Based on a set of high-resolution 3D seismic data from the northern continental margin of the South China Sea,the lithospheric structure,thinning mechanisms and related syn-rift tectonic deformation response processes...Based on a set of high-resolution 3D seismic data from the northern continental margin of the South China Sea,the lithospheric structure,thinning mechanisms and related syn-rift tectonic deformation response processes in the crustal necking zone in the deepwater area of the Pearl River Mouth Basin were systematically analyzed,and the petroleum geological significance was discussed.The necking zone investigated in the study is located in the Baiyun Sag and Kaiping Sag in the deepwater area of the Pearl River Mouth Basin.These areas show extreme crustal thinned geometries of central thinning and flank thickening,characterized by multi-level and multi-dipping detachment fault systems.The necking zone exhibits pronounced lateral heterogeneity in structural architectures,which can be classified into four types of thinned crustal architectures,i.e.the wedge-shaped extremely thinned crustal architecture in the Baiyun Main Sub-sag,dumbbell-shaped moderately thinned crustal architecture in the Baiyun West Sub-sag,box-shaped weakly thinned crustal architecture in eastern Baiyun Sag,and metamorphic core complex weakly thinned crustal architecture in the Kaiping Sag.This shows great variations in the degree and style of crustal thinning,types of detachment faults,distribution of syn-rift sedimentary sequences,and intensity of magmatism.The thinning of the necking zone is controlled by the heterogeneous rheological stratification of lithosphere,intensity of mantle-derived magmatism,and deformation modes of detachment faults.The syn-rift tectonic deformation of the necking zone evolved through three phases,i.e.uniform stretching during the early Wenchang Formation deposition period,necking during the late Wenchang Formation deposition period,and hyperextension during the Enping Formation deposition period.The crustal thinning extent and architectural differentiation in these phases were primarily controlled by three distinct mechanisms,i.e.the pure shear deformation activation of pre-existing thrust faults,the simple shear deformation of crust-mantle and inter-crust detachment faults,and differential coupling of lower crustal flow and ductile domes with main detachment faults.The hydrocarbon accumulation and enrichment in the necking zone exhibit marked spatial heterogeneity.Four distinct crustal thinned architecture-hydrocarbon accumulation models were identified in this study.The hydrocarbon accumulations in the shallow part exhibit significant correlations with their deep crustal thinned architectures.The unique lithospheric structure and deformation process predominantly control the favorable hydrocarbon accumulation zones with excellent source-fault-ridge-sand configurations,which is critical to reservoir-forming.The most promising exploration targets are mainly identified on the uplift zones and their seaward-dipping flanks associated with the middle and lower crustal domes.This research provides additional insights into lithospheric thinning-breakup process at intermediate continental margins of marine sedimentary basins,being significant for guiding the deepwater petroleum exploration in the Pearl River Mouth Basin.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
The heat content(HC)of water masses on the Ross Sea continental shelf plays an important role in regulating the circulations and the basal melting of the Ross Ice Shelf(RIS).Yet,the evolution of the HC on the Ross Sea...The heat content(HC)of water masses on the Ross Sea continental shelf plays an important role in regulating the circulations and the basal melting of the Ross Ice Shelf(RIS).Yet,the evolution of the HC on the Ross Sea continental shelf is still not clear due to the sparsity of observations.By employing a coupled regional ocean-sea ice-ice shelf model for the Ross Sea,this study analyzes the heat budget of water masses over the continental shelf and in the RIS cavity.According to the topographic features and the HC density,the continental shelf region is divided into 17 subdomains.The heat budget of the middle layer for every subdomain is analyzed.In addition,the heat budget for the RIS cavity is assessed for the first time.Owing to Modified Circumpolar Deep Water intrusion,water masses over the eastern shelf are warmer than over the western shelf,with the coldest water identified in the southwestern inner shelf.The horizontal heat flux mainly provides heat to the continental shelf,while the atmospheric forcing tends to warm up the ocean during the ice-melting period and cool down the ocean during the ice-freezing period.The vertical heat flux is generally upward and transports heat from the deep layer to the upper layer.In the RIS cavity,the seasonal cycle of the HC is dominated by the horizontal flux across the RIS front rather than the basal thermal forcing of the RIS.展开更多
The Madden-Julian Oscillation(MJO)is a key atmospheric component connecting global weather and climate.It func-tions as a primary source for subseasonal forecasts.Previous studies have highlighted the vital impact of ...The Madden-Julian Oscillation(MJO)is a key atmospheric component connecting global weather and climate.It func-tions as a primary source for subseasonal forecasts.Previous studies have highlighted the vital impact of oceanic processes on MJO propagation.However,few existing MJO prediction approaches adequately consider these factors.This study determines the critical region for the oceanic processes affecting MJO propagation by utilizing 22-year Climate Forecast System Reanalysis data.By intro-ducing surface and subsurface oceanic temperature within this critical region into a lagged multiple linear regression model,the MJO forecasting skill is considerably optimized.This optimization leads to a 12 h enhancement in the forecasting skill of the first principal component and efficiently decreases prediction errors for the total predictions.Further analysis suggests that,during the years in which MJO events propagate across the Maritime Continent over a more southerly path,the optimized statistical forecasting model obtains better improvements in MJO prediction.展开更多
Two new free-living marine nematode species belonging to the genus Tricoma Cobb,1894(Desmoscolecidae)are identi-fied from the continental shelf region of the Bay of Bengal.Tricoma ajmalia sp.nov.is characterized by th...Two new free-living marine nematode species belonging to the genus Tricoma Cobb,1894(Desmoscolecidae)are identi-fied from the continental shelf region of the Bay of Bengal.Tricoma ajmalia sp.nov.is characterized by the number of main rings(84 male and 85 female),the arrangement of somatic setae,the head shape with broadly truncated end,the relatively long cephalic setae(69%-73%of corresponding head diameter),the amphids extending up to second main ring,slender spicules slightly curved and gu-berbaculum with dorsocaudally directed apophyses.The second new species,Tricoma sampadansis sp.nov.is characterized by the number of rings(64),the arrangement of somatic setae(14-13 subdorsal,16 subvenral),the head shape with broadly truncated end,the relatively long cephalic setae(75%corresponding head diameter),the amphidial fovea extending over first main ring,anterioirly bent spicules and gubernaculum with hooked proximal end.An updated valid species list of Tricoma is also presented.展开更多
