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Polymer grouting materials are increasingly used in the filling of mine fissures. Unlike conventional inorganic grouting materials, the self-expansion of polymers adds complexity to their diffusion process within the crack. The objective of this research was to examine how polymer grouting material spreads in cracks at ambient temperatures and pressure. The investigation involved conducting grouting tests and performing numerical fluid simulation calculations using the finite-volume method in the computational fluid dynamics software, ANSYS FLUENT 2022 R1. The fluid volume approach was employed to determine the boundary between fluid and air and to ascertain the variation patterns of density in the slurry and the fracture system. This study applied the principles of fluid mechanics to investigate the patterns of variation in the physical characteristics of polymer grouting materials, including their density, pressure, flow velocity, and movement distance, during the diffusion process. The results indicated that the density of the polymer grouting material decreased exponentially over time throughout the diffusion process. With the increase in the grouting's volume, the grout's pressure and the permeable distance of the grout increased. The slurry's pressure near the grouting hole exceeded the other points' pressure. The physical parameters of the slurry were numerically simulated by ANSYS FLUENT 2022 R1 software, and the results were compared with the experimental data. After comparing the numerical simulation results with the test data, it was clear that the numerical simulation method was superior in accurately predicting the distribution pattern of each parameter of the polymer slurry during diffusion. The grouting volume, pressure distribution, and real-time change in the position of the flow of slurry could be efficiently determined through numerical calculation and simulated grouting tests. This work can offer valuable information for designing polymer grouting materials used in underground mine fissures. [ABSTRACT FROM AUTHOR]

With the increasing drilling depth of mines, the cross-complexity of fissures in the rock body, and the frequent occurrence of sudden water surges, polymer slurry, with its advantages of good permeability and strong water plugging, is increasingly used in mine grouting projects. Additional research is needed in order to further improve the grouting performance of polymer slurry, ensure the safety of mining operations, and reduce the grouting cost. In this paper, a polymer composite grouting material was prepared with diphenyl methyl diisocyanate, polyether polyol, and fly ash, as the main raw materials, with coupling agent and catalyst as auxiliary reagents. The performance of the composite grouting material in terms of mechanical properties, thermal stability, hydrophobicity, and bonding was explored. This study's findings indicated that incorporating fly ash led to notable enhancements in the thermal stability and water resistance of the polymer slurry. Furthermore, the introduction of fly ash notably raised the starting degradation temperature of the polymer, boosted the water contact angle of the composite material, and reduced the density and reaction temperature of the composite material. In addition, the catalyst and coupling agent as auxiliary reagents affected the polymers in terms of mechanical properties; in this paper, dibutyltin dilaurate was used as the catalyst, and organosilanes were used as the coupling agent. The catalyst successfully sped up the polymer's gel time, however, an excessive quantity of catalyst compromised the polymer's mechanical characteristics. The addition of organosilanes has a positive effect on the dynamic mechanical properties of the composites, fracture toughness, compression, bending, and bond strength. The research can offer a theoretical direction for creating polymer mixtures in mine grouting projects. [ABSTRACT FROM AUTHOR]

Extralow-permeability reservoirs have emerged as a significant area of focus for CO2 geological sequestration due to their stable subterranean structure and expansive storage capacity, offering substantial potential in addressing global climate change. However, the full extent of CO2 geological sequestration potential within these extralow-permeability reservoirs remains largely unexplored. To address this gap, this paper utilizes the Shahejie Formation (Es1 member) of the Shuang 229 block in the Liaohe oilfield, Bohai Bay Basin, as a case study. This section is characterized by its abundant oil-gas reserves and serves as an exemplar for conducting experimental research on CO2 storage within extralow-permeability reservoirs. The results demonstrate that the reservoir lithology of the Es1 member is fine sandstone and siltstone, with high compositional and structural maturity. Moreover, the average porosity is 14.8%, the average permeability is 1.48 mD, and the coefficient of variation of the reservoir is approximately 0.5, which indicates a low- to extralow-permeability homogeneous reservoir. In addition, the overburden pressure is >2.0 MPa, the fault can withstand a maximum gas column height of >200 m, and the reservoir exhibits favorable overburden and fault sealing characteristics. Notably, stepwise increasing gas injection in the Shuang 229-36-62 well reveals that the injected liquid CO2 near the wellhead exhibits a relatively high density, close to 1.0 g/cm3, which gradually decreases to approximately 0.78 g/cm3 near a depth of 2000 m underground. The injected fluid changes into a supercritical state upon entering the formation, and the CO2 injection speed is optimal, at 0.08 HCPV/a. According to these findings, it is predicted that the highest burial CO2 volume via the injection of 1.5 HCPVs in the Wa 128 block area is 1.11 × 105 t/year, and the cumulative burial volume reaches approximately 2.16 × 106 t. This shows that the CO2 sequestration potential of extralow-permeability reservoirs is considerable, providing confidence for similar instances worldwide. [ABSTRACT FROM AUTHOR]

