Relative Plate Research Articles

Soong Classification Using Radiographs Only Moderately Correlates With Distal Radius Plate Position on Computed Tomography

Background: The Soong classification grades the prominence of volar locking plates used to treat distal radius fractures in relation to the volar rim. The basis of the classification scheme is that increasing plate prominence over the volar rim and distal radius watershed zone is associated with increased likelihood of flexor tendon irritation and need for plate removal. However, recent studies report mixed results on the predictive value of the Soong classification for these outcomes. We hypothesized that the decreased predictive accuracy of Soong classification is due to misclassification between Soong grades secondary to a suboptimal correlation between the Soong classification on radiographs (XRs) and computed tomography (CT). Methods: Fifty volarly displaced distal radius fractures treated with a volar locking plate in the international and publicly available ICUC database were reviewed. All cases with a postoperative XR and CT were included. Soong classification of the volar locking plate in relation to the volar ulnar rim was determined on both XR and CT by 2 independent, fellowship-trained hand surgeons using CT imaging as the gold standard. The distribution of Soong grades on XR and CT was compared using Pearson’s χ2 test, and correlation was calculated using the Matthews correlation coefficient (MCC). A multi-class confusion matrix was used to calculate each grade’s positive predictive value (PPV). Results: We found an MCC of 0.65, indicating only moderate correlation between the 2 modalities. Per individual Soong grade, the PPV was the highest for grade 2 (0.96), with lower PPVs for grade 0 (0.63) and grade 1 (0.60). Conclusions: The distribution of Soong grades was significantly different when using XR versus CT ( P < .001). Level of Evidence: Oxford Centre for Evidence-Based Medicine, diagnostic, level 2b

Indian carbonatites in the global tectonic context

Chrono-tectonic settings of the carbonatite occurrences of India are reviewed with a focus on the “big picture” of carbonatite emplacements in the Indian plate in relation to global tectonic events associated with the amalgamation and breakup of supercontinents. Four chrono-tectonic domains, namely, Southern domain, Southeastern domain, Northeastern domain and Northwestern domain, are delineated based on the geographical distribution, tectonic settings and temporal relationships amongst the carbonatite complexes. The Southern domain comprises two sub-domains – Paleoproterozic and Neoproterozoic. The Paleoproterozoic sub-domain is related to extension due to relaxation after the Southern Granulite Terrain-Dharwar accretion, while the Neoproterozoic sub-domain is related to rifting related to the fragmentation of Rodinia. The Southeastern domain is related to the Mesoproterozoic fragmentation of Columbia. The Northeastern domain is related to the Mid-Cretaceous breakup of Greater India from Australia-Antarctica driven by the Kerguelen mantle plume that also produced the Rajmahal-Sylhet Large Igneous Province (LIP). The Northwestern domain is related to the Late-Cretaceous Indo-Seychelles-Madagascar split and the passage of Greater India over the reunion hotspot, which also produced the Deccan LIP.

How Color-Harmony on a Food Plate Affects Consumers Perceptions

The aim of the present research was to explore consumers’ color-harmony preferences on a food plate in relation to four different criteria; aesthetics, taste, healthiness, and satiety. With respect to this aim, four different food plates were designed based on four color-harmony types used in fine arts – analogous, complementary, triadic and quadratic. The sample of the study consisted of 1.162 participants from Turkey who responded to an online survey including pairs of color-combinations and reported their preferences in terms of the selected criteria. The results were analyzed using Cochran’s Q Test and Scheffe Test. The results clearly demonstrated that people respond differently to meals comprising of different color-combinations. One major finding was that people seemed to find quadratic food-color harmony as the least tasty and healthy food even though they found it aesthetics. In correspondence to the results of several other studies, the present study found that attractiveness of food plates could be increased through the use of more colors to a certain level. Food plates with quadratic color-harmony were detected to be the least tasty and healthy and less filling by Turkish consumers.

Microbiological Assessment of Titanium Plates Coated with PLGA, Chitosan, and/or Meropenem: An In Vitro Study.