Large-scale Danian-age(post-K/Pg boundary)Deccan magmatism is well known from the Mumbai metropolitan area,located in the structurally complex Panvel flexure zone along the western Indian rifted continental margin.Thi...Large-scale Danian-age(post-K/Pg boundary)Deccan magmatism is well known from the Mumbai metropolitan area,located in the structurally complex Panvel flexure zone along the western Indian rifted continental margin.This compositionally diverse late-Deccan magmatic suite contains subaerial tholeiitic lavas and dykes typical of the main Deccan province,with many features atypical of the Deccan,such as spilitic pillow lavas,“intertrappean”sediments(often containing considerable volcanic ash),rhyolitic lavas and tuffs,gabbro-granophyre intrusions,and trachyte intrusions containing alkali basalt enclaves.Most of these units,previously dated at 62.5 Ma to 61 Ma,are contemporaneous with or slightly postdate the 62.5 Ma India-Seychelles continental breakup and Panvel flexure formation.In the Dongri-Uttan area,two samples of a>50-m-thick,columnar-jointed rhyolite from the Darkhan Quarry and from a section behind the current Uttan Sagari Police Station have previously been dated at 62.6±0.6 Ma and 62.9±0.2 Ma(^(40)Ar/^(39)Ar,2r errors).New exposures reveal that these two statistically indistinguishable 40 Ar/39 Ar ages correspond to two distinct rhyolite units,separated by well-bedded silicic ash.The columnar rhyolites are microcrystalline,composed of quartz and alkali feldspar,with rare small(1–2 mm),altered feldspar phenocrysts,and no recognisable relict vitroclasts.Given the westerly structural dip,most of their lateral extent is submerged under the Arabian Sea,and we consider them to be possible flood rhyolite lavas.We interpret the ash beds,composed of pumice clasts and glass shards,as a low-grade(nonwelded)vitric ash,derived from a possibly distal Plinian eruption and deposited by fallout.The lavas and ash are peraluminous rhyolites.The lavas are Sr-Ba-poor and Rb-Zr-Nb-rich,and show“seagull-shaped”rare earth element patterns with deep negative europium anomalies.These crystal-poor lavas are“hot-dry-reduced”rhyolites typical of intraplate,continental rift and rifted margin settings.The very different high-field strength element contents of the lavas and the ash indicate compositionally distinct magma batches.The 62.5 Ma Dongri-Uttan sequence provides clear evidence for rapid silicic eruptions of effusive and explosive nature,alternating with each other and sourced from distinct magma chambers and eruptive vents.A newly identified,highly feldspar-phyric trachyte intrusion marks the last phase of magmatic activity in the area,corresponding with late-stage trachyte-syenite intrusions exposed in coastal western India and the Seychelles,and shows that the Mumbai rhyolites and trachytes form a compositional continuum.展开更多
Compared to discrete continental marginal basins,the mechanisms of hydrocarbon migration and enrichment in transform continental marginal basins are poorly understood.In this study,we conducted a comprehensive analysi...Compared to discrete continental marginal basins,the mechanisms of hydrocarbon migration and enrichment in transform continental marginal basins are poorly understood.In this study,we conducted a comprehensive analysis of the main source rocks,reservoirs,and vertical migration pathways within the Rovuma(RB)and Tanzania(TB)basins in East Africa utilizing drilling,logging,seismic,and geochemical data.The results indicate that the enhanced preservation conditions of the Lower Jurassic source rocks in the southwest could lead to the discovery of large natural gas fields in the southern TB and RB.The primary reservoir is a deep-water turbidite sandstone.Due to topographic differences,the expanse of the turbidite sandstones in the RB is significantly larger than those in Tanzania.The main vertical migration pathways are the western boundary fault zone of the Kerimbas Graben(WBFZ)and the Seagap fault zone(SFZ).In the RB,natural gas migrates vertically along the WBFZ and preferentially accumulates in the deep-water turbidite sandstones of the footwall under the control of the fluid potential.Conversely,in the southern TB,the deep natural gas first migrates upward along the SFZ,then moves along the shallow branch faults in the sandstones on both sides of the SFZ.展开更多
The high Ba-Sr rocks can provide significant clues about the evolution of the continent lithosphere,but their petrogenesis remains controversial.Identifying the Late Cretaceous high Ba-Sr granodiorites in the SE Lhasa...The high Ba-Sr rocks can provide significant clues about the evolution of the continent lithosphere,but their petrogenesis remains controversial.Identifying the Late Cretaceous high Ba-Sr granodiorites in the SE Lhasa Block could potentially provide valuable insights into the continent evolution of the Qinghai-Tibet Plateau.Zircon U-Pb ages suggest that the granodiorites were emplaced at 87.32±0.43 Ma.Geochemically,the high Ba-Sr granodiorites are characterized by elevated K_(2)O+Na_(2)O contents(8.18-8.73 wt%)and K_(2)O/Na_(2)O ratios(0.99-1.25,mostly>1),and belong to high-K calc-alkaline to shoshonitic series.The Yonglaga granodiorites show notably high Sr(653-783 ppm)and Ba(1346-1531 ppm)contents,plus high Sr/Y(30.92-38.18)and(La/Yb)_(N)(27.7-34.7)ratios,but low Y(20.0-22.8 ppm)and Yb(1.92-2.19 ppm)contents with absence of negative Eu anomalies(δEu=0.83-0.88),all similar to typical high Ba-Sr granitoids.The variable zirconεHf(t)values of-4.58 to+12.97,elevated initial^(87)Sr/^(86)Sr isotopic ratios of 0.707254 to 0.707322 and lowεNd(t)values of-2.8 to-3.6 with decoupling from the Hf system suggest that a metasomatized mantle source included significant recycled ancient materials.The occurrence of such high Ba-Sr intrusions indicates previous contributions of metasomatized mantle-derived juvenile material to the continents,which imply the growth of continental crust during the Late Cretaceous in the SE Lhasa.Together with regional data,we infer that the underplated mafic magma provides a significant amount of heat,which leads to partial melting of the juvenile crust.The melting of the metasomatized mantle could produce a juvenile mafic lower crust,from which the high Ba-Sr granitoids were derived from reworking of previous mafic crust during the Late Cretaceous(ca.100-80 Ma)in the SE Lhasa.展开更多
In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whe...In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whether the combined patterns of grabens in the Hailar Basin exhibit similar characteristics to those in other NE China rift basins and to identify the underlying causes.To achieve this,a comprehensive analysis of the major fault systems and the combined patterns of faulted sub-depressions,as well as their controlling mechanisms,was conducted.This analysis utilized the latest 3D seismic data that cover nearly the entire Beier Depression.Three groups of pre-existing fault systems were observed in the basement of the Beier Depression,and they are the NEE-EW-trending fault systems,the NE-trending fault systems,and the NW-trending fault systems.The NEE-EW-trending fault systems were distributed in the central part of the Beier Depression and primarily controlled the sedimentary filling of the Tongbomiao and the Lower Nantun Formations.The NE-trending fault systems were distributed in the southwestern part of the Beier Depression and primarily controlled the sedimentary filling of the Upper Nantun Formations.The NW-trending fault systems were distributed rarely in the Beier Depression.Five kinds of combined patterns of the sub-depressions were developed in the Beier Depression,and they are the parallel,en echelon,face-to-face,back-to-back,and S-shaped combined patterns.They were controlled by the NEE-EW-trending and the NE-trending fault systems with different orientations,arrangements,and activation sequences.展开更多
