Lower Liassic rifting of the central Atlantic Ocean over 200 Ma. We present new and existing wide-angle and reflection seismic data from four study regions along the margin located in the south offshore DAKHLA, on the central continental margin offshore Safi, in the northern Moroccan salt basin, and in the Gulf of Cadiz. The thickness of unthinned continental crust decreases from 36 km in the North to about 27 km in the South. Crustal thinning takes place over a region of 150 km in the north and only 70 km in the south. The North Moroccan Basin is underlain by highly thinned continental crust of only 6–8 km thickness. The ocean–continent transition zone shows a variable width between 40 and 70 km and is characterized by seismic velocities in between those of typical oceanic and thinned continental crust. The neighbouring oceanic crust is characterized by a thickness of 7–8 km along the complete margin. Relatively high velocities of up to 7.5 km/s have been imaged between magnetic anomalies S1 and M25, and are probably related to changes in the spreading velocities at the time of the Kimmeridgian/Tithonian plate reorganization. Volcanic activity seems to be mostly confined to the region next to the Canary Islands, and is thus not related to the initial opening of the ocean, which was associated to only weak volcanism. Comparison with the conjugate margin off Nova Scotia shows comparable continental crustal structures, but 2–3 km thinner oceanic crust on the American side than on the African margin. [ABSTRACT FROM AUTHOR]

The breakup of a supercontinent is a vital process of global tectonic evolution. How exactly West Gondwana and Pangea broke up is a controversial topic with many unanswered questions and problems that the reconstruction models attempt to solve. Since the mid-20th century in the course of modeling the South Atlantic tectonic evolution, several works contributed to the understanding of South America and Africa pre-breakup configuration, early stages of rift, and the kinematic involved in the rupture. However, these plate reconstruction models present several misfit problems. Here we review and analyze such misfits based on compiled geophysical and geological data by reproducing and comparing 15 reconstruction models since the pioneering work of Bullard et al. (1965). The location and magnitude of gaps and overlaps in each model are significantly different, in which fit differences mostly result from the assumed deformation. Nevertheless, a few similarities can be drawn, such as the maximum implemented overlap in the Central segment of the South Atlantic. We recognize that the accurate quantification of intraplate deformation is a challenge in refined models, and argue that South Atlantic models that restore intraplate deformation using geological and kinematic constraints tend to achieve a better fit. • Several West Gondwana pre-breakup fits have been proposed in the last 60 years. • Differences in South Atlantic reconstructions result from assumed deformation. • Geological inheritance and intraplate deformation play a pivotal role in tight-fit reconstruction models. [ABSTRACT FROM AUTHOR]

A vast ocean basin has spanned the region between the Americas, Asia and Australasia for well over 100 Myr, represented today by the Pacific Ocean . Its evolution includes a number of plate fragmentation and plate capture events, such as the formation of the Vancouver, Nazca, and Cocos plates from the break-up of the Farallon plate, and the incorporation of the Bellingshausen, Kula, and Aluk (Phoenix) plates, which have been studied individually, but never been synthesised into one coherent model of ocean basin evolution. Previous regional tectonic models of the Pacific typically restrict their scope to either the North or South Pacific , and global kinematic models fail to incorporate some of the complexities in the Pacific plate evolution (e.g. the independent motion of the Bellingshausen and Aluk plates), thereby limiting their usefulness for understanding tectonic events and processes occurring in the Pacific Ocean perimeter. We derive relative plate motions (with 95% uncertainties) for the Pacific –Farallon/Vancouver, Kula– Pacific , Bellingshausen– Pacific , and early Pacific –West Antarctic spreading systems, based on recent data including marine gravity anomalies, well-constrained fracture zone traces and a large compilation of magnetic anomaly identifications. We find our well-constrained relative plate motions result in a good match to the fracture zone traces and magnetic anomaly identifications in both the North and South Pacific . In conjunction with recently published and well-constrained relative plate motions for other Pacific spreading systems (e.g. Aluk–West Antarctic, Pacific-Cocos, recent Pacific –West Antarctic spreading), we explore variations in the age of the oceanic crust, seafloor spreading rates and crustal accretion and find considerable refinements have been made in the central and southern Pacific . Asymmetries in crustal accretion within the overall Pacific basin (where both flanks of the spreading system are preserved) have typically deviated less than 5% from symmetry, and large variations in crustal accretion along the southern East Pacific Rise (i.e. Pacific –Nazca/Farallon spreading) appear to be unique to this spreading corridor. Through a relative plate motion circuit, we explore the implied convergence history along the North and South America s, where we find that the inclusion of small tectonic plate fragments such as the Aluk plate are critical for reconciling the history of convergence with onshore geological evidence. [ABSTRACT FROM AUTHOR]

