The spatiotemporal characterization of plume sedimentation and microorganisms is critical for developing plume ecological monitoring model.To address the limitations of traditional methods in obtaining high-quality se...The spatiotemporal characterization of plume sedimentation and microorganisms is critical for developing plume ecological monitoring model.To address the limitations of traditional methods in obtaining high-quality sediment,a novel sampling system with 6000 m operational capability and three-month endurance was developed.It is equipped with three sediment samplers,a set of formaldehyde preservation solution injection devices.The system is controlled by a low-power,timing-triggered controllers.To investigate low-disturbance rheological mechanisms,gap controlled rheological tests were conducted to optimize the structural design of the sampling and sealing assembly.Stress-controlled shear rheological tests were employed to investigate the mechanisms governing yield stress in sediments under varying temperature conditions and boundary roughness.Additionally,the coupled Eulerian-Lagrangian(CEL)method and sediment rheological constitutive models were employed to simulate tube-soil interaction dynamics and sediment disturbance.The radial heterogeneity of sediment disturbance and friction variation of the sampling tube were revealed.The tube was completely“plugged”at a penetration depth of 261 mm,providing critical data support to the penetration depth parameters.The deep-sea pressure test and South China Sea field trials demonstrated the system’s capability to collect and preserve quantitative time-series sediment samples with high fidelity.展开更多
Comprehending the flow behavior of deep-sea mining plumes is paramount for precise predictions of their propagation range and holds immense significance in advancing the commercial exploitation of deep-sea minerals.As...Comprehending the flow behavior of deep-sea mining plumes is paramount for precise predictions of their propagation range and holds immense significance in advancing the commercial exploitation of deep-sea minerals.As deep-sea mining plumes propagate,they can transition from high-density non-Newtonian fluids to low-density Newtonian fluids.However,a comprehensive rheological model capable of accurately describing this intricate evolutionary process is currently lacking.This study explores the variations in rheological properties observed during the propagation of deep-sea mining plumes,utilizing rheological test data obtained from kaolin clay plumes.Utilizing the Power Law model,we established a power exponential function correlating the plume rheological parameters(consistency index and flow behavior index)with a density range from 1.00 to 1.50 g/cm3 through data fitting,developing a rheological model of deep-sea mining plumes considering the variations in plume density.Subsequently,taking into account the differences in sediment properties,the effects of clay content and clay mineral composition on the rheological parameters of natural sediment plumes were compared and analyzed.This model provides a reference for understanding the rheological properties of deep-sea mining plumes during their propagation.展开更多
The buoyancy-induced flow constitutes a core scientific issue for thermal management of electronic devices and thermal design of energy systems,where accurate characterization of flow and heat transfer is essential to...The buoyancy-induced flow constitutes a core scientific issue for thermal management of electronic devices and thermal design of energy systems,where accurate characterization of flow and heat transfer is essential to improve thermal efficiency.In this work,buoyancy-induced flow above two heating elements flush-mounted at the bottom of a square enclosure containing air is numerically investigated over a range of Rayleigh numbers(0<Ra≤1.5×10^(8)),with a focus on equal and unequal heat flux conditions under a constraint of constant total thermal energy input.Distinct flow transitions are observed in both cases,leading to the identification of three flow regimes:Steady,periodic unsteady,and chaotic unsteady.Two types of periodic flows are distinguished,in which the first is a periodic flow dominated by a fundamental frequency(FF)and its integer-multiple frequencies(INTMF),while the second is a more complex periodic flow featuring FF,INTMF,and their sub-harmonics.The transitions between these regimes are affected by the relative heat flux of the two heaters.When the heat flux of the two heaters is unequal,the range of Rayleigh numbers corresponding to periodic flow is suppressed.It is also found that the time-averaged maximum temperature of the strong heater increases more rapidly with Ra,while that of the weak heater increases more slowly,reflecting the interaction between buoyancy-driven flow dynamics and asymmetric heat input.Analysis of the time-averaged Nusselt number demonstrates that heat dissipation from the isothermal walls remains roughly equivalent,even when the heat flux of the two heaters differs by a factor of two.These findings highlight the critical roles of Rayleigh number,the number of heaters,and the heat flux ratio of the heaters in determining heat transfer and flow characteristics for buoyancy-driven convection systems,providing important theoretical support and design references for engineering scenarios such as electronic devices and design of new energy systems.展开更多
The giant impact hypothesis for the Moon's origin has had difficulty explaining the nearly identical isotopic compositions of Moon rocks and rocks from Earth's silicate mantle and crust.These similarities are ...The giant impact hypothesis for the Moon's origin has had difficulty explaining the nearly identical isotopic compositions of Moon rocks and rocks from Earth's silicate mantle and crust.These similarities are instead more compatible with the Darwin-Wise hypothesis that the Moon arose by fission of a rapidly spinning Earth.To overcome problems with the fission model concerning structural stability and angular momentum conservation,some authors suggested that lunar fission was feasible on a more slowly rotating Earth if assisted by a nuclear explosion near the core-mantle boundary.In this light we consider the possible roles of the large low-velocity provinces(LLVPs).These long-lived structures have been implicated in diverse geophysical processes ranging from deep mantle plumes to continental breakup and mass extinction events.While the LLVPs have been seen as possible remnants of the giant imp actor,we propose that one of them was the site of lunar ejection.Internal heating of the liquid core is suggested to have given rise to an equatorial belt just under the core-mantle boundary analogous to the one recently detected by Ma and Tkalcic[Sci Adv 10(35):eadn5562,2024].Upwellings of heat and volatiles from this belt then generated two antipodal,equatorial bulges:the precursors of the Pacific and African LLVPs.Prior to the emergence of plate tectonics,core heat was mainly dissipated by networks of deep mantle plumes extending above the proto-LLVPs.These plume networks represent conduits of weakened mantle through which proto-lunar materials could later rise in a focused ejection.Continuing heat buildup in the core eventually triggered a cataclysmic explosion in the Pacific proto-LLVP,possibly analogous to a planetary-scale kimberlite eruption.This explosion launched LLVP and overlying mantle material into a low Earth orbit,where it coalesced to form the Moon.Some possible sources of additional energy to power the explosion are considered,including nuclear fission,bolide impacts and a hypothetical gravitational decay process culminating in a'A event'.展开更多
Geological CO_(2) storage is a promising strategy for reducing greenhouse gas emissions and has become a growing focus of research and deployment.This paper presents numerical simulations of CO_(2) injection and stora...Geological CO_(2) storage is a promising strategy for reducing greenhouse gas emissions and has become a growing focus of research and deployment.This paper presents numerical simulations of CO_(2) injection and storage in a depleted gas reservoir within the B Depression and evaluates associated CO_(2) trapping mechanisms.In the base case,a constant injection rate of 3500 m^(3)/d over fifteen years resulted in a cumulative injection of 19.2×10^(6) m^(3).The CO_(2) plume expanded radially during injection and subsequently migrated up-dip under buoyancy forces.The final stored mass of CO_(2) in the reservoir was 10.6 million tonnes(Mt),representing less than 10% of its theoretical capacity.The plume was projected to reach the entrapment crest and the top of the reservoir within a century,indicating secure long-term containment.Structural,stratigraphic,and residual trapping dominate in Reservoir A(approximately 90%).Anticlinal closures with thick overlying mudstones in the Zhujiang Formation provide effective seals,further enhancing storage security.Reservoir properties and heterogeneity play a crucial role in controlling CO_(2) storage.However,reservoir heterogeneity exerts only a limited influence when intrinsic properties are favorable.Overall,the study and implementation of CO_(2) capture,utilization,and storage(CCUS)in China's offshore basins show promising prospects.展开更多
