Dynamic Uplift Research Articles

Mechanism of Coupled Upper Troposphere and Boundary Layer Induces Two Types of Short‐Term Heavy Rainfall Along the Eastern Foothills of the Taihang Mountains

AbstractUsing 11 years of hourly merged rainfall records and ERA reanalysis data, this paper reveals two major circulation modes leading to two types of short‐term heavy rainfall (STHR) along the Taihang Mountains' eastern foothills, and further explains their mechanisms. One circulation mode has a distinct warm anomaly at 300 hPa covering most areas of North China, together with the boundary‐layer westerly anomaly occurring in North China and its southern region (UTWA‐BLWA). UTWA‐BLWA effectively contributes to the reinforcement of the upper‐level divergence and the low‐level moisture convergence by promoting the strengthening of upper anticyclonic and low‐level southwesterly anomalies. The combined effects of low‐level jet (LLJ) and topographic uplift form the central‐northern STHR pattern. The other circulation structure has a 300‐hPa warm anomaly located to the southeastern Russia and a prominent 300‐hPa cold anomaly covering the south, together with the boundary‐layer easterly anomaly occurring over the whole region of eastern China (UTCA‐BLEA). The southern STHR pattern is attributed to the exit of the boundary‐layer jet (BLJ) over lower elevations due to moist transport and dynamic uplift associated with the easterly anomaly. The results indicate that the locations of STHR are related to the direction, intensity, and height of the LLJ. The findings highlight that the upper‐tropospheric temperature anomalies (UTTA) and boundary‐layer easterly flow jointly modulate heavy rainfall. Analysis of the coupled upper troposphere and boundary layer could help understand and forecast heavy rainfall.

Palaeogeography and 3D variability of a dynamically uplifted shelf: Observations from seismic stratigraphy of the Palaeocene East Shetland Platform

AbstractIn 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.

A comparison of intense rainfall characteristics and mechanisms between monsoon onset and retreat over the Yangtze River Basin

ABSTRACT The thermodynamic and convective characteristics of the seasonal progression of the monsoon over eastern China are examined, with the aim of understanding why regional heavy rainfall events (RHREs) over the Yangtze River Basin (YRB) are more frequent and intense during the monsoon progression from mid-June to mid-July than during the retreat from mid-August to mid-September. During the monsoon progression, the southerly monsoon flow at low and mid-levels intensifies and moves northward, while the Western Pacific subtropical high shifts northeastward. These changes result in enhanced moisture advection over eastern China. The stronger southerly flow brings warmer and moist air into the YRB, leading to a higher equivalent potential temperature (θE) and favouring convection. Conversely, during the monsoon retreat, the northerly flow becomes stronger and drier, causing lower θE air over the YRB. Additionally, as the Western Pacific subtropical anticyclone retreats, easterly prevailing winds prevail over eastern China, causing reduced specific humidity. The monsoon progression period exhibits higher convective available potential energy but also higher convective inhibition, which is overcome by the presence of the monsoon front providing sufficient dynamical uplift. Understanding the severity of RHREs, particularly over the YRB, is crucial for improving forecasting capabilities and reducing societal vulnerability.

Nonlinear spring model for dynamic uplift behaviour of suction caisson under impact loading

Suction caissons are widely employed as support structures for various fixed or floating structures. The impact loading in extreme environment is a key condition for marine foundation design. In this paper, a nonlinear spring model is proposed to predict the dynamic behaviour of suction caisson under impact loading, and its reliability is verified by experimental tests and finite element simulations. A mass module is introduced to describe the foundation inertia action, and a novel component consisting of a reverse end bearing spring and a soil plug slider is developed to decouple the overall vertical stiffness of suction caisson. The friction module is updated with t-z springs positioned along the depth to reflect the stress distribution in the soil layer. Afterwards, the influence of impact loading amplitude and loading history are studied. For the impact loadings with different amplitude (Fu), the maximum vertical displacement of caisson is only 0.02D when the uplift loading reaches 0.4Fu, indicating a marked contribution of inertia force. It is recommended to properly consider foundation inertia action under high magnitude impact loading, which can effectively optimize the structure design. In light of this, a design chart for suction caisson applied in engineering practices is presented.

