Geophysical inversion under different stabilizers has different descriptions of the target body boundary,especially in complex geological structures.In this paper,we present an extremum boundary inversion algorithm ba...Geophysical inversion under different stabilizers has different descriptions of the target body boundary,especially in complex geological structures.In this paper,we present an extremum boundary inversion algorithm based on different stabilizers for electrical interface recognition.Firstly,we use the smoothest and minimum-support stabilizing functional to study the applicability of adaptive regularization inversion algorithm.Then,an electrical interface recognition method based on different stabilizers is developed by introducing extremum boundary inversion algorithm.The testing shows that the adaptive regularization inversion method does work for different stabilizers and has a low dependence on the initial models.The ratio of the smooth and focusing upper and lower boundaries obtained using the extremum boundary inversion algorithm can clearly demarcate electrical interfaces.We apply the inversion algorithm to the magnetotelluric(MT)data collected from a preselected area of a high-level-waste clay-rock repository site in the Tamusu area.We recognized regional structures with smooth inversion and the local details with focusing inversion and determined the thickness of the target layer combined with the geological and drilling information,which meets the requirement for the site of the high-level waste clay-rock repository.展开更多
The acquisition of neutron time spectrum data plays a pivotal role in the precise quantification of uranium via prompt fission neutron uranium logging(PFNUL).However,the impact of the detector dead-time effect remains...The acquisition of neutron time spectrum data plays a pivotal role in the precise quantification of uranium via prompt fission neutron uranium logging(PFNUL).However,the impact of the detector dead-time effect remains paramount in the accurate acquisition of the neutron time spectrum.Therefore,it is imperative for neutron logging instruments to establish a dead-time correction method that is not only uncomplicated but also practical and caters to various logging sites.This study has formulated an innovative equation for determining dead time and introduced a dead-time correction method for the neutron time spectrum,called the“dual flux method.”Using this approach,a logging instrument captures two neutron time spectra under disparate neutron fluxes.By carefully selecting specific“windows”on the neutron time spectrum,the dead time can be accurately ascertained.To substantiate its efficacy and discern the influencing factors,experiments were conducted utilizing a deuterium-tritium(D-T)neutron source,a Helium-3(3He)detector,and polyethylene shielding to collate and analyze the neutron time spectrum under varying neutron fluxes(at high voltages).The findings underscore that the“height”and“spacing”of the two windows are the most pivotal influencing factors.Notably,the“height”(fd)should surpass 2,and the“spacing”twd should exceed 200μs.The dead time of the 3 He detector determined in the experiment was 7.35μs.After the dead-time correction,the deviation of the decay coefficients from the theoretical values for the neutron time spectrum under varying neutron fluxes decreased from 12.4%to within 5%.Similarly,for the PFNUL instrument,the deviation in the decay coefficients decreased from 22.94 to 0.49%after correcting for the dead-time effect.These results demonstrate the exceptional efficacy of the proposed method in ensuring precise uranium quantification.The dual flux method was experimentally validated as a universal approach applicable to pulsed neutron logging instruments and holds immense significance for uranium exploration.展开更多
Correction to:Nuclear Science and Techniques(2024)35:162 https://doi.org/10.1007/s41365-024-01514-1 In this article,the citation information for Figures 6 and 7 was published incorrectly.The correct citations should r...Correction to:Nuclear Science and Techniques(2024)35:162 https://doi.org/10.1007/s41365-024-01514-1 In this article,the citation information for Figures 6 and 7 was published incorrectly.The correct citations should read as follows:In the sentence beginning‘the curve of Eq.17 is plotted…..’in this article,the text‘as shown in Fig.7a’should have read‘as shown in Fig.6a’.展开更多
The Dongping gold deposit is located on the northern margin of the North China Craton,and is the largest alkaline pluton-related gold deposit in China(Bao et al.,2014),which is characterized by its large amounts of te...The Dongping gold deposit is located on the northern margin of the North China Craton,and is the largest alkaline pluton-related gold deposit in China(Bao et al.,2014),which is characterized by its large amounts of tellurides.The deposit is largely hosted in the Shuiquangou syenitic complex and consists of auriferous quartz veins and disseminated sulfide ores.It has been extensively studied since its discovery in the 1980s;however the geochronology and genesis of the deposit are still controversial.Nie(1998)considered that the deposit was formed in the Devonian.展开更多
The Yunmeng Shan metamorphic core complex （MCC） is composed of the lower plate, the upper plate and the detachment zone. The detachment zone consists of ductile shear zone （mylonite zone）, chloritized microbreccia...The Yunmeng Shan metamorphic core complex （MCC） is composed of the lower plate, the upper plate and the detachment zone. The detachment zone consists of ductile shear zone （mylonite zone）, chloritized microbreccias zone and the brittle fault plane. The ductile shear zone contains mylonitic rocks, protomylonites, and mylonites. Finite strain measurements of feldspar porphyroclasts from those rocks using the Rf/φ method show that the strain intensities increase from mylonitic rocks （Es=0.66-0.72） to protomylonites （Es=0.66-0.83）, and to mylonites （Es=0.71-1.2）. The strain type is close to flatten strain. Kinematic vorticity estimated by Polar Mohr diagrams suggest that foliations and lineation of mylonite （0.47〈Wk〈0.85） record a bulk simple-dominated general shearing at the initial evolution stage of the Yunmeng Shan MCC＇s detachment zone; and the extensional crenulation cleavage（ecc） （0.34〈Wk〈0.77） recorded a bulk pure-dominated general shearing at the later stage of the evolution. Kinematic vorticity measurements also show that the Yunmeng Shan MCC detachment zone is a result of a combination of simple-dominated general shearing caused by crustal extension at the early stage and pure-dominated general shearing caused by MCC uplifting at the late stage. The ductile thinning estimated by finite strain measurements and estimation of Kinematic vorticity ranges from 52% to 82%, which is the minimum thining estimation. Our studies provide new evidence for mechanisms of the Yunmeng Shan MCC detachement zone.展开更多