This investigation was conducted to evaluate the efficacy of coated titanium plates against gram-positive Staphylococcus aureus (SA) and gram-negative Pseudomonas aeruginosa (PA) using various methods. The Colony-forming unit "CFU" was higher in chitosan (CH) in relation to PA than in poly lactic-co-glycolic acid (PLGA) in relation to SA, followed by meropenem-chitosan "MC" coated plates in relation to PA and SA. A significant difference in the zone of inhibition (ZOI) of SA was determined in MP, MC, and meropenem (MEM). PA was significantly inhibited by MP, MEM, then MC, and the largest ZOI among SA and PA groups were MP coating. Using an MTT assay, MP had the lowest bacterial viability in the SA group, followed by MC and MEM, with no statistically significant difference between the PLGA or CH alone nor the polymers augmented with MEM. Using confocal microscopy, MP-coated plates were seen to have the highest bacterial inhibition, followed by MC, MEM, PLGA, and CH. In the PA group, MP had the highest bacterial inhibition, followed by MEM, MC, CH, and PLGA. The uncoated group presented the lowest inhibition in relation to both SA and PA. Conclusively, coating titanium plates with PLGA or CH with MEM appeared to enhance the antibacterial efficacy as opposed to MEM without polymers through bacterial adhesion inhibition, hindering biofilm formation and preventing bacterial proliferation.

“ Initial experience with augmented reality for treatment of an orbital floor fracture – A Technical Note ”

The marked developments in the fields of 3D planning and printing in the last few decades, have enabled the application of virtual surgical planning (VSP) toward personalization of surgical procedures and implants. Augmented reality superimposes digital content on the real-world reality. The aim of this technical note was to introduce the use of AR to evaluate and guide the insertion and positioning of a patient specific implant (PSI) for orbital floor blow-out fracture reconstruction. A 31-year-old, healthy male was injured and suffered from left orbital floor blow-out fracture. DICOM images of the CT scan were obtained for segmentation and for VSP, PSI design and 3D Printing. Patients’ file with the 3D objects was uploaded to AR software. The patient's left orbital floor was approached via the trans-conjunctival incision, PSI titanium plate was set in place and using AR Special head-mounted displays (HoloLens 1, Microsoft) the correct planned position of the plate was confirmed. The post-operative CT scan showed a <0.3 mm discrepancy in all axes of the plate in relation to the planned position. AR application in medicine and in maxillofacial surgery bears great potential, However, further investigation of this technology is required

Tensile properties of Ti-6Al-4V as-built by laser metal deposition: The relationship between heat affected zone bands, strain localization and anisotropy in ductility

Expanded structural applications of additively fabricated or repaired components rely on a thorough understanding of relationships between the anisotropic microstructure and macroscopic mechanical properties. In the present study, Ti‐6Al‐4V as-built by laser metal deposition using a powder feedstock was investigated through an extensive characterization of microstructure, porosity and tensile properties along different loading directions. While no significant anisotropy in strength was noticed, the ductility was observed to vary significantly depending on the loading direction. Higher ductility along the build direction was found to result from strain delocalization using in-situ tensile tests combined with digital image correlation. Differences in mesoscale strain localization patterns stem from a specific distribution of α’ plates in relation to HAZ bands. In addition, the influence of a variety of other features including the crystallographic textures, the β grain morphology, the distance to the free surface, the porosity and the argon shielding during manufacturing on tensile properties was also examined and discussed in light of existing literature.

Changing Carboniferous Arc Magmatism in the Ossa-Morena Zone (Southwest Iberia): Implications for the Variscan Belt

