Relationship between the characteristics of landforms and sediments as well as the plume front in the Hangzhou Bay

Sedimentary environments in the Hangzhou Bay are introduced by a three-subregional landform pattern and a sedimentation map with six major sedimentation types. The geographic setting, sediment transportation and sedimentation in different subregions are discussed with sediment grain parameters. Sedimentary basin suffering from effect of plume front can be identified by the fine sediments with median ( Mdφ ) 7φ-8φ, clay content 30% - 40% and silt 60% - 70%. Sediment transportation along the plume front seems not to be a direct effect on sedimentary formation of the shoals fringing the south coast of the Hangzhou Bay.

Residual currents in plume front zone of the Hangzhou Bay

It is of some limitations to analyse residual currents by means of the 25 h anchored current measurements. On the basis of the drift tracking and the mooring system data, here, analyses have been done aiming at the structural characteristics and the dynamical mechanisms of the frontal residual current field of the Hangzhou Bay. Especially a theoritical model is given focusing on the frontal density-driven currents. The results indicate that there exists obviously the upper-layer front-driven flow along the orientation of the front during neap tides in the research area of the Hangzhou Bay. But the flow is restrained by the strong vortical viscosity during spring tides. In the lower layer, the effect of the front is little and the subtidal movements are dominated by the tide-induced residual currents. In addition, the influences of wind forcing to the residual current field are also suggested to be important.

Hydrographic features of the plume front in the Hangzhou Bay

A description is given of the distribution , spacial and temporal variation , mixing and transportation processes about the plume front in the Hangzhou Bay. This front is performed as a group of interfaces among, the water masses situated in the bay. A discussion is also given of the circulation feature in the frontal zone ence of the front.

Biogeochemical Character of Dissolved Inorganic Nitrogen and Phosphate at Plume Front in the Changjiang River

Biogeochemical character of dissolved inorganic nitrogen and phosphate at plume front is studied based on the data, which were observed in the Changjiang River Estuary in 1988. The results are as follows: The concentrations of nitrate and phosphate change abruptly -2+4at plume front and halocline. The concentrations of NO and NH are very high at 10~25 -33-4m depth. The vertical circumfluence transports NO and PO , which are released from organisms at the bottom to phytoplankton.

Observation of the supercritical Pearl River plume front under the downwelling-favorable winds

For the Pearl River plume, the supercritical, distinct plume front appears in downwelling-favorable winds, which is easily observed due to the distinct boundary between the plume water and the ambient water. In this paper, in situ and satellite observations of a plume front are utilized to explore the Pearl River plume front properties under the downwelling-favorable winds. Field observations clearly show frontal structure, especially the two-layer structure in the plume water and the downward-motion of water in the frontal region. The Advanced Synthetic Aperture Radar(ASAR) images are also analyzed to unveil the plume front: there is a white stripe on the west side out of the river mouth under downwelling-favorable winds, which is identified as a supercritical plume front, and the width of the plume front is about 250 m. The normalized velocity gradient shows the intense velocity convergence in the front region. Also, analyses of ASAR images imply that the river discharge plays an important role in controlling the location and shape of the front.

Plume-lithosphere interaction in the Comei Large Igneous Province: Evidence from two types of mafic dykes in Gyangze, south Tibet, China

Two suites of mafic dykes,T1193-A and T1194-A,outcrop in Gyangze area,southeast Tibet.They are in the area of Comei LIP and have indistinguishable field occurrences with two other dykes in Gyangze,T0902 dyke with 137.7±1.3 Ma zircon age and T0907 dyke with 142±1.4 Ma zircon age reported by Wang YY et al.(2016),indicating coeval formation time.Taking all the four diabase dykes into consideration,two different types,OIB-type and weak enriched-type,can be summarized.The“OIB-type”samples,including T1193-A and T0907 dykes,show OIB-like geochemical features and have initial Sr-Nd isotopic values similar with most mafic products in Comei Large Igneous Provinces(LIP),suggesting that they represent melts directly generated from the Kerguelen mantle plume.The“weak enriched-type”samples,including T1194-A and T0902 dykes,have REEs and trace element patterns showing withinplate affinity but have obvious Nb-Ta-Ti negative anomalies.They show uniform lowerεNd(t)values(−6‒−2)and higher 87Sr/86Sr(t)values(0.706‒0.709)independent of their MgO variation,indicating one enriched mantle source.Considering their closely spatial and temporal relationship with the widespread Comei LIP magmatic products in Tethyan Himalaya,these“weak enriched-type”samples are consistent with mixing of melts from mantle plume and the above ancient Tethyan Himalaya subcontinental lithospheric mantle(SCLM)in different proportions.These weak enriched mafic rocks in Comei LIP form one special rock group and most likely suggest large scale hot mantle plume-continental lithosphere interaction.This process may lead to strong modification of the Tethyan Himalaya lithosphere in the Early Cretaceous.