Volcanogenic massive sulfide (VMS) deposits are globally significant sources of metals. The Hongtoushan VMS deposit is the only large Archean Cu-Zn VMS deposit in the North China Craton, carrying substantial economic value. Significant deformation and metamorphism have made the tectonic setting of the Hongtoushan VMS deposit the subject of extensive debate. This study investigates the petrogenesis and chronology of the ore-bearing host rocks from the Hongtoushan Cu-Zn VMS deposit in the North China Craton. By utilizing whole-rock geochemical analyses and zircon dating, this research sheds light on the origin and evolution of the ore-bearing rocks within the deposit. The whole-rock geochemical analysis data indicate that the Hongtoushan ore-bearing rock series is mainly composed of amphibole plagioclase gneiss (basalt protolith) and biotite plagioclase gneiss (andesite and rhyolite protolith), suggesting a complete volcanic cycle from basic to medium-acidic volcanic rocks. The amphibole plagioclase gneiss has slight LREE enrichment patterns with unremarkable depletions of Nb, Ta, and Ti and belongs to contaminated ocean plateau basalt (OPB) in terms of composition, which is generally interpreted as being generated from the mantle plume head. Meanwhile, the biotite plagioclase gneiss has relatively steep LREE enrichment distribution patterns with remarkable negative Ta, Nb, and Ti anomalies and a wide range of Zr/Y ratios, indicating their classification as FI- and FII-type felsic rocks; they were likely formed through the fractional crystallization of basic magma combined with crustal assimilation. When combined with the zircon dating results, the ore-bearing host rocks of the Hongtoushan VMS deposit were generated via a continuous magmatic evolution process. The zircon dating of the host rocks indicates a formation age of between 2609 and 2503 Ma, with metamorphic events between 2540 and 2466 Ma, which is consistent with the 2.5 Ga-related global mantle plume event. Further research shows that the ore-bearing host rocks are more likely to have been formed in a mantle plume-related stretching environment, possibly a margin rift. [ABSTRACT FROM AUTHOR]

Diamondiferous kimberlites occur in the Wafangdian area in the eastern part of the North China Craton (NCC). In order to better constrain their magmatic source and emplacement time, we have investigated apatite from two kimberlites, i.e., the #110 dike kimberlite and the #50 root-zone kimberlite by measuring in situ their U–Pb and Sr–Nd isotopic compositions. The crystallization ages of the #110 and #50 apatites are 460.9 ± 16.8 Ma and 455.4 ± 19.3 Ma, respectively. For the #50 apatite, 87Sr/86Sr = 0.70453–0.70613 and εNd(t) = −2.74 to −4.52. For the #110 apatite, 87Sr/86Sr = 0.70394–0.70478 and εNd(t) = −3.46 to −5.65. Based on the similar distribution patterns of the rare earth elements (REEs) and the similar Sr-Nd isotope compositions of the apatite, it is believed that the #110 and #50 kimberlites have the same source region and the kimberlite magmas in Wafangdian were derived from an enriched mantle source (EMI). The primary magmatic composition has little effect on the emplacement pattern. It is more likely that the geological environment played an important role in controlling the retention and removal of volatile components (H2O and CO2). This led to the different evolutionary paths of the kimberlite magma in the later period, resulting in differences in the major element compositions of the apatite. High Sr concentrations may be associated with hydrothermal (H2O-rich fluid) overprinting events in the later magmatic period; the higher light rare earth element (LREE) concentration of the #50 apatite reflects the involvement of the REE3+ + SiO44− ⇔ Ca2+ + PO43− replacement mechanism. Two emplacement patterns of the #110 dike kimberlite (#110 apatite, low Sr, and high Si) and the #50 root-zone (#50 apatite, high Sr, and low Si) kimberlites were identified via major element analysis of the #110 apatite and #50 apatite. [ABSTRACT FROM AUTHOR]

