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The planform is a defining feature of mantle convection. It can be gleaned from the stratigraphic record by mapping the continent-scale distribution of hiatus and no hiatus surfaces serving as a proxy for high and low dynamic topography. We carry this out for all continents apart from Antarctica for eight geological series since the Upper Jurassic, showing that: (i) the planform as indicated by our maps contains wavelengths of the order of 1000 km, smaller than the convective scales implied by the geoid. (ii) The planform changes on timescales of geological series (10–20 Myrs), smaller than the mantle transit time. (iii) Flood basalt eruptions are frequently preceded by hiatus surfaces. (iv) Some hiatus surfaces are not linked to any known plume, potentially reflecting the lateral transport of material in the asthenosphere. Our results reveal the importance of mantle viscosity stratification in shaping the convective planform and the resulting dynamic topography. Geodynamic Earth models should aim to reproduce the global characteristics of our maps, as well as specific regional events identified in this work. Finally, we separate the effects of sea-level variation from regional changes in base level induced by dynamic topography by contrasting the stratigraphic evolution of different regions. [ABSTRACT FROM AUTHOR]

Due to relatively high terrain and negligible active tectonics, the southern Africa region boasts over 30 independent estimates of dynamic topography. These published estimates display a wide variance due to both the variety of methods used in computation and a lack of constraints on the regional mantle structure. Here we show that a focus on regional mantle structure is important to generate models of lithospheric and mantle dynamics. Global average mantle properties are not representative of a particular region, and it is necessary to generate viscosity profiles specific to a region of interest. We develop a Bayesian inversion using dynamic geoid kernels, existing seismic tomography models, and Slepian functions to invert for a localized radial viscosity profile that best explains the geoid in southern Africa. With an understanding of viscosity uncertainty, we constrain dynamic topography in southern Africa to lie between 1,000 and 2,000 m. Additionally, we model vertical displacements from 112 Global Navigation Satellite System stations across our region to examine the long‐term, long wavelength pattern of present‐day vertical motion, suggesting that a mean of 1.5 mm/yr (1σ $\sigma $: 0.8–2.0 mm/yr) of vertical motion may be related to ongoing dynamic topography. Our study demonstrates the utility of dynamic geoid kernels in local nonlinear inversions of non‐unique geophysical data. Furthermore, we present evidence that the mantle beneath southern Africa is generating significant dynamic support for and vertical displacement of the lithosphere in this region. Plain Language Summary: The high topography of southern African is a result of the interaction between the lithosphere and the mantle beneath the region, a process referred to as dynamic topography. The viscosity of Earth's mantle is a primary driver of the buoyancy forces that generate this dynamic topography. There is significant disagreement regarding the amplitude and pattern of dynamic topography in this region, partially owing to the lack of constraints on inputs to geodynamic models, especially viscosity. We use the geoid to constrain mantle viscosity within our study region by combining existing statistical techniques in a novel manner. We generate models of mantle viscosity, dynamic topography, and present‐day vertical displacement for our study region. Our preferred model results in 1,000–2,000 m of dynamic topography, suggesting that the whole of southern Africa is dynamically supported. We also find evidence for around 1.5 mm/yr (1σ $\sigma $: 0.8–2.0 mm/yr) of present‐day vertical displacement within the southern part of the region, suggesting that dynamic topography is currently increasing. We argue that the viscosity within any given region of the mantle differs significantly from the whole‐mantle average, and care must be taken to use a viscosity model that corresponds to the region of interest when creating geodynamic models. Key Points: We generate Bayesian estimates of localized radial mantle viscosity and dynamic topography in southern AfricaWe model present‐day vertical displacement of southern African using Global Navigation Satellite System station timeseries and Slepian localization techniquesThere is evidence for significant dynamic support (>1,000 m) and present‐day vertical motion (1s: 0.8–2.0 mm/yr) due to mantle dynamics [ABSTRACT FROM AUTHOR]

In the Palaeocene North Sea, pulses in turbidite fan deposition and shelfal progradation have been correlated with episodes of regional uplift caused by a precursor of the Icelandic Plume. In the East Shetland Platform, the specific impacts of dynamic uplift on the regional palaeogeographic evolution are less understood. Using new, high‐resolution 3D seismic data from an underexplored proximal area, we investigate the palaeogeography of the East Shetland Platform in terms of the extent and timing of erosion versus deposition, focusing on how these can be used to reconstruct changes in relative sea‐level along strike. Using a combination of well data, clinoform‐based seismic stratigraphy and seismic attribute analysis of >60,000 km2 of 3D data, we have obtained palaeogeographic maps of multiple Palaeocene to Early Eocene units, with high temporal resolution for the Late Palaeocene–Early Eocene Moray Group. This includes six unconformity‐bounded units marked by prograding clinoforms of the Dornoch Formation, which are covered by backstepping sequences of the Beauly Member (Balder Formation). Temporal and spatial changes in the distribution of downdip depocentres and updip unconformities indicate strong lateral variability in patterns of shelf accommodation/erosion and local sediment supply. This results from a complex interplay among laterally uneven relative sea‐level fall, inherited topography, time‐varied sediment entry point distribution and along‐shore sediment transport regimes. Unconformities and palaeogeographic maps suggest a first‐order control on erosion and sediment distribution promoted by the transiently and differentially uplifted topography of Shetland, which is characterized by an anomalous erosive history in the Bressay High, in the centre of our study area, where the Lower Dornoch Formation has been eroded and marked fluvial incision is observed. Ultimately, results indicate shorter‐wavelength and shorter‐period variations in uplift than what is typically assumed for dynamic topography, perhaps as a result of additional modulation by lithospheric structures or influence of previous rift‐related faults. [ABSTRACT FROM AUTHOR]

The flooding record of North America has been used to infer patterns of global erosion and sea level in deep time. Here, we utilize the geospatial dimension of the stratigraphic record provided by the Macrostrat database, and patterns of erosion from thermochronology, to resolve local tectonic subsidence from global sea level. We show that the flooding history of North America correlates in space and time with continent-facing subduction along active margins, consistent with subduction-driven dynamic topographic subsidence of the continental interior. Nonetheless, the continentally aggregated flooding signal of North America is an exaggerated global M-curve of Phanerozoic sea level. This coincidence relates to the closing of the geodynamic loop of the supercontinent cycle: Subduction under North America accommodated both the makeup and breakup of Pangaea, which, coupled with changing ridge length, flattened hypsometry, and increased sea level both locally and globally. The sole Phanerozoic exception to this pattern of global sea level tracking North American near-field geodynamics is the Cambrian Sauk transgression. We argue that this is a far-field record of the inception of circum-Gondwanan subduction, independent of North America, which significantly flattened Earths hypsometry. This hypsometric flattening displaced ocean water globally, flooding tectonically passive North America to seal the Great Unconformity.

Mantle convection plays a fundamental role in driving evolution of oceanic and continental lithosphere. In turn it impacts a broad suite of processes operating at or close to Earth's surface including landscape evolution, glacio‐eustasy, magmatism, and climate. A variety of theoretical approaches now exist to simulate mantle convection. Outputs from such simulations are being used to parameterize models of landscape evolution and basin formation. However, the substantial body of existing simulations has generated a variety of conflicting views on the history of dynamic topography, its evolution and key parameters for modeling mantle flow. The focus of this study is on developing strategies to use large‐scale quantitative stratigraphic observations to assess model predictions and identify simulation parameters that generate realistic predictions of Earth surface evolution. Spot measurements of uplift or subsidence provide useful target observations for models of dynamic topography, but finding areas where tectonics have not also influenced vertical motions is challenging. To address this issue, we use large inventories of stratigraphic data from across North America with contextual geophysical and geodetic data to constrain the regional uplift and subsidence history. We demonstrate that a suite of typical geodynamic simulations struggle to match the amplitude, polarity and timing of observed vertical motions. Building on recent seismological advances, we then explore strategies for understanding patterns of continental uplift and subsidence that incorporate (and test) predicted evolution of the lithosphere, asthenosphere and deep mantle. Our results demonstrate the importance of contributions from the uppermost mantle in driving vertical motions of continental interiors. Key Points: Large‐scale digital inventories of stratigraphic observations used to test predictions from mantle convection simulationsUseful diagnostics include net uplift and subsidence, absolute elevations, paleo‐water depthsUpper mantle thermo‐mechanical evolution—crucial for assessing sub‐plate support—constrained using stratigraphy [ABSTRACT FROM AUTHOR]

