Identifying ore-induced geochemical anomalies at the surface that indicate concealed deposits in buried areas remains a significant challenge in geochemical exploration. In this study, in order to trace the source of ...Identifying ore-induced geochemical anomalies at the surface that indicate concealed deposits in buried areas remains a significant challenge in geochemical exploration. In this study, in order to trace the source of the geochemical anomalies, systematic luminescence intensity analyses were conducted on quartz grains from the Quaternary regolith at the Hadatu sandstone-type uranium deposit in the Erenhot Basin. The optically stimulated luminescence(OSL) ages were much older than the depositional ages of the Quaternary regolith. Moreover, quartz OSL ages were closely related to both borehole grades and sampling depths. Thus, the abnormal mineral OSL ages from near-surface sediments were ultimately controlled by the sandstone-type uranium deposits. This is identical to the rapid changes of quartz OSL ages(0.063 ka/cm) and equivalent doses(0.19 Gy/cm) with depths in a given sampling site. The instantaneous soil radon concentration was positively correlated with the quartz OSL apparent age, indicating their ore-induced origin and, as a result, their effectiveness in the exploration of concealed uranium deposits. Other parameters, including mobile-state uranium and;Po contents, were poorly correlated with quartz OSL ages and therefore should only be used with caution for geochemical exploration. This is the first time an attempt has been made to discriminate the ore-induced sources for different surface anomaly parameters, including instantaneous soil radon, mobile-state uranium and;Po contents for concealed sandstonetype uranium deposits.展开更多
This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved ...This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved that these approaches have yielded good results on classifying the sedimentary fades, defining the redox transitional zones and reflecting deep mineralization information. They may probably become new methods on searching for sandstone-type uranium deposits.展开更多
Outcrop and drill hole data show that the Jurassic coal measures in the northeastern Ordos Basin are composed mainly of the Yan'an Formation and the lowstand system tract of the Zhiluo Formation,and there is a reg...Outcrop and drill hole data show that the Jurassic coal measures in the northeastern Ordos Basin are composed mainly of the Yan'an Formation and the lowstand system tract of the Zhiluo Formation,and there is a regional unconformity between them. The Dongsheng uranium deposit is associated with the Jurassic coal measures. Research data indicate that the Jurassic coal measures in the study area have a certain hydrocarbon-generating capacity,although the metamorphic grade is low(Ro=0.40%–0.58%). In the Dongsheng region alone,the accumulative amount of generated coalbed methane(CBM) is about 2028.29 × 108 –2218.72 × 108 m^3; the residual amount is about 50.92 × 108 m^3,and the lost amount is about 1977 × 108 m^3. Analysis of the burial history of the host rocks and the evolutionary history of the Dongsheng uranium deposit suggests that the Jurassic coal measures generated hydrocarbon mainly from Middle Jurassic to Early Crataceous,which is the main mineralization phase of the Dongsheng uranium deposit. By the Late Cretaceous,a mass of CBM dissipated due to the strong tectonic uplift,and the Dongsheng uranium deposit stepped into the preservation phase. Therefore,the low-mature hydrocarbon-containing fluid in the Jurassic coal measures not only served as a reducing agent for the formation of sandstone-type uranium deposits,but also rendered the second reduction of paleo-interlayer oxidation zone and become the primary reducing agent for ore conservation. Regional strata correlation reveals that the sandstone-type uranium reservoir at the bottom of the Zhiluo Formation is in contact with the underlying industrial coal seams in the Yan'an Formation through incision or in the form of an unconformity surface. In the Dongsheng region with poorly developed fault systems,the unconformity surface and scour surface served as the main migration pathways for low-mature hydrocarbon-containing fluid migrating to the uranium reservoir.展开更多
The major elements, trace elements and REEs were analyzed on the samples collected from the sandstone-type uranium deposits in the Ordos Basin to constrain the mechanism of uranium enrichment. The total REE amount ran...The major elements, trace elements and REEs were analyzed on the samples collected from the sandstone-type uranium deposits in the Ordos Basin to constrain the mechanism of uranium enrichment. The total REE amount ranges from 36.7 to 701.8 μg/g and the REE distribution patterns of the sandstone-type uranium samples are characterized by LREE enrichment and high REE depletion. The results also indicated a high Y abundance and Eu anomalies between 0.77-1.81. High-precision ICP-MS results showed that U abundances are within the range of 0.73-150 μg/g, showing some strong correlation between U enrichment and related elements such as Ti, V, Zr, Mo, and Au. In addition, Th abundance is correlated with ΣREE.展开更多
Generally, sandstone-type uranium deposits can be divided into three zones according to their redox conditions: oxidized zone, ore zone and reduced zone. The Dongsheng uranium deposit belongs to this type. In order to...Generally, sandstone-type uranium deposits can be divided into three zones according to their redox conditions: oxidized zone, ore zone and reduced zone. The Dongsheng uranium deposit belongs to this type. In order to study its geochemical characteristics, 11 samples were taken from the three zones of the Dongsheng uranium deposit. Five samples of them were collected from the oxidized zone, four samples from the ore zone and two samples from the reduced zone. These samples were analyzed using organic and inorganic geochemical methods. The results of GC traces and ICP-MASS indicate that the three zones show different organic and inorganic geochemical characteristics.展开更多