The uncertainty of ocean turbulent mixing parameterization comprises a significant challenge in ocean and climate models. A depth-dependent deep learning ocean turbulent mixing parameterization scheme was proposed wit...The uncertainty of ocean turbulent mixing parameterization comprises a significant challenge in ocean and climate models. A depth-dependent deep learning ocean turbulent mixing parameterization scheme was proposed with the hydrological and microstructure observations conducted in summer 2012 in the shelf sea east of Hainan Island, in South China Sea(SCS). The deep neural network model is used and incorporates the Richardson number Ri, the normalized depth D, the horizontal velocity speed U, the shear S^(2), the stratification N^(2), and the density ρ as input parameters. Comparing to the scheme without parameter D and region division, the depth-dependent scheme improves the prediction of the turbulent kinetic energy dissipation rate ε. The correlation coefficient(r) between predicted and observed lgε increases from 0.49 to 0.62, and the root mean square error decreases from 0.56 to 0.48. Comparing to the traditional physics-driven parameterization schemes, such as the G89 and MG03, the data-driven approach achieves higher accuracy and generalization. The SHapley Additive Explanations(SHAP) framework analysis reveals the importance descending order of the input parameters as: ρ, D, U, N^(2), S^(2), and Ri in the whole depth, while D is most important in the upper and bottom boundary layers(D≤0.3&D≥0.65) and least important in middle layer(0.3<D<0.65). The research shows applicability of constructing deep learning-based ocean turbulent mixing parameterization schemes using limited observational data and well-established physical processes.展开更多
Continental intraplate basalts form by partial melting of the mantle,and can provide important constraints on mantle heterogeneity.However,due to the thick overlying continental lithosphere,the origins of the geochemi...Continental intraplate basalts form by partial melting of the mantle,and can provide important constraints on mantle heterogeneity.However,due to the thick overlying continental lithosphere,the origins of the geochemical characteristics of continental intraplate basalts are controversial.In this study,we examined the geochemistry of Cenozoic basalts in southeast China.These basalts which are divided into four volcanic belts exhibit a DMM-EM2 mixing trend and spatial variations in Pb isotopes from inland(i.e.,thick lithosphere)to coastal(i.e.,thin lithosphere)regions.In contrast to the Pb isotopic variations,there are no spatial variations in Sr-Nd-Hf isotopes.Marked correlations between Pb isotopes and major elements(i.e.,Mg O and Si O_(2))suggest the continental lithospheric lid controlled their petrogenesis.Nonetheless,other factors are needed to explain the variations in Ti/Ti^(*)and Hf/Hf^(*)ratios,and Nd-Hf isotopes of the southeast China basalts.The increasing Pb isotope ratios from the inner to coastal regions are associated with decreases in CaO/Al_(2)O_(3) ratios and increases in FC3MS(FeO^(T)/CaO-3×Mg O/Si O_(2);in wt.%)values,indicating contributions from non-peridotite components in the mantle sources.The similarly depleted Nd-Hf isotopic compositions of the basalts from the three inner belts indicate these basalts have a similar origin,whereas the more enriched isotopic features of the basalts from the outer belt suggest their mantle source contains older recycled oceanic crust.Thus,source(i.e.,lithological)heterogeneity also had a significant role in controlling the geochemistry of these basalts.The DMM-EM2 mixing trend defined by the Pb isotopic compositions of continental intraplate basalts from southeast China was generated by variable degrees of melting of heterogeneous mantle that was controlled by the thickness of the continental lithospheric lid(i.e.,the melting pressure).This caused variable extents of melting of enriched components in the mantle sources of the basalts(i.e.,carbonated peridotite vs.pyroxenite).展开更多
Determining the evolutionary history of the Permian-Triassic Kunlun-Qaidam Continental Arc is essential to understanding the subduction and closure processes of the South Kunlun Ocean.In this paper,we utilize(La/Yb)N ...Determining the evolutionary history of the Permian-Triassic Kunlun-Qaidam Continental Arc is essential to understanding the subduction and closure processes of the South Kunlun Ocean.In this paper,we utilize(La/Yb)N ratios collected from a fi ltered geochemical dataset on Permian to Triassic calc-alkaline rocks(55 wt%–68 wt%SiO_(2))and plutonic rocks within the Kunlun-Qaidam Continental Arc to reconstruct the spatiotemporal variation of the relative crustal thickness.Combined with known geologic observations,we discuss the subduction-accretionary tectonics of the South Kunlun Ocean and the topographic evolution of the Kunlun-Qaidam Continental Arc.Two episodes of crustal thickening and thinning were revealed.The reconstructed thickness reveals two crustal thickening and thinning events for the Kunlun-Qaidam Continental Arc from ca.270 to 210 Ma.The southern sector of the Kunlun-Qaidam Continental Arc is about 7 km thicker than the northern portion,with a maximum thickness of about 55 km at ca.270 and 230 Ma.The ca.270 and 230 Ma crustal thickening events coincide with renewed northward subduction of the South Kunlun Ocean plate and ocean closure,respectively,whereas the ca.270‒240 Ma and ca.230‒210 Ma crustal thinning events may refl ect slab break-off of the oceanic plate and lithospheric collapse during the post-collision extension,respectively.展开更多
The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the...The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the influence of continental and marine air masses over the Pearl River Estuary(PRE)region in winter 2021.The sum concentration of SOA tracers was 6.2–132.8 ng m^(−3),with SOAM and SOAI as the main components in both continental(scenarios A1 and A2)and marine air masses(scenario A3),as well as their combination(scenario A4).The highest and lowest levels of SOAM were observed in A1 and A3,respectively,which were mainly related to the variations in meteorological conditions,precursor concentrations,and the degree of photochemical processes.Higher MBTCA/HGA(3-methyl-1,2,3-butanetricarboxylic acid/3-hydroxyglutaric acid)ratios suggested a less significant contribution fromα-pinene to SOAM.The variations of SOAI in the different scenarios were associated with differences in relative humidity,particle acidity,and isoprene/NOx ratios.The respective highest and lowest concentrations of aromatics SOA tracers in A1 and A3 revealed the influence of anthropogenic precursors from upwind continental areas,which was confirmed by the correlation among biogenic and anthropogenic precursors.The results of the tracer-based-method suggested dominant contributions of SOAs from aromatics and monoterpenes,with the highest concentrations in A1.A WRF-Chem simulation revealed that the SOAs from the above precursors only contributed 12%–25%to the total SOA at DWS,while the spatial distributions of SOAs further highlighted that the abundance of SOAs over the PRE region in winter is highly associated with air masses transported from upwind continental areas.展开更多
Clarify the mechanical properties of different laminations and the fracture mechanism of continental shale under in-situ stress can provide theoretical basis for more comprehensive evaluation of the fracability of con...Clarify the mechanical properties of different laminations and the fracture mechanism of continental shale under in-situ stress can provide theoretical basis for more comprehensive evaluation of the fracability of continental shale oil reservoir.The Chang 72continental shale was used to investigate the mechanical properties of laminations and the effect of natural structure on the crack propagation of the shale.The XRD and thin section tests show that the laminations contain two types:bright sandy lamination with void structure and dark muddy lamination with layer structure.The real-time CT uniaxial compression tests were conducted to investigate the differences of mechanical properties between the muddy lamination and sandy lamination.It found that the uniaxial compression strength and elastic modulus of the sandy lamination are higher,forming a simple crack with large opening,and the Poisson's ratio of the muddy lamination is large,forming obvious lateral deformation and more secondary cracks.On this basis,the cuboid-shaped continental shale specimens were tested under true triaxial compression conditions to study the effect of laminations and interface cracks on crack propagation combining AE and CT techniques.It found that nascent cracks connected laminations and interface cracks to form fracture network under appropriate loading condition,tensile cracks developed in sandy lamination and shear cracks occurred in muddy lamination because of deformation dissonance and brittleness index differences,and more secondary cracks formed in muddy lamination with smaller fracture toughness.Moreover,the combination relationships between nascent and natural cracks mainly conclude direct penetration and deflection,which is affected by the filling degree and morphology of interface cracks and the relationship of lamination types.These conclusions show that laminar continental shale is conducive to forming complex fracture network,which can provide a theoretical basis for the proposal of indicators and methods for fracability evaluation.展开更多