Continental topography is dominantly controlled by a combination of crustal thickness and density variations. Nevertheless, it is clear that some additional topographic component is supported by the buoyancy structure of the underlying lithospheric and convecting mantle. Isolating these secondary sources is not straightforward, but provides valuable information about mantle dynamics. Here, we estimate and correct for the component of topographic elevation that is crustally supported to obtain residual topographic anomalies for the major continents, excluding Antarctica. Crustal thickness variations are identified by assembling a global inventory of 26,725 continental crustal thickness estimates from local seismological data sets (e.g., wide‐angle/refraction surveys, calibrated reflection profiles, receiver functions). In order to convert crustal seismic velocity into density, we develop a parametrization that is based upon a database of 1,136 laboratory measurements of seismic velocity as a function of density and pressure. In this way, 4,120 new measurements of continental residual topography are obtained. Observed residual topography mostly varies between ±1 and 2 km on wavelengths of 1,000–5,000 km. Our results are generally consistent with the pattern of residual depth anomalies observed throughout the oceanic realm, with long‐wavelength free‐air gravity anomalies, and with the distribution of upper mantle seismic velocity anomalies. They are also corroborated by spot measurements of emergent marine strata and by the global distribution of intraplate magmatism that is younger than 10 Ma. We infer that a significant component of residual topography is generated and maintained by a combination of lithospheric thickness variation and sub‐plate mantle convection. Lithospheric composition could play an important secondary role, especially within cratonic regions. Plain Language Summary: Plate tectonic theory holds that the horizontal movement of tectonic plates drives crustal thickening and the formation of mountain ranges where plates collide, and crustal thinning in rift basins where plates diverge. The dominance of this process, however, obscures a key secondary source of topographic variation caused by density variations within the underlying mantle. In this study, we compile two new databases. The first is a global compilation of crustal thickness and seismic velocity measurements obtained from seismic experiments. The second is a compilation of laboratory analyses of seismic velocity in crustal rocks as a function of temperature, pressure and density. We combine these data sets to accurately map that component of continental topography caused by crustal thickness and density variations and use it to isolate the secondary, residual component supported by the mantle. We find that a substantial proportion of topography is supported by the temperature and chemical structure of the mantle and is manifest as topographic swells and basins that can occur within interiors of tectonic plates, have amplitudes of up to 2 km, and length scales ranging from hundreds to thousands of kilometers. Independent geologic evidence suggests that some of these topographic features developed over million‐year time scales. Key Points: Continental residual topography estimated using 26,725 crustal thickness and 4,067 seismic velocity constraintsCrustal velocity to density conversion scheme developed to correct for crustal density variationsResidual topography varies from ∼1 to 2 km over ∼1,000 km wavelengths, consistent with a range of geological observations [ABSTRACT FROM AUTHOR]

One of the main effects of climate change is rising sea levels, which presents challenges due to its geographically heterogenous nature. Often, contradictory results arise from examining different sources of measurement and time spans. This study addresses these issues by analysing both long-term (1995–2022) and decadal (2000–2009 and 2010–2019) sea-level trends in the Baltic Sea. Two independent sources of data, which consist of 13 tide gauge (TG) stations and multi-mission along-track satellite altimetry (SA), are utilized to calculate sea-level trends using the ordinary least-squares method. Given that the Baltic Sea is influenced by geographically varying vertical land motion (VLM), both relative sea level (RSL) and absolute sea level (ASL) trends were examined for the long-term assessment. The results for the long-term ASL show estimates for TG and SA to be 3.3 mm/yr and 3.9 mm/yr, respectively, indicating agreement between sources. Additionally, the comparison of long-term RSL ranges from −2 to 4.5 mm/yr, while ASL varies between 2 and 5.4 mm/yr, as expected due to the VLM. Spatial variation in long-term ASL trends is observed, with higher rates in the northern and eastern regions. Decadal sea-level trends show higher rates, particularly the decade 2000–2009. Comparison with other available sea-level datasets (gridded models) yields comparable results. Therefore, this study evaluates the ability of SA as a reliable source for determining reginal sea-level trends in comparison with TG data. [ABSTRACT FROM AUTHOR]

For the period of satellite altimetry observation 1993–2018, a comparison was made of estimates of the linear meridional shifts of the jet structure and variations in current intensity in the sector of the Antarctic Circumpolar Current (ACC) south of Africa (10° E–25° W), obtained on the basis of the parameters derived from the module of the absolute dynamic topography (ADT) gradient : directly , module of the velocity of geostrophic current |u| on the ocean surface, half of square of the ADT gradient , and specific kinetic energy . The analysis was carried out by a method developed earlier and refined in this paper using linear regression analysis. It is shown that qualitatively the characters of the meridional shifts (displacement of the curves of these parameters averaged over latitude and for each year) in latitude and the corresponding current intensity variations (i.e., variations in the parameters themselves) over 26-year observations, when calculated through each of the four parameters, turned out to be similar. The same similarity was obtained from the calculations with respect to the ADT scale. Meanwhile, the quantitative differences between calculations for different pairs of parameters can be significant even in the and pair. In quantitative terms, the absolute values of shifts of the jet structure and variations in the intensity of currents in the ACC band in the studied sector of the Southern Ocean generally increase from those linearly dependent on the ADT gradient module to quadratically dependent ones. [ABSTRACT FROM AUTHOR]

Dynamic topography (DT) refers to the time-varying component of the sea surface height influenced by factors like ocean currents, temperature, and salinity gradients. Accurate estimation of DT is crucial for comprehending oceanic circulation patterns and their impact on climate. This study introduces two approaches to estimating DT: (1) utilizing satellite altimetry to directly observe sea surface height and (2) considering the steric and non-steric components of sea level anomalies. The steric term is calculated using salinity and temperature data obtained from local buoy data, Argo observations, and the World Ocean Atlas model. The non-steric term is calculated using GRACE Satellite gravimetry data. To estimate the assimilated DT, four methods are utilized, including variance component estimation (VCE), Bayesian theory, Kalman filter, and 3D variational (3DVAR). These methods assimilate the two aforementioned schemes. The validity of the estimated DT is assessed by comparing the calculated sea surface current, derived from the obtained DT, with observations from local current meter stations. The results indicate that the VCE method outperforms other methods in determining the final DT. Furthermore, incorporating the steric and non-steric terms of sea level in determining DT in coastal areas enhances the accuracy of estimating sea surface currents. [ABSTRACT FROM AUTHOR]

Abstract Mantle convection plays a fundamental role in driving evolution of oceanic and continental lithosphere. In turn it impacts a broad suite of processes operating at or close to Earth's surface including landscape evolution, glacio‐eustasy, magmatism, and climate. A variety of theoretical approaches now exist to simulate mantle convection. Outputs from such simulations are being used to parameterize models of landscape evolution and basin formation. However, the substantial body of existing simulations has generated a variety of conflicting views on the history of dynamic topography, its evolution and key parameters for modeling mantle flow. The focus of this study is on developing strategies to use large‐scale quantitative stratigraphic observations to assess model predictions and identify simulation parameters that generate realistic predictions of Earth surface evolution. Spot measurements of uplift or subsidence provide useful target observations for models of dynamic topography, but finding areas where tectonics have not also influenced vertical motions is challenging. To address this issue, we use large inventories of stratigraphic data from across North America with contextual geophysical and geodetic data to constrain the regional uplift and subsidence history. We demonstrate that a suite of typical geodynamic simulations struggle to match the amplitude, polarity and timing of observed vertical motions. Building on recent seismological advances, we then explore strategies for understanding patterns of continental uplift and subsidence that incorporate (and test) predicted evolution of the lithosphere, asthenosphere and deep mantle. Our results demonstrate the importance of contributions from the uppermost mantle in driving vertical motions of continental interiors.