Unexpectedly High Magma Productivity Inferred From Crustal Roughness and Residual Bathymetry on the Eastern Part of the Ultra‐Slow Spreading Gakkel Ridge Since ∼45 Ma, Eurasian Basin, Arctic Ocean

AbstractThe Gakkel Ridge in the Eurasian Basin has the slowest seafloor spreading worldwide. The western Gakkel Ridge (3°W–85°E; 14–11 mm/a) alternate between magmatic and sparsely magmatic zones, while the eastern Gakkel Ridge (85–126°E; 11–6 mm/a) appears to be dominated by magmatic zones despite ultraslow spreading. Little is known about the seafloor spreading conditions in the past along the entire ridge. Here, we exploit the residual bathymetry and basement roughness to assess the crustal accretion process of the Gakkel Ridge over time using 23 published regional multichannel seismic reflection profiles. Full seafloor spreading rates were faster (20–24 mm/a) up to ∼45 Ma, and residual bathymetry for the older crust is deeper than the world average in the entire Eurasian Basin. There is a sharp transition to 300–400 m shallower residual bathymetry for seafloor <45 Ma in the eastern Eurasian Basin. The crustal roughness versus spreading rate of the western Eurasian Basin is on the global trend, while that of the eastern is significantly below. Both low roughness and shallow residual bathymetry of the eastern Eurasian Basin is close to that of oceanic crust for spreading rates above 30 mm/a, demonstrating increased magmatic production of the eastern Gakkel Ridge since ∼45 Ma. A recent mantle tomography model predicts partial melting in the upper mantle based on the low Vs anomaly underneath. The sedimentary pattern toward the Lomonosov Ridge indicates that this hot mantle anomaly started to cause dynamic uplift of the area at ∼45 Ma.

Unraveling the complex phylogeographic history of freshwater fishes in Lower Central America: A study of the electric fish Brachyhypopomus occidentalis

Lower Central America (LCA) has a complex biogeographic history shaped by the rise of the Isthmus of Panama and the global climatic oscillations of the Pleistocene. These events have been crucial in structuring biodiversity in LCA, but their consequences for the distribution and partitions of genetic diversity across the region remain to be elucidated. We combined complete mitochondrial genomes and nuclear ultraconserved elements (UCEs) to study the phylogeographic history and population genetic structure of the electric fish Brachyhypopomus occidentalis in LCA. Our results are consistent with the known phylogeographic history of B. occidentalis in LCA, but we update this history in several important ways that help illuminate the phylogeographic history of freshwater fishes in the region. We provide: i) support for three waves of colonization, two of which occurred prior to the final closure of the Panama Isthmus; ii) a more precise understanding of each colonization event, with evidence for a larger footprint of the first event, as well as genetic exchange across the continental divide in subsequent events; and iii) evidence for high levels of previously unrecognized population genetic structure across LCA. This updated model of colonization and diversification of B. occidentalis consists of three waves of dispersal and colonization, which triggered the evolution of geographic breaks in both nuclear and mitochondrial genomes across LCA. These processes are tightly linked to the dynamic uplift of the Isthmus, recent volcanic activity in the region, and the sea-level oscillations of the Pleistocene. These results improve previous phylogeographic inferences regarding the distribution and diversification of freshwater fishes in LCA, and generate testable hypotheses to guide future research exploring the factors shaping biodiversity in the region.

Designing, analyzing, and experimentally verifying a uniaxial shear box for investigating the length effect of buried pipelines during soil liquefaction

During an earthquake, buried pipelines can be threatened by various factors such as fault movement, ground motion, and soil liquefaction. Among these, fault movement and ground displacement have been identified as the most direct causes of pipeline fracture and rupture, as evidenced by previous earthquake disasters. While numerous studies have focused on the failure modes and mechanisms of pipelines crossing faults, little attention has been given to the dynamic uplift behavior of buried pipelines during soil liquefaction. To address such an issue, this study designed a uniaxial shear box to investigate the dynamic characteristics of buried pipelines during soil liquefaction. The box dimensions are 3600 mm × 1000 mm × 1100 mm and can embed a pipeline specimen of 3000 mm in length for testing. The seismic input motion direction is designed to be consistent with the axial direction of the pipeline to avoid lateral input motion influence. This study used DEEPSOIL analysis software to investigate whether the response of a uniaxial shear box under conditions of dry sand and saturated sand is consistent with theoretical analysis results. In addition, a preliminary test was conducted to ensure compliance with the requirements of subsequent pipeline tests, specifically on the uplift behavior of buried pipelines. The results showed that the soil dynamic responses under both dry sand and saturated sand conditions were consistent with the DEEPSOIL analysis software results. Furthermore, the pipeline test results verified that the input motion did not generate additional forces on the buried pipeline, but did indeed trigger soil liquefaction and cause the pipeline to uplift. These findings demonstrate that the uniaxial shear box designed in this study meets the design requirements and can be used to investigate the dynamic response of buried pipelines subjected to soil liquefaction under the influence of length effects in future studies.