Many theoretical results on sandstone-type uranium mineralization in northern China obtained by the uranium research team of the Tianjin Center of Geological Survey in recent years are presented.From the source sink s...Many theoretical results on sandstone-type uranium mineralization in northern China obtained by the uranium research team of the Tianjin Center of Geological Survey in recent years are presented.From the source sink system of uranium-producing basins,sedimentary environment of uranium-bearing rock series,ore-forming fluid information,evolution of tectonic events,basin formation and development,we redefine and classify uranium orebodies,redox zoning,and ore-controlling structural styles.We then systematically propose a theoretical system of sandstone-type uranium deposits in northern China.We conclude that sandstone-type uranium deposits in northern China are mainly found in sedimentary environments such as rivers,deltas,and alluvial fans in the Mesozoic and Cenozoic lowstand systems tract and in gray sandstone layers in the vertical redox zoning.The orebodies are controlled by the tectonic slope belt,which is in the shape of a strip on the plane,and spreads in a layer or plate on the section.Vertical(ups and downs)tectonic movement triggers large-scale phreatic flow in the basin,which is the real driving force for controlling the ore-forming fluid.The theoretical system of sandstone-type uranium deposits in northern China should be based on global tectonic movement and environmental changes and take into account factors such as basins as a unit to study mineralization background,ore concentration areas as objects to study mineralization,and the correlation between regional tectonic movement and metallogenic process as a breakthrough point to study tectonic events and metallogenic events.It should also be based on different basin types to establish metallogenic models.The innovative research results and ideas are summarized with the aim of promoting the continuous improvement of sandstone-type uranium mineralization theory in northern China.展开更多
The U-Pb isotope system and uranium isotope composition(235U/238U and 234U/238U)were studied in a number of samples from the vertical section of the uranium ore body at the Vershinnoe sandstone-type deposit,Vitim uran...The U-Pb isotope system and uranium isotope composition(235U/238U and 234U/238U)were studied in a number of samples from the vertical section of the uranium ore body at the Vershinnoe sandstone-type deposit,Vitim uranium ore district,Russia.These parameters were determined to broadly vary.Deviations of the 234U/238U ratio from the equilibrium value indicate that the uranium ore was not completely conserved during the postore stage,and uranium was determined to continue migrating at the deposit.Comparison of the U-Pb isotope age value and 234U/238U isotope ratio provides an insight into the migrate direction of uranium in the ore body.The broad variations(137.377–137.772)in the 238U/235U ratio over the vertical section of the ore body can be explained by the different settings of the samples relative to the ore deposition front and changes in the redox conditions when this front shifted.The fact that theδ238U and K234/238 values are correlated indicates that the transfer of the 234U isotope into the aqueous phase may have been coupled with isotope fractionation in the 238U-235U system during the postformation uranium migration within the orebody.展开更多
Synthetic methods of thin section petrography, scanning electron microscope, electron microprobe, energy spectrum analysis, cathodoluminescence, isotopic analysis and temperature measuring for fluid inclusions were us...Synthetic methods of thin section petrography, scanning electron microscope, electron microprobe, energy spectrum analysis, cathodoluminescence, isotopic analysis and temperature measuring for fluid inclusions were used in analyzing sandstone samples collected from the Zhiluo Formation in order to fully understand the diagenesis evolution and the mineralizing response as well as the genesis of the uranium-bearing sandstone in Dongsheng area. The result shows that (1) the sandstone include lithic silicarenite, feldspathic litharenite and litharenite; (2) the authigenic minerals include clay minerals, carbonate minerals, siliceous and ferric minerals; (3) the physical property of sandstone is obviously controlled by diagenesis; and (4) the sandstone with favorable physical property is propitious to migration and storage of ore-forming fluid, and finally, forming the ore deposit. The sandstone of the Zhiluo Formation had undergone the early diagenetic stage (periods A and B) and the epidiagenetic stage. The evolution of diagenetic environment is in the order of acidic oxidation, alkalescent deoxidization, acidity to transitional environment of oxidation-deoxidization and acidity-alkalescence. The uranium exists in forms of pre-enrichment uranyl ion, active uranyl ion, dispersive adsorptive uranium and uranium mineral, respectively. In addition, the authors also hold that the formation of the sandstone-type uranium is not only related to the oxidation-deoxidization environment, but also closely related to the acidic-alkaline transitional environment, which are propitious to uranium mineralization in sandstone.展开更多
The Shihongtan uranium deposit in northwest China is a sandstone-type deposit suitable for alkaline in-situ leaching exploitation of uranium. Alkaline leaching tends to result in CaCO3 precipitation there by affecting...The Shihongtan uranium deposit in northwest China is a sandstone-type deposit suitable for alkaline in-situ leaching exploitation of uranium. Alkaline leaching tends to result in CaCO3 precipitation there by affecting the porosity of the ore-bearing aquifer. CaCO3 deposits can also block pumping and injection holes if the formulation parameters of the leaching solution are not well controlled. However, controlling these parameters to operate the in-situ leaching process is challenging. Our study demonstrates that the dissolved uranium concentration in the leaching solution increases as HCO3-concentration increases. Therefore, the most suitable HCO3-concentration to use as leaching solution is defined by the boundary value of the HCO3-concentration that controls CaCO3 dissolution-precipitation. That is, the dissolution and precipitation of calcite is closely related to pH, Ca2+ and HCO3-concentration. The pH and Ca2+ concentration are the main factors limiting HCO3-concentration in the leaching solution. The higher the pH and Ca2+ concentration, the lower the boundary value of HCO3-concentration, and therefore the more unfavorable to in-situ leaching of uranium.展开更多
The Qianjiadian uranium deposit is located in the Kailu Depression of Songliao Basin.It is a large-scale in-situ leachable uranium deposit of sandstone type and provides a typical case of the uranium deposits in the S...The Qianjiadian uranium deposit is located in the Kailu Depression of Songliao Basin.It is a large-scale in-situ leachable uranium deposit of sandstone type and provides a typical case of the uranium deposits in the Songliao Basin.Here we analyze the impact of oil and gas on reduction alteration,and factors including low grade mineralization.The Qianjiadian uranium deposit is characterized as a typical rolltype deposit with interlayers in oxidized zone.The occurrence of reductive low-permeability sandstone in uranium reservoirs controls the morphology of the uranium-rich orebody.We propose a metallogenic model involving multi-stage superposition characterized by“primary sediment enrichment-interlayer oxidation-superimposed transformation”.Our model would be helpful for formulating guidelines in the exploration for sandstone-type uranium deposits in the Songliao Basin.展开更多
