The Baguamiao superlarge gold deposit in Shaanxi Province is one of the typical cases in China that are hosted by sedimentary rocks. Explorers and researchers have discussed the gold mineralization enrichment conditio...The Baguamiao superlarge gold deposit in Shaanxi Province is one of the typical cases in China that are hosted by sedimentary rocks. Explorers and researchers have discussed the gold mineralization enrichment conditions by studying sulphur, oxygen, carbon, silicon stable isotopes and mineralizing fluid features of the Baguamiao gold deposit and proposed a hydrothermal sedimentation-magmatic reconstructing gold mineralization model featuring multi-sources of ore-forming materials and multistage mineralizations. In addition, prospecting for “Baguamiao-type” gold deposits was started in the Fengtai Basin and a great number of important prospecting targets such as Tonglinggou, Simaoling, Guoansi and Dachaigou were discovered.展开更多
The Nyasirori gold deposit,located in the middle-western end of the Musoma-Mara Archean greenstone belt in Tanzania,is a tectonic altered rock type gold deposit controlled by shear tectonic zone.This work conducted hi...The Nyasirori gold deposit,located in the middle-western end of the Musoma-Mara Archean greenstone belt in Tanzania,is a tectonic altered rock type gold deposit controlled by shear tectonic zone.This work conducted high-precision ground magnetic measurements to delineate fault structures and favorable prospecting targets,utilized induced polarization(IP)intermediate gradient to roughly determine the distribution and extension of the tectonic altered zone and gold ore(mineralized)bodies,and further carried out IP sounding and magnetotelluric sounding to locate the tectonic altered zone and gold ore(mineralized)bodies.The anomalous gradient belt of the combination of positive and negative micromagnetic measurements reflects the detail of shallow surface tectonic alteration zone and gold mineralization body.Micromagnetic profile anomalies indicate the spatial location and occurrence of concealed tectonic alteration zone and gold(mineralized)ore bodies.Soil geochemical measurements indicate that the ore-forming element Au correlates well with As and Sb,and As and Sb anomalies have a good indication to gold orebodies.Based on the multi-source geological-geophysical-geochemical information of the Nyasirori gold deposit,this work established an integrated prospecting model and proposed a set of geophysical and geochemical methods for optimizing prospecting targets.展开更多
Prospectivity analyses are used to reduce the exploration search space for locating areas prospective for mineral deposits.The scale of a study and the type of mineral system associated with the deposit control the ev...Prospectivity analyses are used to reduce the exploration search space for locating areas prospective for mineral deposits.The scale of a study and the type of mineral system associated with the deposit control the evidence layers used as proxies that represent critical ore genesis processes.In particular,knowledge-driven approaches(fuzzy logic)use a conceptual mineral systems model from which data proxies represent the critical components.These typically vary based on the scale of study and the type of mineral system being predicted.Prospectivity analyses utilising interpreted data to represent proxies for a mineral system model inherit the subjectivity of the interpretations and the uncertainties of the evidence layers used in the model.In the case study presented,the prospectivity for remobilised nickel sulphide(NiS)in the west Kimberley,Western Australia,is assessed with two novel techniques that objectively grade interpretations and accommodate alternative mineralisation scenarios.Exploration targets are then identified and supplied with a robustness assessment that reflects the variability of prospectivity value for each location when all models are considered.The first technique grades the strength of structural interpretations on an individual line-segment basis.Gradings are obtained from an objective measure of feature evidence,which is the quantification of specific patterns in geophysical data that are considered to reveal underlying structure.Individual structures are weighted in the prospectivity model with grading values correlated to their feature evidence.This technique allows interpreted features to contribute prospectivity proportional to their strength in feature evidence and indicates the level of associated stochastic uncertainty.The second technique aims to embrace the systemic uncertainty of modelling complex mineral systems.In this approach,multiple prospectivity maps are each generated with different combinations of confidence values applied to evidence layers to represent the diversity of processes potentially leading to ore deposition.With a suite of prospectivity maps,the most robust exploration targets are the locations with the highest prospectivity values showing the smallest range amongst the model suite.This new technique offers an approach that reveals to the modeller a range of alternative mineralisation scenarios while employing a sensible mineral systems model,robust modelling of prospectivity and significantly reducing the exploration search space for Ni.展开更多