Unsecured legacy wells pose significant risks to carbon capture and storage(CCS)as they present potential leakage pathways for stored CO_(2) to return to the atmosphere.In the UK,legacy wells must be assessed for a ca...Unsecured legacy wells pose significant risks to carbon capture and storage(CCS)as they present potential leakage pathways for stored CO_(2) to return to the atmosphere.In the UK,legacy wells must be assessed for a carbon storage permit to be granted and high-risk wells require costly remediation.We use a well risk assessment scheme to evaluate the risk of wells in the Southern North Sea.We then combine our well risk assessment with investigation using the analytical tool CO2BLOCK,which relies on a gravity current model to estimate pressure and plume migration distances.We evaluate the Viking,Camelot and Poseidon projects,which plan to inject CO_(2) into the depleted reservoirs of Southern North Sea gas fields.Carbon dioxide plumes are typically several kilometers wide,and it should be possible to avoid plume migration to high-risk legacy wells.In contrast,pressure fields produced by CO_(2) injection are tens of kilometers wide and low magnitude pressure increases frequently extend beyond the bounds of storage licence areas.The pressure fields encounter hundreds of wells and in the cases of the Camelot and Poseidon projects,interact with each other.展开更多
We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, an...We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in： contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes fiat subduction above the plume, resulting in a ＂bowed＂ shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau ~ plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the over- riding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian Orogen （Altiads）, which are characterised by accreted ophiolite complexes with diverse geochemical affinities, and a protracted evolution of accretion of exotic terranes includinu oceanic Dlateau and terranes with nlume origins.展开更多
Large igneous provinces（LIPs） formed by mantle superplume events have irreversibly changed their composition in the geological evolution of the Earth from high-Mg melts（during Archean and early Paleoproterozoic） t...Large igneous provinces（LIPs） formed by mantle superplume events have irreversibly changed their composition in the geological evolution of the Earth from high-Mg melts（during Archean and early Paleoproterozoic） to Phanerozoic-type geochemically enriched Fe-Ti basalts and picrites at 2.3 Ga.We propose that this upheaval could be related to the change in the source and nature of the mantle superplumes of different generations.The first generation plumes were derived from the depleted mantle,whereas the second generation（thermochemical） originated from the core-mantle boundary（CMB）.This study mainly focuses on the second（Phanerozoic） type of LIPs,as exemplified by the midPaleoproterozoic Jatulian-Ludicovian LIP in the Fennoscandian Shield,the Permian-Triassic Siberian LIP,and the late Cenozoic flood basalts of Syria.The latter LIP contains mantle xenoliths represented by green and black series.These xenoliths are fragments of cooled upper margins of the mantle plume heads,above zones of adiabatic melting,and provide information about composition of the plume material and processes in the plume head.Based on the previous studies on the composition of the mantle xenoliths in within-plate basalts around the world,it is inferred that the heads of the mantle（thermochemical） plumes are made up of moderately depleted spinel peridotites（mainly lherzolites）and geochemically-enriched intergranular fluid/melt.Further,it is presumed that the plume heads intrude the mafic lower crust and reach up to the bottom of the upper crust at depths-20 km.The generation of two major types of mantle-derived magmas（alkali and tholeiitic basalts） was previously attributed to the processes related to different PT-parameters in the adiabatic melting zone whereas this study relates to the fluid regime in the plume heads.It is also suggested that a newly-formed melt can occur on different sides of a critical plane of silica undersaturation and can acquire either alkalic or tholeiitic composition depending on the concentration and composition of the fluids.The presence of melt-pockets in the peridotite matrix indicates fluid migration to the rocks of cooled upper margin of the plume head from the lower portion.This process causes secondary melting in this zone and the generation of melts of the black series and differentiated trachytic magmas.展开更多
Leachate originating from open refuse dumpsite systems can be delineated through an integration of qualitative and quantitative methods. This study was designed to examine extent of leachate and pollution from one of ...Leachate originating from open refuse dumpsite systems can be delineated through an integration of qualitative and quantitative methods. This study was designed to examine extent of leachate and pollution from one of the numerous open refuse dumpsites in Lagos metropolis. Qualitative assessment was determined using electrical resistivity tomography (ERT), vertical electrical sounding (VES) and induced polarization geophysical methods. Both ERT and VES methods revealed persistent low resistivity (1 - 20 Ωm) of leachate to the depth above 35 m. The two methods were projected to produce 3-D view of the site which shows a NW-SE flow pattern of the leachate and possibly, the groundwater. IP values observed over the polluted zone was -2.9 - 8 ms, indicating a sandy layer. Quantitative assessment was achieved by analysis of geochemical substances in the water samples taken from wells and boreholes in the precinct of the dumpsite. Here, we examine the macroelements, salts (sulphates, nitrates and chlorides), heavy metals, radioactive metals contents and physical parameters of the water samples. The analyses reveal the presence of these substances in the water and their strong correlations justified the provenance as the same. As part of the quantitative evaluation, physical parameters (pH, TDS, DO, salinity, total hardness, turbidity, electrical conductivity EC and temperature) of the water samples were also determined. The samples pH plotted in the acidic domain unsuitable for human consumption. Leachate flow direction was generated from the decreasing concentration of measured parameters (geochemical elements and physicals properties) in NW-SE direction which agrees with similar flow pattern deduced from ERT results.展开更多
A 2D-3V implicit immersed-finite-element particle-in-cell(IFE-PIC)model is introduced to investigate the radio-frequency(RF)self-bias accelerating system applied in the RF ion thruster.A set of holes in a two-grid sys...A 2D-3V implicit immersed-finite-element particle-in-cell(IFE-PIC)model is introduced to investigate the radio-frequency(RF)self-bias accelerating system applied in the RF ion thruster.A set of holes in a two-grid system with slit apertures is simulated in Cartesian coordinates.The characteristics of the plasma plume,such as the ion density,the neutralization rate and the ion and electron current density were investigated for different RF voltage amplitudes(600-1200V)and frequencies(6-30 MHz).Furthermore,the performance of the thruster was also carefully studied.The simulation results show that a well-focused plasma beam can be formed when the voltage amplitude is larger than 900 V and the frequency exceeds the reciprocal of ion transit time(≥12 MHz)in our simulation cases.The performance of the system can be evidently improved by increasing the voltage amplitude and the frequency,and the losses of the particle and thrust are reduced correspondingly.The bulk region of the plasma beam downstream shows good quasi-neutrality,and the ions are dominant in the peripheral region when a well-focused state is achieved.The high ion density beamlet in the periphery of the ion beam is closer to the axis when the voltage amplitude is increasing,while it is expanded radially when increasing the frequency.Backstream electrons have been observed upstream,and this mainly occurs in the phase in which the electron cannot escape.展开更多