Objective Banded Iron Formations （BIFs） are ferruginous chemical sedimentary rocks that precipitated throughout the Precambrain, which constitute the most important iron resources in the world. The majority of BIFs...Objective Banded Iron Formations （BIFs） are ferruginous chemical sedimentary rocks that precipitated throughout the Precambrain, which constitute the most important iron resources in the world. The majority of BIFs were developed in the Neoarchean and early Paleoproterozoic periods （3.2-1.8 Ga）, which are well known and have been mined for centuries. Another type of the BIFs which was formed in the Neoproterozoic period （0.85-0.7 Ga） is much smaller in scale but widespread on the Earth and record important information of the evolution of the Earth. The Neoarchean and Paleoproterozoic BIFs have been well studied and understood, while few detailed studies on Neoproterozoic BIFs have been made, and only a few modem geochronology studies were carried out on Neoproterozoic BIFs.展开更多
Oil group separation,gas chromatography-mass spectrometry analysis of saturated hydrocarbons,carbon isotope analysis of fractions and tests on trace elements were all carried out to determine the origin of shallow Jur...Oil group separation,gas chromatography-mass spectrometry analysis of saturated hydrocarbons,carbon isotope analysis of fractions and tests on trace elements were all carried out to determine the origin of shallow Jurassic heavy oils in the northwestern margin of the Junggar Basin,northwestern China.Results showed that all the crude oils had been subjected to different degrees of biodegradation,on an order ranging from PM 6 to 9,which yielded many unresolved complex mixtures(UCM)and formed a huge spike in the mass chromatogram(M/Z=85).Two heavy oils from the Karamay area underwent slight biodegradation,characterized by the consistent ratios of biomarker parameters.C_(21)/C_(23)and C_(23)/H of the two samples were 0.81 and 0.85,while G/H,C_(27)/C_(29)and C_(28)/C_(29)were 0.38 and 0.40,0.16 and 0.27,0.87 and 0.86,respectively.The isomerization parameters of terpane and steranes were 0.50-0.53,and 0.48-0.49,respectively.The above geochemical indices indicated that the crude oils in the study area were in the marginally mature stage.The parent materials were a mixture,consisting of bacteria,algae and some higher plants,formed under reducing depositional conditions,which is in agreement with the source rocks of the Fengcheng Formation in the Mahu depression.The carbon isotopic compositions of saturated hydrocarbon,aromatic hydrocarbon,NSO and asphaltene were−31‰−to−30.3‰,−29.5‰to−29.03‰,−29.4‰to−28.78‰and−28.62‰to−28.61‰,respectively.These findings are in agreement with the light carbon isotope of kerogen from the lower Permian Fengcheng Formation.Furthermore,V/Ni and Cr/Mo of all the crude oils were 0.01 to 0.032,0.837 to 10.649,which is in good agreement with the ratios of the corresponding elements of the extracts from the Fengcheng Fm.carbonate source rock.As a result,a two-stage formation model was established:(1)the oil generated from the carbonate source rocks of the Fengcheng Formation migrated to the Carboniferous,Permian and Triassic traps during the Late Triassic,forming the primary oil reservoirs;(2)during the Late Jurassic period,the intense tectonic activity of Yanshan Episode II resulted in the readjustment of early deep primary reservoirs,the escaped oils gradually migrating to the shallow Jurassic reservoir through cross-cutting faults,unconformities and sand body layers.The oils then finally formed secondary heavy oil reservoirs,due to long-term biodegradation in the later stage.Therefore,joint methods of organic,isotopic and element geochemistry should be extensively applied in order to confirm the source of biodegradation oils.展开更多
The Mazaertag layered intrusion is located in the northwestern part of the Tarim large igneous province where several early Permian layered mafic-ultramafic intrusions host important Fe-Ti oxide deposits. The intrusio...The Mazaertag layered intrusion is located in the northwestern part of the Tarim large igneous province where several early Permian layered mafic-ultramafic intrusions host important Fe-Ti oxide deposits. The intrusion covers an area of -0.13 km-2 and has a vertical stratigraphic thickness of at least300 m. It consists chiefly of olivine clinopyroxenite, and is cut through by the nearby mafic-ultramafic dykes. In this paper, we report new mineral chemistry data and whole-rock chemical and isotopic compositions for the Mazaertag intrusion along with whole-rock isotopic compositions for the nearby mafic dykes. The averaged compositions of cumulus olivine, clinopyroxene and intercumulus plagioclase within individual samples range from Fo71-73,Mg^# = 76 to 79 and An65-75 but they do not define sustained reversals. The observed mineral compositions are consistent with the differentiation of a single batch of magma in a closed system. Rocks of the Mazaertag intrusion are characterized by enrichment in light REE relative to heavy REE, positive Nb and Ta anomalies and a small range of age-corrected εNd（t）（-0.1 to ＋0.9） and initial ^87Sr/^86Sr values（0.7044 to 0.7068）. The slightly lower εNdt）, initial ^206Pb/^204Pb and higher initial ^87Sr/^86Sr values of the intrusion compared to those of the least contaminated dykes[εNdt） =＋2.8 to ＋3.4;^206Pb/^204Pb）i = 18.516-18.521;（^87Sr/^86Sr）i = 0.7038-0.7041] imply that the Mazaertag magma was subjected to small to modest degrees of contamination by the upper crust. The Sr-Nd isotopic compositions of the least contaminated dykes are consistent with derivation from a FOZO-like mantle source. The parental magma of the Mazaertag intrusion, estimated from clinopyroxene compositions using mineral-melt partition coefficients, has trace element compositions similar to some of the most primitive mafic dykes in the same area. This suggests that the Mazaertag intrusion and mafic dykes shared a similar mantle source. Therefore, the parental magma of the Mazaertag intrusion was interpreted to have originated from a mantle plume. Based on the Cr2O3 contents in titanomagnetite and less-evolved characteristics of the Mazaertag intrusion compared to the Wajilitag Fe-Ti oxide deposit in Bachu, it is speculated that there might not be a potential to find economic Fe-Ti oxide mineralization in the intrusion.展开更多
