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
Meso-Cenozoic intracontinental orogenic processes in the Tian Shan orogenic belt have significant effect on the sandstone-hosted uranium deposits in the intramontane basins and those adjacent to the orogen. The Sawafu...Meso-Cenozoic intracontinental orogenic processes in the Tian Shan orogenic belt have significant effect on the sandstone-hosted uranium deposits in the intramontane basins and those adjacent to the orogen. The Sawafuqi uranium deposit, which is located in the South Tian Shan orogenic belt, is investigated to reveal the relationships between uranium mineralization and orogenies. Recent exploration results show that the Sawafuqi uranium deposit has tabular, stratiform, quasi-stratiform, and lens-like orebodies and various geological characteristics different from typical interlayer oxidation zone sandstone-hosted uranium deposits. Systematic studies of ore samples from the Sawafuqi uranium deposit using a variety of techniques, including thin section observation, a-track radiograph, electron microprobe and scanning electron microscope, suggest that uranium mineralization is closely related to pyrite and organic matter. Mineralization-related alterations in the host rocks are mainly silicification and argillation including kaolinite, illite (and illite-smectite mixed layer) and chlorite. Tree stages of mineralization were identified in the Sawafuqi uranium deposit: (i) uranium-bearing detritus and synsedimentary initial pre-enrichment; (ii) interlayer oxidization zone uranium mineralization; and (iii) vein-type uranium mineralization. The synsedimentary uranium pre-enrichment represents an early uranium enrichment in the Sawafuqi uranium deposit, and interlayer oxidation zone uranium mineralization formed the main orebodies, which are superimposed by the vein-type uranium mineralization. Combining the results of this study with previous studies on the Meso-Cenozoic orogenies of South Tian Shan, it is proposed that the synsedimentary uranium pre-enrichment of the Sawafuqi uranium deposit was caused by Triassic Tian Shan uplift, and the interlayer oxidation zone uranium mineralization occurred during the Eocence-Oligocene period, when tectonism was relatively quiet, whereas the vein-type uranium mineralization took place in relation to the strong orogeny of South Tian Shan since Miocene.展开更多
In the southwestern margin of the Ordos Basin,uranium mineralization is primarily hosted by predominantly oxidative red clastic formations in the Lower Cretaceous.The main target layers for uranium exploration are the...In the southwestern margin of the Ordos Basin,uranium mineralization is primarily hosted by predominantly oxidative red clastic formations in the Lower Cretaceous.The main target layers for uranium exploration are the Madongshan and Liwaxia formations of the Liupanshan Group,followed by the Jingchuan Formation of the Zhidan Group.The host rocks(medium-fine feldspar quartz sandstone),which are bleached to a light grayish white color,contain a minor organic matter component and pyrite.Uranium mineralization changes from surficial infiltration or phreatic oxidation in the upper part to interlayer oxidation in the lower part.Uranium ore bodies are mostly lenticular or tabular in shape,locally shaped like crescent rolls.Individual ore bodies are typically small and shallow.Uranium predominantly manifests as pitchblende and coffinite.Coffinite is usually short and columnar or granular in habit,whereas pitchblende occurs as an irregular colloidal covering on the surface or in fissures of ferric oxide,silicate,clay or carbonate.Secondary uranium minerals are torbernite,uranophane,and uranopilite.Minerals associated with uranium are mainly pyrite,chalcopyrite and,to a minor extent,arsenopyrite and fluorite.The associated elements are Mo,V,Se,Co,Ni,and Mn,the host sandstone being high in Cu and Ba.Overall,the red clastic formations in the southwestern margin of the Ordos Basin are characterized by’five multiples but one low’which means multiple target layers,multiple stages of mineralization,multiple ore body shapes,multiple kinds of uranium minerals,multiple associated elements,but low organic matter.This implies an overall complex uranium metallogenic environment and mineralization process.It is recommended that future uranium exploration should take into consideration regional metallogenic conditions and mineralization features,with target layers in the wide-smooth synclinal slope being focused on.Most uranium deposits are small to medium in size,and the main type of uranium mineralization can vary by target layer.展开更多
Black shales are marine sediments with argillaceous, silty and siliceous compositions and high contents of organic materials, disseminated pyrite and uranium. Uraniferous black shale has uranium content of more than 2...Black shales are marine sediments with argillaceous, silty and siliceous compositions and high contents of organic materials, disseminated pyrite and uranium. Uraniferous black shale has uranium content of more than 20 ppm.展开更多