The Bayinqinggeli deposit in the northern Ordos Basin, northwestern of China, is a recently discovered sandstone-type uranium deposit. The uranium(U) orebodies are generally hosted in the lower member of the Jurassic ...The Bayinqinggeli deposit in the northern Ordos Basin, northwestern of China, is a recently discovered sandstone-type uranium deposit. The uranium(U) orebodies are generally hosted in the lower member of the Jurassic Zhiluo Formation(Fm.), and are primarily tabular or irregular in shape. In the study area, 23 sandstone samples were collected from the Zhiluo Fm. and analyzed for major, trace, and rare earth elements(REEs). The geochemical characteristics of these sandstones are used to evaluate the factors controlling U mineralization. The source rocks of the Zhiluo Fm. sandstones are mainly volcanic and felsic magmatic rocks formed in continental arc and active continentalmarginal arc environments, and they provided the material required for the mineralization. The index of compositional variability ranges from 1.02 to 3.29(average1.38), indicating that the Zhiluo Fm. sandstones are immature and composed of first-cycle sediments. The corrected chemical index of alteration averages 56, suggesting that the source rocks underwent weak chemical weathering. The ore host rocks are loose, providing favorable conditions for epigenetic oxidation and U precipitation and enrichment. Ferrous iron in minerals such as chlorite, biotite, ilmenite, and pyrite might have played a role either in adsorbing or reducing the uranium.展开更多
The Mengqiguer deposit in the southern Yili basin Ili Basin is a large interlayer-oxidation-zone type uranium deposit.In this paper,we applied multiple methods including microscopic observation,scanning electron micro...The Mengqiguer deposit in the southern Yili basin Ili Basin is a large interlayer-oxidation-zone type uranium deposit.In this paper,we applied multiple methods including microscopic observation,scanning electron microscope and electronic probe,to analyze the systematical alteration characteristics of the ore-bearing sandstone layer.Fluid inclusion and stable isotope studies on the ore-bearing sandstone have also been carried out to discuss the internal relations between fluid activities,epigenetic alteration and the uranium mineralization.Major epigenetic alteration include clay alteration,carbonatization and pyritization,of which biogenetic pyritization is most closely related to the uranium mineralization.This suggests the existence of microorganism during the uranium mineralization process.The mineralization fluids of low temperature,medium density but varied salinities are suggested to be derived from multi-source,including the meteoric water and organic acidic vapor components from coal-bearing strata.Uranium mineralization,grain-dispersed kaolinite,limonite,colloidal pyrite,and the carbonate cements associated with sulfate-reducing bacteria were formed by meteoric water and vermicular-shaped kaolinite,autologous pyrite,and the carbonate cementation associated with the dehydroxylation of organic matter was formed by organic acidic.Based on these results,we consider that the uranium mineralization and epigenetic alteration both resulted from the reciprocity of organic–inorganic fluid and fluid–rock during the formation of the interlayer oxidation zone.展开更多
The central Zhuguang Mountains in Hunan Province is located at the junction of the three provinces,namely Hunan,Jiangxi,and Guangdong,where the famous Lujing uranium ore field lies.The uranium deposits occurring in th...The central Zhuguang Mountains in Hunan Province is located at the junction of the three provinces,namely Hunan,Jiangxi,and Guangdong,where the famous Lujing uranium ore field lies.The uranium deposits occurring in this area are all granite-related and they can be divided into three types,namely endogranitic ones,perigranitic ones,and contact zone types.The endogranitic uranium deposits are mainly controlled by the structural alteration zones developing within granites,with fragmentation,hematitization,and alkali metasomatism as their main mineralization characteristics.The perigranitic uranium deposits are mainly produced in the carbonaceous,siliceous,and argillaceous composite layers of epimetamorphic rocks and are controlled by fractured zones formed due to interlayer compression.The contact zone type uranium deposits mainly occur in the contact parts between the granites and favorable horizons.They have developed in favorable sections where multiple sets of structures are combined and intersected.The main metallogenic regularities of uranium in the central Zhuguang Mountains are as follows.The basic conditions for the uranium mineralization in this area include the framework consisting of regional deep large faults and their associated multi-set multi-direction favorable metallogenic structures,multi-cycle and multi-stage uranium-rich rock masses,and uranium-rich folded basement.Meanwhile,the uranium deposits in this area are closely related to granites in terms of genesis and space and they are formed in different structural parts subject to the same metallization.Furthermore,based on the summary of the characteristics and regularities of uranium mineralization in this area,the controlling factors of different types of uranium deposits in the area were explored and six metallogenic target areas were predicted.All these will provide references for the exploration of uranium deposits in this area.展开更多
The No. 302 uranium deposit, located in Guangdong Province, is a typical granite-type uranium ore deposit. REE geochemical characteristics of the wall rocks, pitchblende, altered rocks, calcite and fluorite from this ...The No. 302 uranium deposit, located in Guangdong Province, is a typical granite-type uranium ore deposit. REE geochemical characteristics of the wall rocks, pitchblende, altered rocks, calcite and fluorite from this deposit have been systematically studied in this paper. The result showed that the alkali-metasomatic granites and other altered rocks have the same REE distribution patterns as Indosinian granites. It is indicated that the hydrothermal ore-forming solution had altered the Indosinian granites, and ore-forming materials may directly originate from the Indosinian granites. Calcite and fluorite of different stages are the products derived from the same source but different stages. The evolution and degassing of the mineralizing solution might induce LREE enrichment to varying degree. Mantle fluid and a large volume of mineralizer may be the crucial factors controlling uranium mineralization, and the hydrothermal solution with mineralizer played an important role in U transport and concentration. Meanwhile, the degassing of CO2 might promote U and REE precipitation.展开更多