In this study, solutions of hydrazine and its derivatives were irradiated using a pulsed electron beam to determine the half-reaction time of radiolysis. 3 D structures of the hydrazine derivatives were optimized, and...In this study, solutions of hydrazine and its derivatives were irradiated using a pulsed electron beam to determine the half-reaction time of radiolysis. 3 D structures of the hydrazine derivatives were optimized, and their energies were calculated using density functional theory with the B3 LYP method and 6-311 +(3 d, 3 p) basis set.For the first time, the 3 D quantitative structure-activity relationship(QSAR) equation describing the relationship between the hydrazine derivative structures and rate of radiolysis has been established using SPSS software.Pearson correlation analysis revealed a close correlation between the total energies of the molecules and half-reaction times. In the QSAR equation, Y =-7583.464 +54.687 X_1+94333.586 X_2,Y,X_1,and X_2 are the half-reaction time, total energy of the molecule, and orbital transition energy, respectively. The significance levels of the regression coefficients were 0.006 and 0.031, i.e., both less than 0.05. Thus, this model fully explains the relationship between hydrazine derivatives and β radiolysis stability.The results show that the total energy of the molecule and orbital transition energy are the main factors that influence the β radiolysis stability of these hydrazine derivatives.展开更多
The eastern Tianshan has great economic potential with Fe-(Cu)skarn,Cu-Ni-and V-Ti othomagmatic deposits and orogenic Au lodes.In this province the timing relation between Fe-(Cu)skarn-related deposits and the deforma...The eastern Tianshan has great economic potential with Fe-(Cu)skarn,Cu-Ni-and V-Ti othomagmatic deposits and orogenic Au lodes.In this province the timing relation between Fe-(Cu)skarn-related deposits and the deformation is poorly constrained.This study aims to give argument for the chronology between Fe-(Cu)skarn stage展开更多
Objective During the Permian, at least four mafic continental large igneous provinces （LIPs） were tbrmed in eastern Asia, i.e., the Siberian traps （-251 Ma）, Emeishan LIP （-260 Ma）, Tarim LIP （-290-270 Ma） an...Objective During the Permian, at least four mafic continental large igneous provinces （LIPs） were tbrmed in eastern Asia, i.e., the Siberian traps （-251 Ma）, Emeishan LIP （-260 Ma）, Tarim LIP （-290-270 Ma） and Panjal traps （-290 Ma） （Shellnutt et al., 2015）. The Emeishan and Tarim LIPs in China are both known for the presence of several magmatic Fe-Ti-V oxide deposits hosted in layered mafic- ultramafic intrusions. The origin of such magmatic Fe-Ti- V oxide deposits is enigmatic. One of the long-lasting debates is the mechanism by which large amounts of Fe-Ti oxides accumulated in the layered intrusions. Regardless of mechanism, there is still considerable debate regarding the mantle source compositions of the Fe-Ti-V oxide ore- bearing intrusions, in the Tarim LIP, a giant Fe-Ti-V oxide deposit is hosted by the Piqiang layered intrusion at the northern margin of the Tarim block. This intrusion consists mainly of gabbro and minor plagioclase-bearing clinopyroxenite and anorthosite （Fig. l a）. For this study we present new SHRIMP zircon U-Pb age and whole-rock geochemical data for the Piqiang layered gabbroic intrusion to evaluate the nature of its possible source compositions, which in turn aids in understanding the formation of the giant Fe-Ti-V oxide deposit in the plume- related LIPs.展开更多
A passive neutron multiplicity measurement device,FH-NCM/S1,based on field-programmable gate arrays(FPGAs),is developed specifically for measuring the mass of plutonium-240(^(240)Pu)in mixed oxide fuel.FH-NCM/S1 adopt...A passive neutron multiplicity measurement device,FH-NCM/S1,based on field-programmable gate arrays(FPGAs),is developed specifically for measuring the mass of plutonium-240(^(240)Pu)in mixed oxide fuel.FH-NCM/S1 adopts an inte-grated approach,combining the shift register analysis mode with the pulse-position timestamp mode using an FPGA.The optimal effective length of the^(3)He neutron detector was determined to be 30 cm,and the thickness of the graphite reflector was ascertained to be 15 cm through MCNP simulations.After fabricating the device,calibration measurements were per-formed using a^(252)Cf neutron source;a detection efficiency of 43.07%and detector die-away time of 55.79μs were observed.Nine samples of plutonium oxide were measured under identical conditions using the FH-NCM/S1 in shift register analysis mode and a plutonium waste multiplicity counter.The obtained double rates underwent corrections for detection efficiency(ε)and double gate fraction(f_(d)),resulting in corrected double rates(D_(c)),which were used to validate the accuracy of the shift register analysis mode.Furthermore,the device exhibited fluctuations in the measurement results,and within a single 20 s measurement,these fluctuations remained below 10%.After 30 cycles,the relative error in the mass of^(240)Pu was less than 5%.Finally,correlation calculations confirmed the robust consistency of both measurement modes.This study holds specific significance for the subsequent design and development of neutron multiplicity devices.展开更多
Platinum-group elements （PGE） are mainly concentrated in some specific minerals known as PGMs, which commonly occur in podifbrm chromites of ophiolites. In-situ PGM assemblages in chromites can provide valuable info...Platinum-group elements （PGE） are mainly concentrated in some specific minerals known as PGMs, which commonly occur in podifbrm chromites of ophiolites. In-situ PGM assemblages in chromites can provide valuable information on the physico-chemical nature of the parental melt（s） from which chromitite crystallized （Melcher et al., 1997）, and used as a significant petrogenetic indicator.展开更多
NaI(T1) scintillation detectors have been widely applied for gamma-ray spectrum measurements owing to advantages such as high detection efficiency and low price.However,the mitigation of the limited energy resolution ...NaI(T1) scintillation detectors have been widely applied for gamma-ray spectrum measurements owing to advantages such as high detection efficiency and low price.However,the mitigation of the limited energy resolution of these detectors,which detracts from an accurate analysis of the instrument spectra obtained,remains a crucial need.Based on the physical properties and spectrum formation processes of NaI(T1) scintillation detectors,the detector response to gamma photons with different energies is represented by photopeaks that are approximately Gaussian in shape with unique full-width-at-half-maximum(FWHM) values.The FWHM is established as a detector parameter based on resolution calibrations and is used in the construction of a general Gaussian response matrix,which is employed for the inverse decomposition of gamma spectra obtained from the detector.The Gold and Boosted Gold iterative algorithms are employed to accelerate the decomposition of the measured spectrum.Tests of the inverse decomposition method on multiple simulated overlapping peaks and on experimentally obtained U and Th radionuclide series spectra verify the practicability of the method,particularly in the low-energy region of the spectrum,providing for the accurate qualitative and quantitative analysis of radionuclides.展开更多