Drainage rearrangement and landscape evolution: Insights from the Moroccan Massif Central

The Moroccan Massif Central, which is the largest massif of Paleozoic bedrock of the Western Meseta, is located in the foreland of the Alpine Rif orogenic belt. The massif underwent little Cenozoic deformation and represents a peripheral plateau between the Atlantic Ocean and the Cenozoic Middle Atlas chain.On the basis of field observations combined with topographic and fluvial analysis, we show that the upstream part of the Oum Rbia River, which originates from the Middle Atlas Mountains, was once flowing to the northwest in continuity with the Bou Regreg River, which drains the waters of the Moroccan Massif Central to the Atlantic Ocean. A Late Pliocene diversion occurred at the transition between the Middle Atlas and the Massif Central leading the Oum Rbia River to change its course to the southwest into the Tadla Basin and leaving the Bou Regreg River isolated and starved of upstream drainage area. The diversion is documented by a fluvial terrace preserved in a paleostream near the drainage divide between the Oum Rbia and the Bou Regreg catchments, as well as by river profiles and drainage divide instability.Owing to a loss in drainage area, the beheaded Bou Regreg River system could no longer equilibrate the sustained dynamic uplift, which is indicated by lithospheric thinning and Quaternary alkaline volcanism, while the neighboring catchments keep incising. Ultimately, this would have led to a steady decrease in surface relief of the Moroccan Massif Central with the formation of low-relief surfaces that characterize the area as expected by an area-loss feedback model. The bedrock uplift in the Moroccan Massif Central could be related to lithospheric folding associated with the Rif belt.

Patagonian landscape modeling during Miocene to Present-day slab window formation

The subduction of seismic oceanic ridges often results in the formation of slab windows, which can affect not only the heat flow and retroarc volcanism, but also the exhumation and topographic evolution of the upper plate. An active and world-class example of a slab window is southern Patagonia, in southernmost South America, which is related to the subduction of the seismic oceanic South Chile Ridge between the middle–late Miocene and the Present day. How the subduction of the ridge and formation of the slab window have influenced the evolution of the Patagonian landscape, exhumation and topography is still under debate. Some works have proposed orogenic deformation mostly affecting the Pacific margin and hinterland areas, or an inherited early Miocene tectonic relief generated before the slab window formation. Others have preferred epeirogenesis hypotheses, such as dynamic uplift or isostatic rebound as a result of lithospheric thinning associated with asthenospheric or lithospheric mantle changes. In this work, we analyze the landscape evolution at medium (orogen-scale) and long wavelengths (embracing the whole of southern Patagonia, from coast to coast) using FastScape a landscape numerical model. This program was coupled with an optimization scheme (the Neighborhood Algorithm) suitable for nonlinear inverse problems. The “goodness” (fit to data) of our landscape evolution models was evaluated using: i) cooling ages, and ii) maximum elevations, in order to provide constraints on the uplift rates, erosion efficiency and effective elastic thickness. We then used the best values to compare two forward models representing medium- versus long-wavelength processes. Our results indicate that long-wavelength uplift geometry (including dynamic uplift and/or lithospheric rebound from thinning) involving areas from the Andes to the Atlantic coast was required from 12 Myr to the Present day in order to reproduce not only the youngest cooling ages but also Present-day topography.

Constraining Characteristic Morphological Wavelengths for Venus Using Baltis Vallis

AbstractOne of Venus' most enigmatic landforms is Baltis Vallis, the longest channel on the surface (∼7,000 km long). We identify a possible mid‐channel island that implies a south to north flow direction during formation. However, since the flow direction of Baltis Vallis is otherwise not well constrained, we analyze topographic conformity in both flow directions. In either case, topography appears to be altered across most analyzed wavelengths after the formation of Baltis Vallis. Fourier analysis shows two ranges of prominent wavelengths, 225 ± 15 km and ∼3,500 ± 1,200 km. The shorter wavelengths correspond to deformation belts that cross Venus' low plains. The longest is plausibly associated with the dynamic uplift wavelength of the crust by mantle plumes, but is less robustly detected. Higher resolution observations provided by the VERITAS and EnVision missions can help resolve the source location of Baltis Vallis and constrain if the longest wavelength postdated the canale's formation.