According to the oxidation intensity of ore-hosting sandstone, the interlayer oxidation zone of the Shihongtansandstone-type uranium deposit in the Turpan-Hami basin can be divided into 4 geochemical subzones, namely,...According to the oxidation intensity of ore-hosting sandstone, the interlayer oxidation zone of the Shihongtansandstone-type uranium deposit in the Turpan-Hami basin can be divided into 4 geochemical subzones, namely, intensely-oxidized, weakly-oxidized, redox and unoxidized primary subzones. The elemental geochemical characteristics of thefour subzones have been studied in detail, and the results show that U, together with other elements such as Re, Mo, Se, Sr,S, REE, Corganic etc., is enriched in the redox subzone. Re and U have similar geochemical properties in the reduction-oxidation process. The geochemical properties of Mo and Se are similar to those of U in the reduction condition, butdifferent from those of U in the oxidation condition. It is proposed that the ore-hosting layers can provide a curtain mountof uranium for uranium mineralization.展开更多
1 Introduction The Kangdian axis is an important polymetallic metallogenic belt in Southwest China,and it is also an area with a lot of hydrothermal uranium mineralization(Wang Hongjun,et al.,2009.The
The Bayingobi basin is the Mesozoic-Cenozoic basin in North China in which the Tamusu uranium deposit is located.The ore-target layer of the deposit is the Lower Cretaceous Bayingobi Formation,which developed as a fan...The Bayingobi basin is the Mesozoic-Cenozoic basin in North China in which the Tamusu uranium deposit is located.The ore-target layer of the deposit is the Lower Cretaceous Bayingobi Formation,which developed as a fan deltashallow lacustrine deposit.The distributary channel sand body of the fan delta plain and the underwater distributary channel sand body of the fan delta front formed a favorable uranium reservoir,so the study of sequence stratigraphy is extremely important to understanding the genesis of uranium deposits.On the basis of field investigation and a large number of borehole logs,the high resolution sequence stratigraphy of the Lower Cretaceous is divided and the system tracts of different periods are established.The relationship between deposition,interlayer oxidation and uranium enrichment is discussed.The Lower Cretaceous Bayingobi Formation can be divided into two fourth-order sequences(Sq1 and Sq2).The lower member of the Bayingobi Formation is referred to as Sq1,which is composed of a falling-stage system tract(FSST)on top.On the other hand,the upper member of the Bayingobi Formation is referred to as Sq2,which is composed of a lowstand system tract(LST),transgressive system tract(TST)and highstand system tract(HST).The lowstand system tract forms a favorable stratigraphic structure(mud-sand-mud formation)with the lacustrine mudstone of the overlying transgressive system tract,that is conducive for the migration of uranium-bearing oxygen water.The organic matter and pyrite in the fan delta sand body,as well as the dark mudstone in the distributary bay,provided a reducing medium for uranium mineralization.The ore body mainly occurs in the distributary channel,underwater distributary channel or the mouth bar of the fan delta.As a result of the moderate thickness,high permeability,favorable barrier and rich reducing medium,the rich ore body mainly occurs in the underwater distributary channel and mouth bar sand body of the delta front.Based on study of the sequence stratigraphy,the model of the sequence,sedimentation and mineralization of the uranium deposit is established,which enriches uranium metallogenic theory and provides a reference for exploration of the same type of uranium deposits.展开更多
Objective The Hengjian uranium deposit is a typical hydrothermal deposit in the Xiangshan uranium ore field.The uranium mineralization ages of the Xiangshan deposits are poorly constrained,and only a few mineralizatio...Objective The Hengjian uranium deposit is a typical hydrothermal deposit in the Xiangshan uranium ore field.The uranium mineralization ages of the Xiangshan deposits are poorly constrained,and only a few mineralization ages using the pitchblende U–Pb method have been published.These ages are commonly discordant and dispersed for abundant inclusions and an open U–Pb system.Zircon grains after strong hydrothermal alteration are usually characterized by high common Pb contents,and their U–Pb isochron ages recorded the hydrothermal alteration event without interference of common Pb components.The Hengjian gray/grayish-green granite porphyry experienced strong alteration by hydrothermal fluids during the pervasive uranium mineralization in the Xiangshan uranium ore field.Uranium mineralization in the Hengjian deposit may had different stages,and strong hydromicatization alteration occurred at a relatively early stage.Their altered zircon U–Pb isochron ages possibly represent relatively early mineralization age of the Xiangshan uranium deposits.Altered zircon grains from the Hengjian granite porphyry were analyzed using the secondary ion mass spectrometry(SIMS)U-Pb method in this study,and U–Pb isochron ages were measured to constrain the relatively early mineralization age of the Hengjian uranium deposit.展开更多
Objective The Ordos Basin located in the western part of the North China Craton bears various energy resources such as oil,gas,coal and uranium.It is one of the richest uranium-bearing basins in China.Since the discov...Objective The Ordos Basin located in the western part of the North China Craton bears various energy resources such as oil,gas,coal and uranium.It is one of the richest uranium-bearing basins in China.Since the discovery of the large-scale Dongsheng,Hangjinqi and Daying uranium deposits in the north of the Ordos Basin,a展开更多
基金supported by the National Key Research and Development Program of Deep-penetrating Geochemistry(Grant No.2016YFC0600604)。
文摘Identifying ore-induced geochemical anomalies at the surface that indicate concealed deposits in buried areas remains a significant challenge in geochemical exploration. In this study, in order to trace the source of the geochemical anomalies, systematic luminescence intensity analyses were conducted on quartz grains from the Quaternary regolith at the Hadatu sandstone-type uranium deposit in the Erenhot Basin. The optically stimulated luminescence(OSL) ages were much older than the depositional ages of the Quaternary regolith. Moreover, quartz OSL ages were closely related to both borehole grades and sampling depths. Thus, the abnormal mineral OSL ages from near-surface sediments were ultimately controlled by the sandstone-type uranium deposits. This is identical to the rapid changes of quartz OSL ages(0.063 ka/cm) and equivalent doses(0.19 Gy/cm) with depths in a given sampling site. The instantaneous soil radon concentration was positively correlated with the quartz OSL apparent age, indicating their ore-induced origin and, as a result, their effectiveness in the exploration of concealed uranium deposits. Other parameters, including mobile-state uranium and;Po contents, were poorly correlated with quartz OSL ages and therefore should only be used with caution for geochemical exploration. This is the first time an attempt has been made to discriminate the ore-induced sources for different surface anomaly parameters, including instantaneous soil radon, mobile-state uranium and;Po contents for concealed sandstonetype uranium deposits.