Experimental investigation of the inhibition of deep-sea mining sediment plumes by polyaluminum chloride

Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the potential solution of using polyaluminum chloride(PAC)in the water jet.The effects of PAC are examined through a self-designed simulation system for deep-sea polymetallic nodule collection and sediment samples from a potential deep-sea mining area.The experimental results showed that the optimal PAC dose was found to be 0.75 g/L.Compared with the test conditions without the addition of PAC,the presence of PAC leads to a reduction in volume,lower characteristic turbidity,smaller diffusion velocity,and shorter settling time of the plume.This indicates that PAC inhibits the entire development process of the plume.The addition of PAC leads to the flocculation of mm-sized particles,resulting in the formation of cm-sized flocs.The flocculation of particles decreases the rate of erosion on the seabed by around 30%.This reduction in erosion helps to decrease the formation of plumes.Additionally,when the size of suspended particles increases,it reduces the scale at which they diffuse.Furthermore,the settling velocity of flocs(around 10^(-2) m/s)is much higher that of compared to sediment particles(around 10^(-5) m/s),which effectively reduces the amount of time the plume remains in suspension.

U-Net Inspired Deep Neural Network-Based Smoke Plume Detection in Satellite Images

Industrial activities, through the human-induced release of Green House Gas (GHG) emissions, have beenidentified as the primary cause of global warming. Accurate and quantitative monitoring of these emissions isessential for a comprehensive understanding of their impact on the Earth’s climate and for effectively enforcingemission regulations at a large scale. This work examines the feasibility of detecting and quantifying industrialsmoke plumes using freely accessible geo-satellite imagery. The existing systemhas so many lagging factors such aslimitations in accuracy, robustness, and efficiency and these factors hinder the effectiveness in supporting timelyresponse to industrial fires. In this work, the utilization of grayscale images is done instead of traditional colorimages for smoke plume detection. The dataset was trained through a ResNet-50 model for classification and aU-Net model for segmentation. The dataset consists of images gathered by European Space Agency’s Sentinel-2 satellite constellation from a selection of industrial sites. The acquired images predominantly capture scenesof industrial locations, some of which exhibit active smoke plume emissions. The performance of the abovementionedtechniques and models is represented by their accuracy and IOU (Intersection-over-Union) metric.The images are first trained on the basic RGB images where their respective classification using the ResNet-50model results in an accuracy of 94.4% and segmentation using the U-Net Model with an IOU metric of 0.5 andaccuracy of 94% which leads to the detection of exact patches where the smoke plume has occurred. This work hastrained the classification model on grayscale images achieving a good increase in accuracy of 96.4%.

Iceland Plume and its Magmatic Manifestations:LIP-Dornr?schen in the North Atlantic

Plume-lithosphere interactions are key in the coupling of deep Earth and surface processes,impacting deformation and evolution of sedimentary basins and continental topography at different spatial scales(Cloetingh et al.,2022,2023).The North Atlantic region is a prime example of the interaction between plate tectonic movements and thermal instabilities in the Earth's mantle.The opening of the Labrador Sea/Baffin Bay and the North Atlantic,the widespread volcanism and the localized uplift of the topography in Greenland and the North Atlantic are traditionally attributed to the thermal effect of the Iceland mantle plume.