This paper presents fluid mechanics of ventilation system formed by the momentum source and the buoyancy source,which investigates inter-action between the plume and the non-isothermal air jet since buoyancy source is...This paper presents fluid mechanics of ventilation system formed by the momentum source and the buoyancy source,which investigates inter-action between the plume and the non-isothermal air jet since buoyancy source is produced by the plume and momentum source is generated by the air jet,respectively. The interaction is discussed by a mathematical model,an idealized situation of the plume rising from a point heat source of buoyancy alone-in particular the initial momentum flux at the source is zero. Furthermore,the paper discusses the effects of the parameters such as strength of source,air-flow volume and air-flow velocity used in the mathematical-physical model. Considering the effect of the plume generated by the indoor heat source,one expression of trajectory of the non-isothermal air jet produced by jet diffuser is deduced. And field-experiment has also been carried out to illustrate the effect on flowing-action of the air jet and validate the theoretical work. It can be concluded that the heat sources do have effect on the flowing-action of the air jet,and the effect mainly depends on the interaction produced by the plume and the air jet. The results show that the thermal buoyant effect of plumes on the air jet should be taken into account if the indoor heat sources are large enough. Numerical simulation is conducted and coincides with the experimental results as well.展开更多
We statistically validate the 2011-2022 earthquake prediction records of Ada, the sixth finalist of the 2nd China AETA in 2021, who made 147 earthquake predictions (including 60% of magnitude 5.5 earthquakes) with a p...We statistically validate the 2011-2022 earthquake prediction records of Ada, the sixth finalist of the 2nd China AETA in 2021, who made 147 earthquake predictions (including 60% of magnitude 5.5 earthquakes) with a prediction accuracy higher than 70% and a confidence level of 95% over a 12-year period. Since the reliable earthquake precursor signals described by Ada and the characteristics of Alfvén waves match quite well, this paper proposes a hypothesis on how earthquakes are triggered based on the Alfvén (Q G) torsional wave model of Gillette et al. When the plume of the upper mantle column intrudes into the magma and lithosphere of the soft flow layer during the exchange of hot and cold molten material masses deep inside the Earth’s interior during ascent and descent, it is possible to form body and surface plasma sheets under certain conditions to form Alfven nonlinear isolated waves, and Alfven waves often perturb the geomagnetic field, releasing huge heat and kinetic energy thus triggering earthquakes. To explain the complex phenomenon of how Ada senses Alvfen waves and how to locate epicenters, we venture to speculate that special magnetosensory cells in a few human bodies can sense earthquake precursors and attempt to hypothesize an algorithm that analyzes how the human biological nervous system encodes and decodes earthquake precursors and explains how human magnetosensory cells can solve complex problems such as predicting earthquake magnitude and locating epicenters.展开更多
Saline aquifers are considered as highly favored reservoirs for CO_(2)sequestration due to their favorable properties.Understanding the impact of saline aquifer properties on the migration and distribution of CO_(2)pl...Saline aquifers are considered as highly favored reservoirs for CO_(2)sequestration due to their favorable properties.Understanding the impact of saline aquifer properties on the migration and distribution of CO_(2)plume is crucial.This study focuses on four key parameters-permeability,porosity,formation pressure,and temperature-to characterize the reservoir and analyse the petrophysical and elastic response of CO_(2).First,we performed reservoir simulations to simulate CO_(2)saturation,using multiple sets of these four parameters to examine their significance on CO_(2)saturation and the plume migration speed.Subsequently,the effect of these parameters on the elastic properties is tested using rock physics theory.We established a relationship of compressional wave velocity(V_(p))and quality factor(Q_(p))with the four key parameters,and conducted a sensitivity analysis to test their sensitivity to V_(p) and Q_(p).Finally,we utilized visco-acoustic wave equation simulated time-lapse seismic data based on the computed V_(p) and Q_(p) models,and analysed the impact of CO_(2) saturation changes on seismic data.As for the above nu-merical simulations and analysis,we conducted sensitivity analysis using both homogeneous and heterogeneous models.Consistent results are found between homogeneous and heterogeneous models.The permeability is the most sensitive parameter to the CO_(2)saturation,while porosity emerges as the primary factor affecting both Q_(p) and V_(p).Both Q_(p) and V_(p) increase with the porosity,which contradicts the observations in gas reservoirs.The seismic simulations highlight significant variations in the seismic response to different parameters.We provided analysis for these observations,which serves as a valuable reference for comprehensive CO_(2)integrity analysis,time-lapse monitoring,injection planning and site selection.展开更多
The expansion of river plumes is essential for coastal systems and inner-shelf biogeochemical processes.This investigation employs the Coupled Ocean-Atmosphere-Wave-Sediment Transport(COAWST)modeling system to systema...The expansion of river plumes is essential for coastal systems and inner-shelf biogeochemical processes.This investigation employs the Coupled Ocean-Atmosphere-Wave-Sediment Transport(COAWST)modeling system to systematically analyze the governing mechanisms influencing the Changjiang River plume during winter conditions.Model validation through comparison with the observational datasets demonstrates the system’s capability to accurately reproduce hydrodynamic processes and thermohaline variability.A series of sensitivity experiments was implemented to quantify the relative contributions of distinct forcing mechanisms,including tidal dynamics,wind stress,and waveinduced processes on hydrodynamic patterns and associated temperature-salinity distributions.Numerical simulations reveal that wave-induced vertical mixing generates significant nearshore thermal elevation concurrent with salinity reduction.Tidal residual currents exhibit persistent onshore and northward components,potentially facilitating northward advection of the Changjiang River plume during winter months.Conversely,wind-driven currents impose a constraining effect on plume expansion through the establishment of downwelling-favorable circulation patterns.During extreme wave events,wave-driven current contributions to salinity variance account for 30%−90%,relative to tidal mixing effects.These findings collectively establish wave-current interaction as a critical mechanistic component governing wintertime Changjiang River plume dynamics,with particular relevance to stratification modification and cross-shelf transport processes.展开更多
Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative cont...Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative contributions to the overall evolution of rifting margins and possible roles in the formation of microcontinent are still elusive.Here,we use coupled geodynamic and surface processes numerical modeling to assess the extent to which surface processes may determine the formation of microcontinent during lithospheric stretching in presence or absence of a mantle plume underneath.Our modeling results indicate that fast extension rates and hillslope(i.e.,diffusion)erosion promote ridge jump events and therefore the formation of microcontinents.On the contrary,efficient fluvial erosion and far-reaching sediment transport(i.e.,stream power erosion)inhibits ridge jump events and the formation of microcontinents.The ridge jump event and overall evolution in our numerical models is consistent with the shift from the Mascarene Ridge to the Carlsberg Ridge that determined the formation of the Seychelles microcontinent.We therefore speculate that hillslope erosion,rather than fluvial erosion,was predominant during the formation of the Seychelles,a possible indication of overall dry local climate conditions.展开更多