Objective Galuskin et al. (2011) firstly discovered that vorlanite (CaU^6+/4+)04 is a rare Ca-rich mineral with a fluorite-type structure, which is isostructural with uraninite (U^4+O2). Previous studies of ...Objective Galuskin et al. (2011) firstly discovered that vorlanite (CaU^6+/4+)04 is a rare Ca-rich mineral with a fluorite-type structure, which is isostructural with uraninite (U^4+O2). Previous studies of the Xianshi granite-related uranium deposit reported that uraninite and pyrite are the major ore minerals whereas galena, clausthalite (PbSe), and pyrite are minor phases in the ores. A more detailed petrographic and geochronological study of the uranium minerals from the Xianshi deposit showed that there are three distinct types of uraninite-bearing assemblages which formed at three mineralization episodes (Fig. la; Luo et al., 2015).展开更多
The Guidong granitic complex is constituted by Luxi pluton, Xiazhuang pluton, Maofeng pluton, Sundong pluton, Aizi pluton and Siqian pluton, which intruded in Indosinian and early Yanshanian Periods. These plutons var...The Guidong granitic complex is constituted by Luxi pluton, Xiazhuang pluton, Maofeng pluton, Sundong pluton, Aizi pluton and Siqian pluton, which intruded in Indosinian and early Yanshanian Periods. These plutons varies from each other not only in major element content, aluminium saturation index, but also in ∑REE, δEu, and LREE/HREE, (La/Yb)N, (La/Sm) N and (Gd/Yb) N ratios. Uranium mineralization is mainly hosted by strong peraluminous granites, which has undergone intense fluid-rock interaction, and their REE compositions are characterised by M-type tetrad effects and lower ∑REE, δEu value, LREE/HREE, (La/Yb) N, (La/Sm) N and (Gd/Yb) N ratios.展开更多
The Sanjiang area is an important granite distribution area in China,except for South China,in which granites is complex and complete.Based on fully collecting date about it,this paper explores the significance of ura...The Sanjiang area is an important granite distribution area in China,except for South China,in which granites is complex and complete.Based on fully collecting date about it,this paper explores the significance of uranium展开更多
The present work deals with the detailed geology,mineralogy,geochemistry,and spectrometric prospection of the felsic volcanic rocks at the Eastern Desert,Egypt of the Arabian-Nubian Shield.Felsic volcanic rocks are an...The present work deals with the detailed geology,mineralogy,geochemistry,and spectrometric prospection of the felsic volcanic rocks at the Eastern Desert,Egypt of the Arabian-Nubian Shield.Felsic volcanic rocks are an essential source for rare earth elements(REEs)and uranium occurrences in this area.They are compositionally uniform with tholeiitic to calc-alkaline affinities,peraluminous and belong to the series of rhyolite with high-K melt.They exhibit more enrichment in high field strength elements(HFSE,e.g.Zr,Ta,Nd,Th,and U)and large-ion lithophile elements(LILE,e.g.Pb and Rb)compared to the country rocks of the studied area,with REE ranging from 188.20 to 442.70 ppm and strong depletion in Ti,Sr,P with deep negative Eu oddities.The felsic volcanic rocks were mostly generated from the partial melting of quartz-amphibolite facies accreted during the Neoproterozoic.Positive oddities of Zr-U-Th for the felsic volcanic rocks determine the involvement of crustal materials.Felsic volcanic rocks are found in A-type suites of magma and represent highly fractionated rocks derived from rhyolitic magma,with insignificant interaction with continental crust in the low-pressure environment and during fractional crystallization.Felsic volcanic rocks have higher values of radioactivity in which eU range from 0.5 to 121 ppm and eTh from 1.0 to 415.10 ppm.The high values of eU and eTh can be ascribed to the mineralization of uranium and the presence of accessory minerals of radiogenic nature such as uranophane,uranothorite,zircon,and monazite.Uranophane is considered as the mineral with most enriched uranium contents in the studied felsic volcanic rocks in which(UO2=87.30 wt%).Also,they are enriched with REE-bearing accessory minerals comprising allanite,titanite,and apatite.The geological investigations of the felsic volcanic rocks in the studied areas are inappropriate to clear the feasible economic potentialities of rare earth elements and U occurrences;itemized and invaluable explorational work is as yet needed.Whilst,the environmental impact of mineralization,owing to U and Th and their radiogenic daughter products,is observed and must be elaborated minutely.展开更多
Guidong granitic complex is constituted by Luxi intrusion, Xiazhuang intrusion, Maofeng intrusion, Sundong intrusion, Aizi intrusion and Siqian intrusion, which emplaced in Indosinian and early Yanshanian Periods. The...Guidong granitic complex is constituted by Luxi intrusion, Xiazhuang intrusion, Maofeng intrusion, Sundong intrusion, Aizi intrusion and Siqian intrusion, which emplaced in Indosinian and early Yanshanian Periods. These intrusions varied from each other not only in major element content, aluminium saturation index, but also in values of ∑REE, δEu, and LREE/HREE, (La/Yb)N, (La/Sm)N and (Gd/Yb)N. The Maofeng intrusion, which has the closest relationship with uranium mineralization, belongs to strong peraluminous granites. Having undergone much intense fluid-rock interaction, it is characterized by typical M-type tetrad effects and lowest values of ∑REE, δEu, LREE/HREE, (La/Yb)N, (La/Sm)N and (Gd/Yb)N ratios than other studied intrusions.展开更多