文摘This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved that these approaches have yielded good results on classifying the sedimentary fades, defining the redox transitional zones and reflecting deep mineralization information. They may probably become new methods on searching for sandstone-type uranium deposits.
基金sponsored by the National Natural Science Foundation Program of China (Nos.40772072 and 40802023)the Uranium Deposit Geological Program of Bureau of Geology,CNNC,the National Important Basic Research Program of China (No.2003CB214603 and No.2015CB453003)the Dongsheng coal and uranium exploration program of Central Geological exploration Fund (No.2008150013)
文摘Outcrop and drill hole data show that the Jurassic coal measures in the northeastern Ordos Basin are composed mainly of the Yan'an Formation and the lowstand system tract of the Zhiluo Formation,and there is a regional unconformity between them. The Dongsheng uranium deposit is associated with the Jurassic coal measures. Research data indicate that the Jurassic coal measures in the study area have a certain hydrocarbon-generating capacity,although the metamorphic grade is low(Ro=0.40%–0.58%). In the Dongsheng region alone,the accumulative amount of generated coalbed methane(CBM) is about 2028.29 × 108 –2218.72 × 108 m^3; the residual amount is about 50.92 × 108 m^3,and the lost amount is about 1977 × 108 m^3. Analysis of the burial history of the host rocks and the evolutionary history of the Dongsheng uranium deposit suggests that the Jurassic coal measures generated hydrocarbon mainly from Middle Jurassic to Early Crataceous,which is the main mineralization phase of the Dongsheng uranium deposit. By the Late Cretaceous,a mass of CBM dissipated due to the strong tectonic uplift,and the Dongsheng uranium deposit stepped into the preservation phase. Therefore,the low-mature hydrocarbon-containing fluid in the Jurassic coal measures not only served as a reducing agent for the formation of sandstone-type uranium deposits,but also rendered the second reduction of paleo-interlayer oxidation zone and become the primary reducing agent for ore conservation. Regional strata correlation reveals that the sandstone-type uranium reservoir at the bottom of the Zhiluo Formation is in contact with the underlying industrial coal seams in the Yan'an Formation through incision or in the form of an unconformity surface. In the Dongsheng region with poorly developed fault systems,the unconformity surface and scour surface served as the main migration pathways for low-mature hydrocarbon-containing fluid migrating to the uranium reservoir.
基金This study is supported by the Chinese 973 National Key Research and Development Program (2003CB214606) on Accumulation and Formation of Multi-Energy Mineral Deposits Coexisting in the same Basin and Open Foundation of the State Laboratory of Geological Processes and Mineral Resources.
文摘The major elements, trace elements and REEs were analyzed on the samples collected from the sandstone-type uranium deposits in the Ordos Basin to constrain the mechanism of uranium enrichment. The total REE amount ranges from 36.7 to 701.8 μg/g and the REE distribution patterns of the sandstone-type uranium samples are characterized by LREE enrichment and high REE depletion. The results also indicated a high Y abundance and Eu anomalies between 0.77-1.81. High-precision ICP-MS results showed that U abundances are within the range of 0.73-150 μg/g, showing some strong correlation between U enrichment and related elements such as Ti, V, Zr, Mo, and Au. In addition, Th abundance is correlated with ΣREE.
文摘Generally, sandstone-type uranium deposits can be divided into three zones according to their redox conditions: oxidized zone, ore zone and reduced zone. The Dongsheng uranium deposit belongs to this type. In order to study its geochemical characteristics, 11 samples were taken from the three zones of the Dongsheng uranium deposit. Five samples of them were collected from the oxidized zone, four samples from the ore zone and two samples from the reduced zone. These samples were analyzed using organic and inorganic geochemical methods. The results of GC traces and ICP-MASS indicate that the three zones show different organic and inorganic geochemical characteristics.