At the end of the Cretaceous period,66 million years ago,the 7−19 km diameter Chicxulub asteroid hit the Yucatan Peninsula in Mexico,triggering global catastrophic environmental changes and mass extinction.The contrib...At the end of the Cretaceous period,66 million years ago,the 7−19 km diameter Chicxulub asteroid hit the Yucatan Peninsula in Mexico,triggering global catastrophic environmental changes and mass extinction.The contributions of this event towards changes in plate and plume geodynamics are not fully understood.Here we present a range of geological observations indicating that the impact marked a tectonic turning point in the behavior of mantle plume and plate motion in the Caribbean region and worldwide.At a regional scale,the impact coincides with the termination of seafloor spreading in the Caribbean Ridge.Shortly after the Cretaceous-Paleogene transition,magmatism associated with the Caribbean Large Igneous Province waned,and intensive Paleogene volcanism was initiated.These events happened synchronously with anomalously high mid-ocean ridge magmatism worldwide and an abrupt change in the relative motion of the South American and North American tectonic plates.The evidence for such abrupt changes in plate kinematics and plume behavior raises the possibility that the Chicxulub impact triggered a chain of effects that modified melt reservoirs,subducting plates,mantle flows,and lithospheric deformation.To explain how an asteroid impact could modify tectonic behavior,we discuss two end-member mechanisms:quasi-static and dynamic triggering mechanisms.We designed a numerical model to investigate the strain field and the relative plate motion before and after the impact.The model predicts an enhanced deformation associated with the impact,which surficially tapers off∼500 km from the crater.The impact modifies the subjacent mantle flow field,contributing to long-term mantle-driven dynamic changes.Additionally,deformation associated with seismic effects may have contributed to far-field effects and global changes.We conclude that large asteroid impacts,such as the Chicxulub collision,could trigger cascading effects sufficient to disrupt and significantly modify plate geodynamics.展开更多
The role of mantle plume in the final stages of rifting of the East Gondwana crustal fragments remains equivocal with only limited evidence so far reported from the southern part of Peninsular India.Here,we report for...The role of mantle plume in the final stages of rifting of the East Gondwana crustal fragments remains equivocal with only limited evidence so far reported from the southern part of Peninsular India.Here,we report for the first time a suite of columnar basalts from the Mesoarchean Coorg Block in the Southern Granulite Terrain(SGT)of India and characterize these rocks through field,petrological,geo-chemical,and isotope geochronological studies.The basalts show porphyritic texture with phenocrysts of pyroxene and plagioclase embedded in fine groundmass.Geochemical data reveal tholeiitic flood basalt affinity with affinities of plume-related magmatism.The zircon U-Pb data of the rocks yield a weighted mean age of 137 Ma,thus corresponding to the Valanginian Age of the Early Cretaceous Period.We suggest the possible geochemical affinity of the studied rocks Kerguelen plume basalts which provide new insights into magmatism associated with the final stages of East Gondwana rifting.展开更多
A wide northeast-trending belt of intraplate alkaline volcanism,exhibiting similar geochemical characteristics,stretches from the Eastern Atlantic Ocean to the Cenozoic rift system in Europe.Its formation is associate...A wide northeast-trending belt of intraplate alkaline volcanism,exhibiting similar geochemical characteristics,stretches from the Eastern Atlantic Ocean to the Cenozoic rift system in Europe.Its formation is associated with both passive and active mechanisms,but it remains a source of ongoing debate among geoscientists.Here,we show that seismic whole-mantle tomography models consistently identify two extensive low-velocity anomalies beneath the Canary Islands(CEAA)and Western-Central Europe(ECRA)at mid-mantle depths,merging near the core-mantle boundary.These low-velocity features are interpreted as two connected broad plumes originating from the top of the African LLSVP,likely feeding diapir-like upwellings in the upper mantle.The CEAA rises vertically,whereas the ECRA is tilted and dissipates at mantle transition zone depths,possibly due to the interaction with the cold Alpine subducted slab,which hinders its continuity at shallower depths.While plate-boundary forces are considered the primary drivers of rifting,the hypothesis that deep mantle plumes play a role in generating volcanic activity provides a compelling explanation for the European rift-related alkaline volcanism,supported by geological,geophysical,and geochemical evidence.展开更多
Eastern Sichuan Basin is a critical region for oil and gas production in China,and the thermal effect of the Emeishan Mantle Plume(EMP) on the basin remains unclear,which limits the study of the Paleozoic hydrocarbon ...Eastern Sichuan Basin is a critical region for oil and gas production in China,and the thermal effect of the Emeishan Mantle Plume(EMP) on the basin remains unclear,which limits the study of the Paleozoic hydrocarbon accumulation process.Thus,clarifying the thermal history is crucial for oil and gas evaluation and exploration.This study combines zircon fission track(ZFT),zircon(U-Th)/He(ZHe),and vitrinite reflectance analyses to reconstruct the thermal history since the Paleozoic and investigate the maturity evolution of Paleozoic source rocks in the eastern Sichuan Basin.Additionally,the contributing factors of the Permian abnormal heat flow and the thermal effect range of the EMP were analyzed.Thermal history results show a stable low heat flow phase(45-55 mW/m^(2)) from the Cambrian to Permian,a rapid increase to peak values(62-70 mW/m^(2)) during the Middle Permian,and a gradual decline to current stable values(47-62 mW/m^(2)) from the Triassic onward.Thermal evolution revealed that Paleozoic source rocks exhibited maturation stagnation due to tectonic events,while the Permian peak heat flow and the Jurassic-Late Cretaceous rapid burial accelerated maturation.The Cambrian Qiongzhusi Formation and Silurian Longmaxi Formation source rocks began generating hydrocarbons(R_(equ)=0.5%) in the Late Cambrian-Late Ordovician and Late Silurian-Early Devonian,respectively,while it was Late Permian-Early Triassic for Permian source rocks.Peak maturity(R_(equ)> 2%) occurred in the Late Cretaceous,with natural gas as the dominant product The EMP significantly influenced the thermal regime of the western and central Sichuan Basin,with a thermal effect radius of~600-650 km.In contrast,the Permian thermal anomaly in the eastern Sichuan Basin is attributed to the lithospheric extension associated with the Middle Permian Kaijiang-Liangping trough.These findings provide critical insights for deep and ultra-deep gas exploration and enhance the understanding of the EMP's regional thermal impacts.展开更多
The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and ...The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and conducted to investigate the morphological characteristics and concentration evolution of the sediment plumes under different discharge rates(Q)and initial sediment concentrations(c).Viscosity tests,resuspension tests and free settling tests of the sediment solution with different c values were performed to reveal the settling mechanism of the plume diffusion process.The results show that the plume diffusion morphology variation in flowing water has four stages and the plume concentration evolution has three stages.The larger the Q,the smaller the initial incidence angle at the discharge outlet,the larger the diffusion range,the poorer the stability and the more complicated the diffusion morphology.The larger the c,the larger the settling velocity,the faster the formation of high-concentration accumulation zone,the better the stability and the clearer the diffusion boundary.The research results could provide experimental data for assessing the impact of deep-sea mining on the ocean environment.展开更多
基金supported by the National Key R&D Program of China(No.2022YFC2803900)the National Natural Science Foundation of China(No.42276191)Zhejiang University Students Science and Technology Innovation Activity Plan(New Talent Plan)(No.2024R401185).