Constraining the tectonic evolution of rifted continental margins by U–Pb calcite dating

We employ U–Pb calcite dating of structurally-controlled fracture fills within crystalline Caledonian basement in western Norway to reveal subtle large-scale tectonic events that affected this rifted continental margin. The ages (15 in total) fall into four distinct groups with ages mainly ranging from latest Cretaceous to Pleistocene. (1) The three oldest (Triassic-Jurassic) ages refine the complex faulting history of a reactivated fault strand originated from the Caledonian collapse and broadly correlate with known rifting events offshore. (2) Two ages of ca. 90–80 Ma relate to lithospheric stretching and normal fault reactivation of a major ENE-WSW trending late Caledonian shear zone. (3) We correlate five ages between ca. 70 and 60 Ma with far-field effects and dynamic uplift related to the proto-Iceland mantle plume, the effect and extent of which is highly debated. (4) The five youngest ages (< 50 Ma) from distinct NE–SW trending faults are interpreted to represent several episodes of post-breakup fracture dilation, indicating a long-lived Cenozoic deformation history. Our new U–Pb data combined with structural and isotopic data show that much larger tracts of the uplifted continental margin of western Norway have been affected by far-field tectonic stresses than previously anticipated, with deformation continuing into the late Cenozoic.

Mechanisms of Subsidence and Uplift of Southern Patagonia and Offshore Basins During Slab Window Formation

AbstractSubduction 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.

Lithospheric Stress Due to Mantle Convection and Mantle Plume over East Africa from GOCE and Seismic Data

The Afar and Ethiopian plateaus are in a dynamic uplift due to the mantle plume, therefore, considering the plume effect is necessary for any geophysical investigation including the estimation of lithospheric stress in this area. The Earth gravity models of the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) and lithospheric structure models can be applied to estimate the stress tensor inside the Ethiopian lithosphere. To do so, the boundary-value problem of elasticity is solved to derive a general solution for the displacement field in a thin elastic spherical shell representing the lithosphere. After that, general solutions for the elements of the strain tensor are derived from the displacement field, and finally the stress tensor from the strain tensor. The horizontal shear stresses due to mantle convection and the vertical stress due to the mantle plume are taken as the lower boundary value at the base of the lithosphere, and no stress at the upper boundary value of the lithospheric shell. The stress tensor and maximum stress directions are computed at the Moho boundary in three scenarios: considering horizontal shear stresses due to mantle convection, vertical stresses due to mantle plume, and their combination. The estimated maximum horizontal shear stresses’ locations are consistent with tectonics and seismic activities in the study area. In addition, the maximum shear stress directions are highly correlated with the World Stress Map 2016, especially when the effect of the mantle plume is solely considered, indicating the stress in the study area mainly comes from the plume.

Origin of the Sierras Pampeanas, Argentina: Flat-slab subduction and inherited structures

Abstract The Sierras Pampeanas (27°–33°S) in South America are characterized by basementcored uplifts and shortening that occurs &amp;gt;500 km from the nearest convergent margin. The deformation correlates spatially and temporally with an area of flat-slab subduction of the Nazca plate in the last 10 m.y. We use two-dimensional thermal-mechanical models to study the dynamics of Pampean flat-slab subduction and the origin of the Sierras Pampeanas. Models examine a geological time from ca. 12 Ma to present day, during which time the Juan Fernández Ridge subducted beneath South America. Models show that the buoyant ridge triggers slab flattening, resulting in regional continental compression through end loading at the plate margin. Deformation in the continental interior depends on the inherited structure of the continent, where surface uplifts and shortening are concentrated at preexisting weak zones. The inboard migration of deformation is controlled by surface topography caused by the buoyant ridge rather than basal shear from the growing flat slab. Deformation occurs prior to the passage of the ridge and is inhibited when the ridge is beneath the region owing to dynamic uplift.