Foreland basins are ideal laboratories to examine and quantify forces that contribute to Earth's topography. The interaction of these driving mechanisms (atmospheric, lithospheric and asthenospheric) affects the accumulation and preservation of strata in marine or terrestrial depocentres. For foreland basins that cover thousands of kilometres along orogens, geodynamic processes or lithospheric structure might differ and/or overlap differently along or across strike. The Magallanes-Austral basin in the southernmost Patagonia serves as a good analogue to analyse the interactions between subcrustal forces and foreland sedimentation. While to the northern part of southern Patagonia, Cenozoic basins were predominantly terrigenous and above sea level; at the southernmost end of Patagonia, sedimentation in the island of Tierra del Fuego was mostly submarine. We analysed in this contribution the southernmost foreland of Patagonia by combining backstripping with reconstruction of flexural and dynamic subsidence. These results were compared with terrestrial records exposed further north of southern Patagonia. We found that, in addition to crustal contributions (as deformation and sedimentation), subcrustal forces are required to accommodate the proximal and distal foreland strata and explain the palaeoenvironmental and subsidence discrepancies that resulted after our analysis. When our models are compared with dynamic topographic curves, strong correlations are observed during the Palaeogene, whereas strong topographic differences occurred in the Neogene. Dynamic topography models in the Neogene have reproduced clear uplift, whereas our residual topography results show equilibrium (close to the orogen) to subsidence values (to the distal foreland). We propose that changes in the lithospheric mantle had to work together with the rest of the tectonics and dynamic forces to match 1-D backstripping and flexural curves. This suggests that foreland basins in southern Patagonia were controlled differently along strike the southern Andes and that crustal deformation, asthenospheric flows and a heterogeneous lithospheric mantle structure affected the Cenozoic basin evolution. [ABSTRACT FROM AUTHOR]

Patterns of Phanerozoic burial and erosion across the cratonic interior of North America can help constrain the continental hypsometric history and the potential influence of dynamic topography on continental evolution. Large areas of the Canadian Shield currently lack Phanerozoic sedimentary cover, but thermochronology data can help reconstruct the previous extent, thickness, and erosion of Phanerozoic strata that once covered the craton. Here, we report apatite (U-Th)/He (AHe) data for 15 samples of Precambrian basement rocks and 1 sample of Triassic kimberlite from a 1400 km–long east–west transect across the southern Canadian Shield. Single-grain basement AHe dates range from >500 Ma in the west to <250 Ma in the east. AHe dates for the kimberlite in the middle of the transect overlap with the pipe's Triassic eruption age. These data, combined with previous apatite fission-track data, geologic constraints, and thermal history modeling, are used to constrain the first-order regional thermal history that we interpret in the context of continental burial and erosion. Our burial and erosion model is characterized by Paleozoic burial that was greater to the east, unroofing that migrated eastward through Jurassic time, and little to no post-Triassic burial. This pattern suggests dynamic and tectonic forces related to Appalachian convergence, subduction cessation, and later rifting as drivers. The AHe data contribute to efforts to collect thermochronology data across the Canadian Shield to map out continental-scale burial and erosion patterns. The outcomes can be used to refine mantle dynamic models and test how dynamic topography, far-field tectonics, and other effects influence the surface histories of continental interiors. [ABSTRACT FROM AUTHOR]

Variability in subsidence rates within Upper Cretaceous strata of the Western Interior Basin offers crucial insights into the response of surface sedimentation styles to Sevier‐to‐Laramide tectonics and related deep mantle processes. The formation mechanisms of the Late Cretaceous Western Interior Basin in North America have long been a subject of debate. A re‐evaluation of the basin's subsidence history reveals rapid subsidence pulses lasting ca. 2 Myr within longer‐term (average 5.7 Myr) progradational or aggradational clastic wedges. The timing of these wedges, especially the widespread marine flooding resulting from subsidence, is constrained through the calibration of ammonite zonation with absolute dates. Sevier wedges exhibit a different architecture compared to the Laramide wedges. The former recorded initial rapid and widespread marine transgressions followed by long‐term coastal progradation, whereas the latter developed by initial erosional and progradational growth followed by aggradation and long‐term coastal transgression. The Sevier clastic wedges, initially accumulated within a N‐S elongated, long‐wavelength tectonic subsidence zone close to the thrust belt, gradually migrated cratonward. Starting in the early Campanian (ca. 82 Ma), the Laramide Orogeny developed along a NW‐SE trend and then migrated northeastward, roughly consistent with coeval long‐wavelength frontal basin subsidence. The spatio‐temporal variations in long‐wavelength tectonic subsidence indicate a shift in the dynamic subsidence's migration direction from eastward to northeastward, driven by changes in Farallon subduction direction and mode. Our work shows how repeated subsidence behavior in the Sevier‐to‐Laramide transition records evolving architectural responses and the trajectory of coeval dynamic topography. Key Points: Shorter‐term rapid subsidence pulses discerned in longer‐term progradational or aggradational clastic wedges indicate the thrust eventsThe short‐term thrust events of Sevier‐to‐Laramide phase are recorded by different transgression‐regression geometric architecturesThe spatio‐temporal variations of long‐wavelength tectonic subsidence reveal migration of dynamic subsidence induced by plate subduction [ABSTRACT FROM AUTHOR]

For the period of satellite altimetry observation 1993–2018, a comparison was made of estimates of the linear meridional shifts of the jet structure and variations in current intensity in the sector of the Antarctic Circumpolar Current (ACC) south of Africa (10° E–25° W), obtained on the basis of the parameters derived from the module of the absolute dynamic topography (ADT) gradient : directly , module of the velocity of geostrophic current |u| on the ocean surface, half of square of the ADT gradient , and specific kinetic energy . The analysis was carried out by a method developed earlier and refined in this paper using linear regression analysis. It is shown that qualitatively the characters of the meridional shifts (displacement of the curves of these parameters averaged over latitude and for each year) in latitude and the corresponding current intensity variations (i.e., variations in the parameters themselves) over 26-year observations, when calculated through each of the four parameters, turned out to be similar. The same similarity was obtained from the calculations with respect to the ADT scale. Meanwhile, the quantitative differences between calculations for different pairs of parameters can be significant even in the and pair. In quantitative terms, the absolute values of shifts of the jet structure and variations in the intensity of currents in the ACC band in the studied sector of the Southern Ocean generally increase from those linearly dependent on the ADT gradient module to quadratically dependent ones. [ABSTRACT FROM AUTHOR]

Surface currents in oceanic environment are of vital importance from economical, biological and environmental aspects. Modelling ocean currents has generally been performed using numerical ocean circulation models as a solution to initial-boundary value problems in oceanic domain. Due to lack of knowledge about model parameters as well as initial and boundary values, they need to be externally calibrated for accurate local and regional applications. In this study, an alternative approach is proposed to incorporate spaceborne geodetic observations as well as hydrographic data to estimate the total surface current in the Persian Gulf and the Oman Sea. Being the data-driven approach, the method is comparable to numerical ocean models and regionally it is more accurate and simpler in application. The proposed method focuses on the computation of dynamic topography (DT) by least squares variance component estimation combining two different schemes. They are (1) DT estimation via direct observations of sea surface height from satellite altimetry and (2) steric and non-steric modeling of sea level anomaly using temperature and salinity data for the steric component; and Gravity Recovery and Climate Experiment observations for the non-steric component. Ultimately, the total surface current is obtained by computing the horizontal gradient of DT using geostrophic equation and adding the components of the Ekman current. Moreover, the estimated total surface current is further improved by assimilating with in situ current meter data using 3D-Variational data assimilation method and it is validated against two control stations. This assimilation leads to improvement of about 3 to 15 cm/s in total surface current computed using geostrophic equation and Ekman current. Besides, to illustrate the significance of the proposed approach, the estimated total surface current is externally validated and compared with the output of Copernicus Marine Environment Monitoring Service (CMEMS), as a numerical ocean model developed for oceanographic applications. Our comparison reveals that the proposed method is more accurate and reliable than CMEMS products. As for the circulation and current pattern, the estimated surface velocities reveal the existence of eddies in the region of the Persian Gulf and the Oman Sea, indicating the occurrence of cyclonic and anti-cyclonic circulations. Moreover, they elucidate that the velocities are lower in spring and summer and higher in autumn and winter. [ABSTRACT FROM AUTHOR]