文摘The spatiotemporal characterization of plume sedimentation and microorganisms is critical for developing plume ecological monitoring model.To address the limitations of traditional methods in obtaining high-quality sediment,a novel sampling system with 6000 m operational capability and three-month endurance was developed.It is equipped with three sediment samplers,a set of formaldehyde preservation solution injection devices.The system is controlled by a low-power,timing-triggered controllers.To investigate low-disturbance rheological mechanisms,gap controlled rheological tests were conducted to optimize the structural design of the sampling and sealing assembly.Stress-controlled shear rheological tests were employed to investigate the mechanisms governing yield stress in sediments under varying temperature conditions and boundary roughness.Additionally,the coupled Eulerian-Lagrangian(CEL)method and sediment rheological constitutive models were employed to simulate tube-soil interaction dynamics and sediment disturbance.The radial heterogeneity of sediment disturbance and friction variation of the sampling tube were revealed.The tube was completely“plugged”at a penetration depth of 261 mm,providing critical data support to the penetration depth parameters.The deep-sea pressure test and South China Sea field trials demonstrated the system’s capability to collect and preserve quantitative time-series sediment samples with high fidelity.
基金Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering with grant at Ocean University of China,Grant/Award Numbers:MEGE2024001,MEGE2024002National Natural Science Foundation of China,Grant/Award Number:42207181+2 种基金Fundamental Research Funds for the Central Universities,Grant/Award Number:202441003Opening Fund of the State Key Laboratory of Coastal and Offshore Engineering at Dalian University of Technology,Grant/Award Number:LP2310National Key Research and Development Program of China,Grant/Award Number:2024YFC2815400。
文摘Comprehending the flow behavior of deep-sea mining plumes is paramount for precise predictions of their propagation range and holds immense significance in advancing the commercial exploitation of deep-sea minerals.As deep-sea mining plumes propagate,they can transition from high-density non-Newtonian fluids to low-density Newtonian fluids.However,a comprehensive rheological model capable of accurately describing this intricate evolutionary process is currently lacking.This study explores the variations in rheological properties observed during the propagation of deep-sea mining plumes,utilizing rheological test data obtained from kaolin clay plumes.Utilizing the Power Law model,we established a power exponential function correlating the plume rheological parameters(consistency index and flow behavior index)with a density range from 1.00 to 1.50 g/cm3 through data fitting,developing a rheological model of deep-sea mining plumes considering the variations in plume density.Subsequently,taking into account the differences in sediment properties,the effects of clay content and clay mineral composition on the rheological parameters of natural sediment plumes were compared and analyzed.This model provides a reference for understanding the rheological properties of deep-sea mining plumes during their propagation.
基金supported by the Tianjin Education Commission Research Program Project(No.2024KJ105)。
文摘The buoyancy-induced flow constitutes a core scientific issue for thermal management of electronic devices and thermal design of energy systems,where accurate characterization of flow and heat transfer is essential to improve thermal efficiency.In this work,buoyancy-induced flow above two heating elements flush-mounted at the bottom of a square enclosure containing air is numerically investigated over a range of Rayleigh numbers(0<Ra≤1.5×10^(8)),with a focus on equal and unequal heat flux conditions under a constraint of constant total thermal energy input.Distinct flow transitions are observed in both cases,leading to the identification of three flow regimes:Steady,periodic unsteady,and chaotic unsteady.Two types of periodic flows are distinguished,in which the first is a periodic flow dominated by a fundamental frequency(FF)and its integer-multiple frequencies(INTMF),while the second is a more complex periodic flow featuring FF,INTMF,and their sub-harmonics.The transitions between these regimes are affected by the relative heat flux of the two heaters.When the heat flux of the two heaters is unequal,the range of Rayleigh numbers corresponding to periodic flow is suppressed.It is also found that the time-averaged maximum temperature of the strong heater increases more rapidly with Ra,while that of the weak heater increases more slowly,reflecting the interaction between buoyancy-driven flow dynamics and asymmetric heat input.Analysis of the time-averaged Nusselt number demonstrates that heat dissipation from the isothermal walls remains roughly equivalent,even when the heat flux of the two heaters differs by a factor of two.These findings highlight the critical roles of Rayleigh number,the number of heaters,and the heat flux ratio of the heaters in determining heat transfer and flow characteristics for buoyancy-driven convection systems,providing important theoretical support and design references for engineering scenarios such as electronic devices and design of new energy systems.
文摘The giant impact hypothesis for the Moon's origin has had difficulty explaining the nearly identical isotopic compositions of Moon rocks and rocks from Earth's silicate mantle and crust.These similarities are instead more compatible with the Darwin-Wise hypothesis that the Moon arose by fission of a rapidly spinning Earth.To overcome problems with the fission model concerning structural stability and angular momentum conservation,some authors suggested that lunar fission was feasible on a more slowly rotating Earth if assisted by a nuclear explosion near the core-mantle boundary.In this light we consider the possible roles of the large low-velocity provinces(LLVPs).These long-lived structures have been implicated in diverse geophysical processes ranging from deep mantle plumes to continental breakup and mass extinction events.While the LLVPs have been seen as possible remnants of the giant imp actor,we propose that one of them was the site of lunar ejection.Internal heating of the liquid core is suggested to have given rise to an equatorial belt just under the core-mantle boundary analogous to the one recently detected by Ma and Tkalcic[Sci Adv 10(35):eadn5562,2024].Upwellings of heat and volatiles from this belt then generated two antipodal,equatorial bulges:the precursors of the Pacific and African LLVPs.Prior to the emergence of plate tectonics,core heat was mainly dissipated by networks of deep mantle plumes extending above the proto-LLVPs.These plume networks represent conduits of weakened mantle through which proto-lunar materials could later rise in a focused ejection.Continuing heat buildup in the core eventually triggered a cataclysmic explosion in the Pacific proto-LLVP,possibly analogous to a planetary-scale kimberlite eruption.This explosion launched LLVP and overlying mantle material into a low Earth orbit,where it coalesced to form the Moon.Some possible sources of additional energy to power the explosion are considered,including nuclear fission,bolide impacts and a hypothetical gravitational decay process culminating in a'A event'.
基金funded by the National Natural Science Foundation of China(Grant No.42102169)the Shaanxi Province key Research and Development Project(Grant No.2023-ZDLSF-64)+1 种基金the Scientific Research and Technological Development Project of China National Logging Corporation(Grant No.25ZYCJSG013-2504)the Youth Science and Technology Special Fund of PetroChina(Grant No.2024DQ03172)。
文摘Geological CO_(2) storage is a promising strategy for reducing greenhouse gas emissions and has become a growing focus of research and deployment.This paper presents numerical simulations of CO_(2) injection and storage in a depleted gas reservoir within the B Depression and evaluates associated CO_(2) trapping mechanisms.In the base case,a constant injection rate of 3500 m^(3)/d over fifteen years resulted in a cumulative injection of 19.2×10^(6) m^(3).The CO_(2) plume expanded radially during injection and subsequently migrated up-dip under buoyancy forces.The final stored mass of CO_(2) in the reservoir was 10.6 million tonnes(Mt),representing less than 10% of its theoretical capacity.The plume was projected to reach the entrapment crest and the top of the reservoir within a century,indicating secure long-term containment.Structural,stratigraphic,and residual trapping dominate in Reservoir A(approximately 90%).Anticlinal closures with thick overlying mudstones in the Zhujiang Formation provide effective seals,further enhancing storage security.Reservoir properties and heterogeneity play a crucial role in controlling CO_(2) storage.However,reservoir heterogeneity exerts only a limited influence when intrinsic properties are favorable.Overall,the study and implementation of CO_(2) capture,utilization,and storage(CCUS)in China's offshore basins show promising prospects.