Carboniferous magmatism in southwestern Iberia was continuously active for more than 60 m.y. during the development of the Appalachian-Variscan belt of North America, North Africa and Western-Central Europe. This collisional orogen that records the closure of the Rheic Ocean is essential to understanding the late Paleozoic amalgamation of the Pangea supercontinent. However, the oblique convergence between Laurussia and Gondwana that lasted from the Devonian to the Carboniferous was likely more complex. Recently, a new tectonic model has regarded the Iberia Variscan belt as the site of coeval collisional and accretionary orogenic processes. Early Carboniferous plutonic rocks of southwest Iberia indicate arc magmatism in Gondwana. The Ossa-Morena Zone (OMZ) acted as the upper plate in relation to the geometry of the Paleotethys subduction. This active accretionary-extensional margin was progressively involved in a collisional phase during the Late Carboniferous. Together, the Évora Massif and the Beja Igneous Complex include three successive stages of bimodal magmatism, with a chemical composition indicative of a long-lived subduction process lasting from the Tournaisian to the Moscovian in the OMZ. The earliest stage of arc magmatism includes the Tournaisian Beja and Torrão gabbro-dioritic rocks of the Layered Gabbroic Sequence. We present new geochemical and Nd isotopic and U-Pb geochronological data for magmatic rocks from the Main (Visean-Serpukhovian) and Latest (Bashkirian-Moscovian) stages of arc magmatism. Visean Toca da Moura trachyandesite and rhyolites and Bashkirian Baleizão porphyries and Alcáçovas quartz diorite share enriched, continental-crust like characteristics, as indicated by major and trace elements, mainly suggesting the addition of calc-alkaline magma extracted from various mantle sources in a subduction-related setting (i.e., Paleotethys subduction). New U-Pb zircon geochronology data have allowed us to establish a crystallization age of 317 ± 3 Ma (Bashkirian) for Alcáçovas quartz diorite that confirms a temporal link with Baleizão porphyry. Positive εNd(t) values for the Carboniferous igneous rocks of the Beja Igneous Complex and the Évora gneiss dome indicate production of new juvenile crust, whereas negative εNd(t) values also suggest different grades of magma evolution involving crustal contamination. The production and evolution of Carboniferous continental crust in the OMZ was most likely associated with the development of an active continental margin during the convergence of the Paleotethys Ocean with Gondwana, involving juvenile materials and different grades of crustal contamination.

Influence of the plate thickness and material properties on the violin top plate modes

In this paper we analyze the vibrational behavior of the violin top plate, for varying plate thickness and material properties via finite element method (FEM) numerical simulations. It is well known that the vibrational properties of the top plates of string instruments influence their sound emission characteristics. Due to the impact of global warming on wood formation and due to their configurability, many manufacturers investigate the use of composite materials to produce musical instruments. Therefore, composite, carbon fiber reinforced epoxy (CFRE) prepreg along with traditional wooden material, such as spruce, are adopted in this study. FEM modal analysis along with a frequency response function (FRF) FEM analysis are performed. The vibrational variations of the plate's response are computed under free conditions. The main vibrational modes and the natural frequencies obtained by the simulations show the influence of the different mechanical and geometric properties on the top plate's vibrational response. The resulting eigenmode frequencies and shapes of the plate in relation to the varying thickness and the material properties used, are discussed. The results of this study offer valuable information on the evaluation of the acoustical characteristics of violins and may be further used on their vibrational behavior optimization and control.

Study of power flow mechanism of capacitive power transfer system based on Poynting vector analysis

In this paper, the power flow mechanism of a typical Capacitive Power Transfer (CPT) system is studied by analysing the electric field, magnetic field, and Poynting vector, to determine the power distribution as well as the average power flow to the load. It is found that the average power from the source flows along the wires on the transmitting side and passes the external areas of the coupling plates mainly along the channel between the two coupling pairs (instead of going through the air gaps in between), then converges along the wires before reaching the load. The average power calculated by integrating the real part of the Poynting vector across a defined power flow plane at the receiving end is consistent with CST (Computer Simulation Technology) simulation, circuit analysis, and practical measurements of the CPT system. Although the power density described by Poynting vector changes with the separation distance between the two coupling pairs, the total average power keeps approximately constant because the power flow area changes accordingly. Compared to the traditional lumped circuit analysis, the Poynting vector analysis shows the power distribution around the coupling plates in relation to their physical configuration. This research reveals the power flow mechanism and distribution in a CPT system from field point of view, which is useful to gain deeper understanding of the CPT system beyond the traditional circuit theory and would also be helpful to improve practical system design in the future.