The Christmas Island Seamount Province is an extensive zone of volcanism in the Northeast Indian Ocean, consisting of numerous submerged seamounts and flat-topped guyots. Within this region lies two subaerial island groups, Christmas Island, and the Cocos Keeling archipelago. Christmas Island has experienced multiple episodes of volcanism that are exposed sporadically along its coastline. Here, we dated these volcanics using 40 Ar/ 39 Ar geochronology and analysed them for paleomagnetism. The oldest exposed volcanism occurred in the Eocene between 43 and 37 Ma. This is followed by a time gap of ~ 33 million years, before the eruption of a younger episode of Pliocene age (4.32 ± 0.17 Ma). It has, however, been suggested by previous workers that there is a much older Late Cretaceous event beneath the limestone which is unexposed. In addition, this study conducted the first paleomagnetic analysis of samples from Christmas Island to determine its paleoposition and the paleomagnetic polarity of the sampled sites. Two normal and two reversal magnetic events have been recorded, that agree with the geomagnetic reversal timescales. Late Eocene (38–39 Ma) palaeomagnetic data suggest a palaeolatitude of − 43.5 ° − 11.2 ° + 9.0 ° , which is further south than palaeolatitudes (around 30° S) derived from existing plate reconstruction models for the Australian plate. However, the Late Eocene palaeomagnetic data are limited (only two sites) and secular variation may not have been averaged out. During the Pliocene (ca. 4 Ma) we estimate a palaeolatitude of approximately 13° S. The presence of the Late Eocene ages at Christmas Island correlates well with the cessation of spreading of the Wharton Ridge (~ 43 Ma), the initiation of spreading along the South East Indian Ridge, and the transit of Christmas Island over a broad low velocity zone in the upper mantle. This suggests that changes in stress regimes following the tectonic reorganisation of the region (prior to~ 43 Ma) may have allowed deeper-origin mantle melts to rise. Similarly, changes in the plate's stress regime at the flexural bulge of the Sunda–Java subduction zone may be implicated in renewed melting at ~ 4 Ma, suggesting that tectonic stresses have exerted a first-order effect on the timing and emplacement of volcanism at Christmas Island. [ABSTRACT FROM AUTHOR]

Mandibular reconstruction with a plate, with or without a vascularised free (bone) flap, is commonly used to treat patients with a segmental mandibular defect. Common complications are loosening of the osteosynthesis screws, malposition, intraoral or extraoral exposure, or infection. To define prognostic factors for premature loss of such plates and improve future planning, we designed a retrospective study of all patients operated on between 2005 and 2011 for reconstruction of a mandibular segmental defect with a reconstruction plate with or without a free vascularised (bone) flap. Prognostic factors collected from medical records were the patient's age, sex, and American Society of Anesthesiologists (ASA) grade; treatment with radiotherapy; whether they had diabetes or smoked; the site of the mandibular defect; whether there was a dental occlusion; the number of screws used on each side, and the use of a free vascularised (bone) flap; and whether the diagnosis was of oral cancer, benign tumour, or trauma. One hundred patients were included, 79 with oral cancer, 19 with benign tumours, and 2 with trauma. In 20 patients the Martin 2.7 reconstruction plate failed. Diabetes and smoking were significant prognostic factors for premature loss of the reconstruction plate with a hazard ratio of 2.95 (95% CI 1.068–8.172), p value = 0.04, for diabetes, and 2.42 (95% CI 1.006–5.824), p value = 0.05, for smoking. Smokers and diabetic patients have a higher risk of failure after mandibular reconstruction with a 2.7 reconstruction plate. [ABSTRACT FROM AUTHOR]

The Caribbean oceanic crust was formed west of the North and South American continents, probably from Late Jurassic through Early Cretaceous time. Its subsequent evolution has resulted from a complex tectonic history governed by the interplay of the North American, South American and (Paleo-)Pacific plates. During its entire tectonic evolution, the Caribbean plate was largely surrounded by subduction and transform boundaries, and the oceanic crust has been overlain by the Caribbean Large Igneous Province (CLIP) since ~ 90 Ma. The consequent absence of passive margins and measurable marine magnetic anomalies hampers a quantitative integration into the global circuit of plate motions. Here, we present an updated, quantitatively described kinematic reconstruction of the Caribbean region back to 200 Ma, integrated into the global plate circuit, and implemented with GPlates free software. Our reconstruction includes description of the tectonic units in terms of Euler poles and finite rotation angles. Our analysis of Caribbean tectonic evolution incorporates an extensive literature review. To constrain the Caribbean plate motion between the American continents, we use a novel approach that takes structural geological observations rather than marine magnetic anomalies as prime input, and uses regionally extensive metamorphic and magmatic phenomena such as the Great Arc of the Caribbean, the CLIP and the Caribbean high-pressure belt as correlation markers. The resulting model restores the Caribbean plate back along the Cayman Trough and major strike-slip faults in Guatemala, offshore Nicaragua, offshore Belize and along the Northern Andes towards its position of origin, west of the North and South American continents in Early Cretaceous time. We provide the paleomagnetic reference frame for the Caribbean region by rotating the Global Apparent Polar Wander Path into coordinates of the Caribbean plate interior, Cuba, and the Chortis Block. We conclude that formation of the Caribbean plate, west of the North and South Americas, as a result of Panthalassa/Pacific spreading leads to a much simpler plate kinematic scenario than Proto-Caribbean/Atlantic spreading. Placing our reconstruction in the most recent mantle reference frames shows that the CLIP originated 2000–3000 km east of the modern Galápagos hotspot, and may not have been derived from the corresponding mantle plume. Finally, our reconstruction suggests that most if not all modern subduction zones surrounding the Caribbean plate initiated at transform faults, two of these (along the southern Mexican and NW South American margins) evolved diachronously as a result of migrating trench–trench–transform triple junctions. [ABSTRACT FROM AUTHOR]