The increasing demand for unconventional oil and gas resources,especially oil shale,has highlighted the urgent need to develop rapid and accurate strata characterization methods.This paper is the first case and examin...The increasing demand for unconventional oil and gas resources,especially oil shale,has highlighted the urgent need to develop rapid and accurate strata characterization methods.This paper is the first case and examines the drilling process monitoring(DPM)method as a digital,accurate,cost-effective method to characterize oil shale reservoirs in the Ordos Basin,China.The digital DPM method provides real-time in situ testing of the relative variation in rock mechanical strength along the drill bit depth.Furthermore,it can give a refined rock quality designation based on the DPM zoning result(RQD(V_(DPM)))and a strength-grade characterization at the site.Oil shale has high heterogeneity and low strata strength.The digital results are further compared and verified with manual logging,cored samples,and digital panoramic borehole cameras.The findings highlight the innovative potential of the DPM method in identifying the zones of oil shale reservoir along the drill bit depth.The digital results provide a better understanding of the oil shale in Tongchuan and the potential for future oil shale exploration in other regions.展开更多
Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and...Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.展开更多
Mozambique's continental margin in East Africa was formed during the break-off stage of the east and west Gondwana lands. Studying the geological structure and division of continent-ocean boundary(COB) in Mozambiq...Mozambique's continental margin in East Africa was formed during the break-off stage of the east and west Gondwana lands. Studying the geological structure and division of continent-ocean boundary(COB) in Mozambique's continental margin is considered of great significance to rebuild Gondwana land and understand its movement mode. Along these lines, in this work, the initial Moho was fit using the known Moho depth from reflection seismic profiles, and a 3D multi-point constrained gravity inversion was carried out. Thus, highaccuracy Moho depth and crustal thickness in the study area were acquired. According to the crustal structure distribution based on the inversion results, the continental crust at the narrowest position of the Mozambique Channel was detected. According to the analysis of the crustal thickness, the Mozambique ridge is generally oceanic crust and the COB of the whole Mozambique continental margin is divided.展开更多
Around 71% of the Earth’s surface is covered by oceans with depths that exceed several kilometers, while continents are geographically enclosed by these vast bodies of water. The principle of fluid mechanics stipulat...Around 71% of the Earth’s surface is covered by oceans with depths that exceed several kilometers, while continents are geographically enclosed by these vast bodies of water. The principle of fluid mechanics stipulates that water yields pressure everywhere in the container that holds it, and the water pressure against the wall of container generates force. Ocean basins are naturally gigantic containers of water, in which continents form the walls of the containers. In this study, we present that the ocean water pressure against the walls of continents generates enormous force, and determine the distribution of this force around continents and estimate its amplitude to be of the order of 1017 N per kilometer of continent width. Our modelling suggests that the stresses yielded by this force are mostly concentrated on the upper part of the continental crust, and their magnitudes reach up to 2.0 - 6.0 MPa. Our results suggest that the force may have significantly impacted the dynamics of continent (lithospheric plate) and its evolution.展开更多
Based on the production curves,changes in hydrocarbon composition and quantities over time,and production systems from key trial production wells in lacustrine shale oil areas in China,fine fraction cutting experiment...Based on the production curves,changes in hydrocarbon composition and quantities over time,and production systems from key trial production wells in lacustrine shale oil areas in China,fine fraction cutting experiments and molecular dynamics numerical simulations were conducted to investigate the effects of changes in shale oil composition on macroscopic fluidity.The concept of“component flow”for shale oil was proposed,and the formation mechanism and conditions of component flow were discussed.The research reveals findings in four aspects.First,a miscible state of light,medium and heavy hydrocarbons form within micropores/nanopores of underground shale according to similarity and intermiscibility principles,which make components with poor fluidity suspended as molecular aggregates in light and medium hydrocarbon solvents,such as heavy hydrocarbons,thereby decreasing shale oil viscosity and enhancing fluidity and outflows.Second,small-molecule aromatic hydrocarbons act as carriers for component flow,and the higher the content of gaseous and light hydrocarbons,the more conducive it is to inhibit the formation of larger aggregates of heavy components such as resin and asphalt,thus increasing their plastic deformation ability and bringing about better component flow efficiency.Third,higher formation temperatures reduce the viscosity of heavy hydrocarbon components,such as wax,thereby improving their fluidity.Fourth,preservation conditions,formation energy,and production system play important roles in controlling the content of light hydrocarbon components,outflow rate,and forming stable“component flow”,which are crucial factors for the optimal compatibility and maximum flow rate of multi-component hydrocarbons in shale oil.The component flow of underground shale oil is significant for improving single-well production and the cumulative ultimate recovery of shale oil.展开更多
By benchmarking with the iteration of drilling technology,fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and develop...By benchmarking with the iteration of drilling technology,fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin,East China,the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development,drilling and fracturing technologies.The technology system supports the rapid growth of shale oil production and reduces the development investment cost.By comparing it with the shale oil development technology in the United States,the prospect of the shale oil development technology iteration in continental rift lake basins is proposed.It is suggested to continuously strengthen the overall three-dimensional development,improve the precision level of engineering technology,upgrade the engineering technical indicator system,accelerate the intelligent optimization of engineering equipment,explore the application of complex structure wells,form a whole-process integrated quality management system from design to implementation,and constantly innovate the concept and technology of shale oil development,so as to promote the realization of extensive,beneficial and high-quality development of shale oil in continental rift lake basins.展开更多
基金Supported by the Prospective Basic Research Project of CNOOC China Limited(KJQZ-2023-2001)Major Science and Technology Project of CNOOC(KJGG2022-0103-03).