1 Introduction The Sanjiang metallogenic belt is one of the important nonferrous metal metallogenic belts in China,the potential resources of copper,lead,zinc,silver,gold and tin are huge(Zhengqian et al.,1993).In the...1 Introduction The Sanjiang metallogenic belt is one of the important nonferrous metal metallogenic belts in China,the potential resources of copper,lead,zinc,silver,gold and tin are huge(Zhengqian et al.,1993).In the west of Yunnan province has a lot of Yanshanian granite,according to 1:20 million test data,development of granite belt rich in radioactive minerals in the west of Yunnan展开更多
Uranium is a typical lithophile element, having outstanding geo-chemical characteristics of association whith high SiO<sub>2</sub>, peraluminousand marginally peralkalic rocks. In evolution process of all ...Uranium is a typical lithophile element, having outstanding geo-chemical characteristics of association whith high SiO<sub>2</sub>, peraluminousand marginally peralkalic rocks. In evolution process of all geologicalhistory, uranium gathers without interruption in upper crust. Urani-um mineralization is closely realted with evolution characteristics of thecontinent crust.1. It was not until the continent crust evolved to certain maturedegree that uranium began metallization. The oldest uranium depositon the earth occurred in the Delanshiwa (Kapuwaer) district,展开更多
The purpose of this study is to determine the distribution and geochemical features of uranium mineralization in the Ragillar region in the Manisa-Koprübasi in western Turkey. Sixteen whole rock samples were coll...The purpose of this study is to determine the distribution and geochemical features of uranium mineralization in the Ragillar region in the Manisa-Koprübasi in western Turkey. Sixteen whole rock samples were collected from sites showing the highest levels of radioactivity (7600 cps) as measured by a gamma spectrometer in the dolomitic limestones. SEM-EDS (Scanning Electron Microscopy-Energy Dispersive Spectrometry), XRF (X-Ray Fluorescence), an ICP-OES (Inductively Coupled Plasma Optic Emission Spectrometer), and a Leco carbon-sulfur analyzer were used to determine the mineralogical and chemical characteristics of the whole rock samples. The mineralogical features showed that uranium mineralization is associated with fluorapatite-rich rocks formed within calcite matrix fractures;cracks systems;and limestone, claystone, marl and silicified breccia zones in the lacustrine sediments that are observed around the Kale crest dolomitic limestones in the Demirci basin. The geochemical data for these samples show a strong positive correlation between uranium and P<sub>2</sub>O<sub>5</sub> concentrations. The geochemical data also indicate that uranium is deposited in the oxidation zone by dissolving the primary minerals (banded gneisses from the Menderes Massif, and dacitic and andesitic tuff) and moving the metal-rich hydrothermal fluids as phosphorus compounds, before passing through fractures, cracks, and permeable sandstone units, or along carbonate and clay layers.展开更多
1 Introduction The uranium deposits related with Indosinian and Yanshanian granite have provided the abundant resource of uranium during the past several decades in China.The deposits are mainly distributing in the Gu...1 Introduction The uranium deposits related with Indosinian and Yanshanian granite have provided the abundant resource of uranium during the past several decades in China.The deposits are mainly distributing in the Guidong granite展开更多
The sandstone-hosted uranium deposits in the SW Songliao Basin differ from typical sandstone-hosted uranium deposits in terms of the geological features of the ore-deposits,including the geometry of the orebodies,mine...The sandstone-hosted uranium deposits in the SW Songliao Basin differ from typical sandstone-hosted uranium deposits in terms of the geological features of the ore-deposits,including the geometry of the orebodies,mineral assemblage and petrography.Detailed drill core and microscopic observations,scanning electron microscopy(SEM),electron microprobe analysis(EMPA),heavy mineral concentrates,and fluid inclusion studies of the Upper Cretaceous Yaojia Formation,i.e.,the uranium-bearing layer,were integrated to investigate the roles of hydrothermal fluids in the formation of these uranium deposits.We found that the kaolinite alteration is developed in the mineralized zones,but it is less common in the peripheral areas.The fluid inclusions are hydrothermal fluids with a medium-low temperature(67 to 179 ℃) and a high salinity(5.9 wt.% to 20.1 wt.%).According to the analyses,three kinds of hydrothermal fluids,i.e.,the acid fluid,the groundwater heated by the mafic magma,and the alkaline fluid rich in Ca^(2+) and CO_(3)^(2-),were identified.The fluids might have low U content,but they have participated in the formation of the uranium deposits successively.Kaolinite formed by the acid-hydrothermal fluid absorbed large amounts of uranium.Subsequently,the thermal energy from the hydrothermal fluids changed the intrastratal redox environment and increased the solubility of the uranium minerals in the fluid.The alkaline-hydrothermal fluid rich in Ca^(2+) and C0_(3)^(2-) facilitated the formation of stable Ca-U(Ⅵ)-CO_(3) complex,which led to the enrichment of soluble uranium in solution,and final precipitation as pitchblende,brannerite and Ti-bearing uranium minerals in the uranium ores.展开更多