Late Mesozoic multi-plate convergence in East Asia: Insights from 3-D global mantle flow models

Due to the Mesozoic multi-plate convergence, prominent continental marginal tectonic belts were formed in East Asia. The significant intra-continental magmatic events in the interior of East Asia were also closely related to the subduction of the surrounding oceans. Therefore, clarifying the subduction-related mantle dynamics during the Mesozoic super-convergence in East Asia is critical in understanding the crust-mantle interactions and the episodic tectono-magmatism. In this study, we obtain the subduction-related dynamic topography by coupling global mantle flow and plate reconstruction motions to capture the evolution scenarios in 200–90 Ma. Our modeling results are as follows: (1) In the Early Jurassic, the East Asian continental margin breakup is closely related to the mantle-driven dynamic topography. The offshore dynamic subsidence dominates the continental breakup. (2) The closure of the Paleo-Tethys Ocean and the subduction of the Bangonghu-Nujiang Ocean contribute to the southward migration of the dynamic topography. Concurrently, the continuous subduction of the Paleo-Pacific Plate leads to the onshore dynamic uplift, which results in subduction-related orogenesis in eastern East Asia. The dynamic uplift does not massively progress westward in Mainland China, suggesting that extensive intra-continental compressional deformation results from tectonic uplift rather than mantle-induced dynamic uplift. (3) The regression of the dynamic subsidence zone since 130 Ma marks the start of the topographic collapse in the East Asian continental margin through the back-arc extension. (4) The alternating compression-extension scenarios are identified in the main compressional and extensional stages, respectively, showing that dynamic topography is closely related to the evolution of the marginal tectonic belts in eastern East Asia. In conclusion, the subduction-related dynamic topography systematically reveals the deep dynamics involved in the formation, evolution, and collapse of the marginal tectonic belts in East Asia and is of great significance in understanding the related mantle dynamics during the Late Mesozoic.

Location, extent, and magnitude of dynamic topography in the Late Cretaceous Cordilleran Foreland Basin, USA: New insights from 3D flexural backstripping

AbstractMantle‐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 &gt;100 m dynamic subsidence is approximately 400 by 500 km, within which significant (&gt;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.

On the Contributions of the Northeast Cold Vortex to the Formation and Evolution of Backflow Blizzard

Blizzard is a severe weather-related disaster with significant environmental, economic, and social impacts. What is worse, the blizzard is increasingly frequent along with climate change. To enhance resilience, it is important to accurately estimate the blizzards. While some studies have reported the blizzard formation and characteristics, limited studies have not well presented the backflow blizzard associated with the cold vortex in Northeast China. In order to overcome this research gap, this study aims to analyze the characteristics of a backflow blizzard in Liaoning, China, and reveal the reasons behind the spatial heterogeneity of snowstorm intensity and duration. With observation data and mesoscale numerical simulation, this study discovered that the northeast cold vortex was the combined results of airflows from the Sea of Japan transported by the easterly airflow, the East China Sea, and the Yellow Sea transported by the southeast airflow, and the low-level southwest airflow, and the vortex was an important driver to the blizzard. Results further indicate that the interactions of airflow movement, water vapor variation, and frontogenesis occurrence at different layers caused the differences in snowfall intensity, duration, and volume at Zhangwu and Huanren stations. In particular, at Zhangwu station, there was an interaction of warm-wet and cold-dry airflows, but low-layer water vapor content was small, under which background only the cold air pushed the warm air as the southwest wind did not increase significantly, leading warm-humid air to be forced to climb and resulting in frontogenesis at 700–925 hPa. Therefore, the situation of no frontogenesis and poor humidity conditions in the low-level cold air contributed to the weak and a short-duration of snowfall at Zhangwu Station. The water vapor content of warm-wet and cold-wet airflows over Huanren station was better than that at Zhangwu so that during cold and warm air interaction, there was frontogenesis at 500–925 hPa. Near the top of the inverted trough in the ground layer, there was a convergence of the southeasterly wind and the northeasterly winds, resulting in the occurrence of horizontal frontogenesis throughout the layer of 500 hPa and forming an upward movement column. Moreover, a deep near-saturated water vapor layer formed below 600 hPa due to the upward movement column. Overall, the abundant water vapor combined with the deep dynamic uplift led to the heavy and long duration of snowfall at the Huanren station. Overall, this study is an important reference for understanding the backflow blizzard and its mechanism. Moreover, it is conducive to the accurate estimation of backflow blizzards in Northeast China and eastern China, the eastern coast of the Korean peninsula, and other similar areas where on the east part of the continent is the ocean.