Application of Anatomically Designed 2-Dimensional V Plate in Management of Mandible Fracture: A Pilot Study.

Mandible is the only mobile facial jaw bone and it aides in various functions such as phonation and mastication. Therefore, management of mandible fracture becomes inevitable due to its functional and anatomical importance. Fracture fixation methods and techniques have steadily evolved with various osteosynthesis systems. In this article, we discuss the management of mandible fracture using a newly designed two-dimensional (2D) hybrid V-shaped plate. In this paper, we have evaluated the efficacy of the newly developed 2D V-shaped locking plate in the management of mandibular fractures. We have assessed 12 cases of different mandibular fractures ranging from symphysis, parasymphysis, angle and subcondylar region. Treatment outcome was assessed both clinically and radiologically at regular intervals with various intraoperative and postoperative parameters. Results of this study suggest that fixation of mandible fracture with the 2D hybrid V-shaped plate facilitates anatomic reduction and functional stability and carries a low morbidity and infection rate. The 2D anatomic hybrid V-shaped plate can be a suitable alternative to conventional miniplate and 3D plates as it offers satisfactory anatomic reduction and functional stability. Positioning the plate in relation to the mental nerve and plate adaptation along the angle region are much easier.

Analysis and comparison of computer programs to analyze the irradiation performance of Uranium Molybdenum monolithic fuel plates and Uranium dioxide cylindrical fuel rods in power reactors.

The aim of this work is to present a comparative analysis in terms of the irradiation performance of cylindrical uranium dioxide fuel rods and monolithic uranium molybdenum fuel plates in pressurized light water reactors.To analyze the irradiation performance of monolithic uranium molybdenum fuel plates when subjected to steady state operating conditions in light water pressurized reactors, the computer program PADPLAC-UMo was used, which performs thermal and mechanical analysis of the fuel taking into account the physical , chemicals and irradiation effects to which this fuel is subjected. For the analysis of the uranium dioxide fuel rods, the code FRAPCON was used, which is an analytical tool that verifies the irradiation performance of fuel rods of pressurized light water reactor, when the power variations and the boundary conditions are slow enough for the term permanent regime to be applied. The analysis for a small nuclear power reactor, despite the higher power density applied to the fuel plate in relation to the fuel rod, showed that the fuel plates have lower temperatures and lower fission gas releases throughout the analyzed power history, allowing the use of a more compact reactor core without exceeding the design limits imposed on nuclear fuel.

Infographic: Cast immobilization is non-inferior to volar locking plates in relation to QuickDASH after one year in patients aged 65 years and older: a randomized controlled trial of displaced distal radius fractures.

Infographic: Cast immobilization is non-inferior to volar locking plates in relation to QuickDASH after one year in patients aged 65 years and older: a randomized controlled trial of displaced distal radius fractures

Lake Van (Southeastern Turkey) Experiment: Receiver Function Analyses of Lithospheric Structure from Teleseismic Observations

The P and S wave receiver functions and their joint inversions are used to study the lithosphere beneath the Lake Van region using approximately 600 teleseismic earthquake data (Mw ≥ 5.8) at different azimuths collected from 10 permanent broadband stations operated by Kandilli Observatory and Earthquake Research Institute and Disaster and Emergency Management Authority in the region. The dataset is taken from the European Integrated Data Archive. The simulated annealing method is used for the joint inversion of P-wave and S-wave receiver functions, since the P410s phase cannot be detected reliably in the depth stacks. This may be due to the low olivine content and high basalt content at this depth. The inversion process is therefore performed without travel time residuals. The crustal thickness is observed at nearly 45 km in all the velocity models obtained from the inversion. The relatively low-velocity layer (Vs = 3.4 km/s) at depths of the middle crust may be associated with volcanic centers near Nemrut, in the west of the region. Additionally, another low-velocity layer (Vs = ~ 3.0 km/s) is observed in the upper crust around the Suphan Volcano. Also, Vp/Vs and Poisson’s ratios are calculated for the study area. Their high values (Vp/Vs ≥ 1.85, and σ ≥ 0.285) correspond to the partial melting of the lower crust in the region. According to velocity models obtained from the inversion results, the most important outcome is that the average variance of the Moho discontinuity (~ 45 km) and lithosphere–asthenosphere boundary (~ 90 km) under the seismograph stations can be interpreted as a likely part of the Arabian oceanic plate in relation to the collision zone.