Paleoproterozoic Bijawars of the Sonrai basin consists of(a) Sonrai(mostly carbonate carbonaceous shale and phosphatic breccia) and(b) Solda Formations(commonly chloritic and ferruginous shale) with well-developed cla...Paleoproterozoic Bijawars of the Sonrai basin consists of(a) Sonrai(mostly carbonate carbonaceous shale and phosphatic breccia) and(b) Solda Formations(commonly chloritic and ferruginous shale) with well-developed clay-organo-rich facies,often marked with hydrothermal activities.Previous studies revealed abundance order of kaolinite> chlorite> illite> smectite;and kaolinite> illite> chlorite in clay(0.2-2.0 μm) fractions separated from the Sonrai and Solda Formations,respectively.To understand atomic substitutions and trace elemental concentrations,clay minerals were analyzed by fusion ICPMS and SEM-EDS.PAAS normalized data plots show U,Th,Rb,Ba,Pb Sr,and large-ion lithophiles enrichment,whereas,Bandai sandstone and Rohini carbonate clays show HREE enrichment with asymmetrical patterns,similar to those reported from the well-established McArthur River,Cigar Lake,and Sue UTUD of Canada.For Rohni carbonate,chondrite-normalized REE data plots revealed M shape REE patterns,ascribed to Gd-Tb-Dy-Ho tetrad effect and anomalous Y,Zr,and Hf concentrations.Owing to HREE incorporation in the clay inter-layers,linear and flattened REE trends were noticed.Flat REE patterns associated with the highly altered chlorite and illite represent negative Eu anomaly related to the dilational nature of the uraninite structure and is suggestive of anoxic conditions.展开更多
Miaoershan(MES) uranium ore field is one of the most important uranium sources in China, hosts the largest Chanziping carbonaceous-siliceous-pelitic rock type uranium deposit in South China together with many other ...Miaoershan(MES) uranium ore field is one of the most important uranium sources in China, hosts the largest Chanziping carbonaceous-siliceous-pelitic rock type uranium deposit in South China together with many other granite-hosted uranium deposits. The Shazijiang(SZJ) uranium deposit is one of the representative granite-hosted uranium deposits in the MES uranium ore field, situated in the Ziyuan, Guangxi Province, South China. Uranium mineralization in the SZJ deposit mainly occurs as uraninite with quartz and calcite veins that is spatially associated with mafic dykes in the region. The hydrothermal alteration includes silicification, carbonation and hematitization. New uraninite chemical U-Pb geochronology and petrographic evidences provide the timing constraints and new insights into the formation of the SZJ uranium deposit. The results show that the first stage of uranium mineralization formed at 97.5±4.0 Ma, whereas another stage of uranium mineralization occurred at 70.2±1.6 Ma. Two stages of uranium mineralization are fairly consistent with two episodic crustal extensions that occurred at -100 and -70 Ma throughout South China. This study indicates that there are two uranium mineralization events in SZJ uranium ore field controlled by mafic dyke, supporting that mafic dykes play an important topochemical role in uranium concentration and/or mobilization. Therefore, geochemical U-Pb age firstly reinforces that ore-forming age of the SZJ uranium deposit mainly yields at 97.5±4.0 and 70.2±1.6 Ma. Additionally, geochemical age method is particularly useful for interest samples which record information on multi-stage uranium mineralizations in South China.展开更多
Carbonaceous debris(CD),common dispersed organic matter(i.e.,DOM),is widely disseminated in sandstones from uranium-bearing strata from the Dongsheng uranium ore field of the northern Ordos Basin.Compositions of macer...Carbonaceous debris(CD),common dispersed organic matter(i.e.,DOM),is widely disseminated in sandstones from uranium-bearing strata from the Dongsheng uranium ore field of the northern Ordos Basin.Compositions of maceral,element and biomarkers of CD were investigated through a series of methods with optical microscope,elemental analyzer and gas chromatography-mass spectrometry analyses(GC-MS)to study origin of CD.The results show that CD,centrally distributed nearby channel erosion surface,decreases with the increased distances to channel erosion surface,which indicates the CD might be related to the coal seam from the upper unit of the J2y Formation or synsedimentary plant from the J2z Formation.Macerals of CD are composed of vitrinite(i.e.,V),inertinite(i.e.,I),and minerals,including that V is primary.Compared with the coals from the J2y Formation classed into vitrinertite-V(V+I>95%,V>I),CD is grouped into vitrite(V>95%).Although,CD and coal are similar in element composition,the former is of lower organic carbon,H,N,and higher S.The(C27+C29)/(C31+C33)ratios of n-alkanes biomarkers indicate that the percentage of woody plants accounting for vegetation composition of CD predominate over that of coal,which is also evidenced by the higher C/N ratios and oleanane contents of CD.The evidence is also supported by plant branch buried in sandstones.The distribution characteristics of CD and differences in vegetation types between CD and coal suggest that CD might be not from the coal seam from J2y.The tissue preservation index,gelification index,ground water level index,and