Novel mineral prospectivity modelling presented here applies knowledge-driven feature extraction to a datadriven machine learning approach for tungsten mineralisation.The method emphasises the importance of appropriat...Novel mineral prospectivity modelling presented here applies knowledge-driven feature extraction to a datadriven machine learning approach for tungsten mineralisation.The method emphasises the importance of appropriate model evaluation and develops a new Confidence Metric to generate spatially refined and robust exploration targets.The data-driven Random ForestTM algorithm is employed to model tungsten mineralisation in SW England using a range of geological,geochemical and geophysical evidence layers which include a depth to granite evidence layer.Two models are presented,one using standardised input variables and a second that implements fuzzy set theory as part of an augmented feature extraction step.The use of fuzzy data transformations mean feature extraction can incorporate some user-knowledge about the mineralisation into the model.The typically subjective approach is guided using the Receiver Operating Characteristics(ROC)curve tool where transformed data are compared to known training samples.The modelling is conducted using 34 known true positive samples with 10 sets of randomly generated true negative samples to test the random effect on the model.The two models have similar accuracy but show different spatial distributions when identifying highly prospective targets.Areal analysis shows that the fuzzy-transformed model is a better discriminator and highlights three areas of high prospectivity that were not previously known.The Confidence Metric,derived from model variance,is employed to further evaluate the models.The new metric is useful for refining exploration targets and highlighting the most robust areas for follow-up investigation.The fuzzy-transformed model is shown to contain larger areas of high model confidence compared to the model using standardised variables.Finally,legacy mining data,from drilling reports and mine descriptions,is used to further validate the fuzzy-transformed model and gauge the depth of potential deposits.Descriptions of mineralisation corroborate that the targets generated in these models could be undercover at depths of less than 300 m.In summary,the modelling workflow presented herein provides a novel integration of knowledge-driven feature extraction with data-driven machine learning modelling,while the newly derived Confidence Metric generates reliable mineral exploration targets.展开更多
A method is proposed for the prospecting prediction of subsurface mineral deposits based on soil geochemistry data and a deep convolutional neural network model.This method uses three techniques(window offset,scaling,...A method is proposed for the prospecting prediction of subsurface mineral deposits based on soil geochemistry data and a deep convolutional neural network model.This method uses three techniques(window offset,scaling,and rotation)to enhance the number of training data for the model.A window area is used to extract the spatial distribution characteristics of soil geochemistry and measure their correspondence with the occurrence of known subsurface deposits.Prospecting prediction is achieved by matching the characteristics of the window area of an unknown area with the relationships established in the known area.This method can efficiently predict mineral prospective areas where there are few ore deposits used for generating the training dataset,meaning that the deep-learning method can be effectively used for deposit prospecting prediction.Using soil active geochemical measurement data,this method was applied in the Daqiao area,Gansu Province,for which seven favorable gold prospecting target areas were predicted.The Daqiao orogenic gold deposit of latest Jurassic and Early Jurassic age in the southern domain has more than 105 t of gold resources at an average grade of 3-4 g/t.In 2020,the project team drilled and verified the K prediction area,and found 66 m gold mineralized bodies.The new method should be applicable to prospecting prediction using conventional geochemical data in other areas.展开更多
The demand for fluorite resource is increasing rapidly as most fluorite deposits on Earth’s surface have been exhausted.The newly discovered fluorite deposits in Inner Mongolia are hosted by Permian metamorphosed san...The demand for fluorite resource is increasing rapidly as most fluorite deposits on Earth’s surface have been exhausted.The newly discovered fluorite deposits in Inner Mongolia are hosted by Permian metamorphosed sandy slate,intermediate-acid intrusive rocks and Cretaceous volcanic sedimentary rocks.The ore bodies are strictly controlled by faults and buried by cover rocks.The feasibility and effectiveness of multi-techniques for prospecting concealed fluorite ore bodies are evaluated,and 10 anomalies are delineated.On the basis of geological features and effectiveness of different methods,the optimum combinations of ore prospecting techniques are proposed for the exploration of zonal type and burial type concealed fluorite ore bodies.Based on comprehensive researches,an integrated exploration model is proposed:(i)select key prospecting targets based on geological backgrounds,regional geochemical anomalies of F and Ca,and remote sensing images;(ii)identify the spatial distribution of low resistivity anomaly and ore-controlling structure from geophysical survey;(iii)evaluate the mineralization potential in fault zone based on F and Ca anomalies in key sections selected from low resistivity anomaly zones;and(iv)evaluate the mineralization potential and reveal the spatial distribution of fluorite ore bodies and ore-controlling faults based on integrated geophysical and geochemical anomalies.The integrated exploration model is verified to be a powerful tool for prospecting concealed fluorite ore bodies in coverage area.展开更多