Monitored conditions in wooden wall plates in relation to mold and wood decaying fungi

In historic masonry buildings, wood can be embedded in the walls as storey partition beams, or as supportive wall plates. Half-timbered masonry constructions, or wooden frames, e.g. combined with internal insulation, are other examples of wooden elements. Wood decaying fungi can cause serious damage to wood, which may lose mass and strength, ultimately yielding the risk of collapse. In addition, some fungal species may even be hazardous for occupants. All wood decaying fungi depend on favorable moisture and temperature conditions, although the threshold conditions may vary with various fungal species and types, and state of the wood. To predict the risk of occurrence of wood rot, several models have been developed, however most of these are based on a limited number of experiments, or very specific cases. For these reasons, the applicability of the models to other scenarios (fungal species, wood species) may not be appropriate. Furthermore, another failure mode for wood and moisture, is mold growth, which is initiated at lower moisture levels. An indication of risk of mold growth would indicate problems or risks before the initiation of wood rot. Mold growth does not deteriorate the wood, but is usually equally undesired due to health concerns of occupants. For this reason, there might be places where some mold growth would be acceptable, e.g. embedded beam ends if there is no transfer of air from the moldy area to the indoor air. Therefore, risk of rot could be important. The paper investigates models for mass loss due to wood decay and mold growth based on exposure time to favorable hygrothermal conditions. The investigation is based on inspection of wood samples (wall plates) from a full-scale experimental setup of masonry with embedded wood and monitored conditions, to which the prediction models will be applied. Monitored hygrothermal conditions were implemented in mold and wood decay models, and samples were removed from the test setup. The implemented models yielded high mold index and mass loss, whereas neither mold nor decay was observed in the physical samples. Results indicate that the implemented models, in these cases appear to overestimate the risks of mold and rot in the supportive lath behind the insulation.

Comprehensive evaluation of grafting the preservable narrow plates with consideration of native plate width at primary hypospadias surgery

Dorsal inlay graft urethroplasty using inner-face preputial graft was described as an adjunct method to the classic tubularized incised plate (TIP) urethroplasty, aiming at reducing the risk of neourethral stenosis. To evaluate the impact of dorsal inlay grafting of preservable narrow plates, in relation to native plate width. Consecutive children with penile hypospadias with narrow plate (width<8mm) were evaluated prospectively between Jan 2014 and Jun 2018. Included cases were stratified into two groups: group A (plate width: 4 to <8mm) and group B (plate width: < 4mm). All cases were approached by TIPurethroplasty, with dorsal inlay grafting (inner-face prepuce). Cases with significant chordee (non-preservable plates), circumcised cases, and redo cases were excluded. A total of 104 hypospadias cases with narrow plates were included in this study. Among group A (n=81), the need for postrepair urethral dilations was reported in two cases (2.5%) vs seven cases (30%) in group B (n=23) (P-value<0.001). Another two cases (2.5%) in group A developed urethrocutaneous fistulae vs three cases (13%) in group B (P-value=0.0624). Surgical repair of the reported five cases with fistulae, revealed an ample neourethral wall; disclosing well-taken grafts in both groups. Few published studies evaluated grafting the incised plate in penile hypospadias. To the authors knowledge, this is the first study that selectively evaluated the impact of grafting narrow plates in relation to its native pre-incision width. According to the presented authors' experience, 4mm width is the border line of clinical relevance that defines poor urethral plate. Grafting that plate failed to compensate for its native poor characteristics; however, it offered a valuable neourethral wall that proved indispensable when redo surgery deemed necessary, without adding grafting-related problems. Nevertheless, further extended comparative studies came across as a necessity to verify the long-term outcomes of grafting the incised poor plates.