基金supported by the Natural Environment Research Council[grant number NE/S007415/1]Shell as iCASE sponsors。
文摘Unsecured legacy wells pose significant risks to carbon capture and storage(CCS)as they present potential leakage pathways for stored CO_(2) to return to the atmosphere.In the UK,legacy wells must be assessed for a carbon storage permit to be granted and high-risk wells require costly remediation.We use a well risk assessment scheme to evaluate the risk of wells in the Southern North Sea.We then combine our well risk assessment with investigation using the analytical tool CO2BLOCK,which relies on a gravity current model to estimate pressure and plume migration distances.We evaluate the Viking,Camelot and Poseidon projects,which plan to inject CO_(2) into the depleted reservoirs of Southern North Sea gas fields.Carbon dioxide plumes are typically several kilometers wide,and it should be possible to avoid plume migration to high-risk legacy wells.In contrast,pressure fields produced by CO_(2) injection are tens of kilometers wide and low magnitude pressure increases frequently extend beyond the bounds of storage licence areas.The pressure fields encounter hundreds of wells and in the cases of the Camelot and Poseidon projects,interact with each other.
基金Monash Research Acceleration Program,which funded part of the researchsupport from the Australian Research Council's Discovery Projects funding scheme(projects Nos.DP130101946 and DP110101697)+1 种基金use of the NCI National Facility in Canberra, Australia,which is supported by the Australian Commonwealth GovernmentNSFCAREER award EAR-1054638
文摘We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in： contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes fiat subduction above the plume, resulting in a ＂bowed＂ shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau ~ plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the over- riding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian Orogen （Altiads）, which are characterised by accreted ophiolite complexes with diverse geochemical affinities, and a protracted evolution of accretion of exotic terranes includinu oceanic Dlateau and terranes with nlume origins.
基金supported by grants RFBR(projects Nos.14-0500458a and 16-05-00708)
文摘Large igneous provinces（LIPs） formed by mantle superplume events have irreversibly changed their composition in the geological evolution of the Earth from high-Mg melts（during Archean and early Paleoproterozoic） to Phanerozoic-type geochemically enriched Fe-Ti basalts and picrites at 2.3 Ga.We propose that this upheaval could be related to the change in the source and nature of the mantle superplumes of different generations.The first generation plumes were derived from the depleted mantle,whereas the second generation（thermochemical） originated from the core-mantle boundary（CMB）.This study mainly focuses on the second（Phanerozoic） type of LIPs,as exemplified by the midPaleoproterozoic Jatulian-Ludicovian LIP in the Fennoscandian Shield,the Permian-Triassic Siberian LIP,and the late Cenozoic flood basalts of Syria.The latter LIP contains mantle xenoliths represented by green and black series.These xenoliths are fragments of cooled upper margins of the mantle plume heads,above zones of adiabatic melting,and provide information about composition of the plume material and processes in the plume head.Based on the previous studies on the composition of the mantle xenoliths in within-plate basalts around the world,it is inferred that the heads of the mantle（thermochemical） plumes are made up of moderately depleted spinel peridotites（mainly lherzolites）and geochemically-enriched intergranular fluid/melt.Further,it is presumed that the plume heads intrude the mafic lower crust and reach up to the bottom of the upper crust at depths-20 km.The generation of two major types of mantle-derived magmas（alkali and tholeiitic basalts） was previously attributed to the processes related to different PT-parameters in the adiabatic melting zone whereas this study relates to the fluid regime in the plume heads.It is also suggested that a newly-formed melt can occur on different sides of a critical plane of silica undersaturation and can acquire either alkalic or tholeiitic composition depending on the concentration and composition of the fluids.The presence of melt-pockets in the peridotite matrix indicates fluid migration to the rocks of cooled upper margin of the plume head from the lower portion.This process causes secondary melting in this zone and the generation of melts of the black series and differentiated trachytic magmas.
文摘Leachate originating from open refuse dumpsite systems can be delineated through an integration of qualitative and quantitative methods. This study was designed to examine extent of leachate and pollution from one of the numerous open refuse dumpsites in Lagos metropolis. Qualitative assessment was determined using electrical resistivity tomography (ERT), vertical electrical sounding (VES) and induced polarization geophysical methods. Both ERT and VES methods revealed persistent low resistivity (1 - 20 Ωm) of leachate to the depth above 35 m. The two methods were projected to produce 3-D view of the site which shows a NW-SE flow pattern of the leachate and possibly, the groundwater. IP values observed over the polluted zone was -2.9 - 8 ms, indicating a sandy layer. Quantitative assessment was achieved by analysis of geochemical substances in the water samples taken from wells and boreholes in the precinct of the dumpsite. Here, we examine the macroelements, salts (sulphates, nitrates and chlorides), heavy metals, radioactive metals contents and physical parameters of the water samples. The analyses reveal the presence of these substances in the water and their strong correlations justified the provenance as the same. As part of the quantitative evaluation, physical parameters (pH, TDS, DO, salinity, total hardness, turbidity, electrical conductivity EC and temperature) of the water samples were also determined. The samples pH plotted in the acidic domain unsuitable for human consumption. Leachate flow direction was generated from the decreasing concentration of measured parameters (geochemical elements and physicals properties) in NW-SE direction which agrees with similar flow pattern deduced from ERT results.
基金supported by the China Postdoctoral Science Foundation(No.2022M710977)National Natural Science Foundation of China(No.51907039)+1 种基金the Natural Science Foundation of Guangdong Province(Nos.2022A1515110215 and 2023A1515010137)Shenzhen Technology Projects(Nos.JCYJ20190806142603534 and ZDSYS201707280904031)。
文摘A 2D-3V implicit immersed-finite-element particle-in-cell(IFE-PIC)model is introduced to investigate the radio-frequency(RF)self-bias accelerating system applied in the RF ion thruster.A set of holes in a two-grid system with slit apertures is simulated in Cartesian coordinates.The characteristics of the plasma plume,such as the ion density,the neutralization rate and the ion and electron current density were investigated for different RF voltage amplitudes(600-1200V)and frequencies(6-30 MHz).Furthermore,the performance of the thruster was also carefully studied.The simulation results show that a well-focused plasma beam can be formed when the voltage amplitude is larger than 900 V and the frequency exceeds the reciprocal of ion transit time(≥12 MHz)in our simulation cases.The performance of the system can be evidently improved by increasing the voltage amplitude and the frequency,and the losses of the particle and thrust are reduced correspondingly.The bulk region of the plasma beam downstream shows good quasi-neutrality,and the ions are dominant in the peripheral region when a well-focused state is achieved.The high ion density beamlet in the periphery of the ion beam is closer to the axis when the voltage amplitude is increasing,while it is expanded radially when increasing the frequency.Backstream electrons have been observed upstream,and this mainly occurs in the phase in which the electron cannot escape.