Objectives: Our study aimed to investigate the feasibility of using high‐density surface electromyography (HD‐sEMG) for swallowing assessment by comparing the quantitative parameters and topographic patterns of HD‐sEMG between post‐irradiated patients and healthy individuals. Methods: Ten healthy volunteers and ten post‐irradiated nasopharyngeal carcinoma patients were recruited. 96‐channel HD‐sEMG was recorded although each participant consumed different consistencies of food (thin and thick liquid, puree, congee, and soft rice). Dynamic topography was generated from the root mean square (RMS) of the HD‐sEMG signals to illustrate the anterior neck muscle function in the swallowing process. The averaged power of muscles and the symmetry of swallowing patterns were assessed by objective parameters including average RMS, Left/Right Energy Ratio, and Left/Right Energy Difference. Results: The study showed different swallowing patterns between patients with dysphagia and healthy individuals. The mean RMS values were higher in the patient group compared to the healthy group, but the difference was not statistically significant. Asymmetrical patterns were shown in patients with dysphagia. Conclusion: HD‐sEMG is a promising technique that could be used to quantitatively evaluate the average power of neck muscles and the symmetry of swallowing activities in patients with swallowing difficulties. Level of Evidence: Level 3 Laryngoscope, 133:2920–2928, 2023 [ABSTRACT FROM AUTHOR]

Geoid anomalies offer crucial information on the internal density structure of the Earth, and thus, on its constitution and dynamic state. In order to interpret geoid undulations in terms of depth, magnitude and lateral extension of density anomalies in the lithosphere and upper mantle, the effects of lower mantle density anomalies need to be removed from the full geoid (thus obtaining the residual "upper mantle geoid"). However, how to achieve this seemingly simple filtering exercise has eluded consensus for decades in the solid Earth community. While there is wide agreement regarding the causative masses of degrees >10 in spherical harmonic expansions of the upper mantle geoid, those contributing to degrees <7–8 remain ambiguous. Here we use spherical harmonic analysis and recent tomography and density models from joint seismic‐geodynamic inversions to derive a representative upper mantle geoid, including the contributions from low harmonic degrees. We show that the upper mantle geoid contains important contributions from degrees 5 and 6 and interpret the causative masses as arising from the coupling between the long‐wavelength lithospheric structure and the sublithospheric upper mantle convection pattern. Importantly, the contributions from degrees 3 < l < 8 do not show a simple power‐law behavior (e.g., Kaula's rule), which precludes the use of standard filtering techniques in the spectral domain. Our upper mantle geoid model will be useful in studies of (a) lithospheric structure, (b) dynamic topography and mantle viscosity, (c) lithosphere‐asthenosphere interactions and (d) the global stress field within the lithosphere and its associated hazards. Plain Language Summary: Satellite measurements of the gravity field of the Earth constitute one of the most useful data sets to study the Earth's internal structure and its natural resources. A specific observation related to gravity is the so‐called geoid. Historically, the geoid has played a critical role in the development of theories regarding the inner workings of the Earth, including plate tectonics and earthquake activity. However, using geoid observations to constrain the structure of the tectonic plates down to depths of around 350 km is plagued with technical difficulties. This steam from the fact that the geoid is not only sensitive to the structure of the tectonic plates, but to the density structure of the entire planet. Removing the undesirable effects associated with the Earth's deep structure to isolate the signal related to the shallower tectonic plates has been, and still is, an unresolved problem. In this study, we present a new model of the Earth's geoid that achieves exactly that, thus providing a new way to study the internal constitution and structure of tectonic plates and the location of critical natural resources. Key Points: We present a new model of the upper mantle geoid to inform studies of the physical state of the lithosphere and sublithospheric upper mantleWe constrain the often ignored contributions of low degrees (<8) in spherical harmonic expansions of the upper mantle geoid and clarify their geodynamic origin and impact on lithospheric studies [ABSTRACT FROM AUTHOR]

Infections are a significant risk to patients who receive medical implants, and can often lead to implant failure, tissue necrosis, and even amputation. So far, although various surface modification approaches are proposed for prevention and treatment of microbial biofilms on indwelling medical devices, most are too expensive/complicated to fabricate, unscalable, or limited in durability for clinical use. Here, this work presents a new bottom‐up design for fabricating scalable and durable nano‐patterned coatings with dynamic topography for long‐term antibacterial effects. This work shows that MXene layer‐by‐layer (LbL) self‐assembled coatings—with finely tunable crumpled structures with nanometer resolution and excellent mechanical durability—can be successfully fabricated on stretchable poly(dimethylsiloxane) (PDMS). The crumpled MXene coating with sharp‐edged peaks shows potent antibacterial effects against Staphylococcus aureus and Escherichia coli. In addition, this work finds that on‐demand dynamic deformation of the crumpled coating can remove ≥99% of adhered bacterial cells for both species, resulting in a clean surface with restored functionality. This approach offers improved practicality, scalability, and antibacterial durability over previous methods, and its flexibility may lend itself to many types of biomaterials and implantable devices. [ABSTRACT FROM AUTHOR]

Subduction of bathymetric anomalies (e.g., an active ridge) can alter the morphology of subducted slabs and their coupling to surface processes. A natural laboratory to study these effects is the subduction of the Oceanic Chilean Ridge beneath the South American plate, which led to the formation of the Patagonian slab window. Its formation and subsequent northward migration contributed to the regression of Patagoniense sea and exhumation of marine strata to their present elevation. To date, there is no quantitative analysis of the effects on the sediment routing system of the slab window. We modeled the Neogene topographic change and foreland sedimentary evolution from the Andean Cordillera to Atlantic margin. Our results show that subcrustal‐driven subsidence correlated with accelerated subduction of the Nazca plate is required to explain the timing of the Patagonian transgression and thickness and spatial extent of marine beds during the incursion. In other words, traditional mechanisms, such as foreland flexure and global sea‐level rise, are insufficient. The subsequent regression and accumulation of mid‐Miocene alluvial‐fluvial deposits were associated with the growth of the Cordillera and a possible flattening of Nazca subduction in the middle Miocene. Isostatic uplift of ∼1 km due to lithospheric thinning during slab window formation can explain the foreland exhumation, sediment bypass, and increases in the offshore sedimentation rate. However, spatial‐temporal varying dynamic uplift is required to explain the along‐strike variations in foreland sedimentation. Our study provides new insights into the interplay between slab window formation, crustal deformation, and landscape evolution. Plain Language Summary: The geological evolution of southern Patagonia has been strongly affected by the subduction of Nazca Plate and the subsequent formation of Patagonian slab window. Different uplift and subsidence mechanisms have been proposed to explain its landscape and sedimentary history. However, it remains challenging to elucidate and quantify the impacts of contributing processes. This study focuses on modeling the surface evolution from the Andean Cordillera to the Atlantic margin over the entire Neogene. We propose that the landscape evolution of southern Patagonia involves three stages. Our results not only reveal the substantial contribution of Nazca Plate subduction to foreland sedimentation in early Miocene, but also a potential flattening of the subduction morphology in middle Miocene. Lastly, the isostatic uplift due to lithospheric thinning that accompanies Patagonian slab window formation could explain the foreland exhumation, sediment bypass, and increases in offshore sedimentation rate. Key Points: We modeled the landscape and sedimentary evolution across southern Patagonia and offshore basins since NeogeneThe Nazca plate subduction induced long‐wavelength foreland subsidence; it has likely flattened in mid‐Miocene, generating surface upliftThe Patagonian slab window affected the surface sediment routing system by generating isostatic/dynamic uplift since late Miocene [ABSTRACT FROM AUTHOR]

This prospective, double-masked, contralateral study aimed to analyze and compare daytime changes in pre-lens tear film (PLTF) stability and optical quality in symptomatic subjects wearing two contact lenses (CL). A secondary goal was to assess the performance of the PLTF by using dynamic topography techniques and analyzing surface asymmetry and irregularity indexes (SAI and SRI, respectively). Measurements were conducted on 20 symptomatic subjects (OSDI score > 13). Participants were fitted contralaterally and randomly with spherical Delefilcon A and Stenfilcon A CLs and underwent a series of measurements over 3 consecutive days: three in the morning (after 1–2 h of CL wear) and three in the afternoon (after 7–9 h of CL wear). High- and low-contrast visual acuity (HCVA and LCVA, respectively), pre-lens NIBUT, and dynamic topography were assessed. The contralateral fit of the two lenses allowed a direct and better comparison between them since they were exposed to the same conditions during the day. Consequently, both lenses demonstrated similar performance in HCVA, LCVA, and PLTF stability, with no statistically significant differences between them, although some fluctuations were observed throughout the day. Dynamic topography proved sensitive in evaluating temporal changes in the PLTF. The SRI index showed greater sensitivity to topographic changes due to lacrimal destabilization, making it potentially valuable for evaluating dry eye patients.