The Hongqiling large nickel-copper-cobalt deposit(hereafter referred to as the Hongqiling deposit),a typical mafic-ultramafic copper-nickel deposit in China,boasts proven Ni(Ni)resources of approximately 22×10^(4...The Hongqiling large nickel-copper-cobalt deposit(hereafter referred to as the Hongqiling deposit),a typical mafic-ultramafic copper-nickel deposit in China,boasts proven Ni(Ni)resources of approximately 22×10^(4)t,associated copper resources of 2×10^(4)t,and associated cobalt(Co)resources of 0.5×10^(4)t,with Ni reserves ranking 10th among China's magmatic nickel deposits.Geotectonically,the Hongqiling deposit is situated in the superimposed zone between the Xing'an-Mongolian orogenic belt and the circum-Western Pacific's active continental margin belt.Its ore-bearing plutons occur within the metamorphic rocks of the Ordovician Hulan Group,with the emplacement of plutons and the locations of orebodies governed by the deep-seated Huifahe fault and its secondary NW-trending Fujia-Hejiagou-Beixinglong-Changsheng fault zone.In the deposit,the rock assemblages of ore-bearing plutons predominantly encompass gabbro-pyroxenite-olivine pyroxenite-pyroxene peridotite(pluton No.1)and norite-orthopyroxenite-harzburgite(pluton No.7),with ore-bearing lithofacies consisting primarily of olivine pyroxenite and pyroxenite facies.The Hongqiling deposit hosts stratoid,overhanging lentoid,veined,and pure-sulfide veined orebodies.Its ores principally contain metallic minerals including pyrrhotite,pentlandite,chalcopyrite,violarite,and pyrite.Despite unidentified magma sources of ore-bearing mafic-ultramafic rocks,it is roughly accepted that the magmatic evolution in the Hongqiling deposit primarily involved fractional crystallization and crustal contamination.The ore-forming materials were primarily derived from the upper mantle,mixed with minor crustal materials.The ore-bearing mafic-ultramafic rocks in the deposit,primarily emplaced during the Indosinian(208-239 Ma),were formed in an intense extension setting followed by the collisional orogeny between the North China Plate and the Songnen-Zhangguangcai Range Block during the Middle-Late Triassic.From the perspective of the metallogenic geological setting,surrounding rocks,ore-controlling structures,and rock assemblages,this study identified one favorable condition and seven significant indicators for prospecting for Hongqiling-type nickel deposits and developed a prospecting model of the Hongqiling deposit.These serve as valuable references for exploring similar nickel deposits in the region,as well as the deep parts and margins of the Hongqiling deposit.展开更多
文摘The Baguamiao superlarge gold deposit in Shaanxi Province is one of the typical cases in China that are hosted by sedimentary rocks. Explorers and researchers have discussed the gold mineralization enrichment conditions by studying sulphur, oxygen, carbon, silicon stable isotopes and mineralizing fluid features of the Baguamiao gold deposit and proposed a hydrothermal sedimentation-magmatic reconstructing gold mineralization model featuring multi-sources of ore-forming materials and multistage mineralizations. In addition, prospecting for “Baguamiao-type” gold deposits was started in the Fengtai Basin and a great number of important prospecting targets such as Tonglinggou, Simaoling, Guoansi and Dachaigou were discovered.
基金This work is financially supported by the Special Fund for Foreign Mineral Resources Risk Exploration(201210B01600234).
文摘The Nyasirori gold deposit,located in the middle-western end of the Musoma-Mara Archean greenstone belt in Tanzania,is a tectonic altered rock type gold deposit controlled by shear tectonic zone.This work conducted high-precision ground magnetic measurements to delineate fault structures and favorable prospecting targets,utilized induced polarization(IP)intermediate gradient to roughly determine the distribution and extension of the tectonic altered zone and gold ore(mineralized)bodies,and further carried out IP sounding and magnetotelluric sounding to locate the tectonic altered zone and gold ore(mineralized)bodies.The anomalous gradient belt of the combination of positive and negative micromagnetic measurements reflects the detail of shallow surface tectonic alteration zone and gold mineralization body.Micromagnetic profile anomalies indicate the spatial location and occurrence of concealed tectonic alteration zone and gold(mineralized)ore bodies.Soil geochemical measurements indicate that the ore-forming element Au correlates well with As and Sb,and As and Sb anomalies have a good indication to gold orebodies.Based on the multi-source geological-geophysical-geochemical information of the Nyasirori gold deposit,this work established an integrated prospecting model and proposed a set of geophysical and geochemical methods for optimizing prospecting targets.