In this study, organic polymer polyurethane grouting materials were prepared using isocyanate and polyether polyol as the main agents and various additives, the slurry coagulation process was investigated, and the mechanical properties of the polymer samples were tested to explore the influence of the density and soaking time of the polymer on the strength of the samples. The microstructure of the polymer was observed via electron microscopy, and relying on image analysis software, the structural parameters of the polymer cell were analyzed and calculated; the model equation between density and yield strength was established based on the strength model of porous materials developed by Gibson and Ashby. The results show that the initial viscosity and gel time of the polyurethane slurry decrease with the increase of the initial temperature, and the viscosity changes abruptly when the slurry reaches the gel point. The mechanical properties of the polymer increased with increasing density and decreased with increasing soaking time. The interior of the polymer is a porous structure and the pores are approximately spherical; the higher the density of the polymer material, the more uniform the stress distribution of the material, and the higher the percentage of the matrix, which in turn leads to better mechanical properties of the material. The diameter of the polymer cell is negatively correlated with the density, and the model established based on the microscopic parameters of the cell can better predict the yield strength of the polymer. This study helps to deepen the understanding of the microstructure and mechanical properties of polyurethane and provides a certain reference for the application of polyurethane in underground mine reinforcement engineering. [ABSTRACT FROM AUTHOR]

Deep learning‐based single view 3D reconstruction is a hot topic in computer vision. However, predicting a more realistic 3D point cloud from a single image is an ill‐posed problem. In recent years, most of the 3D point cloud prediction methods based on single view are straight‐through structure, which will cause the loss of part of feature information and the loss of part of detail information of the resulting point clouds, which will lead to the unsatisfactory visual effect of reconstructed point clouds. In this paper, a Feature‐Enhanced 3D point clouds generation Network (3D‐FENet) from a single image is proposed. In order to enhance the feature information of RGB image, edge extraction module is adopted. In the process of point cloud generation, a point cloud pyramid is designed, which combines low resolution point cloud with high resolution point cloud to enhance the local details of the generated point clouds. In the fine‐tuning stage, the differential projection module is used to fine‐tune the whole network by 2D projection of reconstructed point clouds. Experimental results show that the performance of the authors' proposed method is better than the state‐of‐the‐art studies. [ABSTRACT FROM AUTHOR]

Infrared image systems often generate stripe noise because of the non-uniformity of the focal plane array, which significantly reduces the visual quality of the image. To solve this problem, we proposed an effective single-frame denoising method in this paper. First, the wavelet function extracts the approximate and vertical components of the original image containing stripe noise. Then, the approximation component is denoised by parameter estimation, and the vertical component is denoised by guided filtering. Finally, wavelet reconstruction is performed to realize the denoising process of the original image. This method avoids the loss of details of other components of the image and achieves an excellent denoising effect. The experimental results on the public datasets indicate that our proposed method can effectively eliminate the stripe noise of infrared images compared with some advanced methods. [ABSTRACT FROM AUTHOR]

The Gongchangling deposit is a representative banded iron formation (BIF) in China, in which developed several high-grade magnetite ores. The surrounding alteration rocks recorded the genesis information of the high-grade ores. However, the study related to alteration processes remains poor. In this study, we investigate the sub-types and formation temperature of chlorite using hyperspectral imaging and electronic probe microanalysis (EPMA), and deciphered the elemental migration trend during alteration processes by whole-rock geochemistry. The chlorites in the alteration rocks were divided into three sub-types according to the spectral features of the Fe-OH band near 2250 nm. The range of wavelength position is approximately 2250–2255 nm for chlorite-I, 2255–2260 nm for chlorite-II, and 2260–2265 nm for chlorite-III. The variation in Mg# is 0.32–0.44 in chlorite-I, 0.20–0.34 in chlorite-II, and 0.15–0.23 in chlorite-III, which is consistent with the range of wavelength position. The hydrothermal alteration resulted in the enrichment of iron and the depletion of silicon. The results shed new light on the recognition of chlorite sub-types and deciphered the hydrothermal alteration processes of high-grade magnetite ores, which proposed an effective method for mineralogical mapping. [ABSTRACT FROM AUTHOR]