Abstract Infections are a significant risk to patients who receive medical implants, and can often lead to implant failure, tissue necrosis, and even amputation. So far, although various surface modification approaches are proposed for prevention and treatment of microbial biofilms on indwelling medical devices, most are too expensive/complicated to fabricate, unscalable, or limited in durability for clinical use. Here, this work presents a new bottom‐up design for fabricating scalable and durable nano‐patterned coatings with dynamic topography for long‐term antibacterial effects. This work shows that MXene layer‐by‐layer (LbL) self‐assembled coatings—with finely tunable crumpled structures with nanometer resolution and excellent mechanical durability—can be successfully fabricated on stretchable poly(dimethylsiloxane) (PDMS). The crumpled MXene coating with sharp‐edged peaks shows potent antibacterial effects against Staphylococcus aureus and Escherichia coli. In addition, this work finds that on‐demand dynamic deformation of the crumpled coating can remove ≥99% of adhered bacterial cells for both species, resulting in a clean surface with restored functionality. This approach offers improved practicality, scalability, and antibacterial durability over previous methods, and its flexibility may lend itself to many types of biomaterials and implantable devices.

Accurate determination of dynamic topography (DT) is expected to quantify a realistic sea surface with respect to its vertical datum and in identifying sub-mesoscale features of ocean dynamics. This study explores a method that derives DT by using satellite altimetry (SA) in conjunction with a high-resolution marine geoid model. To assess the method, DT was computed using along-track SA from Sentinel- 3A (S3A), Sentinel-3B (S3B), and Jason-3 (JA3), then compared with DT derived from a tide-gauge-corrected hydrodynamic model (HDM) for the period 2017–2019 over the Baltic Sea. Comparison of SA-derived DT and corrected HDM showed average discrepancies in the range of ±20 cm, with root mean square errors of 9 cm (for S3B) and 6 cm (for S3A and JA6) and a standard deviation between 2 and 16 cm. Inter-comparisons between data sources and multi-mission SA over the Baltic Sea also potentially identified certain persistent and semi-persistent problematic areas that are either associated with deficiencies in the geoid, tide gauge, HDM, and SA or a combination of all of these. In addition, it was observed that SA data have the potential to show a more realistic (detailed) variation of DT compared to HDM, which tended to generate only a smooth (low-pass) surface and underestimate DT. [ABSTRACT FROM AUTHOR]

The paper describes a method for analyzing the seasonal variability of the structure of the gradient field of the absolute dynamic topography (ADT) based on satellite altimetry data. This structure is understood as alternation in the meridional direction of zones of increased values of the ADT gradient modulus and zones of their lower values, i.e. jets and inter-jet gaps. The technique uses linear and harmonic regression analyses and makes it possible to calculate the amplitudes and phases of stationary harmonic oscillations that approximate seasonal variations in the meridional shift of the structure of the ADT gradient field and in the absolute values of the ADT gradient, as well as to estimate the calculation error. This technique was used to perform corresponding calculations for the Antarctic Circumpolar Current (ACC) band south of Africa (from 10° W to 25° E). In particular, the amplitude of the seasonal variations of the meridional shift of the ADT gradient field for the ACC as a whole was 0.009 ± 0.013° of latitude with a maximum northward shift in December. At the same time, there are zones within the ACC band where this amplitude reaches 0.12°, 0.16°, and 0.28° of latitude. The amplitude of the variations of the shift of the indicated field with respect to the scale of the ADT itself within the ACC band at different scale values is 0.6–2.5 cm. It is shown that this variations are mainly due to the seasonal variability of the ADT at geographic points. The amplitude of the seasonal variations of the ADT gradient modulus both in latitude and in relation the ADT scale increases from 1 × 10–3 cm/km in the central part of the ACC to 6–7 × 10–3 cm/km at the southern and northern peripheries. [ABSTRACT FROM AUTHOR]

The modelling errors of marine geoid models may reach up to a few decimetres in the shorter wavelength spectrum due to gravity data void areas and/or inaccurate data. Various data acquisition methods can provide sea surface heights more accurately. Similarly, hydrodynamic model data in conjunction with tide gauge readings allow the derivation of reliable dynamic topography. Geometrical marine geoid heights, independent of the usual gravity-based marine geoid models, can be obtained by removing the estimated dynamic topography from sea surface height measurements. This study exploits such geometry information to refine marine geoid models. A data assimilation approach was developed that iteratively combines sea surface height and dynamic topography datasets with an initial gravimetric geoid model. A case study is presented using sea surface heights from shipborne GNSS campaigns and an airborne laser scanning survey for refining the EIGEN-6C4 global geopotential model. Comparisons with a high-resolution regional marine geoid model reveal that the initial discrepancies of up to around two decimetres reduce to sub-decimetre within the study area. It is concluded that the developed iterative data assimilation approach can significantly improve the accuracy of marine geoid models, especially in regions where gravity data are of poor quality or unavailable. [ABSTRACT FROM AUTHOR]

Mantle‐induced dynamic topography (i.e., subsidence and uplift) has been increasingly recognized as an important process in foreland basin development. However, characterizing and distinguishing the effects (i.e., location, extent and magnitude) of dynamic topography in ancient foreland basins remains challenging because the spatio‐temporal footprint of dynamic topography and flexural topography (i.e., generated by topographic loading) can overlap. This study employs 3D flexural backstripping of Upper Cretaceous strata in the central part of the North American Cordilleran foreland basin (CFB) to better quantify the effects of dynamic topography. The extensive stratigraphic database and good age control of the CFB permit the regional application of 3D flexural backstripping in this basin for the first time. Dynamic topography started to influence the development of the CFB during the late Turonian to middle Campanian (90.2–80.2 Ma) and became the dominant subsidence mechanism during the middle to late Campanian (80.2–74.6 Ma). The area influenced by >100 m dynamic subsidence is approximately 400 by 500 km, within which significant (>200 m) dynamic subsidence occurs in an irregular‐shaped (i.e., lunate) subregion. The maximum magnitude of dynamic subsidence is 300 ± 100 m based on the 80.2–74.6 Ma tectonic subsidence maps. With the maximum magnitude of dynamic uplift being constrained to be 200–300 m, the gross amount of dynamic topography in the Late Cretaceous CFB is 500–600 m. Although the location of dynamic subsidence revealed by tectonic subsidence maps is generally consistent with isopach map trends, tectonic subsidence maps developed through 3D flexural backstripping provide more accurate constraints of the areal extent, magnitude and rate of dynamic topography (as well as flexural topography) in the CFB through the Late Cretaceous. This improved understanding of dynamic topography in the CFB is critical for refining current geodynamic models of foreland basins and understanding the surface expression of mantle processes. [ABSTRACT FROM AUTHOR]

We investigate the evolution of stress fields during the supercontinent cycle using the 2D Cartesian geometry model of thermochemical convection with the non-Newtonian rheology in the presence of floating deformable continents. In the course of the simulation, the supercontinent cycle is implemented several times. The number of continents considered in our model as a function of time oscillates around 3. The lifetime of a supercontinent depends on its dimension. Our results suggest that immediately before a supercontinent breakup, the over-lithostatic horizontal stresses in it (referring to the mean value by the computational area) are tensile and can reach −250 MPa. At the same time, a vast area beneath a supercontinent with an upward flow exhibits clearly the over-lithostatic compressive horizontal stresses of 50–100 МРа. The reason for the difference in stresses in the supercontinent and the underlying mantle is a sharp difference in their viscosity. In large parts of the mantle, the over-lithostatic horizontal stresses are in the range of ±25 MPa, while the horizontal stresses along subduction zones and continental margins are significantly larger. During the process of continent-to-continent collisions, the compressive stresses can approximately reach 130 MPa, while within the subcontinental mantle, the tensile over-lithostatic stresses are about −50 MPa. The dynamic topography reflects the main features of the supercontinent cycle and correlates with real ones. Before the breakup and immediately after the disintegration of the supercontinent, continents experience maximum uplift. During the supercontinent cycle, topographic heights of continents typically vary within the interval of about ±1.5 km, relatively to a mean value. Topographic maxima of orogenic formations to about 2–4 km are detected along continent-to-continent collisions as well as when adjacent subduction zones interact with continental margins.