The spatial-temporal variations in dynamic uplift and deep mantle upwelling in the northwest South China Sea margin: Insights into continental rifting and magmatism

Complex subduction system surrounding the South China Sea (SCS) region drove vigorous mantle upwelling, however, its time and pattern are not well constrained. Hot mantle upwelling induced broad OIB-type volcanisms, caused dynamic uplift, altered basin subsidence and was consecutively recorded by strata in the SCS region. The northwest SCS margin is located in the center of diffusive igneous provinces and featured by significant subsidence anomaly and along-strike variable rifting styles and magmatism, being an ideal place to explore the time-space variations in dynamic uplift and mantle upwelling, and reveal the effects on continental rifting and magmatism via seismic interpretation, strain rate calculation and residual subsidence analysis. Results show that the margin experienced two stages of extension during the syn-rifting period (45–23 Ma), a slow strain rate (1.5e-15 to 3.5e-15) in 45–28.4 Ma and a fast, eastward increasing strain rate (4e-15 to 7e-15) in 28.4–23 Ma. Subsidence analysis reveals that the entire margin initiated dynamic uplift and mantle upwelling at ca. 28.4 Ma, then increased to ca. 23 Ma, during which continental stretching and faulting were promoted, but the syn-rifting subsidence was inhibited. In the post-rifting period, mantle upwelling remained vigorous in 23–11.6 Ma, then decayed in 11.6–5.5 Ma to generate a fast post-rifting subsidence. Spatially, the dynamic uplift of more than 1 km has a long bar shape with the wider side in the east sub-basin, implying stronger mantle upwelling occurring in the east, which well explains why higher strain rates, more symmetric rifts and intense post-rifting magmatism (23–11.6 Ma) appeared in the east. Combined with plate reconstructions, it is inferred that the mantle return flow induced by slab subduction of the proto-SCS and the following SCS caused the mantle rising in the northwest SCS margin.

Uplift evolution along the Red Sea continental rift margin from stream profile inverse modeling and drainage analysis

Continental rifted margins can have complex uplift histories related to different processes including footwall uplift by mechanical unloading, dynamic uplift and interaction with transfer margins. Deciphering uplift histories along rift flanks is integral to understanding the margin evolution as a whole. Here, a combination of drainage analysis and stream profile inverse modeling is utilized to estimate the rift flank uplift along the north-eastern Red Sea onshore margin. The drainage network was extracted from an ASTER DEM (∼30 x 30 m-horizontal resolution) and the uplift history was calculated using an inverse model, which builds on the relationship between uplift, erosion and stream profile shape. Local relief, minimum erosion volumes and minimum erosion volume:catchment area ratios (Rva) were also calculated and compared to uplift estimates. Within the study area, small catchments represent footwall drainage and larger catchments are mostly associated with pre-rift structures and syn-rift accommodation zones. Uplift initiated in the southern part during early rifting (21-15 Ma) before shifting northward (12-0 Ma). This uplift distribution is reflected in Rva and relief maps. Early-rift uplift is interpreted as a record of early-rift faulting with possible additional mantle support, whereas later uplift was driven by fault linkage and mantle upwelling (12-6 Ma) as well as transform tectonics (6-0 Ma). These modeling results are largely in agreement with other independent data (low-temperature thermochronology and dated carbonate terraces). Our workflow benefits from its utilization of ubiquitous drainage data. The combination of drainage analysis and inverse modeling proves to be more discerning than either one method in isolation, and may have application to analysis of other margins.

Slow Geodynamics and Fast Morphotectonics in the Far East Tethys

AbstractHow can the sluggish, long‐wavelength mantle convection be expressed by so many time and space scales of morphotectonic activity? To investigate these relationships, we explore the Java‐Banda subduction zone, where geodynamic records cluster. In the far‐East Tethys, the exceptionally arcuate Banda subduction zone circumscribes the deepest oceanic basin on Earth, seismotectonic activity slices the upper plate more efficiently than anywhere else, and uncommonly vast expanses of continents are flooded in Sundaland and Northern Australia. By comparing numerical simulations of subduction dynamics to a set of independent observations, we reveal the many facets of tectonic and physiographic changes that the sole docking of the Australian continent onto the subduction zone triggered. While mantle flow remains slow and long‐wavelength at depth, intense tectonic activity, and dynamic uplift and subsidence profoundly rework the physiography at many spatial scales. These results demonstrate that a modest disruption in the slow geodynamic tempo may trigger manifold morphotectonic disturbances.