Geological storage of carbon dioxide (CO2) is an important way to mitigate global warming, making CO2 enhanced oil recovery (CO2-EOR) and storage technology with sequestration and economic benefits a hot research topic and making positive progress in medium- to high-permeability reservoirs. However, the research on extra-low-permeability reservoirs is still poorly understand, facing the dual challenges of high cost and low efficiency. In order to clarify the potential of CO2-EOR and storage in extra-low-permeability reservoirs, this study takes the extra-low-permeability reservoir in Liaohe Oilfield, Northeast China, as an example, and integrates experimental analyzes, numerical simulations, and on-site trial injections to carry out a pilot test study of CO2-EOR and storage. The results show that the production capacity of natural energy development decreases rapidly and the recovery rate is low (~ 7.5%); The start-up and displacement pressure gradient of water injection is high, making it impossible to achieve continuous and effective injection; Gas injection can effectively displace replacement, with a reservoir gas absorption index of 3.67 m3/MPa is 4–6 times the water. At 41 MPa, compared to the injection of air, nitrogen, natural gas, and CO2, the crude oil expansion was 2.7%, 2.4%, 10.7%, and 25.2%, respectively. The viscosity decreased from 0.42 to 0.35 mPa·s, 0.35 mPa·s, 0.30 mPa·s, and 0.22 mPa·s, respectively. Meanwhile, the minimum miscible replacement pressure of CO2 (31.8 MPa) is closest to the reservoir pressure (37.1–44.5 MPa), and the efficiency of oil repulsion is also the highest (79.5%). Therefore, CO2 is the optimal miscible replacement medium with high swelling and strong viscosity reduction. Accordingly, the W-128 well area was preferred for the experiment, and the injection and recovery analysis revealed that the cumulative CO2 burial and oil production were 216.44 × 104 t and 143.28 × 104 t, respectively, and the final recovery rate (40%) was 32.5% higher than that of the natural energy, demonstrating the good potential of the CO2-EOR and storage technology for large-scale application in the extra-low-permeability reservoirs. This study is expected to further expand the application of CO2 storage and provide an important scientific basis for efficient CO2-EOR in extra-low-permeability reservoirs. [ABSTRACT FROM AUTHOR]

The Ekou banded iron formation (BIF) in the Wutai area is hosted within the late Archean Baizhiyan formation. The mineral assemblage is used to identify oxide and silicate facies. The oxide facies is composed of magnetite and quartz, and the silicate facies is characterized by the presence of silicate minerals. A geochemical analysis shows that the major elemental compositions are dominantly SiO2 and Fe2O3T, with very little Al2O3 and TiO2 and minor abundances of incompatible elements and transition elements. These results indicate that negligible terrigenous materials were involved in the BIF deposition. The rare-earth elements (REEs), normalized by post-Archean Australian shale, exhibit the characteristics of light REE (LREE) depletion, heavy REE (HREE) enrichment, and positive La, Y, and Eu anomalies. The Y/Ho ratios are superchondritic. These results indicate that the material that formed the Ekou BIF originated from the mixing of seawater and submarine hydrothermal fluids. A Ce anomaly deficiency and heavy Fe isotope enrichment indicate that the Ekou BIF formed in an anoxic marine environment. The δ30SiNBS-28 values for quartz in the Ekou BIF are similar to those of other BIFs with distribution ranges of modern sinters and black smokers. The δ18OV-SMOW distribution is similar to that of hydrothermal sedimentary siliceous rocks. These results suggest that the formation of the Ekou BIF was closely connected to submarine volcanic exhalation activity. [ABSTRACT FROM AUTHOR]

Stripe non-uniformity severely affects the quality of infrared images. It is challenging to remove stripe noise in low-texture images without blurring the details. We propose a single-frame image stripe correction algorithm that removes infrared noise while preserving image details. Firstly, wavelet transform is used for multi-scale analysis of the image. At the same time, Total variation model is used for small window to smooth the original image. The small-scale total variation model can well preserve the edge information of the image, but it will leave stripe noise. Therefore, according to the prior knowledge of the vertical component of the stripe noise, the spatial filtering is finally performed: the smoothed image is used as the guide image for the stripe noise denoising. It is possible to prevent the lead filter from mistaking the strong stripe noise as edge detail, resulting in corrected image residual streak noise. The algorithm is systematically evaluated by experiments on simulated images and original infrared images, as well as compared with the current advanced infrared stripe non-uniformity correction algorithms. It is proved that our algorithm can better eliminate stripe noise and preserve edge details. [ABSTRACT FROM AUTHOR]