Dynamic topography (DT) refers to the time-varying component of the sea surface height influenced by factors like ocean currents, temperature, and salinity gradients. Accurate estimation of DT is crucial for comprehending oceanic circulation patterns and their impact on climate. This study introduces two approaches to estimating DT: (1) utilizing satellite altimetry to directly observe sea surface height and (2) considering the steric and non-steric components of sea level anomalies. The steric term is calculated using salinity and temperature data obtained from local buoy data, Argo observations, and the World Ocean Atlas model. The non-steric term is calculated using GRACE Satellite gravimetry data. To estimate the assimilated DT, four methods are utilized, including variance component estimation (VCE), Bayesian theory, Kalman filter, and 3D variational (3DVAR). These methods assimilate the two aforementioned schemes. The validity of the estimated DT is assessed by comparing the calculated sea surface current, derived from the obtained DT, with observations from local current meter stations. The results indicate that the VCE method outperforms other methods in determining the final DT. Furthermore, incorporating the steric and non-steric terms of sea level in determining DT in coastal areas enhances the accuracy of estimating sea surface currents.

Lithospheric slab tearing, the process by which a subducted lithospheric plate is torn apart and sinks into the Earth’s mantle, has been proposed as a cause for surface vertical motions in excess of 100 s of meters. However, little is known about the mechanisms that help initiate and control the propagation of slab tearing and the associated uplift. This study aims to explore these processes by means of 3D thermo-mechanical geodynamic modelling of a slab retreat oblique to a continental margin, using the Gibraltar Arc region (Betic Cordillera) as a scenario for inspiration. Our results suggest that the obliquity of the continental passive margin relative to the subduction trench leads to an asymmetric distribution of subduction forces and strength, facilitating the initiation of slab tearing. The model results predict a lateral migration of the tearing point at a velocity ranging between 38 and 68 cm/yr for a sublithospheric-mantle viscosity of up to 1e+22 Pa s. This fast slab tearing propagation yields uplift rates of 0.23–2.16 mm/yr above the areas where the subducted slab is torn apart, depending on mantle viscosity. Although a more detailed parametric exploration is needed, this range of uplift rates is compatible with the uplift rates required to overcome seaway erosion along the Atlantic-Mediterranean marine corridors during the Late Miocene, as proposed for the onset of the Messinian Salinity Crisis.

This study presents a geophysical‐geochemical integrated model of the thermochemical structure of the lithosphere and uppermost mantle along a transect from the Northern Tyrrhenian Sea to the Pannonian Basin, crossing the northern Apennines, the Adriatic Sea, and the Dinarides fold‐thrust belt. The objectives are to image crustal thickness variations and characterize the different mantle domains. In addition, we evaluate the topographic response of opposed subductions along this transect and discuss their implications in the evolution of the region. Results show a more complex structure and slightly higher average crustal density of Adria compared to Tisza microplate. Below the Tyrrhenian Sea and Western Apennines, Moho lays at <25 km depth while along the Eastern Apennines it is as deep as 55 km. The modeled lithosphere‐asthenosphere boundary (LAB) below the Tyrrhenian Sea and Pannonian Basin is flat lying at ∼75 and 90 km, respectively. Below the External Apennines and Dinarides the LAB deepens to 150 km, slightly shallowing toward the Adriatic foreland basin at 125 km depth. Our results are consistent with the presence of two mantle wedges, resulting from the rollback of the Ligurian‐Tethys and Vardar‐NeoTethys oceanic slabs followed by continental mantle delamination of the eastern and western distal margins of Adria. These two opposed slabs beneath the Apennines and Dinarides are modeled as two thermal sublithospheric anomalies of −200°C. Most of the elevation along the profile is under thermal isostasy and departures can be explained by regional isostasy with an elastic thickness between 10 and 20 km. Plain Language Summary: This study integrates a wide range of geological and geophysical observations (e.g., elevation, gravity, geoid, seismic tomography) to investigate the density and temperature variations down to 400 km along a transect that extends from the Tyrrhenian Sea and northern Apennines in Italy to the Dinarides and Pannonian Basin in southern Europe. The main objectives are to study the present‐day structure and composition of the lithosphere and uppermost mantle, and to evaluate the resulting topography, and finally to discuss their implications in the tectonic evolution of the region. Our results show that the crust and the base of the lithosphere vary significantly in the study region, lying shallow below the basins to much deeper underneath the mountain belts where topography is higher. We also observe two cold and dense zones sitting in the distal margins of the Adria microplate, beneath the northern Apennines and Dinarides, that are interpreted as two opposed subducting slabs that have largely controlled the geodynamic evolution of the study region in the last 30 My. Key Points: A new thermochemical structure of the crust and uppermost mantle is obtained along the northern Apennines, Dinarides, and Pannonian BasinThe model distinguishes Adria and Tisza microplates with different crustal structures and lithosphere mantle compositionsTwo mantle wedges occur below the northern Apennines and Dinarides, resulting from the mantle delamination of Adria beneath its margins [ABSTRACT FROM AUTHOR]

Subduction zones are associated with spatially heterogeneous pressure fields that, depending on location, push/pull on Earth's surface producing dynamic topography (DT). Despite this, subduction zones, and associated pressure fields, are typically over‐simplified within global mantle flow models. Here, I use subduction models within a global domain to probe mantle pressure build‐up beneath subducting plates (SPs) and the resulting DT. Positive pressure develops beneath the SP in most subduction models. This produces positive DT (≤450 m) and tilts the SP upwards toward the trench (≤0.25 m/km). As SP size increases, the pressure magnitude increases producing greater topography/tilting. At a global scale, I find potential evidence for the modeled tilting in published residual topography. I argue that the rigorous incorporation of subduction zones into mantle flow models, and hence the inclusion of this signal, is needed to continue to bring future DT predictions and observational estimates into closer alignment. Plain Language Summary: Over millions of years, the solid mantle behaves as a fluid and its movement causes Earth's outer surface to deform (producing "dynamic" topography). Computational models of this movement are now able to match the main features of observational estimates of dynamic topography (DT), but models and observations do not match in all regions. Here, I explore whether a component of this mismatch could be due to a simplified treatment of subduction zones (i.e., plate boundaries where one tectonic plate descends beneath another) in these models. I create and analyze subduction models to isolate the topographic signature of subduction, focusing on topography above the subducting oceanic plate. In the models, mantle material gets trapped beneath the plate, which pushes up on the surface and produces positive topography. This upwards‐push also tilts the plate up toward the subduction zone. On average, this plate tilt appears to be present within observational estimates of Earth's DT, but more detailed future work is needed to confirm this. Key Points: Positive dynamic pressure develops beneath subducting plates in subduction models within global domainsSlab dip is inversely correlated with the magnitude of this positive pressureThis pressure produces positive oceanic dynamic topography and tilts the plate upwards toward the trench [ABSTRACT FROM AUTHOR]