文摘Based on a set of high-resolution 3D seismic data from the northern continental margin of the South China Sea,the lithospheric structure,thinning mechanisms and related syn-rift tectonic deformation response processes in the crustal necking zone in the deepwater area of the Pearl River Mouth Basin were systematically analyzed,and the petroleum geological significance was discussed.The necking zone investigated in the study is located in the Baiyun Sag and Kaiping Sag in the deepwater area of the Pearl River Mouth Basin.These areas show extreme crustal thinned geometries of central thinning and flank thickening,characterized by multi-level and multi-dipping detachment fault systems.The necking zone exhibits pronounced lateral heterogeneity in structural architectures,which can be classified into four types of thinned crustal architectures,i.e.the wedge-shaped extremely thinned crustal architecture in the Baiyun Main Sub-sag,dumbbell-shaped moderately thinned crustal architecture in the Baiyun West Sub-sag,box-shaped weakly thinned crustal architecture in eastern Baiyun Sag,and metamorphic core complex weakly thinned crustal architecture in the Kaiping Sag.This shows great variations in the degree and style of crustal thinning,types of detachment faults,distribution of syn-rift sedimentary sequences,and intensity of magmatism.The thinning of the necking zone is controlled by the heterogeneous rheological stratification of lithosphere,intensity of mantle-derived magmatism,and deformation modes of detachment faults.The syn-rift tectonic deformation of the necking zone evolved through three phases,i.e.uniform stretching during the early Wenchang Formation deposition period,necking during the late Wenchang Formation deposition period,and hyperextension during the Enping Formation deposition period.The crustal thinning extent and architectural differentiation in these phases were primarily controlled by three distinct mechanisms,i.e.the pure shear deformation activation of pre-existing thrust faults,the simple shear deformation of crust-mantle and inter-crust detachment faults,and differential coupling of lower crustal flow and ductile domes with main detachment faults.The hydrocarbon accumulation and enrichment in the necking zone exhibit marked spatial heterogeneity.Four distinct crustal thinned architecture-hydrocarbon accumulation models were identified in this study.The hydrocarbon accumulations in the shallow part exhibit significant correlations with their deep crustal thinned architectures.The unique lithospheric structure and deformation process predominantly control the favorable hydrocarbon accumulation zones with excellent source-fault-ridge-sand configurations,which is critical to reservoir-forming.The most promising exploration targets are mainly identified on the uplift zones and their seaward-dipping flanks associated with the middle and lower crustal domes.This research provides additional insights into lithospheric thinning-breakup process at intermediate continental margins of marine sedimentary basins,being significant for guiding the deepwater petroleum exploration in the Pearl River Mouth Basin.
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.
基金supported by the National Key R&D Program of China (Grant No. 2024YFF0506603)the Independent Research Foundation of the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant Nos. SML2023SP201 and SML2021SP306)+2 种基金the Natural Science Foundation of Guangdong Province, China (Grant No. 2024A1515012717)the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant Nos. 313021004, 313022009 and 313022001)the Program of Innovation 2030 on Smart Ocean, Zhejiang University
文摘The heat content(HC)of water masses on the Ross Sea continental shelf plays an important role in regulating the circulations and the basal melting of the Ross Ice Shelf(RIS).Yet,the evolution of the HC on the Ross Sea continental shelf is still not clear due to the sparsity of observations.By employing a coupled regional ocean-sea ice-ice shelf model for the Ross Sea,this study analyzes the heat budget of water masses over the continental shelf and in the RIS cavity.According to the topographic features and the HC density,the continental shelf region is divided into 17 subdomains.The heat budget of the middle layer for every subdomain is analyzed.In addition,the heat budget for the RIS cavity is assessed for the first time.Owing to Modified Circumpolar Deep Water intrusion,water masses over the eastern shelf are warmer than over the western shelf,with the coldest water identified in the southwestern inner shelf.The horizontal heat flux mainly provides heat to the continental shelf,while the atmospheric forcing tends to warm up the ocean during the ice-melting period and cool down the ocean during the ice-freezing period.The vertical heat flux is generally upward and transports heat from the deep layer to the upper layer.In the RIS cavity,the seasonal cycle of the HC is dominated by the horizontal flux across the RIS front rather than the basal thermal forcing of the RIS.
基金supported by the National Key Program for Developing Basic Science(Nos.2022YFF0801702 and 2022YFE0106600)the National Natural Science Foundation of China(Nos.42175060 and 42175021)the Jiangsu Province Science Foundation(No.BK20250200302).
文摘The Madden-Julian Oscillation(MJO)is a key atmospheric component connecting global weather and climate.It func-tions as a primary source for subseasonal forecasts.Previous studies have highlighted the vital impact of oceanic processes on MJO propagation.However,few existing MJO prediction approaches adequately consider these factors.This study determines the critical region for the oceanic processes affecting MJO propagation by utilizing 22-year Climate Forecast System Reanalysis data.By intro-ducing surface and subsurface oceanic temperature within this critical region into a lagged multiple linear regression model,the MJO forecasting skill is considerably optimized.This optimization leads to a 12 h enhancement in the forecasting skill of the first principal component and efficiently decreases prediction errors for the total predictions.Further analysis suggests that,during the years in which MJO events propagate across the Maritime Continent over a more southerly path,the optimized statistical forecasting model obtains better improvements in MJO prediction.
基金the Centre for Marine Living Resources and Ecology (CMLRE),Ministry of Earth Sciences (MoES), Kochi, Government of India, for the support of crew ‘FORV Sagar Sampada’Funding was provided by the Centre for Marine Living Resources and Ecology (CMLRE), Ministry of Earth Sciences (MoES), Kochi, Government of India
文摘Two new free-living marine nematode species belonging to the genus Tricoma Cobb,1894(Desmoscolecidae)are identi-fied from the continental shelf region of the Bay of Bengal.Tricoma ajmalia sp.nov.is characterized by the number of main rings(84 male and 85 female),the arrangement of somatic setae,the head shape with broadly truncated end,the relatively long cephalic setae(69%-73%of corresponding head diameter),the amphids extending up to second main ring,slender spicules slightly curved and gu-berbaculum with dorsocaudally directed apophyses.The second new species,Tricoma sampadansis sp.nov.is characterized by the number of rings(64),the arrangement of somatic setae(14-13 subdorsal,16 subvenral),the head shape with broadly truncated end,the relatively long cephalic setae(75%corresponding head diameter),the amphidial fovea extending over first main ring,anterioirly bent spicules and gubernaculum with hooked proximal end.An updated valid species list of Tricoma is also presented.
基金supported by the research award project RI/0220-10000618-001 to Sheth from the Industrial Research and Consultancy Centre(IRCC)IIT Bombay.Shekhar and Astha were supported by Prime Minister’s Research Fellowships(PMRF,File Nos.1303100 and 1303103,respectively)+4 种基金Naik was initially supported by an IIT Bombay Institute Post-Doctoral Fellowship(File No.HR-1(HRM-1)/Rect/33/2022/20003002)subsequently by a Goa State Research Foundation Post-doctoral Fellowship(File No.PDF2024003)We express our sincere gratitude to Prof.N.Prabhakar for kindly granting us access to the WD-XRF spectrometry facility(SIP ProjectWBS Code:IN/22-1111039E-01)the ICP-MS facility,and the SERB-funded EPMA National Facility(IRPHA Grant No.IR/S4/ESF-16/2009(G))in the Department of Earth Sciences,IIT Bombay.