vegetation index reflect that the paleoenvironment of CD is controlled by fluctuating water,which is also supported by the existences of round CD.Compared with peat,sedimentary paleoenvironment where CD deposits is of weaker reducibility,higher salinity by analyzing Pr/Ph ratios and gammacerane index.Distributions of n-alkanes carbon number of CD with the presence of unknown complex mixtures show that microbial activities exist in sand bodies.Differences in hydrodynamic intensity,redox condition,and microbial activity intensity between sedimentary paleoenvironment of CD and peat,show that CD is born in synsedimentary sandstone environment not in peat.Hence,it comprehensively draws conclusions that immature‘non-peatborn’CD is formed from the trunk,stem,branch,root fragments buried in sandstones,depositing in(micro)allochthonous positions by the influences of fluctuating water.The DOM from synsedimentary plant debris might play more roles in adsorption and complexation,and microorganisms may participate in uranium mineralization,which could provide certain guidance for uranium exploration and mining.展开更多
Large quantities of metal sulfides are widely distributed in uranium ores from the Middle Jurassic Zhiluo Formation of the Shuanglong uranium deposit,southern Ordos Basin,providing a convenient condition to study the ...Large quantities of metal sulfides are widely distributed in uranium ores from the Middle Jurassic Zhiluo Formation of the Shuanglong uranium deposit,southern Ordos Basin,providing a convenient condition to study the relationship between metal sulfides and uranium minerals.The morphology and composition of uranium minerals and metal sulfides are illustrated to study uranium mineralization and mechanisms of metallogenesis.Uranium minerals can be broadly categorized as pitchblende,coffinite and brannerite.Metal sulfides associated with uranium minerals are pyrite,sphalerite,chalcopyrite and galena.Some assemblages of various metal sulfides and uranium minerals indicate that they are coeval,but the order of formation is different.Based on mineralogical observations,paragenetic sequences for mineral assemblages are discussed.Alteration of Fe-Ti oxides forms Ti oxides,brannerite and pyrite.The formation of chalcopyrite was later than that of pyrite.Clausthalite(Pb Se)replaces sphalerite or shows isomorphism with galena.There are three genetic types of galena,of which typeⅠis related to tectonic thermal events and can interact with uranyl ions to form uranium oxides and Pb;.When sulfur activity is relatively high,Pb;can form new anhedral galena,that is,typeⅡ.TypeⅢof galena is related to the decay of uranium minerals.The genetic order of the main minerals was determined as follows:Fe-Ti oxides>Ti oxides/sphalerite/pyrite>clausthalite/galenaⅠ/chalcopyrite>galenaⅡ/uranium minerals>galenaⅢduring the diagenetic stage.Hydrogen sulfide(H;S)is a decisive factor in the interaction between metal sulfides and uranium.Metal ions can react with H;S,accompanied by precipitation and enrichment of uranium minerals.展开更多
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supported by the National Key Basic Research Program of China (No.2015CB453004)National Pre-research Project (No.3210402)
文摘Meso-Cenozoic intracontinental orogenic processes in the Tian Shan orogenic belt have significant effect on the sandstone-hosted uranium deposits in the intramontane basins and those adjacent to the orogen. The Sawafuqi uranium deposit, which is located in the South Tian Shan orogenic belt, is investigated to reveal the relationships between uranium mineralization and orogenies. Recent exploration results show that the Sawafuqi uranium deposit has tabular, stratiform, quasi-stratiform, and lens-like orebodies and various geological characteristics different from typical interlayer oxidation zone sandstone-hosted uranium deposits. Systematic studies of ore samples from the Sawafuqi uranium deposit using a variety of techniques, including thin section observation, a-track radiograph, electron microprobe and scanning electron microscope, suggest that uranium mineralization is closely related to pyrite and organic matter. Mineralization-related alterations in the host rocks are mainly silicification and argillation including kaolinite, illite (and illite-smectite mixed layer) and chlorite. Tree stages of mineralization were identified in the Sawafuqi uranium deposit: (i) uranium-bearing detritus and synsedimentary initial pre-enrichment; (ii) interlayer oxidization zone uranium mineralization; and (iii) vein-type uranium mineralization. The synsedimentary uranium pre-enrichment represents an early uranium enrichment in the Sawafuqi uranium deposit, and interlayer oxidation zone uranium mineralization formed the main orebodies, which are superimposed by the vein-type uranium mineralization. Combining the results of this study with previous studies on the Meso-Cenozoic orogenies of South Tian Shan, it is proposed that the synsedimentary uranium pre-enrichment of the Sawafuqi uranium deposit was caused by Triassic Tian Shan uplift, and the interlayer oxidation zone uranium mineralization occurred during the Eocence-Oligocene period, when tectonism was relatively quiet, whereas the vein-type uranium mineralization took place in relation to the strong orogeny of South Tian Shan since Miocene.