Objective The Guangshigou uranium deposit is located in the eastern part of the Shangdan triangular domain, which is currently the most productive pegmatite-hosted uranium deposit in China. Previous studies have focus...Objective The Guangshigou uranium deposit is located in the eastern part of the Shangdan triangular domain, which is currently the most productive pegmatite-hosted uranium deposit in China. Previous studies have focused on the migration and precipitation of uraninite and biotite clusters in the uraniferous pegmatites(Li Yanhe et al., 2016; Yuan et al., 2018). However, the accurate uranium mineralization age still remains poorly constrained, thus展开更多
The Na I(Tl) scintillation detector has a number of unique advantages, including wide use, high light yield,and its low price. It is difficult to obtain the decomposition of instrument response spectrum because of lim...The Na I(Tl) scintillation detector has a number of unique advantages, including wide use, high light yield,and its low price. It is difficult to obtain the decomposition of instrument response spectrum because of limitations associated with the Na I(Tl) scintillation detector's energy resolution. This paper, based on the physical process of c photons released from decay nuclides, generating an instrument response spectrum, uses the Monte Carlo method to simulate c photons with Na I(Tl) scintillation detector interaction. The Monte Carlo response matrix is established by different single energy γ-rays with detector effects. The Gold and the improved Boosted-Gold iterative algorithms have also been used in this paper to solve the response matrix parameters through decomposing tests,such as simulating a multi-characteristic energy c-ray spectrum and simulating synthesized overlapping peaks cray spectrum. An inversion decomposition of the c instrument response spectrum for measured samples(U series, Th series and U–Th mixed sources, among others)can be achieved under the response matrix. The decomposing spectrum can be better distinguished between the similar energy characteristic peaks, which improve the error levels of activity analysis caused by the overlapping peak with significant effects.展开更多
Identification of nuclear pulse signal is of importance in radioactive measurements,especially in recognizing adjacent overlapping nuclear pulses.In this article,we propose an estimation method for parameters of typic...Identification of nuclear pulse signal is of importance in radioactive measurements,especially in recognizing adjacent overlapping nuclear pulses.In this article,we propose an estimation method for parameters of typical overlapping nuclear pulse signals.First,the nuclear pulses are regarded as individual genes and the norm is set as the fitness function.Second,the global optimal solution is found by searching the population of genetic algorithm,so as to estimate the parameters of nuclear pulse.With high precision,this method can identify parameters of overlapping nuclear pulses in the Sallen-Key Gaussian signal decomposition experiments.This pulse recognition method is of great significance to improve the precision of radioactive measurement and is suitable for serious overlap of nuclear pluses.展开更多
Objective Large igneous provinces （LIPs） are sites of spatially contiguous, rapidly emplaced magmatic rocks, which represent the physical and chemical transfer of material from the mantle to the crust. Exposed with...Objective Large igneous provinces （LIPs） are sites of spatially contiguous, rapidly emplaced magmatic rocks, which represent the physical and chemical transfer of material from the mantle to the crust. Exposed within some continental LIPs are felsic and rnafic plutonic and volcanic rocks. Although their volumes are minor compared to the flood basalts, the plutonic rocks of continental LIPs are often associated with economic deposits of precious metals. Within the Permian Tarim LIP of NW China, there are at least two layered ultramafic-mafic intrusions （e.g. Wajilitag and Piqiang） contain economically important Fe- Ti-V oxide deposits. Spatially associated with these layered ultramafic-mafic intrusions are syenitic and granitic plutons, which have chemical characteristics of A- type granitoids.展开更多
A direct method of constructing the Hamiltonian structure of the soliton hierarchy with self-consistent sources is proposed through computing the functional derivative under some constraints. The Hamiltonian functiona...A direct method of constructing the Hamiltonian structure of the soliton hierarchy with self-consistent sources is proposed through computing the functional derivative under some constraints. The Hamiltonian functional is related with the conservation densities of the corresponding hierarchy. Three examples and their two reductions are given.展开更多
基金supported by the National Natural Science Foundation of China(Nos.41604104,41674077 and 41404057)PRC High-level Radioactive Waste Geological Disposal Project([2014] No.1578)+2 种基金Open Fund of State Key Laboratory of Marine Geology(Tongji University)(MGK1704)Jiangxi Province Youth Science Fund(No.20171BAB213031)Scientific Research Starting Foundation for Doctors of East China University of Technology(DHBK201403)
文摘Geophysical inversion under different stabilizers has different descriptions of the target body boundary,especially in complex geological structures.In this paper,we present an extremum boundary inversion algorithm based on different stabilizers for electrical interface recognition.Firstly,we use the smoothest and minimum-support stabilizing functional to study the applicability of adaptive regularization inversion algorithm.Then,an electrical interface recognition method based on different stabilizers is developed by introducing extremum boundary inversion algorithm.The testing shows that the adaptive regularization inversion method does work for different stabilizers and has a low dependence on the initial models.The ratio of the smooth and focusing upper and lower boundaries obtained using the extremum boundary inversion algorithm can clearly demarcate electrical interfaces.We apply the inversion algorithm to the magnetotelluric(MT)data collected from a preselected area of a high-level-waste clay-rock repository site in the Tamusu area.We recognized regional structures with smooth inversion and the local details with focusing inversion and determined the thickness of the target layer combined with the geological and drilling information,which meets the requirement for the site of the high-level waste clay-rock repository.