Sensitivity of Marine Controllable Source Electromagnetic Soundings for Identifying Plume Migration in Offshore CO_(2) Storage

Offshore carbon dioxide(CO_(2)) storage is an effective method for reducing greenhouse gas emissions. However, when using traditional seismic wave methods to monitor the migration of sequestration CO_(2) plumes, the characteristics of wave velocity changes tend to become insignificant beyond a certain limit. In contrast, the controllable source electromagnetic method(CSEM) remains highly sensitive to resistivity changes. By simulating different CO_(2) plume migration conditions, we established the relevant models and calculated the corresponding electric field response characteristic curves, allowing us to analyze the CSEM's ability to monitor CO_(2) plumes. We considered potential scenarios for the migration and diffusion of offshore CO_(2) storage, including various burial depths, vertical extension diffusion, lateral extension diffusion,multiple combinations of lateral intervals, and electric field components. We also obtained differences in resistivity inversion imaging obtained by CSEM to evaluate its feasibility in monitoring and to analyze all the electric field(Ex, Ey, and Ez) response characteristics. CSEM has great potential in monitoring CO_(2) plume migration in offshore saltwater reservoirs due to its high sensitivity and accuracy. Furthermore, changes in electromagnetic field response reflect the transport status of CO_(2) plumes, providing an important basis for monitoring and evaluating CO_(2)transport behavior during storage processes.

Influence of bias voltage and oxygen addition on the discharge aspects of a diffuse argon plume in an atmospheric pressure plasma jet

A remote plasma,also referred to as a plasma plume(diffuse or filamentary),is normally formed downstream of an atmospheric pressure plasma jet.In this study,a diffuse plume is formed by increasing the bias voltage(U_(b))applied to the downstream electrode of an argon plasma jet excited by a negatively pulsed voltage.The results indicate that the plume is filamentary when U_(b)is low,which transits to the diffuse plume with increasing U_(b).The discharge initiated at the rising edge of the pulsed voltage is attributed to the diffuse plume,while that at the falling edge contributes to the filament in the plume.For the diffuse plume,the discharge intensity decreases with the increasing oxygen content(C_o).Fast photography reveals that the diffuse plume results from a negative streamer,which has a dark region near the nozzle with C_o=0%.However,the dark region is absent with C_o=0.5%.From the optical emission spectrum,the electron density,electron excitation temperature,gas temperature,and oxygen atom concentration are investigated.

Impact of Viscous Dissipation and Ohmic Heating on Natural Convection Heat Transfer in Thermo-Magneto Generated Plume

The present investigation centers on the impact of viscous dissipation and ohmic heating on the plume generated by a line heat source under the impact of an aligned magnetic field.In this study,the flow model is adapted to incorporate ohmic heating and viscous dissipation by including the respective terms in the energy equation.A mathematical model is formulated as a system of coupled partial differential equations to analyze the flow problem.Subsequently,a numerical solution is derived with stream function formulation for the system of coupled partial differential equations,which transmutes it into ordinary differential equations.To achieve this,the numerical properties of the problem are established through the utilization of the Shooting method in tandem with the MATLAB tool bvp4c.The graphical representations of both missing and specified boundary conditions depict the effects of the magnetic parameter,viscous dissipation variable,magnetic force parameter,Prandtl number,and magnetic Prandtl number.These are accompanied by a discussion of their respective physical implications.The observed results claimed that the velocity,current density,and temperature distribution decrease for enhancing magnetic parameters.Meanwhile,the skin friction and magnetic flux drop while the heat transfer rate increases with an increment in magnetic parameters.These fluid flow and heat transfer characteristics were observed to decrease for increasing viscous dissipation.The current work is novel in incorporating ohmic heating viscous dissipation in energy equations coupled with Max-well and magnetic induction equations.

Analysis of high-power disk laser welding stability based on classification of plume and spatter characteristics

Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Characteristic parameters such as the area and number of spatters, the average grayscale of a spatter image, the entropy of a spatter grayscale image, the coordinate ratio of the plume centroid and the welding point, the polar coordinates of the plume centroid were defined and extracted. Karhunen-Loeve transform method was used to change the seven characteristics into three primary characteristics to reduce the dimensions. Also, K-nearest neighbor method was used to classify the plume and spatter images into two categories such as good and poor welding quality. The results show that plume and spatter have a close relationship with the welding stability, and two categories could be recognized effectively using K-nearest neighbor method based on Karhunen-Loeve transform.