The mechanical and hydraulic behaviors of rock fractures are strongly dependent on the properties of the surface morphology. In this study, a sandstone fracture surface is taken as the research object. The morphological properties of the fracture surface characterized by parameters Z2s, Z2, and SRv are analyzed under the different sampling windows and profile lines. The results show that the large sampling window is more conducive to obtaining stable values of the morphology parameter Z2s. The coefficient of variation (CV) and the percentage of variation (PV) are proposed to determine the stable values of the morphology parameter Z2s, which is defined as a representative elementary surface (RES). It is confirmed that there is a RES with a size of 220 mm in the study region. The large sampling window generates a long correlation length of the morphology parameter Z2s. The differential sensitivities of the morphology parameters Z2 and SRv are compared under the different profile lines. It is found that the parameter Z2 can better describe the random variation properties of the surface morphology, while the parameter SRv is more suitable for describing the spatial structural variation properties of the surface morphology. The findings of this work are of great significance for investigating the size effect and anisotropy of rock fracture permeability. [ABSTRACT FROM AUTHOR]

The Yuanjiacun banded iron formation (BIF) is hosted in lower Proterozoic metamorphic strata, and its structures are dominated by bands or streaks. Based on their differences in mineral compositions, the iron ores can be subdivided into haematite quartzite, magnetite quartzite, stilpnomelane magnetite quartzite and stilpnomelane haematite quartzite. The geochemical characteristics of the surrounding rocks show that the protoliths consisted of argillaceous and arenaceous sedimentary rocks. The predominant provenance was a high-maturity felsic sedimentary terrane. The absence of syn-depositional igneous rocks and the tectonic setting discrimination diagrams indicate that the Yuanjiacun BIF formed in a passive continental margin setting. Negligible terrigenous materials were involved in the precipitation of the Yuanjiacun BIF. The precipitation of the Yuanjiacun BIF was predominantly controlled by the mixing of seawater and hydrothermal fluids. Its metallogenic material originated from the leaching of mafic oceanic crust by hydrothermal fluids. The observed Ce anomaly deficiency and heavy Fe isotope enrichment indicate that the Yuanjiacun BIF formed in an anoxic marine environment. In a redox-stratified palaeo-ocean, the Yuanjiacun BIF formed in reducing seawater below the oxidation–reduction transition zone. The Si and O isotope compositions of quartz suggest that the formation of the Yuanjiacun BIF was closely related to submarine hydrothermal activity. The Si and Fe erupted from the seafloor and precipitated by supersaturation and biological oxidation under anoxic conditions, respectively. [ABSTRACT FROM AUTHOR]

• Propose a road extraction method based on quadratic estimation for a variety of lighting and shooting environments. • A new linear regression method is used to deal with the illumination invariant image. • Propose the simple and robust method of probability maps combining. • The method is stable and fast computing. Road extraction is an important part of the intelligent vehicle systems for automatic driving, navigation, and traffic warning. For the complicated road scene, we present a road detection method based on illumination invariant image and quadratic estimation. The algorithm firstly extracts the illumination invariant image, and a priori triangular road region is used as the color sample to analyze the illumination invariant image and obtain the probability maps. Next, based on the histogram analysis, the combined probability map is significantly resettled, and the road region is estimated for the first time. Then gradient images of the illumination invariant image and the probability map are extracted, and the gradient image is analyzed by the estimated road region. Finally, the effective road boundary is extracted, and the more accurate road region is obtained. The experimental results show that our method can adapt to the road image in a variety of environments. Compared with other algorithms, our algorithm is more stable, and the computational efficiency is improved obviously. [ABSTRACT FROM AUTHOR]