基金supported by the National Natural Science Foundation of China(No.42374226)Jiangxi Provincial Natural Science Foundation(Nos.20232BAB201043 and 20232BCJ23006)+2 种基金Nuclear Energy Development Project(20201192-01)National Key Laboratory of Uranium Resource Exploration-Mining and Nuclear Remote Sensing(ECUT)(2024QZ-TD-09)Fundamental Science on Radioactive Geology and Exploration Technology Laboratory(2022RGET20).
文摘The acquisition of neutron time spectrum data plays a pivotal role in the precise quantification of uranium via prompt fission neutron uranium logging(PFNUL).However,the impact of the detector dead-time effect remains paramount in the accurate acquisition of the neutron time spectrum.Therefore,it is imperative for neutron logging instruments to establish a dead-time correction method that is not only uncomplicated but also practical and caters to various logging sites.This study has formulated an innovative equation for determining dead time and introduced a dead-time correction method for the neutron time spectrum,called the“dual flux method.”Using this approach,a logging instrument captures two neutron time spectra under disparate neutron fluxes.By carefully selecting specific“windows”on the neutron time spectrum,the dead time can be accurately ascertained.To substantiate its efficacy and discern the influencing factors,experiments were conducted utilizing a deuterium-tritium(D-T)neutron source,a Helium-3(3He)detector,and polyethylene shielding to collate and analyze the neutron time spectrum under varying neutron fluxes(at high voltages).The findings underscore that the“height”and“spacing”of the two windows are the most pivotal influencing factors.Notably,the“height”(fd)should surpass 2,and the“spacing”twd should exceed 200μs.The dead time of the 3 He detector determined in the experiment was 7.35μs.After the dead-time correction,the deviation of the decay coefficients from the theoretical values for the neutron time spectrum under varying neutron fluxes decreased from 12.4%to within 5%.Similarly,for the PFNUL instrument,the deviation in the decay coefficients decreased from 22.94 to 0.49%after correcting for the dead-time effect.These results demonstrate the exceptional efficacy of the proposed method in ensuring precise uranium quantification.The dual flux method was experimentally validated as a universal approach applicable to pulsed neutron logging instruments and holds immense significance for uranium exploration.
文摘Correction to:Nuclear Science and Techniques(2024)35:162 https://doi.org/10.1007/s41365-024-01514-1 In this article,the citation information for Figures 6 and 7 was published incorrectly.The correct citations should read as follows:In the sentence beginning‘the curve of Eq.17 is plotted…..’in this article,the text‘as shown in Fig.7a’should have read‘as shown in Fig.6a’.
基金financially supported by the National Natural Science Foundation of China (grant 41573036)the Fundamental Research Funds for the Central Universities, China University of Geosciences (grant No. 2652017262)
文摘The Dongping gold deposit is located on the northern margin of the North China Craton,and is the largest alkaline pluton-related gold deposit in China(Bao et al.,2014),which is characterized by its large amounts of tellurides.The deposit is largely hosted in the Shuiquangou syenitic complex and consists of auriferous quartz veins and disseminated sulfide ores.It has been extensively studied since its discovery in the 1980s;however the geochronology and genesis of the deposit are still controversial.Nie(1998)considered that the deposit was formed in the Devonian.
基金supported by National Natural Science Foundation of China(Grant No.41102129,90714006 and 41002073)the foundation of Fundamental Science on Radioactive Geology and Exploration Technology Laboratory,East China Institute of Technology(Grant No.REGT1207)+1 种基金the Deep Exploration Technology and Experimentation Program of China(Grant No.SinoProbe-08-01-03)projects of China Geological Survey(1212011120135,1212010611803,1212011085474,1212011085473)
文摘The Yunmeng Shan metamorphic core complex （MCC） is composed of the lower plate, the upper plate and the detachment zone. The detachment zone consists of ductile shear zone （mylonite zone）, chloritized microbreccias zone and the brittle fault plane. The ductile shear zone contains mylonitic rocks, protomylonites, and mylonites. Finite strain measurements of feldspar porphyroclasts from those rocks using the Rf/φ method show that the strain intensities increase from mylonitic rocks （Es=0.66-0.72） to protomylonites （Es=0.66-0.83）, and to mylonites （Es=0.71-1.2）. The strain type is close to flatten strain. Kinematic vorticity estimated by Polar Mohr diagrams suggest that foliations and lineation of mylonite （0.47〈Wk〈0.85） record a bulk simple-dominated general shearing at the initial evolution stage of the Yunmeng Shan MCC＇s detachment zone; and the extensional crenulation cleavage（ecc） （0.34〈Wk〈0.77） recorded a bulk pure-dominated general shearing at the later stage of the evolution. Kinematic vorticity measurements also show that the Yunmeng Shan MCC detachment zone is a result of a combination of simple-dominated general shearing caused by crustal extension at the early stage and pure-dominated general shearing caused by MCC uplifting at the late stage. The ductile thinning estimated by finite strain measurements and estimation of Kinematic vorticity ranges from 52% to 82%, which is the minimum thining estimation. Our studies provide new evidence for mechanisms of the Yunmeng Shan MCC detachement zone.