Microwave Attenuation of Solid Propellant Exhaust Plume in Oblique Orientation

Aim To investigate the effects of the incident orientation on the microwave attenuation. Methods Attenuation allowing microwave signal transmitting in an oblique or vertical direction through the solid propellant exhaust plume was computed, and the experiments were performed utilizing a lab scale solid rocket motor with a fully expanded nozzle. Results The predicted results accord well with the experimental results. Conclusion The microwave attenuation in the oblique path is greater than that in the vertical path.

Computation of Electromagnetic Properties of Mildly Overexpanded and Underexpanded Rocket Exhaust Plume

An improved near far field divided coupled method was established to investigate the electromagnetic properties of mildly overexpanded and underexpanded rocket exhaust plumes. Firstly, axisymmetric Navier Stokes equations incorporated with k ε two equation turbulence models were solved using time dependent approach to calculate the pressure of the near filed. Secondly, parabolized axisymmetric Navier Stokes equations incorporated with finite rate chemical kinetics models were marching on the detailed pressure map of the near field. The termination of the near field would yield the initial line for the far field. In addition, in the far field, the spatial marching method was directly used under the constant pressure condition, but considering more complicated chemically reacting process. Finally, the electromagnetic parameters of the whole plume were calculated with the electron conductive model. The calculated results of the overexpanded and underexpanded rocket exhaust plume were discussed. The predicted microwave attenuation accorded with the experimental results. This improved method is feasible for calculating the microwave attenuation characteristics of mildly non fully expanded rocket exhaust plumes.

应用DNAPL plume快速评估场地DNAPL污染

地下水污染中DNAPL污染危害人体健康,且难以修复,所以对DNAPL污染的评估很重要。文章介绍了一种模拟DNAPL污染物运移的软件——DNAPL plume,并基于该软件快速评估场地DNAPL污染。针对长期污染泄漏场地的调查问题,本文简化了DNAPL plume模型,并用它快速评估燕子矶污染场地DNAPL污染,提出了修复建议。针对突发性污染泄漏场地的调查问题,本文模拟了一次假想的槽罐车泄漏事故,评估了这次事故对地下水的影响,并模拟了几种可行的修复方案,对比并选择了最优方案。

Geochemistry of Two Types of Basalts in the Emeishan Basaltic Province: Evidence for Mantle Plume-Lithosphere Interaction

Based on the temporal-spatial distribution and geochemical characteristics,the Emeishan basalts can be divided into two types: high-P_2O-TiO_2 basalt (HPT) andlow-P_2O_5-TiO_2 basalt (LPT), which differ distinctly in geochemistry: the LPTs are characterizedby relatively high abundances of MgO, total FeO and P_2O_5 and compatible elements (Cr, Ni, Sc), andrelatively low contents of moderately compatible elements (V, Y, Yb, Co), LREE and otherincompatible elements compared with the HPT. On the diagrams of trace element ratios, they areplotted on an approximately linear mixing line between depleted and enriched mantle sources,suggesting that these two types of basalts resulted from interactions of varying degrees betweenmantle plume and lithospheric mantle containing such volatile-rich minerals as amphibole andapatite. The source region of the LPT involves a smaller proportion of lithospheric components,while that of the HTP has a larger proportion of lithospheric components. Trachyte is generated bypartial melting of the basic igneous rocks at the base of the lower continental crust. Both the twotypes of magmas underwent certain crystal fractionation and contamination of the lower crest athigh-level magma chambers and en route to the surface.

Cascaded Evolution of Mantle Plumes and Metallogenesis of Core- and Mantle-derived Elements