• A sediment-hosted reduced intrusion-related gold deposit in metasedimentary terranes. • The bleached alteration zones arise from the reaction of reducing ore-forming fluids. • The reddish-purple sandy slates is a geochemical barrier in mineralization. The Herenping gold deposit is a typical gold deposit in the Xuefengshan arcuate tectonic zone in the southern margin of the Yangtze Craton, and the major feature of the gold mineralisation in the zone is the varying degrees of tungsten and antimony mineralisation in the ore deposits. The Herenping gold deposit occurs in the reddish-purple sandy slate in the middle section of the Madiyi Formation of the Neoproterozic Banxi Group and is controlled by the fault-fold zone associated with the Liulincha anticlinorium and F 8 fault zone. However, its sources of mineralisation and relationships between hydrothermal fluids and magmatic rocks are unclear, which similar to those of many gold deposits in metasedimentary terranes in the worldwide. The mineralisation can be divided into four stages: an albite-quartz stage (I), an albite-quartz-pyrite-gold stage (II), a quartz-gold-polymetallic sulphide stage (III), and a quartz-carbonate stage (IV). The gold mineralisation occurred in albite-quartz veins in stage II and in sulphide-rich quartz veins in stage III in the deposit. A study of the fluid inclusions reveals that the homogenisation temperature and salinity were slightly higher in stage II (T h. , 186–348 °C; W., 5.2–17.43 wt% NaCl equiv.) than in stage III (T h. , 145–249 °C; W., 2.9–15.57 wt% NaCl equiv.), indicating that the temperature and salinity of the ore-forming fluid are gradually decreasing. The H-O (δD = −62.3 to −53.0‰; δ18O = 4.2–11.8‰) isotope characteristics reveals that the ore-forming fluid is a magmatic hydrothermal source. The sulphur (δ34S, −4.8–2.0‰) isotope characteristics and the alteration mineral assemblage (sericite-chlorite-pyrite) indicates that the ore-forming fluids was reduced. The lead (206Pb/204Pb = 17.419–17.436, 207Pb/204Pb = 15.519–15.535, and 208Pb/204Pb = 37.86–37.90) isotope characteristics reflect the ore-forming materials were likely derived from a deep magmatic source. In addition, the geochemical characteristics of albitite veins show that they are silicon rich (64.02–66.26 wt%) and significantly reduced. Notably, the Herenping gold deposit is located in the western portion of the tungsten/tin metallogenic provinces in South China, is host in epimetamorphic detrital rocks and was formed at least two stages of mineralisation; typical gold-bearing albite-quartz veins developed during the primary stage. These characteristics are consistent with those of reduced intrusion-related deposits such as the Muruntau, Kumtor and Telfer deposits. Thus, the Herenping gold deposit may be a sediment-hosted intrusion-related gold deposit. Based on the phase transition pattern from sulphide-rich quartz veins to albite-quartz veins to albitite veins with increasing depth in the deposit, we propose that reduced intrusions deep in the Herenping gold deposit could be discovered in the future, which implies the possible existence of a reduced intrusion-related gold system in the Xuefengshan arcuate tectonic zone. [ABSTRACT FROM AUTHOR]

In this work, N vacancies embedded g-C 3 N 4 was prepared by dielectric barrier discharge plasma treatment. The plasma treatment does not change the structure, specific surface area and morphology of catalyst, but introduce nitrogen vacancies into g-C 3 N 4. The atmosphere has a significant effect on the nitrogen photofixation performance of as-prepared catalyst using methanol as hole scavenger. Under the atmosphere of 50% O 2 and 50% N 2 , the as-prepared N vacancies embedded g-C 3 N 4 displays the ammonium ion production rate as high as 5.5 mg·L−1·h−1·g cat −1, which is 2.1 times higher than that under pure nitrogen atmosphere. The effect of oxygen on the N 2 photofixation ability over N vacancies embedded g-C 3 N 4 is investigated. A "two-path" ammonia production mechanism is proposed in this work. Unlabelled Image • N vacancies doped g-C 3 N 4 was synthesized. • N vacancies act as chemical adsorption sites to activate nitrogen. • The atmosphere influences nitrogen photofixation ability of catalyst. • A "two-path" ammonia production mechanism is proposed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Gaosongshan Au deposit is a typical LS epithermal deposit. • U–Pb and Rb–Sr ages place the Au mineralization between 101 Ma and 98 Ma. • The ore-forming fluids were mixtures of magmatic and meteoric water, but still dominated by meteoric water. • The metals were at least in part derived from late Early Cretaceous magmatic intrusion. Abstract The Gaosongshan epithermal gold (Au) deposit is located in the northern margin of the Lesser Khingan Range polymetallic ore belt, northeast (NE) China, and contains Au resources of more than 23 tons at an average grade of 6.3 g/t. Gold orebodies are mainly hosted in intensely altered volcanic rocks of the Lower Cretaceous Banzifang Formation, and as exploration has continued, gold has also been discovered in extensively altered porphyritic intrusions with the highest Au grade of 70 g/t. However, the ages of metallogenesis and related magmatism have not been well constrained yet, which have hindered the summary of metallogenic regularities. In this study, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating from the granite porphyry yields a weighted mean 206Pb/238U age of 101.6 ± 1.2 Ma, slightly older than the Rb–Sr isotope age of 98 ± 1.6 Ma for the auriferous quartz samples, indicating that the Gaosongshan Au mineralization is genetically related to the granite porphyry. The fluid δD and δ18O H2O values vary from −136% to −111% and from −9.3% to −2.5%, respectively, and the 4He and 40Ar isotope compositions range from 15.7 × 10−9 to 35.5 × 10−9 cm3 STP/g and 13.4 × 10−7 cm3 to 34.1 × 10−7 cm3 STP/g, respectively. The obtained isotopic data show that the ore-forming fluids were mixtures of magmatic and meteoric water but were dominated by meteoric water. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of ores in the Gaosongshan deposit are 17.752–18.856, 15.514–15.674, and 38.005–39.921, respectively, which are similar to those of the Gaosongshan granite porphyry, implying that Pb and possibly Au originated primarily from late Early Cretaceous magmatic intrusions. Combining these results with data from previous studies, we propose that the Gaosongshan Au deposit formed in an extensional tectonic setting during the rollback of the Paleo-Pacific oceanic plate in NE China. [ABSTRACT FROM AUTHOR]