文摘Large-scale Danian-age(post-K/Pg boundary)Deccan magmatism is well known from the Mumbai metropolitan area,located in the structurally complex Panvel flexure zone along the western Indian rifted continental margin.This compositionally diverse late-Deccan magmatic suite contains subaerial tholeiitic lavas and dykes typical of the main Deccan province,with many features atypical of the Deccan,such as spilitic pillow lavas,“intertrappean”sediments(often containing considerable volcanic ash),rhyolitic lavas and tuffs,gabbro-granophyre intrusions,and trachyte intrusions containing alkali basalt enclaves.Most of these units,previously dated at 62.5 Ma to 61 Ma,are contemporaneous with or slightly postdate the 62.5 Ma India-Seychelles continental breakup and Panvel flexure formation.In the Dongri-Uttan area,two samples of a>50-m-thick,columnar-jointed rhyolite from the Darkhan Quarry and from a section behind the current Uttan Sagari Police Station have previously been dated at 62.6±0.6 Ma and 62.9±0.2 Ma(^(40)Ar/^(39)Ar,2r errors).New exposures reveal that these two statistically indistinguishable 40 Ar/39 Ar ages correspond to two distinct rhyolite units,separated by well-bedded silicic ash.The columnar rhyolites are microcrystalline,composed of quartz and alkali feldspar,with rare small(1–2 mm),altered feldspar phenocrysts,and no recognisable relict vitroclasts.Given the westerly structural dip,most of their lateral extent is submerged under the Arabian Sea,and we consider them to be possible flood rhyolite lavas.We interpret the ash beds,composed of pumice clasts and glass shards,as a low-grade(nonwelded)vitric ash,derived from a possibly distal Plinian eruption and deposited by fallout.The lavas and ash are peraluminous rhyolites.The lavas are Sr-Ba-poor and Rb-Zr-Nb-rich,and show“seagull-shaped”rare earth element patterns with deep negative europium anomalies.These crystal-poor lavas are“hot-dry-reduced”rhyolites typical of intraplate,continental rift and rifted margin settings.The very different high-field strength element contents of the lavas and the ash indicate compositionally distinct magma batches.The 62.5 Ma Dongri-Uttan sequence provides clear evidence for rapid silicic eruptions of effusive and explosive nature,alternating with each other and sourced from distinct magma chambers and eruptive vents.A newly identified,highly feldspar-phyric trachyte intrusion marks the last phase of magmatic activity in the area,corresponding with late-stage trachyte-syenite intrusions exposed in coastal western India and the Seychelles,and shows that the Mumbai rhyolites and trachytes form a compositional continuum.
基金financially supported by the National Natural Science Foundation of China(Grant No.42002150)the Open Foundation of Cooperative Innovation Center of Unconventional Oil and Gas,Yangtze University(Ministry of Education&Hubei Province,Grant No.UOG2024-12)+1 种基金the Open Foundation Project of the Key Laboratory of Polar Geology and Marine Mineral Resources(China University of Geosciences,Beijing,China),Ministry of Education(Grant No.PGMR-2023-201)the National Key Research Program of China(Grant No.2017ZX05032-002)。
文摘Compared to discrete continental marginal basins,the mechanisms of hydrocarbon migration and enrichment in transform continental marginal basins are poorly understood.In this study,we conducted a comprehensive analysis of the main source rocks,reservoirs,and vertical migration pathways within the Rovuma(RB)and Tanzania(TB)basins in East Africa utilizing drilling,logging,seismic,and geochemical data.The results indicate that the enhanced preservation conditions of the Lower Jurassic source rocks in the southwest could lead to the discovery of large natural gas fields in the southern TB and RB.The primary reservoir is a deep-water turbidite sandstone.Due to topographic differences,the expanse of the turbidite sandstones in the RB is significantly larger than those in Tanzania.The main vertical migration pathways are the western boundary fault zone of the Kerimbas Graben(WBFZ)and the Seagap fault zone(SFZ).In the RB,natural gas migrates vertically along the WBFZ and preferentially accumulates in the deep-water turbidite sandstones of the footwall under the control of the fluid potential.Conversely,in the southern TB,the deep natural gas first migrates upward along the SFZ,then moves along the shallow branch faults in the sandstones on both sides of the SFZ.
基金supported by the National Natural Science Foundation of China[Grants.41802054]supported by a Royal Society SinoBritish Fellowship Trust International Exchanges Award[Grant No.IESR3213093]。
文摘The high Ba-Sr rocks can provide significant clues about the evolution of the continent lithosphere,but their petrogenesis remains controversial.Identifying the Late Cretaceous high Ba-Sr granodiorites in the SE Lhasa Block could potentially provide valuable insights into the continent evolution of the Qinghai-Tibet Plateau.Zircon U-Pb ages suggest that the granodiorites were emplaced at 87.32±0.43 Ma.Geochemically,the high Ba-Sr granodiorites are characterized by elevated K_(2)O+Na_(2)O contents(8.18-8.73 wt%)and K_(2)O/Na_(2)O ratios(0.99-1.25,mostly>1),and belong to high-K calc-alkaline to shoshonitic series.The Yonglaga granodiorites show notably high Sr(653-783 ppm)and Ba(1346-1531 ppm)contents,plus high Sr/Y(30.92-38.18)and(La/Yb)_(N)(27.7-34.7)ratios,but low Y(20.0-22.8 ppm)and Yb(1.92-2.19 ppm)contents with absence of negative Eu anomalies(δEu=0.83-0.88),all similar to typical high Ba-Sr granitoids.The variable zirconεHf(t)values of-4.58 to+12.97,elevated initial^(87)Sr/^(86)Sr isotopic ratios of 0.707254 to 0.707322 and lowεNd(t)values of-2.8 to-3.6 with decoupling from the Hf system suggest that a metasomatized mantle source included significant recycled ancient materials.The occurrence of such high Ba-Sr intrusions indicates previous contributions of metasomatized mantle-derived juvenile material to the continents,which imply the growth of continental crust during the Late Cretaceous in the SE Lhasa.Together with regional data,we infer that the underplated mafic magma provides a significant amount of heat,which leads to partial melting of the juvenile crust.The melting of the metasomatized mantle could produce a juvenile mafic lower crust,from which the high Ba-Sr granitoids were derived from reworking of previous mafic crust during the Late Cretaceous(ca.100-80 Ma)in the SE Lhasa.
基金supported by the Major National Science and Technology Programs of China(No.2016E-0202,No.QGYQZYPJ2022-1).
文摘In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whether the combined patterns of grabens in the Hailar Basin exhibit similar characteristics to those in other NE China rift basins and to identify the underlying causes.To achieve this,a comprehensive analysis of the major fault systems and the combined patterns of faulted sub-depressions,as well as their controlling mechanisms,was conducted.This analysis utilized the latest 3D seismic data that cover nearly the entire Beier Depression.Three groups of pre-existing fault systems were observed in the basement of the Beier Depression,and they are the NEE-EW-trending fault systems,the NE-trending fault systems,and the NW-trending fault systems.The NEE-EW-trending fault systems were distributed in the central part of the Beier Depression and primarily controlled the sedimentary filling of the Tongbomiao and the Lower Nantun Formations.The NE-trending fault systems were distributed in the southwestern part of the Beier Depression and primarily controlled the sedimentary filling of the Upper Nantun Formations.The NW-trending fault systems were distributed rarely in the Beier Depression.Five kinds of combined patterns of the sub-depressions were developed in the Beier Depression,and they are the parallel,en echelon,face-to-face,back-to-back,and S-shaped combined patterns.They were controlled by the NEE-EW-trending and the NE-trending fault systems with different orientations,arrangements,and activation sequences.