基金The“Northern Sandstone-type Uranium Deposits Investigation Project”(Project 0108)of the China Geological Survey has led to the discovery of many new sandstone-type uranium depositsThe National Basic Research Program(973 Program)(No.2015CB453000)+1 种基金the National Key R&D Program of China(No.2018YFC0604200)both from the Ministry of Science and Technology of the People’s Republic of China have led to innovations in many theoretical understandings of sandstone-type uranium depositsUnder the International Geoscience Programme(No.IGCP-675),a comparative study of sandstone-type uranium deposits between China and the rest of the world has been conducted。
文摘Many theoretical results on sandstone-type uranium mineralization in northern China obtained by the uranium research team of the Tianjin Center of Geological Survey in recent years are presented.From the source sink system of uranium-producing basins,sedimentary environment of uranium-bearing rock series,ore-forming fluid information,evolution of tectonic events,basin formation and development,we redefine and classify uranium orebodies,redox zoning,and ore-controlling structural styles.We then systematically propose a theoretical system of sandstone-type uranium deposits in northern China.We conclude that sandstone-type uranium deposits in northern China are mainly found in sedimentary environments such as rivers,deltas,and alluvial fans in the Mesozoic and Cenozoic lowstand systems tract and in gray sandstone layers in the vertical redox zoning.The orebodies are controlled by the tectonic slope belt,which is in the shape of a strip on the plane,and spreads in a layer or plate on the section.Vertical(ups and downs)tectonic movement triggers large-scale phreatic flow in the basin,which is the real driving force for controlling the ore-forming fluid.The theoretical system of sandstone-type uranium deposits in northern China should be based on global tectonic movement and environmental changes and take into account factors such as basins as a unit to study mineralization background,ore concentration areas as objects to study mineralization,and the correlation between regional tectonic movement and metallogenic process as a breakthrough point to study tectonic events and metallogenic events.It should also be based on different basin types to establish metallogenic models.The innovative research results and ideas are summarized with the aim of promoting the continuous improvement of sandstone-type uranium mineralization theory in northern China.
文摘The U-Pb isotope system and uranium isotope composition(235U/238U and 234U/238U)were studied in a number of samples from the vertical section of the uranium ore body at the Vershinnoe sandstone-type deposit,Vitim uranium ore district,Russia.These parameters were determined to broadly vary.Deviations of the 234U/238U ratio from the equilibrium value indicate that the uranium ore was not completely conserved during the postore stage,and uranium was determined to continue migrating at the deposit.Comparison of the U-Pb isotope age value and 234U/238U isotope ratio provides an insight into the migrate direction of uranium in the ore body.The broad variations(137.377–137.772)in the 238U/235U ratio over the vertical section of the ore body can be explained by the different settings of the samples relative to the ore deposition front and changes in the redox conditions when this front shifted.The fact that theδ238U and K234/238 values are correlated indicates that the transfer of the 234U isotope into the aqueous phase may have been coupled with isotope fractionation in the 238U-235U system during the postformation uranium migration within the orebody.
文摘Synthetic methods of thin section petrography, scanning electron microscope, electron microprobe, energy spectrum analysis, cathodoluminescence, isotopic analysis and temperature measuring for fluid inclusions were used in analyzing sandstone samples collected from the Zhiluo Formation in order to fully understand the diagenesis evolution and the mineralizing response as well as the genesis of the uranium-bearing sandstone in Dongsheng area. The result shows that (1) the sandstone include lithic silicarenite, feldspathic litharenite and litharenite; (2) the authigenic minerals include clay minerals, carbonate minerals, siliceous and ferric minerals; (3) the physical property of sandstone is obviously controlled by diagenesis; and (4) the sandstone with favorable physical property is propitious to migration and storage of ore-forming fluid, and finally, forming the ore deposit. The sandstone of the Zhiluo Formation had undergone the early diagenetic stage (periods A and B) and the epidiagenetic stage. The evolution of diagenetic environment is in the order of acidic oxidation, alkalescent deoxidization, acidity to transitional environment of oxidation-deoxidization and acidity-alkalescence. The uranium exists in forms of pre-enrichment uranyl ion, active uranyl ion, dispersive adsorptive uranium and uranium mineral, respectively. In addition, the authors also hold that the formation of the sandstone-type uranium is not only related to the oxidation-deoxidization environment, but also closely related to the acidic-alkaline transitional environment, which are propitious to uranium mineralization in sandstone.
基金supported by the basic science research project (A3420060142) from China National Defence Science and Technology Industry BureauChina National Natural Science Fund Project (40872165)
文摘The Shihongtan uranium deposit in northwest China is a sandstone-type deposit suitable for alkaline in-situ leaching exploitation of uranium. Alkaline leaching tends to result in CaCO3 precipitation there by affecting the porosity of the ore-bearing aquifer. CaCO3 deposits can also block pumping and injection holes if the formulation parameters of the leaching solution are not well controlled. However, controlling these parameters to operate the in-situ leaching process is challenging. Our study demonstrates that the dissolved uranium concentration in the leaching solution increases as HCO3-concentration increases. Therefore, the most suitable HCO3-concentration to use as leaching solution is defined by the boundary value of the HCO3-concentration that controls CaCO3 dissolution-precipitation. That is, the dissolution and precipitation of calcite is closely related to pH, Ca2+ and HCO3-concentration. The pH and Ca2+ concentration are the main factors limiting HCO3-concentration in the leaching solution. The higher the pH and Ca2+ concentration, the lower the boundary value of HCO3-concentration, and therefore the more unfavorable to in-situ leaching of uranium.
基金Financial support for this study was provided by New Energy Technology Development and Application Research(grant No.2019A-4809(JT)).