The Hadamengou gold deposit, which is located in a high-grade metamorphic terrane at the northern margin of the North China Craton, is characterized by K-feldspar-quartz vein gold mineralization. The 40 Ar/ 39 Ar dating of hydrothermal K-feldspar indicates that the mineralization formed over 45 Ma commencing at 243.5 ± 1.3 Ma and ending at 199.0 ± 0.8 Ma. The Pb, C and O isotope compositions and the geochronology of the gold-bearing K-feldspar-quartz veins imply a close genetic association between the gold mineralization and alkaline magmatism, which are both products of the Indosinian alkaline magmatic event caused by the extensional tectonic setting that prevailed during the late Hercynian collisional orogeny. We propose an Indosinian phase of gold mineralization in addition to the abundant mineral deposits formed during the Yanshan Epoch. [ABSTRACT FROM AUTHOR]

Three NE-striking zoned polymetallic ore districts were found at the transition between the Shanhaiguan-Beizhen paleo-uplift and the Liaoxi depression at the midway point of the northern margin of the North China Plate. Although these deposits are located proximal to one another, they are metallogenic different and closely associated with the granite intrusions, and Au, Pb-Zn, and Mo are the major ore-forming elements. This paper investigates the rock/ore rare earth elements and trace elements and part of the whole-rock major elements of the Wenzhangzi Au-polymetallic deposit in western Liaoning Province. The results indicate that the andesite, granodiorite, and Au-rich polymetallic ore-forming fluids in the deposits exhibit the same crustal origin and closely associated with the Archean Au-rich crystalline basement. Granodiorite in the area tends to show a transition from quasi-aluminous to peraluminous → S-type granite, whereas the closely associated granite in the Yangjiazhangzi-Lanjiagou Mo metallogenic district is a differentiated I-type granite. These granites differ in age, with the former emplacing during the Mesozoic tectonic regime transition period and the latter emplacing during the intra-plate extrusion-uplift orogeny. [ABSTRACT FROM AUTHOR]

The article presents research related to deep exploration integration technology application in gold deposits in Paishanlou, China, with the help of three dimensional (3D) geological spatial information system. Topics discussed include principle of deep prospecting information integration technology (DPIIT), establishment of 3D geological spatial information models, and application of DPIIT in the Paishanlou gold deposit in China.

Due to the limitation of less information in a single image, it is very difficult to generate a high-precision 3D model based on the image. There are some problems in the generation of 3D voxel models, e.g., the information loss at the upper level of a network. To solve these problems, we design a 3D model generation network based on multi-modal data constraints and multi-level feature fusion, named as 3DMGNet. Moreover, 3DMGNet is trained by self-supervised method to achieve 3D voxel model generation from an image. The image feature extraction network (2DNet) and 3D feature extraction network (3D auxiliary network) are used to extract the features of the image and 3D voxel model. Then, feature fusion is used to integrate the low-level features into the high-level features in the 3D auxiliary network. To extract more effective features, each layer of the feature map in feature extraction network is processed by an attention network. Finally, the extracted features generate 3D models by a 3D deconvolution network. The feature extraction of 3D model and the generation of voxelization play an auxiliary role in the training of the whole network for the 3D model generation based on an image. Additionally, a multi-view contour constraint method is proposed, to enhance the effect of the 3D model generation. In the experiment, the ShapeNet dataset is adapted to prove the effect of the 3DMGNet, which verifies the robust performance of the proposed method. [ABSTRACT FROM AUTHOR]