Mathematical modelling of thermal dynamic stresses on the basis of a dual – Phase lag model

Using the modified Hooke’s law equation that takes into account the relaxation of stresses and strains, we have obtained the relaxed thermal dynamic stresses equation that includes summands subject to the relaxation properties of materials. An exact analytical solution to a heat conductivity equation derived with the local nonequilibrium of the thermal process in mind was used as a temperature function. An analysis of the exact analytical solution to the thermal dynamic stresses equation for an infinite plate with outer surfaces affected by heat impact indicated the elimination of the abrupt stress variation caused by solutions to classic equations, which do not take into account the relaxation properties of materials. The analysis also showed that in each point of the plate, stresses change following the harmonic law with an oscillation amplitude damped in time. Displacement changes also follow the harmonic law and result in high-frequency harmonic oscillations due to the periodic compression and expansion of the plate in relation to the centre of its thermal symmetry.

Microcracks in subchondral bone plate is linked to less cartilage damage.

Osteoarthritis (OA) is a disease of the whole joint characterized by cartilage loss and subchondral bone remodeling. The role of microcracks in cartilage integrity and subchondral bone homeostasis is not fully understood. The main goal of this work was to evaluate microcrack density in both calcified cartilage and subchondral bone plate in relation to cartilage damage in humans and to better define the association of microcracks and osteocyte density in subchondral bone. We investigated 18 bone cores from cadaveric human knees that were stained with En-Bloc Basic Fuchsin. We quantified microcrack density, osteocyte density, cartilage surfaces and cartilage damage. The presence of microcracks was confirmed for each bone core by scanning electron microscopy. Finally, trabecular subchondral bone parameters were measured by micro-CT. Microcracks were detected in both calcified cartilage and subchondral bone plate. The density of microcracks in both calcified cartilage (CC) and subchondral bone plate (SBP) was negatively correlated with cartilage damage (r = -0.45, p < 0.05). The presence of microcracks in SBP was associated with a lower histological OA score. Osteocytes formed a dendrite network that abruptly stopped at the border of calcified cartilage. Osteocyte density in subchondral bone plate was increased in the presence of microcracks in calcified cartilage. Subchondral bone plate microcracks might be required for maintaining cartilage homeostasis. Microcracks in calcified cartilage may trigger osteocyte density in subchondral bone plate with subsequent regulation of subchondral bone remodeling to prevent cartilage damage.

Verificação de modelo computacional para placas com enrijecedores considerando condição de contorno de simetria

O presente artigo apresenta a modelagem computacional de placas enrijecidas submetidas a uma carga transversal uniformemente distribuída, permitindo a análise numérica de deslocamentos e tensões. O modelo computacional foi desenvolvido no software ANSYS, baseado no Método dos Elementos Finitos (MEF), empregando o elemento finito SHELL281. Este modelo foi elaborado considerando a condição de contorno de simetria, possibilitando que somente um quarto da placa enrijecida fosse simulado numericamente. As simulações com esta condição de contorno demonstraram um ganho de processamento computacional em relação às simulações da placa completa. Além disso, a sua utilização possibilitou o uso de discretizações espaciais (malhas) mais refinadas do que as usadas em modelos que consideram a placa inteira. Com o objetivo de verificar esse modelo computacional assim como avaliar sua acurácia em relação aos resultados obtidos com o modelo que considera toda a placa, análises de deflexão e de tensão foram realizadas. A verificação do modelo foi feita usando a solução independente de malha, obtida através de um teste de convergência de malha. Os resultados do modelo numérico utilizando a condição de contorno de simetria demonstraram uma boa precisão em relação ao modelo computacional da placa completa, tanto na verificação quanto em um comparativo da placa inteira em relação a seu equivalente com simetria.