Pacific‐Panthalassa plate tectonics are the most challenging on Earth to reconstruct during the Mesozoic and Cenozoic eras due to extensive subduction, which has resulted in large (>9,000 km length) unconstrained gaps between the Pacific and Laurasia (now NE Asia) back to the Early Jurassic. We build four contrasted NW Pacific‐Panthalassa global plate reconstructions and assimilate their velocity fields into global geodynamic models. We compare our predicted present mantle structure, synthetic geoid and dynamic topography to Earth observations. P‐wave tomographic filtering of predicted mantle structures allows for more explicit comparisons to global tomography. Plate reconstructions that include intra‐oceanic subduction in NW Pacific‐Panthalassa fit better to the observed geoid and residual topography, challenging popular models of Andean‐style subduction along East Asia. Our geodynamic models predict significant SE‐ward lateral slab advections within the NW Pacific basin lower mantle (∼2,500 km from Mesozoic times to present) that would confound "vertical slab sinking"‐style restorations of imaged slabs and past subduction zone locations. Plain Language Summary: Our knowledge of Earth's past tectonic plate configurations becomes increasingly uncertain going back into geologic time. Northwest Pacific‐Panthalassa plate tectonics along East Asia and the northern Pacific margin are among the most uncertain place on Earth to reconstruct during the Mesozoic‐Cenozoic eras. Numerous hypotheses have been proposed: one popular hypothesis suggests a large oceanic plate subducted continuously and exclusively under the eastern margin of Asia throughout Jurassic and Cretaceous times (i.e., Andean‐type subduction); a second hypothesis assumes that a number of smaller plates existed within the Northwestern Pacific that subducted both under the Asian margin and at offshore subduction zones (i.e., intra‐oceanic subduction). Using numerical models of mantle convection, we computed where each hypothesis predicts the subducted lithospheric plates to be at present in the Earth's interior. We compared these predictions against tomographic images of the Earth's mantle. We also calculated the gravitational attraction caused by the predicted mass distributions and compared them against the observed geoid. The warping of the Earth's surface caused by mantle flow was also computed and compared against non‐hydrostatic topography measurements. Our results favor plate reconstructions featuring intra‐oceanic subduction within Northwestern Pacific‐Panthalassa, with implications for past global CO2 and reconstructing disappeared ocean basins. Key Points: Six fully kinematic, end‐member western Pacific plate tectonic reconstructions were assimilated into global geodynamic modelsIntra‐oceanic subduction in western Pacific produces synthetic geoid and dynamic topography best fit observed geoid and residual topographyGeodynamic models predict significant SE‐ward lateral slab advections within NW Pacific lower mantle (∼2,500 km from Jurassic to present) [ABSTRACT FROM AUTHOR]

Abstract Pacific‐Panthalassa plate tectonics are the most challenging on Earth to reconstruct during the Mesozoic and Cenozoic eras due to extensive subduction, which has resulted in large (>9,000 km length) unconstrained gaps between the Pacific and Laurasia (now NE Asia) back to the Early Jurassic. We build four contrasted NW Pacific‐Panthalassa global plate reconstructions and assimilate their velocity fields into global geodynamic models. We compare our predicted present mantle structure, synthetic geoid and dynamic topography to Earth observations. P‐wave tomographic filtering of predicted mantle structures allows for more explicit comparisons to global tomography. Plate reconstructions that include intra‐oceanic subduction in NW Pacific‐Panthalassa fit better to the observed geoid and residual topography, challenging popular models of Andean‐style subduction along East Asia. Our geodynamic models predict significant SE‐ward lateral slab advections within the NW Pacific basin lower mantle (∼2,500 km from Mesozoic times to present) that would confound “vertical slab sinking”‐style restorations of imaged slabs and past subduction zone locations.

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The tectonics of East Asia are notoriously complex. Consisting of an intricate patchwork of microplates and accreted terranes, even the Cenozoic tectonic history of the region remains controversial, and many differing reconstructions have been proposed. While the exact kinematics remain poorly constrained, it is generally accepted that East Asia has been characterised by a long history of subduction and downwelling. However, numerous geological observations, at a first glance, appear to lie in stark contrast to this history. For example, seismically slow anomalies in the uppermost mantle are extensive in this region and coincide spatially with widespread intraplate volcanism since the latest Paleogene, which is seemingly at odds with the cold upper mantle and downwelling flow expected from a history of subduction. Here, we propose a solution to this paradox, in which hot asthenospheric material flows through the slab window opened by the subduction of the Izanagi-Pacific ridge during the early Cenozoic, passing from the Pacific domain into East Asia. To investigate this hypothesis, we compare several independent geological observations to the asthenospheric flow predicted by a suite of recently published global mantle circulation models. The timing and location of intraplate volcanism is compared with the predicted distribution of this hot material through time, while observations linked to uplift and erosion are compared to the changes in dynamic topography that it induces. These include the widespread late Eocene–Oligocene sedimentary hiatus in far eastern China and the regional erosion of the South China Block since the Miocene inferred from Apatite Fission Track Thermochronology studies. The westward influx of hot asthenospheric material is a robust feature in the models, being predicted regardless of the implemented Cenozoic tectonic reconstruction. However, we find that a small Philippine Sea Plate that overrides a marginal “vanished ocean” during the late Cenozoic provides an optimal fit to the geological observations considered. Flow of hot asthenospheric material through gaps in subduction has the potential to significantly affect the geodynamic and geologic history of backarc and hinterland regions, and might have been a recurring phenomenon throughout Earth’s history. However, further research will be required in order to establish this.

Kupavõh, A.; Delpeche-Ellmann, N.; Ellmann, A., and Soomere, T., 2024. Examining the performance of satellite altimetry (SWOT) sea level data in the coastal areas of the Baltic Sea. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 534-538. Charlotte (North Carolina), ISSN 0749-0208. The Surface Water and Ocean Topography (SWOT) satellite mission is expected to bring new possibilities for detecting and assessing water level both at sea and land. To explore its performance, the SWOT nadir altimeter (Poseidon-3C) and the new Ka-band Radar Interferometer (KaRIn) were examined in coastal areas of the eastern Baltic Sea using the 'Basic' version in July–December 2023 using 15 geoid referred tide gauges (TG), vertical land uplift model and a high resolution geoid BSCD2000. The use of geoid enabled a direct comparison with TG data. Comparison with SA and TG was performed with varying distance from the TG. Specific examination of SWOT performance was made in areas affected by archipelagos, islands and sea ice. On average KaRIn altimeter RMSD values are around 13 cm compared to that of the nadir altimeter of 10 cm. One of the benefits of KaRIn is the improved spatial resolution of sea level data. It shows promising capabilities of detecting marine dynamics in the coastal areas. KaRIn altimeter showed improved performance in near-coast areas for within 40 km from TG, 97% of valid measurements were retrieved and within 0–2 km around 40% of valid data was obtained. Sea level was also accurately determined in ice covered areas. [ABSTRACT FROM AUTHOR]

Mantle convection is a fundamental process that shapes the Earth's surface by providing the driving and resisting forces for horizontal motion of tectonic plates, as well as for inducing non-isostatic vertical motion commonly termed "dynamic topography". Growing observational constraints of past plate motion and dynamic topography have led to better understanding of the history of surface expression induced by mantle flow. Often these two surface motion signals are studied separately. However, the existence of a thin, mechanically weak asthenosphere allows geodynamicists to link horizontal and vertical motion changes together via mantle flow properties in the context of pressure-driven Poiseuille-type flow. In this paper, we utilize publicly available geologic and geophysical datasets to study early Paleogene plate kinematics and spatiotemporal evolution of dynamic topography in the North Atlantic region. We find that the North America (NAM) and Greenland (GRN) plates experienced a rapid kinematic change around late Paleocene–early Eocene, coinciding with episodes of surface uplift inferred from stage-resolution stratigraphic information around the North Atlantic, Labrador Sea and Baffin Bay. We quantitatively tie these surface motion signals together to underlying asthenospheric flow processes by estimating torque variations on NAM and GRN. These are parameterized in terms of reconstructed kinematic changes as well as predicted Poiseuille-type flow induced by increasing Icelandic plume flux and speedup of Farallon slab. Our analysis indicates (1) that the torque-change associated with the Icelandic plume flux closely resembles the ones inferred from kinematic reconstructions, and (2) that the inclusion of slab effects does not modify significantly such a scenario. Our findings shed light on the role of asthenospheric channelized flow generated by the Icelandic plume in influencing the early Paleogene North Atlantic surface dynamics. • The North American and Greenland plates experienced a speedup in the early Paleogene. • This speedup correlates with inferred uplifts of the North Atlantic region. • Torque analysis shows that the Icelandic plume drives both surface motion changes. [ABSTRACT FROM AUTHOR]