文摘The Qianjiadian uranium deposit is located in the Kailu Depression of Songliao Basin.It is a large-scale in-situ leachable uranium deposit of sandstone type and provides a typical case of the uranium deposits in the Songliao Basin.Here we analyze the impact of oil and gas on reduction alteration,and factors including low grade mineralization.The Qianjiadian uranium deposit is characterized as a typical rolltype deposit with interlayers in oxidized zone.The occurrence of reductive low-permeability sandstone in uranium reservoirs controls the morphology of the uranium-rich orebody.We propose a metallogenic model involving multi-stage superposition characterized by“primary sediment enrichment-interlayer oxidation-superimposed transformation”.Our model would be helpful for formulating guidelines in the exploration for sandstone-type uranium deposits in the Songliao Basin.
基金jointly supported by the CNNC Research and Innovation Project(grant no.Geo-SD04and Geo-LTD-1601)funded by the project“Geology of mineral resources in China”from China Geological Survey(grant nos.DD20160346,DD20190379)。
文摘The Bayinqinggeli deposit in the northern Ordos Basin, northwestern of China, is a recently discovered sandstone-type uranium deposit. The uranium(U) orebodies are generally hosted in the lower member of the Jurassic Zhiluo Formation(Fm.), and are primarily tabular or irregular in shape. In the study area, 23 sandstone samples were collected from the Zhiluo Fm. and analyzed for major, trace, and rare earth elements(REEs). The geochemical characteristics of these sandstones are used to evaluate the factors controlling U mineralization. The source rocks of the Zhiluo Fm. sandstones are mainly volcanic and felsic magmatic rocks formed in continental arc and active continentalmarginal arc environments, and they provided the material required for the mineralization. The index of compositional variability ranges from 1.02 to 3.29(average1.38), indicating that the Zhiluo Fm. sandstones are immature and composed of first-cycle sediments. The corrected chemical index of alteration averages 56, suggesting that the source rocks underwent weak chemical weathering. The ore host rocks are loose, providing favorable conditions for epigenetic oxidation and U precipitation and enrichment. Ferrous iron in minerals such as chlorite, biotite, ilmenite, and pyrite might have played a role either in adsorbing or reducing the uranium.
基金financially supported by Ministry of Science and Technology(No.2015CB453004)China National Nuclear Corporation(No.LTD1612-4)。
文摘The Mengqiguer deposit in the southern Yili basin Ili Basin is a large interlayer-oxidation-zone type uranium deposit.In this paper,we applied multiple methods including microscopic observation,scanning electron microscope and electronic probe,to analyze the systematical alteration characteristics of the ore-bearing sandstone layer.Fluid inclusion and stable isotope studies on the ore-bearing sandstone have also been carried out to discuss the internal relations between fluid activities,epigenetic alteration and the uranium mineralization.Major epigenetic alteration include clay alteration,carbonatization and pyritization,of which biogenetic pyritization is most closely related to the uranium mineralization.This suggests the existence of microorganism during the uranium mineralization process.The mineralization fluids of low temperature,medium density but varied salinities are suggested to be derived from multi-source,including the meteoric water and organic acidic vapor components from coal-bearing strata.Uranium mineralization,grain-dispersed kaolinite,limonite,colloidal pyrite,and the carbonate cements associated with sulfate-reducing bacteria were formed by meteoric water and vermicular-shaped kaolinite,autologous pyrite,and the carbonate cementation associated with the dehydroxylation of organic matter was formed by organic acidic.Based on these results,we consider that the uranium mineralization and epigenetic alteration both resulted from the reciprocity of organic–inorganic fluid and fluid–rock during the formation of the interlayer oxidation zone.
基金funded by the project titled Prospect Survey and Exploration Demonstration of Hardrock Mineral Resources such as Uranium and Thorium(12120115014101)initiated by the Tianjin Center of China Geological Survey.The data and achievements cited in this paper are mainly from relevant scientific research,geological survey,and mineral exploration projects undertaken by the No.302 Brigade of Hunan Nuclear Industry Geology Bureau in recent years.
文摘The central Zhuguang Mountains in Hunan Province is located at the junction of the three provinces,namely Hunan,Jiangxi,and Guangdong,where the famous Lujing uranium ore field lies.The uranium deposits occurring in this area are all granite-related and they can be divided into three types,namely endogranitic ones,perigranitic ones,and contact zone types.The endogranitic uranium deposits are mainly controlled by the structural alteration zones developing within granites,with fragmentation,hematitization,and alkali metasomatism as their main mineralization characteristics.The perigranitic uranium deposits are mainly produced in the carbonaceous,siliceous,and argillaceous composite layers of epimetamorphic rocks and are controlled by fractured zones formed due to interlayer compression.The contact zone type uranium deposits mainly occur in the contact parts between the granites and favorable horizons.They have developed in favorable sections where multiple sets of structures are combined and intersected.The main metallogenic regularities of uranium in the central Zhuguang Mountains are as follows.The basic conditions for the uranium mineralization in this area include the framework consisting of regional deep large faults and their associated multi-set multi-direction favorable metallogenic structures,multi-cycle and multi-stage uranium-rich rock masses,and uranium-rich folded basement.Meanwhile,the uranium deposits in this area are closely related to granites in terms of genesis and space and they are formed in different structural parts subject to the same metallization.Furthermore,based on the summary of the characteristics and regularities of uranium mineralization in this area,the controlling factors of different types of uranium deposits in the area were explored and six metallogenic target areas were predicted.All these will provide references for the exploration of uranium deposits in this area.
基金This work was funded jointly by the Important Research 0rientation Project under the Knowledge Innovation Program sponsored by the Chinese Academy of Sciences(Grant No.KZCX3-SW-125)the National 0utstanding Young Scientists Science Foundation of China(Grant No.49925309).