基金jointly supported by Key Factors Identification and Targets Delineation of Sandstone Type Uranium Deposits in the Southern Ordos Basin(CNNC Integrated R&D Project,Code:Geo LTD1601–3)Scientific Research in Production Project issued by the Bureau of Geology,CNNC(Code:201902-7)the Chinese Geological Survey project(Code:DD201908135)。
文摘In the southwestern margin of the Ordos Basin,uranium mineralization is primarily hosted by predominantly oxidative red clastic formations in the Lower Cretaceous.The main target layers for uranium exploration are the Madongshan and Liwaxia formations of the Liupanshan Group,followed by the Jingchuan Formation of the Zhidan Group.The host rocks(medium-fine feldspar quartz sandstone),which are bleached to a light grayish white color,contain a minor organic matter component and pyrite.Uranium mineralization changes from surficial infiltration or phreatic oxidation in the upper part to interlayer oxidation in the lower part.Uranium ore bodies are mostly lenticular or tabular in shape,locally shaped like crescent rolls.Individual ore bodies are typically small and shallow.Uranium predominantly manifests as pitchblende and coffinite.Coffinite is usually short and columnar or granular in habit,whereas pitchblende occurs as an irregular colloidal covering on the surface or in fissures of ferric oxide,silicate,clay or carbonate.Secondary uranium minerals are torbernite,uranophane,and uranopilite.Minerals associated with uranium are mainly pyrite,chalcopyrite and,to a minor extent,arsenopyrite and fluorite.The associated elements are Mo,V,Se,Co,Ni,and Mn,the host sandstone being high in Cu and Ba.Overall,the red clastic formations in the southwestern margin of the Ordos Basin are characterized by’five multiples but one low’which means multiple target layers,multiple stages of mineralization,multiple ore body shapes,multiple kinds of uranium minerals,multiple associated elements,but low organic matter.This implies an overall complex uranium metallogenic environment and mineralization process.It is recommended that future uranium exploration should take into consideration regional metallogenic conditions and mineralization features,with target layers in the wide-smooth synclinal slope being focused on.Most uranium deposits are small to medium in size,and the main type of uranium mineralization can vary by target layer.
文摘Black shales are marine sediments with argillaceous, silty and siliceous compositions and high contents of organic materials, disseminated pyrite and uranium. Uraniferous black shale has uranium content of more than 20 ppm.
基金supported by the National Key R&D Program of China (grant No. 2016YFC0600405)the Strategic Priority Research Program (B) of CAS (grant No. XDB18030202)+2 种基金the Natural Science Foundation of China (41603051)the Key Program of Science and Technology of Guizhou (grant No. [2018]1423)CSC program to Luo
文摘Objective Galuskin et al. (2011) firstly discovered that vorlanite (CaU^6+/4+)04 is a rare Ca-rich mineral with a fluorite-type structure, which is isostructural with uraninite (U^4+O2). Previous studies of the Xianshi granite-related uranium deposit reported that uraninite and pyrite are the major ore minerals whereas galena, clausthalite (PbSe), and pyrite are minor phases in the ores. A more detailed petrographic and geochronological study of the uranium minerals from the Xianshi deposit showed that there are three distinct types of uraninite-bearing assemblages which formed at three mineralization episodes (Fig. la; Luo et al., 2015).
文摘The Guidong granitic complex is constituted by Luxi pluton, Xiazhuang pluton, Maofeng pluton, Sundong pluton, Aizi pluton and Siqian pluton, which intruded in Indosinian and early Yanshanian Periods. These plutons varies from each other not only in major element content, aluminium saturation index, but also in ∑REE, δEu, and LREE/HREE, (La/Yb)N, (La/Sm) N and (Gd/Yb) N ratios. Uranium mineralization is mainly hosted by strong peraluminous granites, which has undergone intense fluid-rock interaction, and their REE compositions are characterised by M-type tetrad effects and lower ∑REE, δEu value, LREE/HREE, (La/Yb) N, (La/Sm) N and (Gd/Yb) N ratios.
基金the China Nuclear Industry Geological Bureau Project (Grant No. 201637,201638)
文摘The Sanjiang area is an important granite distribution area in China,except for South China,in which granites is complex and complete.Based on fully collecting date about it,this paper explores the significance of uranium
文摘The present work deals with the detailed geology,mineralogy,geochemistry,and spectrometric prospection of the felsic volcanic rocks at the Eastern Desert,Egypt of the Arabian-Nubian Shield.Felsic volcanic rocks are an essential source for rare earth elements(REEs)and uranium occurrences in this area.They are compositionally uniform with tholeiitic to calc-alkaline affinities,peraluminous and belong to the series of rhyolite with high-K melt.They exhibit more enrichment in high field strength elements(HFSE,e.g.Zr,Ta,Nd,Th,and U)and large-ion lithophile elements(LILE,e.g.Pb and Rb)compared to the country rocks of the studied area,with REE ranging from 188.20 to 442.70 ppm and strong depletion in Ti,Sr,P with deep negative Eu oddities.The felsic volcanic rocks were mostly generated from the partial melting of quartz-amphibolite facies accreted during the Neoproterozoic.Positive oddities of Zr-U-Th for the felsic volcanic rocks determine the involvement of crustal materials.Felsic volcanic rocks are found in A-type suites of magma and represent highly fractionated rocks derived from rhyolitic magma,with insignificant interaction with continental crust in the low-pressure environment and during fractional crystallization.Felsic volcanic rocks have higher values of radioactivity in which eU range from 0.5 to 121 ppm and eTh from 1.0 to 415.10 ppm.The high values of eU and eTh can be ascribed to the mineralization of uranium and the presence of accessory minerals of radiogenic nature such as uranophane,uranothorite,zircon,and monazite.Uranophane is considered as the mineral with most enriched uranium contents in the studied felsic volcanic rocks in which(UO2=87.30 wt%).Also,they are enriched with REE-bearing accessory minerals comprising allanite,titanite,and apatite.The geological investigations of the felsic volcanic rocks in the studied areas are inappropriate to clear the feasible economic potentialities of rare earth elements and U occurrences;itemized and invaluable explorational work is as yet needed.Whilst,the environmental impact of mineralization,owing to U and Th and their radiogenic daughter products,is observed and must be elaborated minutely.