基金Supported by the National Natural Science Foundation of China(No.42276019)the Guangdong Provincial Observation and Research Station for Tropical Ocean Environment in Western Coastal Waters(No.GSTOEW)。
文摘The uncertainty of ocean turbulent mixing parameterization comprises a significant challenge in ocean and climate models. A depth-dependent deep learning ocean turbulent mixing parameterization scheme was proposed with the hydrological and microstructure observations conducted in summer 2012 in the shelf sea east of Hainan Island, in South China Sea(SCS). The deep neural network model is used and incorporates the Richardson number Ri, the normalized depth D, the horizontal velocity speed U, the shear S^(2), the stratification N^(2), and the density ρ as input parameters. Comparing to the scheme without parameter D and region division, the depth-dependent scheme improves the prediction of the turbulent kinetic energy dissipation rate ε. The correlation coefficient(r) between predicted and observed lgε increases from 0.49 to 0.62, and the root mean square error decreases from 0.56 to 0.48. Comparing to the traditional physics-driven parameterization schemes, such as the G89 and MG03, the data-driven approach achieves higher accuracy and generalization. The SHapley Additive Explanations(SHAP) framework analysis reveals the importance descending order of the input parameters as: ρ, D, U, N^(2), S^(2), and Ri in the whole depth, while D is most important in the upper and bottom boundary layers(D≤0.3&D≥0.65) and least important in middle layer(0.3<D<0.65). The research shows applicability of constructing deep learning-based ocean turbulent mixing parameterization schemes using limited observational data and well-established physical processes.
基金supported by the National Natural Science Foundation of China(No.41906051)the National Key R&D Program of China(No.2018YFE0202402)+1 种基金sponsored by the Fundamental Research Funds for the Central Universities(Tongji University)(No.22120210525)Shanghai Pilot Program for Basic Research。
文摘Continental intraplate basalts form by partial melting of the mantle,and can provide important constraints on mantle heterogeneity.However,due to the thick overlying continental lithosphere,the origins of the geochemical characteristics of continental intraplate basalts are controversial.In this study,we examined the geochemistry of Cenozoic basalts in southeast China.These basalts which are divided into four volcanic belts exhibit a DMM-EM2 mixing trend and spatial variations in Pb isotopes from inland(i.e.,thick lithosphere)to coastal(i.e.,thin lithosphere)regions.In contrast to the Pb isotopic variations,there are no spatial variations in Sr-Nd-Hf isotopes.Marked correlations between Pb isotopes and major elements(i.e.,Mg O and Si O_(2))suggest the continental lithospheric lid controlled their petrogenesis.Nonetheless,other factors are needed to explain the variations in Ti/Ti^(*)and Hf/Hf^(*)ratios,and Nd-Hf isotopes of the southeast China basalts.The increasing Pb isotope ratios from the inner to coastal regions are associated with decreases in CaO/Al_(2)O_(3) ratios and increases in FC3MS(FeO^(T)/CaO-3×Mg O/Si O_(2);in wt.%)values,indicating contributions from non-peridotite components in the mantle sources.The similarly depleted Nd-Hf isotopic compositions of the basalts from the three inner belts indicate these basalts have a similar origin,whereas the more enriched isotopic features of the basalts from the outer belt suggest their mantle source contains older recycled oceanic crust.Thus,source(i.e.,lithological)heterogeneity also had a significant role in controlling the geochemistry of these basalts.The DMM-EM2 mixing trend defined by the Pb isotopic compositions of continental intraplate basalts from southeast China was generated by variable degrees of melting of heterogeneous mantle that was controlled by the thickness of the continental lithospheric lid(i.e.,the melting pressure).This caused variable extents of melting of enriched components in the mantle sources of the basalts(i.e.,carbonated peridotite vs.pyroxenite).
基金support for this study was jointly given by the NSFC(grants 41930217,42072260 and 42372253)the Youth Innovation Team of Shaanxi Universities.
文摘Determining the evolutionary history of the Permian-Triassic Kunlun-Qaidam Continental Arc is essential to understanding the subduction and closure processes of the South Kunlun Ocean.In this paper,we utilize(La/Yb)N ratios collected from a fi ltered geochemical dataset on Permian to Triassic calc-alkaline rocks(55 wt%–68 wt%SiO_(2))and plutonic rocks within the Kunlun-Qaidam Continental Arc to reconstruct the spatiotemporal variation of the relative crustal thickness.Combined with known geologic observations,we discuss the subduction-accretionary tectonics of the South Kunlun Ocean and the topographic evolution of the Kunlun-Qaidam Continental Arc.Two episodes of crustal thickening and thinning were revealed.The reconstructed thickness reveals two crustal thickening and thinning events for the Kunlun-Qaidam Continental Arc from ca.270 to 210 Ma.The southern sector of the Kunlun-Qaidam Continental Arc is about 7 km thicker than the northern portion,with a maximum thickness of about 55 km at ca.270 and 230 Ma.The ca.270 and 230 Ma crustal thickening events coincide with renewed northward subduction of the South Kunlun Ocean plate and ocean closure,respectively,whereas the ca.270‒240 Ma and ca.230‒210 Ma crustal thinning events may refl ect slab break-off of the oceanic plate and lithospheric collapse during the post-collision extension,respectively.
基金supported by the State Key Program of the National Natural Science Foundation of China(Grant Nos.42230701,91644215)the National Natural ScienceFoundation of China(Grant Nos.42122062 and 42307137)+3 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010852)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(Grant No.23hytd002)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2023SP218)L.M.acknowledges the Zhuhai Science and Technology Plan Project(Grant No.ZH22036201210115PWC).
文摘The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the influence of continental and marine air masses over the Pearl River Estuary(PRE)region in winter 2021.The sum concentration of SOA tracers was 6.2–132.8 ng m^(−3),with SOAM and SOAI as the main components in both continental(scenarios A1 and A2)and marine air masses(scenario A3),as well as their combination(scenario A4).The highest and lowest levels of SOAM were observed in A1 and A3,respectively,which were mainly related to the variations in meteorological conditions,precursor concentrations,and the degree of photochemical processes.Higher MBTCA/HGA(3-methyl-1,2,3-butanetricarboxylic acid/3-hydroxyglutaric acid)ratios suggested a less significant contribution fromα-pinene to SOAM.The variations of SOAI in the different scenarios were associated with differences in relative humidity,particle acidity,and isoprene/NOx ratios.The respective highest and lowest concentrations of aromatics SOA tracers in A1 and A3 revealed the influence of anthropogenic precursors from upwind continental areas,which was confirmed by the correlation among biogenic and anthropogenic precursors.The results of the tracer-based-method suggested dominant contributions of SOAs from aromatics and monoterpenes,with the highest concentrations in A1.A WRF-Chem simulation revealed that the SOAs from the above precursors only contributed 12%–25%to the total SOA at DWS,while the spatial distributions of SOAs further highlighted that the abundance of SOAs over the PRE region in winter is highly associated with air masses transported from upwind continental areas.