基金supported by the Geological Society of Australia(Honours Endowment Fund)the Australian Institute of Geoscientists(Honours Bursary)by ARC LP140100267
文摘Prospectivity analyses are used to reduce the exploration search space for locating areas prospective for mineral deposits.The scale of a study and the type of mineral system associated with the deposit control the evidence layers used as proxies that represent critical ore genesis processes.In particular,knowledge-driven approaches(fuzzy logic)use a conceptual mineral systems model from which data proxies represent the critical components.These typically vary based on the scale of study and the type of mineral system being predicted.Prospectivity analyses utilising interpreted data to represent proxies for a mineral system model inherit the subjectivity of the interpretations and the uncertainties of the evidence layers used in the model.In the case study presented,the prospectivity for remobilised nickel sulphide(NiS)in the west Kimberley,Western Australia,is assessed with two novel techniques that objectively grade interpretations and accommodate alternative mineralisation scenarios.Exploration targets are then identified and supplied with a robustness assessment that reflects the variability of prospectivity value for each location when all models are considered.The first technique grades the strength of structural interpretations on an individual line-segment basis.Gradings are obtained from an objective measure of feature evidence,which is the quantification of specific patterns in geophysical data that are considered to reveal underlying structure.Individual structures are weighted in the prospectivity model with grading values correlated to their feature evidence.This technique allows interpreted features to contribute prospectivity proportional to their strength in feature evidence and indicates the level of associated stochastic uncertainty.The second technique aims to embrace the systemic uncertainty of modelling complex mineral systems.In this approach,multiple prospectivity maps are each generated with different combinations of confidence values applied to evidence layers to represent the diversity of processes potentially leading to ore deposition.With a suite of prospectivity maps,the most robust exploration targets are the locations with the highest prospectivity values showing the smallest range amongst the model suite.This new technique offers an approach that reveals to the modeller a range of alternative mineralisation scenarios while employing a sensible mineral systems model,robust modelling of prospectivity and significantly reducing the exploration search space for Ni.
基金funded by the British Geological Survey,United Kingdom(S267)the Natural Environment Research Council(NERC),United Kingdom。
文摘Novel mineral prospectivity modelling presented here applies knowledge-driven feature extraction to a datadriven machine learning approach for tungsten mineralisation.The method emphasises the importance of appropriate model evaluation and develops a new Confidence Metric to generate spatially refined and robust exploration targets.The data-driven Random ForestTM algorithm is employed to model tungsten mineralisation in SW England using a range of geological,geochemical and geophysical evidence layers which include a depth to granite evidence layer.Two models are presented,one using standardised input variables and a second that implements fuzzy set theory as part of an augmented feature extraction step.The use of fuzzy data transformations mean feature extraction can incorporate some user-knowledge about the mineralisation into the model.The typically subjective approach is guided using the Receiver Operating Characteristics(ROC)curve tool where transformed data are compared to known training samples.The modelling is conducted using 34 known true positive samples with 10 sets of randomly generated true negative samples to test the random effect on the model.The two models have similar accuracy but show different spatial distributions when identifying highly prospective targets.Areal analysis shows that the fuzzy-transformed model is a better discriminator and highlights three areas of high prospectivity that were not previously known.The Confidence Metric,derived from model variance,is employed to further evaluate the models.The new metric is useful for refining exploration targets and highlighting the most robust areas for follow-up investigation.The fuzzy-transformed model is shown to contain larger areas of high model confidence compared to the model using standardised variables.Finally,legacy mining data,from drilling reports and mine descriptions,is used to further validate the fuzzy-transformed model and gauge the depth of potential deposits.Descriptions of mineralisation corroborate that the targets generated in these models could be undercover at depths of less than 300 m.In summary,the modelling workflow presented herein provides a novel integration of knowledge-driven feature extraction with data-driven machine learning modelling,while the newly derived Confidence Metric generates reliable mineral exploration targets.
基金funded by a pilot project entitled“Deep Geological Survey of Benxi-Linjiang Area”(1212011220247)of the 3D Geological Mapping and Deep Geological Survey of China Geological Survey。
文摘A method is proposed for the prospecting prediction of subsurface mineral deposits based on soil geochemistry data and a deep convolutional neural network model.This method uses three techniques(window offset,scaling,and rotation)to enhance the number of training data for the model.A window area is used to extract the spatial distribution characteristics of soil geochemistry and measure their correspondence with the occurrence of known subsurface deposits.Prospecting prediction is achieved by matching the characteristics of the window area of an unknown area with the relationships established in the known area.This method can efficiently predict mineral prospective areas where there are few ore deposits used for generating the training dataset,meaning that the deep-learning method can be effectively used for deposit prospecting prediction.Using soil active geochemical measurement data,this method was applied in the Daqiao area,Gansu Province,for which seven favorable gold prospecting target areas were predicted.The Daqiao orogenic gold deposit of latest Jurassic and Early Jurassic age in the southern domain has more than 105 t of gold resources at an average grade of 3-4 g/t.In 2020,the project team drilled and verified the K prediction area,and found 66 m gold mineralized bodies.The new method should be applicable to prospecting prediction using conventional geochemical data in other areas.