文摘The No. 302 uranium deposit, located in Guangdong Province, is a typical granite-type uranium ore deposit. REE geochemical characteristics of the wall rocks, pitchblende, altered rocks, calcite and fluorite from this deposit have been systematically studied in this paper. The result showed that the alkali-metasomatic granites and other altered rocks have the same REE distribution patterns as Indosinian granites. It is indicated that the hydrothermal ore-forming solution had altered the Indosinian granites, and ore-forming materials may directly originate from the Indosinian granites. Calcite and fluorite of different stages are the products derived from the same source but different stages. The evolution and degassing of the mineralizing solution might induce LREE enrichment to varying degree. Mantle fluid and a large volume of mineralizer may be the crucial factors controlling uranium mineralization, and the hydrothermal solution with mineralizer played an important role in U transport and concentration. Meanwhile, the degassing of CO2 might promote U and REE precipitation.
文摘According to the oxidation intensity of ore-hosting sandstone, the interlayer oxidation zone of the Shihongtansandstone-type uranium deposit in the Turpan-Hami basin can be divided into 4 geochemical subzones, namely, intensely-oxidized, weakly-oxidized, redox and unoxidized primary subzones. The elemental geochemical characteristics of thefour subzones have been studied in detail, and the results show that U, together with other elements such as Re, Mo, Se, Sr,S, REE, Corganic etc., is enriched in the redox subzone. Re and U have similar geochemical properties in the reduction-oxidation process. The geochemical properties of Mo and Se are similar to those of U in the reduction condition, butdifferent from those of U in the oxidation condition. It is proposed that the ore-hosting layers can provide a curtain mountof uranium for uranium mineralization.
基金supported by the China Nuclear Industry Geological Bureau Foundation (No.201637 and 201638)
文摘1 Introduction The Kangdian axis is an important polymetallic metallogenic belt in Southwest China,and it is also an area with a lot of hydrothermal uranium mineralization(Wang Hongjun,et al.,2009.The
基金funded by the project of Investigation and Exploration of Uranium Deposits in Bayingobi Basin(Grant No.201903,202203)China Nuclear Geology,CNNC。
文摘The Bayingobi basin is the Mesozoic-Cenozoic basin in North China in which the Tamusu uranium deposit is located.The ore-target layer of the deposit is the Lower Cretaceous Bayingobi Formation,which developed as a fan deltashallow lacustrine deposit.The distributary channel sand body of the fan delta plain and the underwater distributary channel sand body of the fan delta front formed a favorable uranium reservoir,so the study of sequence stratigraphy is extremely important to understanding the genesis of uranium deposits.On the basis of field investigation and a large number of borehole logs,the high resolution sequence stratigraphy of the Lower Cretaceous is divided and the system tracts of different periods are established.The relationship between deposition,interlayer oxidation and uranium enrichment is discussed.The Lower Cretaceous Bayingobi Formation can be divided into two fourth-order sequences(Sq1 and Sq2).The lower member of the Bayingobi Formation is referred to as Sq1,which is composed of a falling-stage system tract(FSST)on top.On the other hand,the upper member of the Bayingobi Formation is referred to as Sq2,which is composed of a lowstand system tract(LST),transgressive system tract(TST)and highstand system tract(HST).The lowstand system tract forms a favorable stratigraphic structure(mud-sand-mud formation)with the lacustrine mudstone of the overlying transgressive system tract,that is conducive for the migration of uranium-bearing oxygen water.The organic matter and pyrite in the fan delta sand body,as well as the dark mudstone in the distributary bay,provided a reducing medium for uranium mineralization.The ore body mainly occurs in the distributary channel,underwater distributary channel or the mouth bar of the fan delta.As a result of the moderate thickness,high permeability,favorable barrier and rich reducing medium,the rich ore body mainly occurs in the underwater distributary channel and mouth bar sand body of the delta front.Based on study of the sequence stratigraphy,the model of the sequence,sedimentation and mineralization of the uranium deposit is established,which enriches uranium metallogenic theory and provides a reference for exploration of the same type of uranium deposits.
基金financially supported by the National Key R&D Program of China(Grant No.2017YFC0602600)Project of Nuclear Power Development(No.HXS1403)Project of Core Competency Improvement(No.LTC1605).
文摘Objective The Hengjian uranium deposit is a typical hydrothermal deposit in the Xiangshan uranium ore field.The uranium mineralization ages of the Xiangshan deposits are poorly constrained,and only a few mineralization ages using the pitchblende U–Pb method have been published.These ages are commonly discordant and dispersed for abundant inclusions and an open U–Pb system.Zircon grains after strong hydrothermal alteration are usually characterized by high common Pb contents,and their U–Pb isochron ages recorded the hydrothermal alteration event without interference of common Pb components.The Hengjian gray/grayish-green granite porphyry experienced strong alteration by hydrothermal fluids during the pervasive uranium mineralization in the Xiangshan uranium ore field.Uranium mineralization in the Hengjian deposit may had different stages,and strong hydromicatization alteration occurred at a relatively early stage.Their altered zircon U–Pb isochron ages possibly represent relatively early mineralization age of the Xiangshan uranium deposits.Altered zircon grains from the Hengjian granite porphyry were analyzed using the secondary ion mass spectrometry(SIMS)U-Pb method in this study,and U–Pb isochron ages were measured to constrain the relatively early mineralization age of the Hengjian uranium deposit.
基金This work was supported by the National Natural Science Foundation of China(grant No.41330315)China geological survey(grant No.12120114009201)
文摘Objective The Ordos Basin located in the western part of the North China Craton bears various energy resources such as oil,gas,coal and uranium.It is one of the richest uranium-bearing basins in China.Since the discovery of the large-scale Dongsheng,Hangjinqi and Daying uranium deposits in the north of the Ordos Basin,a