Mineral deposits are unevenly distributed in the Earth's crust, which is closely related to the formation and evolution of the Earth. In the early history of the Earth, controlled by the gravitational contraction and thermal expansion, lighter elements, such as radioactive, halogen-family, rare and rare earth elements and alkali metals, migrated upwards; whereas heavier elements, such as iron-family and platinum-family elements, base metals and noble metals, had a tendency of sinking to the Earth's core, so that the elements iron, nickel, gold and silver are mainly concentrated in the Earth's core. However, during the formation of the stratified structure of the Earth, the existence of temperature, pressure and viscosity differences inside and outside the Earth resulted in vertical material movement manifested mainly by cascaded evolution of mantle plumes in the Earth. The stratifications and vertical movement of the Earth were interdependent and constituted the motive force of the mantle-core movement. The cascaded evolution of mantle plumes opens the passageways for the migration of deep-seated ore-forming material, and thus elements such as gold and silver concentrated in the core and on the core-mantle boundary migrate as the gaseous state together with the hot material flow of mantle plumes against the gravitational force through the passageways to the lithosphere, then migrate as the mixed gas-liquid state to the near-surface level and finally are concentrated in favorable structural expansion zones, forming mineral deposits. This is possibly the important metallogenic mechanism for gold, silver, lead, zinc, copper and other many elements. Take for example the NE-plunging crown of the Fuping mantle-branch structure, the paper analyzes ductile-brittle shear zone-type gold fields (Weijiayu) at the core of the magmatic-metamorphic complex, principal detachment-type gold fields (Shangmingyu) and hanging-wall cover fissure-vein-type lead-zinc polymetallic ore fields (Lianbaling) and further briefly analyzes the source of ore-forming material and constructs an ore-forming and -controlling model.

The dominant driving force for supercontinent breakup: Plume push or subduction retreat?

Understanding the dominant force responsible for supercontinent breakup is crucial for establishing Earth＇s geodynamic evolution that includes supercontinent cycles and plate tectonics. Conventionally,two forces have been considered： the push by mantle plumes from the sub-continental mantle which is called the active force for breakup, and the dragging force from oceanic subduction retreat which is called the passive force for breakup. However, the relative importance of these two forces is unclear. Here we model the supercontinent breakup coupled with global mantle convection in order to address this question. Our global model features a spherical harmonic degree-2 structure, which includes a major subduction girdle and two large upwelling（superplume） systems. Based on this global mantle structure,we examine the distribution of extensional stress applied to the supercontinent by both subsupercontinent mantle upwellings and subduction retreat at the supercontinent peripheral. Our results show that：（1） at the center half of the supercontinent, plume push stress is ～3 times larger than the stress induced by subduction retreat;（2） an average hot anomaly of no higher than 50 K beneath the supercontinent can produce a push force strong enough to cause the initialization of supercontinent breakup;（3） the extensional stress induced by subduction retreat concentrates on a ～600 km wide zone on the boundary of the supercontinent, but has far less impact to the interior of the supercontinent. We therefore conclude that although circum-supercontinent subduction retreat assists supercontinent breakup, sub-supercontinent mantle upwelling is the essential force.

Eastern Dharwar Craton,India:Continental lithosphere growth by accretion of diverse plume and arc terranes

Abstract Greenstone belts of the eastern Dharwar Craton, India are reinterpreted as composite tecto- nostratigraphic terranes of accreted plume-derived and convergent margin-derived magmatic sequences based on new high-precision elemental data. The former are dominated by a komatiite plus Mg-tholeiitic basalt volcanic association, with deep water siliciclastic and banded iron formation （BIF） sedimentary rocks. Plumes melted at 〈90 km under thin rifted continental lithosphere to preserve intrao- ceanic and continental margin aspects. Associated alkaline basalts record subduction-recycling of Me- soarchean oceanic crust, incubated in the asthenosphere, and erupted coevally with Mg basalts from a heterogeneous mantle plume. Together, komatiites-Mg basalts-alkaline basalts plot along the Phanero- zoic mantle array in Th/Yb versus Nb/Yb coordinate space, representing zoned plumes, establishing that these reservoirs were present in the Neoarchean mantle. Convergent margin magmatic associations are dominated by tholeiitic to calc-alkaline basalts compo- sitionally similar to recent intraoceanic arcs. As well, boninitic flows sourced in extremely depleted mantle are present, and the association of arc basalts with Mg-andesites-Nb enriched basalts-adakites documented from Cenozoic arcs characterized by subduction of young （〈20 Ma）, hot, oceanic litho- sphere. Consequently, Cenozoic style ＂hot＂ subduction was operating in the Neoarchean. These diverse volcanic associations were assembled to give composite terranes in a subduction-accretion orogen at -2.7 Ga, coevally with a global accretionary orogen at -2.7 Ga, and associated orogenic gold mineralization.