基金Project supported bythe National Key Science Foundation of China (40132010)the National Science Foundation of China(40642010 ,40772068)
文摘Guidong granitic complex is constituted by Luxi intrusion, Xiazhuang intrusion, Maofeng intrusion, Sundong intrusion, Aizi intrusion and Siqian intrusion, which emplaced in Indosinian and early Yanshanian Periods. These intrusions varied from each other not only in major element content, aluminium saturation index, but also in values of ∑REE, δEu, and LREE/HREE, (La/Yb)N, (La/Sm)N and (Gd/Yb)N. The Maofeng intrusion, which has the closest relationship with uranium mineralization, belongs to strong peraluminous granites. Having undergone much intense fluid-rock interaction, it is characterized by typical M-type tetrad effects and lowest values of ∑REE, δEu, LREE/HREE, (La/Yb)N, (La/Sm)N and (Gd/Yb)N ratios than other studied intrusions.
基金supported by the China Nuclear Industry Geological Bureau Foundation (No.201637 and 201638)
文摘1 Introduction The Sanjiang metallogenic belt is one of the important nonferrous metal metallogenic belts in China,the potential resources of copper,lead,zinc,silver,gold and tin are huge(Zhengqian et al.,1993).In the west of Yunnan province has a lot of Yanshanian granite,according to 1:20 million test data,development of granite belt rich in radioactive minerals in the west of Yunnan
文摘Uranium is a typical lithophile element, having outstanding geo-chemical characteristics of association whith high SiO<sub>2</sub>, peraluminousand marginally peralkalic rocks. In evolution process of all geologicalhistory, uranium gathers without interruption in upper crust. Urani-um mineralization is closely realted with evolution characteristics of thecontinent crust.1. It was not until the continent crust evolved to certain maturedegree that uranium began metallization. The oldest uranium depositon the earth occurred in the Delanshiwa (Kapuwaer) district,
文摘The purpose of this study is to determine the distribution and geochemical features of uranium mineralization in the Ragillar region in the Manisa-Koprübasi in western Turkey. Sixteen whole rock samples were collected from sites showing the highest levels of radioactivity (7600 cps) as measured by a gamma spectrometer in the dolomitic limestones. SEM-EDS (Scanning Electron Microscopy-Energy Dispersive Spectrometry), XRF (X-Ray Fluorescence), an ICP-OES (Inductively Coupled Plasma Optic Emission Spectrometer), and a Leco carbon-sulfur analyzer were used to determine the mineralogical and chemical characteristics of the whole rock samples. The mineralogical features showed that uranium mineralization is associated with fluorapatite-rich rocks formed within calcite matrix fractures;cracks systems;and limestone, claystone, marl and silicified breccia zones in the lacustrine sediments that are observed around the Kale crest dolomitic limestones in the Demirci basin. The geochemical data for these samples show a strong positive correlation between uranium and P<sub>2</sub>O<sub>5</sub> concentrations. The geochemical data also indicate that uranium is deposited in the oxidation zone by dissolving the primary minerals (banded gneisses from the Menderes Massif, and dacitic and andesitic tuff) and moving the metal-rich hydrothermal fluids as phosphorus compounds, before passing through fractures, cracks, and permeable sandstone units, or along carbonate and clay layers.