基金supported by the Fundamental Research Funds for the Central Universities(No.2652019191)China Geological Survey(No.1212011120187)the National Natural Science Foundation of China(No.41502347)。
文摘The demand for fluorite resource is increasing rapidly as most fluorite deposits on Earth’s surface have been exhausted.The newly discovered fluorite deposits in Inner Mongolia are hosted by Permian metamorphosed sandy slate,intermediate-acid intrusive rocks and Cretaceous volcanic sedimentary rocks.The ore bodies are strictly controlled by faults and buried by cover rocks.The feasibility and effectiveness of multi-techniques for prospecting concealed fluorite ore bodies are evaluated,and 10 anomalies are delineated.On the basis of geological features and effectiveness of different methods,the optimum combinations of ore prospecting techniques are proposed for the exploration of zonal type and burial type concealed fluorite ore bodies.Based on comprehensive researches,an integrated exploration model is proposed:(i)select key prospecting targets based on geological backgrounds,regional geochemical anomalies of F and Ca,and remote sensing images;(ii)identify the spatial distribution of low resistivity anomaly and ore-controlling structure from geophysical survey;(iii)evaluate the mineralization potential in fault zone based on F and Ca anomalies in key sections selected from low resistivity anomaly zones;and(iv)evaluate the mineralization potential and reveal the spatial distribution of fluorite ore bodies and ore-controlling faults based on integrated geophysical and geochemical anomalies.The integrated exploration model is verified to be a powerful tool for prospecting concealed fluorite ore bodies in coverage area.
基金funded by projects of the China Geological Survey(Nos.DD20242070,DD20230763,DD20221695,DD20190379,and DD20160346)。
文摘The Hongqiling large nickel-copper-cobalt deposit(hereafter referred to as the Hongqiling deposit),a typical mafic-ultramafic copper-nickel deposit in China,boasts proven Ni(Ni)resources of approximately 22×10^(4)t,associated copper resources of 2×10^(4)t,and associated cobalt(Co)resources of 0.5×10^(4)t,with Ni reserves ranking 10th among China's magmatic nickel deposits.Geotectonically,the Hongqiling deposit is situated in the superimposed zone between the Xing'an-Mongolian orogenic belt and the circum-Western Pacific's active continental margin belt.Its ore-bearing plutons occur within the metamorphic rocks of the Ordovician Hulan Group,with the emplacement of plutons and the locations of orebodies governed by the deep-seated Huifahe fault and its secondary NW-trending Fujia-Hejiagou-Beixinglong-Changsheng fault zone.In the deposit,the rock assemblages of ore-bearing plutons predominantly encompass gabbro-pyroxenite-olivine pyroxenite-pyroxene peridotite(pluton No.1)and norite-orthopyroxenite-harzburgite(pluton No.7),with ore-bearing lithofacies consisting primarily of olivine pyroxenite and pyroxenite facies.The Hongqiling deposit hosts stratoid,overhanging lentoid,veined,and pure-sulfide veined orebodies.Its ores principally contain metallic minerals including pyrrhotite,pentlandite,chalcopyrite,violarite,and pyrite.Despite unidentified magma sources of ore-bearing mafic-ultramafic rocks,it is roughly accepted that the magmatic evolution in the Hongqiling deposit primarily involved fractional crystallization and crustal contamination.The ore-forming materials were primarily derived from the upper mantle,mixed with minor crustal materials.The ore-bearing mafic-ultramafic rocks in the deposit,primarily emplaced during the Indosinian(208-239 Ma),were formed in an intense extension setting followed by the collisional orogeny between the North China Plate and the Songnen-Zhangguangcai Range Block during the Middle-Late Triassic.From the perspective of the metallogenic geological setting,surrounding rocks,ore-controlling structures,and rock assemblages,this study identified one favorable condition and seven significant indicators for prospecting for Hongqiling-type nickel deposits and developed a prospecting model of the Hongqiling deposit.These serve as valuable references for exploring similar nickel deposits in the region,as well as the deep parts and margins of the Hongqiling deposit.