基金financially supported by the National Nature Science Foundation of China(grant No.41302069)
文摘Objective Banded Iron Formations （BIFs） are ferruginous chemical sedimentary rocks that precipitated throughout the Precambrain, which constitute the most important iron resources in the world. The majority of BIFs were developed in the Neoarchean and early Paleoproterozoic periods （3.2-1.8 Ga）, which are well known and have been mined for centuries. Another type of the BIFs which was formed in the Neoproterozoic period （0.85-0.7 Ga） is much smaller in scale but widespread on the Earth and record important information of the evolution of the Earth. The Neoarchean and Paleoproterozoic BIFs have been well studied and understood, while few detailed studies on Neoproterozoic BIFs have been made, and only a few modem geochronology studies were carried out on Neoproterozoic BIFs.
基金funded by a grant from the Natural Science Foundation of China (project 41902084)a grant project (QNYC2018-1) from the Chinese National Nuclear Corporationa grant-aided open fund (project RGET1801) of the Key National Defense Subject Laboratory of Radioactive Geology and Exploration Technology, East China University of Technology
文摘Oil group separation,gas chromatography-mass spectrometry analysis of saturated hydrocarbons,carbon isotope analysis of fractions and tests on trace elements were all carried out to determine the origin of shallow Jurassic heavy oils in the northwestern margin of the Junggar Basin,northwestern China.Results showed that all the crude oils had been subjected to different degrees of biodegradation,on an order ranging from PM 6 to 9,which yielded many unresolved complex mixtures(UCM)and formed a huge spike in the mass chromatogram(M/Z=85).Two heavy oils from the Karamay area underwent slight biodegradation,characterized by the consistent ratios of biomarker parameters.C_(21)/C_(23)and C_(23)/H of the two samples were 0.81 and 0.85,while G/H,C_(27)/C_(29)and C_(28)/C_(29)were 0.38 and 0.40,0.16 and 0.27,0.87 and 0.86,respectively.The isomerization parameters of terpane and steranes were 0.50-0.53,and 0.48-0.49,respectively.The above geochemical indices indicated that the crude oils in the study area were in the marginally mature stage.The parent materials were a mixture,consisting of bacteria,algae and some higher plants,formed under reducing depositional conditions,which is in agreement with the source rocks of the Fengcheng Formation in the Mahu depression.The carbon isotopic compositions of saturated hydrocarbon,aromatic hydrocarbon,NSO and asphaltene were−31‰−to−30.3‰,−29.5‰to−29.03‰,−29.4‰to−28.78‰and−28.62‰to−28.61‰,respectively.These findings are in agreement with the light carbon isotope of kerogen from the lower Permian Fengcheng Formation.Furthermore,V/Ni and Cr/Mo of all the crude oils were 0.01 to 0.032,0.837 to 10.649,which is in good agreement with the ratios of the corresponding elements of the extracts from the Fengcheng Fm.carbonate source rock.As a result,a two-stage formation model was established:(1)the oil generated from the carbonate source rocks of the Fengcheng Formation migrated to the Carboniferous,Permian and Triassic traps during the Late Triassic,forming the primary oil reservoirs;(2)during the Late Jurassic period,the intense tectonic activity of Yanshan Episode II resulted in the readjustment of early deep primary reservoirs,the escaped oils gradually migrating to the shallow Jurassic reservoir through cross-cutting faults,unconformities and sand body layers.The oils then finally formed secondary heavy oil reservoirs,due to long-term biodegradation in the later stage.Therefore,joint methods of organic,isotopic and element geochemistry should be extensively applied in order to confirm the source of biodegradation oils.
基金provided by the National Basic Research Program of China(Grant No.2011CB808906)National Natural Science Foundation of China(Grant No.41703030)+1 种基金research grants from the East China University of Technology(Grant No.DHBK2015323 and RGET1504)the Jiangxi Provincial Department of Education(Grant No.GJJ150556)
文摘The Mazaertag layered intrusion is located in the northwestern part of the Tarim large igneous province where several early Permian layered mafic-ultramafic intrusions host important Fe-Ti oxide deposits. The intrusion covers an area of -0.13 km-2 and has a vertical stratigraphic thickness of at least300 m. It consists chiefly of olivine clinopyroxenite, and is cut through by the nearby mafic-ultramafic dykes. In this paper, we report new mineral chemistry data and whole-rock chemical and isotopic compositions for the Mazaertag intrusion along with whole-rock isotopic compositions for the nearby mafic dykes. The averaged compositions of cumulus olivine, clinopyroxene and intercumulus plagioclase within individual samples range from Fo71-73,Mg^# = 76 to 79 and An65-75 but they do not define sustained reversals. The observed mineral compositions are consistent with the differentiation of a single batch of magma in a closed system. Rocks of the Mazaertag intrusion are characterized by enrichment in light REE relative to heavy REE, positive Nb and Ta anomalies and a small range of age-corrected εNd（t）（-0.1 to ＋0.9） and initial ^87Sr/^86Sr values（0.7044 to 0.7068）. The slightly lower εNdt）, initial ^206Pb/^204Pb and higher initial ^87Sr/^86Sr values of the intrusion compared to those of the least contaminated dykes[εNdt） =＋2.8 to ＋3.4;^206Pb/^204Pb）i = 18.516-18.521;（^87Sr/^86Sr）i = 0.7038-0.7041] imply that the Mazaertag magma was subjected to small to modest degrees of contamination by the upper crust. The Sr-Nd isotopic compositions of the least contaminated dykes are consistent with derivation from a FOZO-like mantle source. The parental magma of the Mazaertag intrusion, estimated from clinopyroxene compositions using mineral-melt partition coefficients, has trace element compositions similar to some of the most primitive mafic dykes in the same area. This suggests that the Mazaertag intrusion and mafic dykes shared a similar mantle source. Therefore, the parental magma of the Mazaertag intrusion was interpreted to have originated from a mantle plume. Based on the Cr2O3 contents in titanomagnetite and less-evolved characteristics of the Mazaertag intrusion compared to the Wajilitag Fe-Ti oxide deposit in Bachu, it is speculated that there might not be a potential to find economic Fe-Ti oxide mineralization in the intrusion.