基金Sponsored by the National Natural Science Foundation of China (Grant No 50478113)the Key Project of Shanghai Education Committee (Grant NoJ50502)Special Research Fund in Shanghai Colleges and Universities to Select and Train Outstanding Young Teachers (Grant No slg09011)
文摘This paper presents fluid mechanics of ventilation system formed by the momentum source and the buoyancy source,which investigates inter-action between the plume and the non-isothermal air jet since buoyancy source is produced by the plume and momentum source is generated by the air jet,respectively. The interaction is discussed by a mathematical model,an idealized situation of the plume rising from a point heat source of buoyancy alone-in particular the initial momentum flux at the source is zero. Furthermore,the paper discusses the effects of the parameters such as strength of source,air-flow volume and air-flow velocity used in the mathematical-physical model. Considering the effect of the plume generated by the indoor heat source,one expression of trajectory of the non-isothermal air jet produced by jet diffuser is deduced. And field-experiment has also been carried out to illustrate the effect on flowing-action of the air jet and validate the theoretical work. It can be concluded that the heat sources do have effect on the flowing-action of the air jet,and the effect mainly depends on the interaction produced by the plume and the air jet. The results show that the thermal buoyant effect of plumes on the air jet should be taken into account if the indoor heat sources are large enough. Numerical simulation is conducted and coincides with the experimental results as well.
文摘We statistically validate the 2011-2022 earthquake prediction records of Ada, the sixth finalist of the 2nd China AETA in 2021, who made 147 earthquake predictions (including 60% of magnitude 5.5 earthquakes) with a prediction accuracy higher than 70% and a confidence level of 95% over a 12-year period. Since the reliable earthquake precursor signals described by Ada and the characteristics of Alfvén waves match quite well, this paper proposes a hypothesis on how earthquakes are triggered based on the Alfvén (Q G) torsional wave model of Gillette et al. When the plume of the upper mantle column intrudes into the magma and lithosphere of the soft flow layer during the exchange of hot and cold molten material masses deep inside the Earth’s interior during ascent and descent, it is possible to form body and surface plasma sheets under certain conditions to form Alfven nonlinear isolated waves, and Alfven waves often perturb the geomagnetic field, releasing huge heat and kinetic energy thus triggering earthquakes. To explain the complex phenomenon of how Ada senses Alvfen waves and how to locate epicenters, we venture to speculate that special magnetosensory cells in a few human bodies can sense earthquake precursors and attempt to hypothesize an algorithm that analyzes how the human biological nervous system encodes and decodes earthquake precursors and explains how human magnetosensory cells can solve complex problems such as predicting earthquake magnitude and locating epicenters.
基金supported by the State Key Laboratory of Offshore Oil and Gas Exploitation, Open Fund Project (No. CCL2023RCPS0162RQN)the primary funding, National Natural Science Foundation of China (No. ZX20230400)
文摘Saline aquifers are considered as highly favored reservoirs for CO_(2)sequestration due to their favorable properties.Understanding the impact of saline aquifer properties on the migration and distribution of CO_(2)plume is crucial.This study focuses on four key parameters-permeability,porosity,formation pressure,and temperature-to characterize the reservoir and analyse the petrophysical and elastic response of CO_(2).First,we performed reservoir simulations to simulate CO_(2)saturation,using multiple sets of these four parameters to examine their significance on CO_(2)saturation and the plume migration speed.Subsequently,the effect of these parameters on the elastic properties is tested using rock physics theory.We established a relationship of compressional wave velocity(V_(p))and quality factor(Q_(p))with the four key parameters,and conducted a sensitivity analysis to test their sensitivity to V_(p) and Q_(p).Finally,we utilized visco-acoustic wave equation simulated time-lapse seismic data based on the computed V_(p) and Q_(p) models,and analysed the impact of CO_(2) saturation changes on seismic data.As for the above nu-merical simulations and analysis,we conducted sensitivity analysis using both homogeneous and heterogeneous models.Consistent results are found between homogeneous and heterogeneous models.The permeability is the most sensitive parameter to the CO_(2)saturation,while porosity emerges as the primary factor affecting both Q_(p) and V_(p).Both Q_(p) and V_(p) increase with the porosity,which contradicts the observations in gas reservoirs.The seismic simulations highlight significant variations in the seismic response to different parameters.We provided analysis for these observations,which serves as a valuable reference for comprehensive CO_(2)integrity analysis,time-lapse monitoring,injection planning and site selection.
基金The Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDC0190102the National Key Research and Development Program of China under contract No.2022YFC3105005the Guangdong Key Project under contract No.2019BT02H594.
文摘The expansion of river plumes is essential for coastal systems and inner-shelf biogeochemical processes.This investigation employs the Coupled Ocean-Atmosphere-Wave-Sediment Transport(COAWST)modeling system to systematically analyze the governing mechanisms influencing the Changjiang River plume during winter conditions.Model validation through comparison with the observational datasets demonstrates the system’s capability to accurately reproduce hydrodynamic processes and thermohaline variability.A series of sensitivity experiments was implemented to quantify the relative contributions of distinct forcing mechanisms,including tidal dynamics,wind stress,and waveinduced processes on hydrodynamic patterns and associated temperature-salinity distributions.Numerical simulations reveal that wave-induced vertical mixing generates significant nearshore thermal elevation concurrent with salinity reduction.Tidal residual currents exhibit persistent onshore and northward components,potentially facilitating northward advection of the Changjiang River plume during winter months.Conversely,wind-driven currents impose a constraining effect on plume expansion through the establishment of downwelling-favorable circulation patterns.During extreme wave events,wave-driven current contributions to salinity variance account for 30%−90%,relative to tidal mixing effects.These findings collectively establish wave-current interaction as a critical mechanistic component governing wintertime Changjiang River plume dynamics,with particular relevance to stratification modification and cross-shelf transport processes.
基金financially supported by the National Science Foundation of China(No.41920104010)the China Postdoctoral Science Foundation(No.2024M762767)+3 种基金the Fundamental Research Funds for the Central University,CHD(No.300102264104)by the Postdoctoral Fellowship Program of CPSF(No.GZC20241444)supported by Fondazione Cariplo and Fondazione CDP(No.2022-1546_001)by the Italian Ministry of Education,MUR(Project Dipartimenti di Eccellenza,TECLA,Department of Earth and Environmental Sciences,University of Milano-Bicocca)。
文摘Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative contributions to the overall evolution of rifting margins and possible roles in the formation of microcontinent are still elusive.Here,we use coupled geodynamic and surface processes numerical modeling to assess the extent to which surface processes may determine the formation of microcontinent during lithospheric stretching in presence or absence of a mantle plume underneath.Our modeling results indicate that fast extension rates and hillslope(i.e.,diffusion)erosion promote ridge jump events and therefore the formation of microcontinents.On the contrary,efficient fluvial erosion and far-reaching sediment transport(i.e.,stream power erosion)inhibits ridge jump events and the formation of microcontinents.The ridge jump event and overall evolution in our numerical models is consistent with the shift from the Mascarene Ridge to the Carlsberg Ridge that determined the formation of the Seychelles microcontinent.We therefore speculate that hillslope erosion,rather than fluvial erosion,was predominant during the formation of the Seychelles,a possible indication of overall dry local climate conditions.