Morphostructure of the Galicia continental margin and adjacent deep ocean floor: From hyperextended rifted to convergent margin styles

A joint study and mapping of the morphological features and architecture of the Galicia margin based on high-resolution multibeam bathymetry data and multichannel seismic profiles, provides new insights of the margin morphostructure. Tectonic processes are the major control of the margin's morphology, where the imprint of the North Atlantic rifting and opening and later subduction of the Bay of Biscay and compressional events are still well preserved. The West Galicia margin, which is up to 350 km wide, is composed from east to the west of inner, transitional and outer sectors. The inner sector shows a graded upper slope strongly dissected by a system of submarine canyons and valleys that flow into the 170 km long and 40–60 km wide NW-SE Valle Inclán Valley. The transitional sector, which is up to 75 km wide, displays a smooth relief dominated by landslides and giant craters. Finally, the outer sector is characterised by several banks, N-S sub-parallel ridges and elongated valleys that project seaward over 200 km (i.e., Galicia Bank, Half-Graben, Deep Galicia margin and Peridotite Ridge domains). The North Galicia margin is characterised by a system of terraces up to 30 km wide, that form a stepped slope followed by an abrupt lower slope affected by large-scale rotational failures.The Galicia margin constitutes an exceptional area within the Atlantic margins for identifying different morphostructure styles that characterised the main stages of the margin's evolution along the Wilson cycle. The Galicia margin hosts the transition between two end-members of continental margin styles: a western hyperextended rifted margin (being the conjugate with the Newfoundland margin during the Late Jurassic) and a northern convergent margin (now fossilised) associated with the partial subduction of the southern sector of the Bay of Biscay underneath the North Iberian margin, which occurred in Paleocene-Eocene times. Thus, the morphostructure of the West Galicia margin still reflects the detached fault systems and tilted blocks that resulted from the Mesozoic North Atlantic rifting. Furthermore, the Coruña and Jean Charcot seamounts, which are adjacent to the Galicia margin, correspond to spreading ridges formed by the simultaneous opening of North Atlantic Ocean and the Bay of Biscay in the Upper Cretaceous. The rest of the terraced morphology of the North Galicia margin is derived from extensional faults caused by an overriding of the Iberian plate in relation to the subduction of the Bay of Biscay oceanic crust during Cenozoic times. Since the late Neogene, compressional tectonics resulting from the reorganisation of the Eurasia/Iberia and Africa plates is also reflected on the present-day morphology as the following: (i) an elevation of the Biscay Abyssal Plain up to 150 m over the Iberia Abyssal Plain; (ii) deep-seated landslides associated with an uplift of the Galicia Bank; and (iii) an orientation of submarine canyons along NW-SE strike slip faults.

Emergence/Subsidence Histories Along the Carnegie and Cocos Ridges and Their Bearing Upon Biological Speciation in the Galápagos

AbstractUsing plate motion reconstructions for the Nazca, Cocos, and South American plates in relation to the Galápagos hotspot, we find that age‐depth dependence of bathymetry, Galápagos plume dynamic topography, crustal relaxation, and magmatic production permit reasonable estimates for the subsidence of former islands along the Carnegie and Cocos Ridges. Our dynamic topography estimates are partially based upon geodynamic theory (fluid mechanics and elasticity) and also upon detailed bathymetric observations and analysis. For three different target areas over Carnegie Ridge and two over Cocos Ridge, we infer subaerial landmasses over the past ~20 Ma. We provide rough estimates of the surface areas of these paleo‐archipelagos, which were comparable to that of the present‐day Galápagos archipelago. We construct a history of emerged (paleo‐island) topography along the conjugate pair Carnegie‐Cocos hotspot tracks and infer that significant subaerial landscapes existed for at least the past ~20 Ma. The genetic ancestors of endemic faunal species in Galápagos (e.g., marine iguanas) migrated away from South America, genetically diverging from their land counterparts much earlier than the age of the present Galápagos Islands (~3 Ma). At 16.5 Ma, the total emerged landmass on the Carnegie Ridge alone may have been ~2.5 times that of the current Galápagos archipelago. (The conjugate landmass along the Cocos Ridge has been subducted.) We propose that this large landmass, at least one‐fourth the size of Iceland, be called Darwinia in recognition of its importance in the evolution of some Galápagos endemic flora and fauna made famous by Darwin's explorations.