文摘In this study, solutions of hydrazine and its derivatives were irradiated using a pulsed electron beam to determine the half-reaction time of radiolysis. 3 D structures of the hydrazine derivatives were optimized, and their energies were calculated using density functional theory with the B3 LYP method and 6-311 +(3 d, 3 p) basis set.For the first time, the 3 D quantitative structure-activity relationship(QSAR) equation describing the relationship between the hydrazine derivative structures and rate of radiolysis has been established using SPSS software.Pearson correlation analysis revealed a close correlation between the total energies of the molecules and half-reaction times. In the QSAR equation, Y =-7583.464 +54.687 X_1+94333.586 X_2,Y,X_1,and X_2 are the half-reaction time, total energy of the molecule, and orbital transition energy, respectively. The significance levels of the regression coefficients were 0.006 and 0.031, i.e., both less than 0.05. Thus, this model fully explains the relationship between hydrazine derivatives and β radiolysis stability.The results show that the total energy of the molecule and orbital transition energy are the main factors that influence the β radiolysis stability of these hydrazine derivatives.
文摘The eastern Tianshan has great economic potential with Fe-(Cu)skarn,Cu-Ni-and V-Ti othomagmatic deposits and orogenic Au lodes.In this province the timing relation between Fe-(Cu)skarn-related deposits and the deformation is poorly constrained.This study aims to give argument for the chronology between Fe-(Cu)skarn stage
基金financially supported by the National Natural Science Foundation of China(grant No.41703030)research grants from the East China University of Technology(grants No.DHBK2015323 and RGET1504)
文摘Objective During the Permian, at least four mafic continental large igneous provinces （LIPs） were tbrmed in eastern Asia, i.e., the Siberian traps （-251 Ma）, Emeishan LIP （-260 Ma）, Tarim LIP （-290-270 Ma） and Panjal traps （-290 Ma） （Shellnutt et al., 2015）. The Emeishan and Tarim LIPs in China are both known for the presence of several magmatic Fe-Ti-V oxide deposits hosted in layered mafic- ultramafic intrusions. The origin of such magmatic Fe-Ti- V oxide deposits is enigmatic. One of the long-lasting debates is the mechanism by which large amounts of Fe-Ti oxides accumulated in the layered intrusions. Regardless of mechanism, there is still considerable debate regarding the mantle source compositions of the Fe-Ti-V oxide ore- bearing intrusions, in the Tarim LIP, a giant Fe-Ti-V oxide deposit is hosted by the Piqiang layered intrusion at the northern margin of the Tarim block. This intrusion consists mainly of gabbro and minor plagioclase-bearing clinopyroxenite and anorthosite （Fig. l a）. For this study we present new SHRIMP zircon U-Pb age and whole-rock geochemical data for the Piqiang layered gabbroic intrusion to evaluate the nature of its possible source compositions, which in turn aids in understanding the formation of the giant Fe-Ti-V oxide deposit in the plume- related LIPs.
基金supported by the National Natural Science Foundation of China(No.42374226)Natural Science Foundation of Jiangxi Province(Nos.20232BAB201043 and 20232BCJ23006)+1 种基金a sub-project of the nuclear energy development project of the China National Defense Science and Industry Bureau‘n-γfusion logging method theory research’(No.20201192-01)the Fundamental Science on Radioactive Geology and Exploration Technology Laboratory(No.2022RGET20)。
文摘A passive neutron multiplicity measurement device,FH-NCM/S1,based on field-programmable gate arrays(FPGAs),is developed specifically for measuring the mass of plutonium-240(^(240)Pu)in mixed oxide fuel.FH-NCM/S1 adopts an inte-grated approach,combining the shift register analysis mode with the pulse-position timestamp mode using an FPGA.The optimal effective length of the^(3)He neutron detector was determined to be 30 cm,and the thickness of the graphite reflector was ascertained to be 15 cm through MCNP simulations.After fabricating the device,calibration measurements were per-formed using a^(252)Cf neutron source;a detection efficiency of 43.07%and detector die-away time of 55.79μs were observed.Nine samples of plutonium oxide were measured under identical conditions using the FH-NCM/S1 in shift register analysis mode and a plutonium waste multiplicity counter.The obtained double rates underwent corrections for detection efficiency(ε)and double gate fraction(f_(d)),resulting in corrected double rates(D_(c)),which were used to validate the accuracy of the shift register analysis mode.Furthermore,the device exhibited fluctuations in the measurement results,and within a single 20 s measurement,these fluctuations remained below 10%.After 30 cycles,the relative error in the mass of^(240)Pu was less than 5%.Finally,correlation calculations confirmed the robust consistency of both measurement modes.This study holds specific significance for the subsequent design and development of neutron multiplicity devices.
基金financially supported by the National Natural Science Foundation of China (40930313, 41262002)National Industry Special Projects (Sino Probe-05-02)China Bureau of Geological Survey Projects (12120115027201, 1212011121263)
文摘Platinum-group elements （PGE） are mainly concentrated in some specific minerals known as PGMs, which commonly occur in podifbrm chromites of ophiolites. In-situ PGM assemblages in chromites can provide valuable information on the physico-chemical nature of the parental melt（s） from which chromitite crystallized （Melcher et al., 1997）, and used as a significant petrogenetic indicator.