基金funded by the National Natural Science Foundation of China(42102309 and 42007243)the Natural Science Foundation of Liaoning Province(2023-MSBA-120)the National Key Research and Development Program(2022YFB3304705)。
文摘Clarify the mechanical properties of different laminations and the fracture mechanism of continental shale under in-situ stress can provide theoretical basis for more comprehensive evaluation of the fracability of continental shale oil reservoir.The Chang 72continental shale was used to investigate the mechanical properties of laminations and the effect of natural structure on the crack propagation of the shale.The XRD and thin section tests show that the laminations contain two types:bright sandy lamination with void structure and dark muddy lamination with layer structure.The real-time CT uniaxial compression tests were conducted to investigate the differences of mechanical properties between the muddy lamination and sandy lamination.It found that the uniaxial compression strength and elastic modulus of the sandy lamination are higher,forming a simple crack with large opening,and the Poisson's ratio of the muddy lamination is large,forming obvious lateral deformation and more secondary cracks.On this basis,the cuboid-shaped continental shale specimens were tested under true triaxial compression conditions to study the effect of laminations and interface cracks on crack propagation combining AE and CT techniques.It found that nascent cracks connected laminations and interface cracks to form fracture network under appropriate loading condition,tensile cracks developed in sandy lamination and shear cracks occurred in muddy lamination because of deformation dissonance and brittleness index differences,and more secondary cracks formed in muddy lamination with smaller fracture toughness.Moreover,the combination relationships between nascent and natural cracks mainly conclude direct penetration and deflection,which is affected by the filling degree and morphology of interface cracks and the relationship of lamination types.These conclusions show that laminar continental shale is conducive to forming complex fracture network,which can provide a theoretical basis for the proposal of indicators and methods for fracability evaluation.
基金supported by grants from the Research Grant Council of the Hong Kong Special Administrative Region,China(Grant No.HKU 7137/03E)the National Natural Science Foundation of China(Grant No.41977248)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB10030100).
文摘The increasing demand for unconventional oil and gas resources,especially oil shale,has highlighted the urgent need to develop rapid and accurate strata characterization methods.This paper is the first case and examines the drilling process monitoring(DPM)method as a digital,accurate,cost-effective method to characterize oil shale reservoirs in the Ordos Basin,China.The digital DPM method provides real-time in situ testing of the relative variation in rock mechanical strength along the drill bit depth.Furthermore,it can give a refined rock quality designation based on the DPM zoning result(RQD(V_(DPM)))and a strength-grade characterization at the site.Oil shale has high heterogeneity and low strata strength.The digital results are further compared and verified with manual logging,cored samples,and digital panoramic borehole cameras.The findings highlight the innovative potential of the DPM method in identifying the zones of oil shale reservoir along the drill bit depth.The digital results provide a better understanding of the oil shale in Tongchuan and the potential for future oil shale exploration in other regions.
基金Supported by the National Science and Technology Major Project of China(2024ZD1400101)China National Key Research and Development Project(2022YFF0801204)Major Science and Technology Project of CNPC(2023ZZ15YJ01,2021DJ0702)。
文摘Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.
基金The National Natural Science Foundation of China under contract No. 42076078China–Mozambique Joint Cruise under contract No. GASI-01-DLJHJ-CM。
文摘Mozambique's continental margin in East Africa was formed during the break-off stage of the east and west Gondwana lands. Studying the geological structure and division of continent-ocean boundary(COB) in Mozambique's continental margin is considered of great significance to rebuild Gondwana land and understand its movement mode. Along these lines, in this work, the initial Moho was fit using the known Moho depth from reflection seismic profiles, and a 3D multi-point constrained gravity inversion was carried out. Thus, highaccuracy Moho depth and crustal thickness in the study area were acquired. According to the crustal structure distribution based on the inversion results, the continental crust at the narrowest position of the Mozambique Channel was detected. According to the analysis of the crustal thickness, the Mozambique ridge is generally oceanic crust and the COB of the whole Mozambique continental margin is divided.
文摘Around 71% of the Earth’s surface is covered by oceans with depths that exceed several kilometers, while continents are geographically enclosed by these vast bodies of water. The principle of fluid mechanics stipulates that water yields pressure everywhere in the container that holds it, and the water pressure against the wall of container generates force. Ocean basins are naturally gigantic containers of water, in which continents form the walls of the containers. In this study, we present that the ocean water pressure against the walls of continents generates enormous force, and determine the distribution of this force around continents and estimate its amplitude to be of the order of 1017 N per kilometer of continent width. Our modelling suggests that the stresses yielded by this force are mostly concentrated on the upper part of the continental crust, and their magnitudes reach up to 2.0 - 6.0 MPa. Our results suggest that the force may have significantly impacted the dynamics of continent (lithospheric plate) and its evolution.
基金Supported by the National Natural Science Foundation of China(U22B6004)Scientific Research and Technological Development Project of RIPED(2022yjcq03)Technology Research Project of PetroChina Changqing Oilfield Company(KJZX2023-01)。
文摘Based on the production curves,changes in hydrocarbon composition and quantities over time,and production systems from key trial production wells in lacustrine shale oil areas in China,fine fraction cutting experiments and molecular dynamics numerical simulations were conducted to investigate the effects of changes in shale oil composition on macroscopic fluidity.The concept of“component flow”for shale oil was proposed,and the formation mechanism and conditions of component flow were discussed.The research reveals findings in four aspects.First,a miscible state of light,medium and heavy hydrocarbons form within micropores/nanopores of underground shale according to similarity and intermiscibility principles,which make components with poor fluidity suspended as molecular aggregates in light and medium hydrocarbon solvents,such as heavy hydrocarbons,thereby decreasing shale oil viscosity and enhancing fluidity and outflows.Second,small-molecule aromatic hydrocarbons act as carriers for component flow,and the higher the content of gaseous and light hydrocarbons,the more conducive it is to inhibit the formation of larger aggregates of heavy components such as resin and asphalt,thus increasing their plastic deformation ability and bringing about better component flow efficiency.Third,higher formation temperatures reduce the viscosity of heavy hydrocarbon components,such as wax,thereby improving their fluidity.Fourth,preservation conditions,formation energy,and production system play important roles in controlling the content of light hydrocarbon components,outflow rate,and forming stable“component flow”,which are crucial factors for the optimal compatibility and maximum flow rate of multi-component hydrocarbons in shale oil.The component flow of underground shale oil is significant for improving single-well production and the cumulative ultimate recovery of shale oil.
基金Supported by the Strategic Research and Technical Consultation Project of Sinopec Science and Technology CommissionSinopec Major Science and Technology Project(P22037)。
文摘By benchmarking with the iteration of drilling technology,fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin,East China,the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development,drilling and fracturing technologies.The technology system supports the rapid growth of shale oil production and reduces the development investment cost.By comparing it with the shale oil development technology in the United States,the prospect of the shale oil development technology iteration in continental rift lake basins is proposed.It is suggested to continuously strengthen the overall three-dimensional development,improve the precision level of engineering technology,upgrade the engineering technical indicator system,accelerate the intelligent optimization of engineering equipment,explore the application of complex structure wells,form a whole-process integrated quality management system from design to implementation,and constantly innovate the concept and technology of shale oil development,so as to promote the realization of extensive,beneficial and high-quality development of shale oil in continental rift lake basins.