Keypoint matching is of fundamental importance in computer vision applications. Fish-eye lenses are convenient in such applications that involve a very wide angle of view. However, their use has been limited by the lack of an effective matching algorithm. The Scale Invariant Feature Transform (SIFT) algorithm is an important technique in computer vision to detect and describe local features in images. Thus, we present a Tri-SIFT algorithm, which has a set of modifications to the SIFT algorithm that improve the descriptor accuracy and matching performance for fish-eye images, while preserving its original robustness to scale and rotation. After the keypoint detection of the SIFT algorithm is completed, the points in and around the keypoints are back-projected to a unit sphere following a fish-eye camera model. To simplify the calculation in which the image is on the sphere, the form of descriptor is based on the modification of the Gradient Location and Orientation Histogram (GLOH). In addition, to improve the invariance to the scale and the rotation in fish-eye images, the gradient magnitudes are replaced by the area of the surface, and the orientation is calculated on the sphere. Extensive experiments demonstrate that the performance of our modified algorithms outweigh that of SIFT and other related algorithms for fish-eye images. [ABSTRACT FROM AUTHOR]

The article presents a study on the metallogenic age or chronology of the gold deposit located in Jiao Liao peninsula area. Topics discussed include the Archean metallogeny theory and Yanshan stage mineralization theory by researcher Guo Wenkui, differences in different mineralization ages of gold deposit formed in different mineralization; and types of gold deposit such as metamorphic hydrothermal superimposition and magmatic hydrothermal altered rock.

Image dehazing is a useful technique which can eliminate the bad effect of haze on images and enhance the performances of image/video processing algorithms in the hazy weather. In this study, a single image dehazing method is proposed. The authors estimate the initial transmission properly based on latent region‐segmentation and refine the estimated initial transmission by an objective function with a novel weighted L1‐norm regularisation term. The half‐quadratic splitting minimisation method is employed to solve this optimisation problem. They also define an evaluation function to estimate the reliable global atmospheric light. With the refined transmission map and atmospheric light they recover the haze‐free image by the haze imaging model. The authors' method is compared with three state‐of‐the‐art methods and is also validated by two image quality assessment methods. The comparative experimental results and evaluations demonstrate that their method can recover comparable and even better results with clear details, low contrast loss and high contrast in most cases. [ABSTRACT FROM AUTHOR]

The detection and evaluation of concealed mineral resources deep in metallic mines and in the surrounding areas remain technically difficult. In particular, due to the complex topographic and geomorphic conditions on the surface, the detection environments in these areas limit the choices of detection equipment and data collection devices. In this study, based on metallogenic theory and the metallogenic geological characteristics of banded iron formation (BIF)-type iron ores, equipment for surface geophysical surveys (i.e., the high-precision ground magnetic survey method, the transient electromagnetic method, and the magnetotelluric method) and data collection devices capable of taking single-point continuous measurements were employed to detect the concealed iron ore bodies in the transition zone CID-1 between the Hejia and Dumu iron deposits in the Gongchangling iron ore concentration area in the Anshan-Benxi area (Liaoyang, China), a representative area of BIF-type iron ores. The results showed that an optimal combination of these geophysical survey methods accurately determined the anomalous planar spatial locations and anomalous profile morphologies of the concealed iron ore bodies. On this basis, we determined their locations, burial depths, and scales. Two anomalous zones induced by concealed iron ore bodies, YC-1 and YC-2, were discovered in zone CID-1. Two concealed iron-bearing zones, one shallow (0–150 m) and one deep (300–450 m), were found in YC-1. A 100 m scale drilling test showed that the cumulative thickness of the shallow iron-bearing zone was over 23.6 m. [ABSTRACT FROM AUTHOR]

A critical step for kriging in geostatistics is estimation of the variogram. Traditional variogram modeling comprise of the experimental variogram calculation, appropriate variogram model selection and model parameter determination. Selecting of the variogram model and fitting of model parameters is the most controversial aspect of geostatistics. Shapes of valid variogram models are finite, and sometimes, the optimal shape of the model can not be fitted, leading to reduced estimation accuracy. In this paper, a new method is presented to automatically construct a model shape and fit model parameters to experimental variograms using Support Vector Regression (SVR) and Multi-Gene Genetic Programming (MGGP). The proposed method does not require the selection of a variogram model and can directly provide the model shape and parameters of the optimal variogram. The validity of the proposed method is demonstrated in a number of cases. [ABSTRACT FROM AUTHOR]