基金supported by the National Natural Science Foundation of China(Grant No.11365001)National Major Scientific Equipment Development Projects(Grant No.041514065)+2 种基金the Educational Commission of Jiangxi Province of China(Grant No.GJJ13464)Plan of Science and Technology of Jiangxi Province(Grant No.20141BBE50024)the Fundamental Science on Radioactive Geology and Exploration Technology Laboratory,East China Institute of Technology(Grant No.RGET1316)
文摘NaI(T1) scintillation detectors have been widely applied for gamma-ray spectrum measurements owing to advantages such as high detection efficiency and low price.However,the mitigation of the limited energy resolution of these detectors,which detracts from an accurate analysis of the instrument spectra obtained,remains a crucial need.Based on the physical properties and spectrum formation processes of NaI(T1) scintillation detectors,the detector response to gamma photons with different energies is represented by photopeaks that are approximately Gaussian in shape with unique full-width-at-half-maximum(FWHM) values.The FWHM is established as a detector parameter based on resolution calibrations and is used in the construction of a general Gaussian response matrix,which is employed for the inverse decomposition of gamma spectra obtained from the detector.The Gold and Boosted Gold iterative algorithms are employed to accelerate the decomposition of the measured spectrum.Tests of the inverse decomposition method on multiple simulated overlapping peaks and on experimentally obtained U and Th radionuclide series spectra verify the practicability of the method,particularly in the low-energy region of the spectrum,providing for the accurate qualitative and quantitative analysis of radionuclides.
基金provided by the Bureau of Geology of the Chinese National Nuclear Corporation (grants No. 2016YFE0206300, (2018)294, 3210402 and LTC1605-1)
文摘Objective The Guangshigou uranium deposit is located in the eastern part of the Shangdan triangular domain, which is currently the most productive pegmatite-hosted uranium deposit in China. Previous studies have focused on the migration and precipitation of uraninite and biotite clusters in the uraniferous pegmatites(Li Yanhe et al., 2016; Yuan et al., 2018). However, the accurate uranium mineralization age still remains poorly constrained, thus
基金supported by National Natural Science Foundation of China(No.11365001)National Major Scientific Equipment Development Projects(No.041514065)+1 种基金Natural Science Foundation of Jiangxi(No.20161BAB201035)Fundamental Science on Radioactive Geology and Exploration Technology Laboratory,East China Institute of Technology(No.RGET1316)
文摘The Na I(Tl) scintillation detector has a number of unique advantages, including wide use, high light yield,and its low price. It is difficult to obtain the decomposition of instrument response spectrum because of limitations associated with the Na I(Tl) scintillation detector's energy resolution. This paper, based on the physical process of c photons released from decay nuclides, generating an instrument response spectrum, uses the Monte Carlo method to simulate c photons with Na I(Tl) scintillation detector interaction. The Monte Carlo response matrix is established by different single energy γ-rays with detector effects. The Gold and the improved Boosted-Gold iterative algorithms have also been used in this paper to solve the response matrix parameters through decomposing tests,such as simulating a multi-characteristic energy c-ray spectrum and simulating synthesized overlapping peaks cray spectrum. An inversion decomposition of the c instrument response spectrum for measured samples(U series, Th series and U–Th mixed sources, among others)can be achieved under the response matrix. The decomposing spectrum can be better distinguished between the similar energy characteristic peaks, which improve the error levels of activity analysis caused by the overlapping peak with significant effects.
基金supported by the National Natural Science Foundation of China(No.41204133)Sichuan Province Science and Technology Support Program(No.2014GZ0020)+1 种基金the Open Science Fund from Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense,East China Institute of Technology(No.RGET1401)Scientific Research Fund of Sichuan Provincial Education Department(No.13ZA0066)
文摘Identification of nuclear pulse signal is of importance in radioactive measurements,especially in recognizing adjacent overlapping nuclear pulses.In this article,we propose an estimation method for parameters of typical overlapping nuclear pulse signals.First,the nuclear pulses are regarded as individual genes and the norm is set as the fitness function.Second,the global optimal solution is found by searching the population of genetic algorithm,so as to estimate the parameters of nuclear pulse.With high precision,this method can identify parameters of overlapping nuclear pulses in the Sallen-Key Gaussian signal decomposition experiments.This pulse recognition method is of great significance to improve the precision of radioactive measurement and is suitable for serious overlap of nuclear pluses.
基金financially supported by the National Natural Science Foundation of China (Grant No.41703030)research grants from the East China University of Technology (Grants No.DHBK2015323 and RGET1504)the Jiangxi Provincial Department of Education (Grant No.GJJ150556)
文摘Objective Large igneous provinces （LIPs） are sites of spatially contiguous, rapidly emplaced magmatic rocks, which represent the physical and chemical transfer of material from the mantle to the crust. Exposed within some continental LIPs are felsic and rnafic plutonic and volcanic rocks. Although their volumes are minor compared to the flood basalts, the plutonic rocks of continental LIPs are often associated with economic deposits of precious metals. Within the Permian Tarim LIP of NW China, there are at least two layered ultramafic-mafic intrusions （e.g. Wajilitag and Piqiang） contain economically important Fe- Ti-V oxide deposits. Spatially associated with these layered ultramafic-mafic intrusions are syenitic and granitic plutons, which have chemical characteristics of A- type granitoids.
基金ACKNOWLEDGMENTS The work was supported by the National Nature Science Foundation of China （Nos.11161002 and 41001320）, Natural Science Foundation of Jiangxi province （No.20114BAB201016）. Thanks for the useful advices of the editors and the reviewers.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10371070, 10671121the President Foundation of East China Institute of Technology under Grant No. DHXK0810
文摘A direct method of constructing the Hamiltonian structure of the soliton hierarchy with self-consistent sources is proposed through computing the functional derivative under some constraints. The Hamiltonian functional is related with the conservation densities of the corresponding hierarchy. Three examples and their two reductions are given.