文摘At the end of the Cretaceous period,66 million years ago,the 7−19 km diameter Chicxulub asteroid hit the Yucatan Peninsula in Mexico,triggering global catastrophic environmental changes and mass extinction.The contributions of this event towards changes in plate and plume geodynamics are not fully understood.Here we present a range of geological observations indicating that the impact marked a tectonic turning point in the behavior of mantle plume and plate motion in the Caribbean region and worldwide.At a regional scale,the impact coincides with the termination of seafloor spreading in the Caribbean Ridge.Shortly after the Cretaceous-Paleogene transition,magmatism associated with the Caribbean Large Igneous Province waned,and intensive Paleogene volcanism was initiated.These events happened synchronously with anomalously high mid-ocean ridge magmatism worldwide and an abrupt change in the relative motion of the South American and North American tectonic plates.The evidence for such abrupt changes in plate kinematics and plume behavior raises the possibility that the Chicxulub impact triggered a chain of effects that modified melt reservoirs,subducting plates,mantle flows,and lithospheric deformation.To explain how an asteroid impact could modify tectonic behavior,we discuss two end-member mechanisms:quasi-static and dynamic triggering mechanisms.We designed a numerical model to investigate the strain field and the relative plate motion before and after the impact.The model predicts an enhanced deformation associated with the impact,which surficially tapers off∼500 km from the crater.The impact modifies the subjacent mantle flow field,contributing to long-term mantle-driven dynamic changes.Additionally,deformation associated with seismic effects may have contributed to far-field effects and global changes.We conclude that large asteroid impacts,such as the Chicxulub collision,could trigger cascading effects sufficient to disrupt and significantly modify plate geodynamics.
基金supported by the“Startup Grant for the University Teachers”of the University of Kerala.
文摘The role of mantle plume in the final stages of rifting of the East Gondwana crustal fragments remains equivocal with only limited evidence so far reported from the southern part of Peninsular India.Here,we report for the first time a suite of columnar basalts from the Mesoarchean Coorg Block in the Southern Granulite Terrain(SGT)of India and characterize these rocks through field,petrological,geo-chemical,and isotope geochronological studies.The basalts show porphyritic texture with phenocrysts of pyroxene and plagioclase embedded in fine groundmass.Geochemical data reveal tholeiitic flood basalt affinity with affinities of plume-related magmatism.The zircon U-Pb data of the rocks yield a weighted mean age of 137 Ma,thus corresponding to the Valanginian Age of the Early Cretaceous Period.We suggest the possible geochemical affinity of the studied rocks Kerguelen plume basalts which provide new insights into magmatism associated with the final stages of East Gondwana rifting.
基金supported by grant D86-RALMI23CIVIE_01 awarded by the Italian Ministry of University and Research under the Program for Young Researchers“Rita Levi Montalcini”.
文摘A wide northeast-trending belt of intraplate alkaline volcanism,exhibiting similar geochemical characteristics,stretches from the Eastern Atlantic Ocean to the Cenozoic rift system in Europe.Its formation is associated with both passive and active mechanisms,but it remains a source of ongoing debate among geoscientists.Here,we show that seismic whole-mantle tomography models consistently identify two extensive low-velocity anomalies beneath the Canary Islands(CEAA)and Western-Central Europe(ECRA)at mid-mantle depths,merging near the core-mantle boundary.These low-velocity features are interpreted as two connected broad plumes originating from the top of the African LLSVP,likely feeding diapir-like upwellings in the upper mantle.The CEAA rises vertically,whereas the ECRA is tilted and dissipates at mantle transition zone depths,possibly due to the interaction with the cold Alpine subducted slab,which hinders its continuity at shallower depths.While plate-boundary forces are considered the primary drivers of rifting,the hypothesis that deep mantle plumes play a role in generating volcanic activity provides a compelling explanation for the European rift-related alkaline volcanism,supported by geological,geophysical,and geochemical evidence.
基金supported by The National Natural Science Foundation of China [U2244208, 42302138]the Science Foundation of China University of Petroleum, Beijing[2462024XKQY001]。
文摘Eastern Sichuan Basin is a critical region for oil and gas production in China,and the thermal effect of the Emeishan Mantle Plume(EMP) on the basin remains unclear,which limits the study of the Paleozoic hydrocarbon accumulation process.Thus,clarifying the thermal history is crucial for oil and gas evaluation and exploration.This study combines zircon fission track(ZFT),zircon(U-Th)/He(ZHe),and vitrinite reflectance analyses to reconstruct the thermal history since the Paleozoic and investigate the maturity evolution of Paleozoic source rocks in the eastern Sichuan Basin.Additionally,the contributing factors of the Permian abnormal heat flow and the thermal effect range of the EMP were analyzed.Thermal history results show a stable low heat flow phase(45-55 mW/m^(2)) from the Cambrian to Permian,a rapid increase to peak values(62-70 mW/m^(2)) during the Middle Permian,and a gradual decline to current stable values(47-62 mW/m^(2)) from the Triassic onward.Thermal evolution revealed that Paleozoic source rocks exhibited maturation stagnation due to tectonic events,while the Permian peak heat flow and the Jurassic-Late Cretaceous rapid burial accelerated maturation.The Cambrian Qiongzhusi Formation and Silurian Longmaxi Formation source rocks began generating hydrocarbons(R_(equ)=0.5%) in the Late Cambrian-Late Ordovician and Late Silurian-Early Devonian,respectively,while it was Late Permian-Early Triassic for Permian source rocks.Peak maturity(R_(equ)> 2%) occurred in the Late Cretaceous,with natural gas as the dominant product The EMP significantly influenced the thermal regime of the western and central Sichuan Basin,with a thermal effect radius of~600-650 km.In contrast,the Permian thermal anomaly in the eastern Sichuan Basin is attributed to the lithospheric extension associated with the Middle Permian Kaijiang-Liangping trough.These findings provide critical insights for deep and ultra-deep gas exploration and enhance the understanding of the EMP's regional thermal impacts.
基金supported by the Major Project of Hunan Natural Science Foundation,China(No.2021JC0010)the National Natural Science Foundation of China(No.51274251)。
文摘The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and conducted to investigate the morphological characteristics and concentration evolution of the sediment plumes under different discharge rates(Q)and initial sediment concentrations(c).Viscosity tests,resuspension tests and free settling tests of the sediment solution with different c values were performed to reveal the settling mechanism of the plume diffusion process.The results show that the plume diffusion morphology variation in flowing water has four stages and the plume concentration evolution has three stages.The larger the Q,the smaller the initial incidence angle at the discharge outlet,the larger the diffusion range,the poorer the stability and the more complicated the diffusion morphology.The larger the c,the larger the settling velocity,the faster the formation of high-concentration accumulation zone,the better the stability and the clearer the diffusion boundary.The research results could provide experimental data for assessing the impact of deep-sea mining on the ocean environment.