The Cretaceous-Cenozoic General Levalle rift basin (GLB) in Central Argentina, near 900 km east from the modern Chile-Peru trench, is an exploratory hydrocarbon frontier located within an intracratonic setting. The basin is 4.5 km deep and can be divided into three major evolutionary stages, synrift , intermediate and postrift. To date, the basin subsidence has not been yet addressed. We particularly made emphasis on the postrift sequence given that records of thousands of metres of Cretaceous and Cenozoic Strata and tectonic and thermal events are not known to account for these large accumulations. In this work we performed a backstripping analysis, in combination with a stretching-thermal model, which were then compared to different dynamic topography studies. From our backstripping models we found a typical rift basin curve, with the largest subsidence at the synrift stage followed by a decrease in values during the postrift. Assuming the synrift stage was driven by tectonic extension, we correlated the tectonic subsidence curve, obtained from backstripping studies, with a stretching-thermal subsidence model. The best fit among subsidence curves was obtained with a stretching factor β = 1.285. However, we observed a mismatch along the postrift part of both curves, resulting in a residual subsidence of ∼323 m. When this anomalous tectonic subsidence was compared to the latest six dynamic topography models, we found a good correlation with one of them. For the models that did not match and using simple isostatic computations, we estimated a lithospheric mantle thickening of 35.4 km to account for the residual subsidence and dynamic topography models. From our analysis it turns out that, in addition to stretching and thermal subsidence, mantle thickening in the lithosphere and in the asthenosphere, controlled the total subsidence in the General Levalle basin. The subduction history of Nazca Plate could have affected the postrift stage in this basin. • The tectonic subsidence curves show the highest values in the main basin depocenter. • The highest tectonic subsidence was estimated during the end of the synrift stage between 100 and 65 My. • The best fitting between stretching-thermal and backstripping curves was obtained using β = 1.285. • Comparison between different subsidence curves evidence a residual subsidence that can be explained by a mantle thickening of 35.4 km. [ABSTRACT FROM AUTHOR]

Topography and bathymetry are principally supported by some combination of crustal and sub‐crustal density variations. However, dynamic topography is generated by vertical deflection of the Earth's surface as a result of mantle convection. Isolating and quantifying observable dynamic topography yields valuable information about mantle processes. Here, we investigate global dynamic topography by calculating residual depth anomalies throughout the oceanic realm and residual topographic anomalies across the continents. We correct for sedimentary and crustal loading by exploiting a variety of seismologic datasets that include seismic reflection profiles, wide‐angle/refraction surveys, and receiver functions. In this way, an extensively revised and augmented global compilation of 10,874 oceanic residual depth measurements and 3,777 continental residual topographic measurements is constructed. In the oceanic realm, the methodology has been revised to improve accuracy and resolution. First, quartz/clay content of the sedimentary column is adjusted to remove minor skewness of residual depth anomalies as a function of plate age. Secondly, variation of bulk density as a function of crustal thickness is taken into account. Our global compilation is used to generate spherical harmonic representations of observable dynamic topography out to degree 40 (i.e., ∼1,000 km). Resultant spectra demonstrate that dynamic topographic power varies linearly with inverse wavenumber. The spectral slope directly reflects the way by which dynamic topography is generated by Stokes' flow. Our global results are consistent with independent and diverse geologic markers of uplift and subsidence together with Neogene‐Quaternary intraplate basalt magmatism. Plain Language Summary: The Earth's surface consists of interlocking tectonic plates that move with respect to each other at rates which we can now observe using the global positioning system. The story of how plate tectonics was discovered in the late 1960s is a very exciting one but the emphasis on horizontal movement of plates has tended to deflect attention away from a significant and related topic. Plate motion must be caused by slow stirring of the Earth's interior and this stirring should also generate lazy up‐and‐down displacement of the surface we live on. Unfortunately, these vertical movements are probably very slow and so hard to directly measure. In this study, we build upon previous attempts to measure vertical movements across the globe that we think can be attributed to slow stirring of the interior. Our analysis of depth measurements from the oceans and of anomalous topography onshore has enabled us to pinpoint the surface effects of stirring, which appear to occur on a whole host of length scales from hundreds of kilometers to tens of thousands of kilometers. Key Points: 7,601 seismic profiles yield residual depth measurements throughout the oceanic realmSpherical harmonic representations of dynamic topography are generated from combined oceanic and continental measurementsResultant power spectra are consistent with Stokes' flow of convecting mantle [ABSTRACT FROM AUTHOR]

Histories of large-scale horizontal and vertical lithosphere motion hold important information on mantle convection. Here, we compare continent-scale hiatus maps as a proxy for mantle flow induced dynamic topography and plate motion variations in the Atlantic and Indo-Australian realms since the Upper Jurassic, finding they frequently correlate, except when plate boundary forces may play a significant role. This correlation agrees with descriptions of asthenosphere flow beneath tectonic plates in terms of Poiseuille/Couette flow, as it explicitly relates plate motion changes, induced by evolving basal shear forces, to non-isostatic vertical motion of the lithosphere. Our analysis reveals a timescale, on the order of a geological series, between the occurrence of continent-scale hiatus and plate motion changes. This is consistent with the presence of a weak upper mantle. It also shows a spatial scale for interregional hiatus, on the order of 2000–3000 km in diameter, which can be linked by fluid dynamic analysis to active upper mantle flow regions. Our results suggest future studies should pursue large-scale horizontal and vertical lithosphere motion in combination, to track the expressions of past mantle flow. Such studies would provide powerful constraints for adjoint-based geodynamic inverse models of past mantle convection. [ABSTRACT FROM AUTHOR]

With an increasing demand for accurate and reliable estimates of sea surface heights (SSH) from coastal and marine applications, approaches based on GNSS positioning have become favored, to bridge the gap between tide gauge (TG) and altimetry measurements in the coastal zone, and to complement offshore altimetry data. This study developed a complete methodology for jointly deriving and validating shipborne GNSS-determined SSH, using a geoid model and realistic dynamic topography estimates. An approach that combines the properties of hydrodynamic models and TG data was developed to obtain the latter. Tide gauge data allow estimating the spatiotemporal bias of a hydrodynamic model and, thus, linking it to the used vertical datums (e.g., a novel geoid-based Baltic Sea Chart Datum 2000). However, TG data may be erroneous and represent different conditions than offshore locations. The qualities of spatiotemporal bias are, hence, used to constrain TG data errors. Furthermore, a rigid system of four GNSS antennas was used to ensure SSH accuracy. Besides eliminating the vessel's attitude effect on measurement data, the rigid system also provides a means for internal validation, suggesting a 4.1 cm height determination accuracy in terms of standard deviation. The methodology also involves eliminating the effect of sea state conditions via a low-pass filter and empirical estimation of vessel sailing-related corrections, such as the squat effect. The different data validation (e.g., examination of residual values and intersection analyses) results, ranging from 1.8 cm to 5.5 cm in terms of standard deviation, indicate an SSH determination accuracy of around 5 cm. [ABSTRACT FROM AUTHOR]

Marine and coastal applications require now more than ever accurate and expansive understanding of the marine surface topography in the offshore domain, with the relationship of sea surface heights and geoid (equipotential surface of the Earth) being the key components. This study demonstrates some of the under-utilised and unexplored marine applications of airborne laser scanning (ALS) with respect to geoid heights verification and validation, as well as identification of surface waves properties. A synergistic methodology was developed that combines ALS measurements, hydrodynamic models and tide gauge records in conjunction with geoid models. Examination of the determined discrepancies with respect to the ALS-derived sea surface heights reveals concealed characteristics of the geoid and dynamic topography. A sea surface height accuracy of 1.7 cm in terms of standard deviation was achieved using a high-resolution regional geoid model. Furthermore, ALS point cloud data can be used to retrieve surface wavefield properties (waves heights, wavelengths and directions). In this study a direct method approach is presented. Such a deeper insight into the wave dynamics plays an enormous contribution in the understanding and quantification of coastal processes (erosion and sediment transport), as well as validation and calibration of wave models and relevant sensors.