基金supported by projects from Chinese Geological Survery Programme (12120115035601)
文摘1 Introduction The uranium deposits related with Indosinian and Yanshanian granite have provided the abundant resource of uranium during the past several decades in China.The deposits are mainly distributing in the Guidong granite
基金supported by the National Natural Science Foundation of China (Nos. U2067202, 41772068, 42172098)the Natural Science Foundation of Jiangxi Province (No. 20202BAB213017)+1 种基金the Joint Innovation Fund of China Uranium Industry Co., LTD and East China University of Technology (No. NRE2021-02)Open Foundation of State Key Laboratory of Nuclear Resources and Environment (No. JELRGBDT202007)。
文摘The sandstone-hosted uranium deposits in the SW Songliao Basin differ from typical sandstone-hosted uranium deposits in terms of the geological features of the ore-deposits,including the geometry of the orebodies,mineral assemblage and petrography.Detailed drill core and microscopic observations,scanning electron microscopy(SEM),electron microprobe analysis(EMPA),heavy mineral concentrates,and fluid inclusion studies of the Upper Cretaceous Yaojia Formation,i.e.,the uranium-bearing layer,were integrated to investigate the roles of hydrothermal fluids in the formation of these uranium deposits.We found that the kaolinite alteration is developed in the mineralized zones,but it is less common in the peripheral areas.The fluid inclusions are hydrothermal fluids with a medium-low temperature(67 to 179 ℃) and a high salinity(5.9 wt.% to 20.1 wt.%).According to the analyses,three kinds of hydrothermal fluids,i.e.,the acid fluid,the groundwater heated by the mafic magma,and the alkaline fluid rich in Ca^(2+) and CO_(3)^(2-),were identified.The fluids might have low U content,but they have participated in the formation of the uranium deposits successively.Kaolinite formed by the acid-hydrothermal fluid absorbed large amounts of uranium.Subsequently,the thermal energy from the hydrothermal fluids changed the intrastratal redox environment and increased the solubility of the uranium minerals in the fluid.The alkaline-hydrothermal fluid rich in Ca^(2+) and C0_(3)^(2-) facilitated the formation of stable Ca-U(Ⅵ)-CO_(3) complex,which led to the enrichment of soluble uranium in solution,and final precipitation as pitchblende,brannerite and Ti-bearing uranium minerals in the uranium ores.
基金JPS acknowledges Delhi University for financial support towards this work in the form of R&D Project Grant(No.DRCH/R&D/2012-2013/4155).
文摘Paleoproterozoic Bijawars of the Sonrai basin consists of(a) Sonrai(mostly carbonate carbonaceous shale and phosphatic breccia) and(b) Solda Formations(commonly chloritic and ferruginous shale) with well-developed clay-organo-rich facies,often marked with hydrothermal activities.Previous studies revealed abundance order of kaolinite> chlorite> illite> smectite;and kaolinite> illite> chlorite in clay(0.2-2.0 μm) fractions separated from the Sonrai and Solda Formations,respectively.To understand atomic substitutions and trace elemental concentrations,clay minerals were analyzed by fusion ICPMS and SEM-EDS.PAAS normalized data plots show U,Th,Rb,Ba,Pb Sr,and large-ion lithophiles enrichment,whereas,Bandai sandstone and Rohini carbonate clays show HREE enrichment with asymmetrical patterns,similar to those reported from the well-established McArthur River,Cigar Lake,and Sue UTUD of Canada.For Rohni carbonate,chondrite-normalized REE data plots revealed M shape REE patterns,ascribed to Gd-Tb-Dy-Ho tetrad effect and anomalous Y,Zr,and Hf concentrations.Owing to HREE incorporation in the clay inter-layers,linear and flattened REE trends were noticed.Flat REE patterns associated with the highly altered chlorite and illite represent negative Eu anomaly related to the dilational nature of the uraninite structure and is suggestive of anoxic conditions.
基金supported by the Key Program of National Natural Science Foundation of China (No. 40634020)the National 973 Program of China (No. 2014CB440906)
文摘Miaoershan(MES) uranium ore field is one of the most important uranium sources in China, hosts the largest Chanziping carbonaceous-siliceous-pelitic rock type uranium deposit in South China together with many other granite-hosted uranium deposits. The Shazijiang(SZJ) uranium deposit is one of the representative granite-hosted uranium deposits in the MES uranium ore field, situated in the Ziyuan, Guangxi Province, South China. Uranium mineralization in the SZJ deposit mainly occurs as uraninite with quartz and calcite veins that is spatially associated with mafic dykes in the region. The hydrothermal alteration includes silicification, carbonation and hematitization. New uraninite chemical U-Pb geochronology and petrographic evidences provide the timing constraints and new insights into the formation of the SZJ uranium deposit. The results show that the first stage of uranium mineralization formed at 97.5±4.0 Ma, whereas another stage of uranium mineralization occurred at 70.2±1.6 Ma. Two stages of uranium mineralization are fairly consistent with two episodic crustal extensions that occurred at -100 and -70 Ma throughout South China. This study indicates that there are two uranium mineralization events in SZJ uranium ore field controlled by mafic dyke, supporting that mafic dykes play an important topochemical role in uranium concentration and/or mobilization. Therefore, geochemical U-Pb age firstly reinforces that ore-forming age of the SZJ uranium deposit mainly yields at 97.5±4.0 and 70.2±1.6 Ma. Additionally, geochemical age method is particularly useful for interest samples which record information on multi-stage uranium mineralizations in South China.
基金supported by the fellowship of China postdoctoral science foundation (No.2021M703001)the National Natural Science Foundation of China (No.42172128)+4 种基金the fundamental research funds for the Central Universities from China University of Geosciences (Wuhan)(No.G1323521101)the National Key Research and Development Program of China (No.2018YFC0604200)the International Geoscience Programme,IGCP 675:Supergene Fluid Ore-forming Process of Sandstone-type Uranium Depositsthe open fund of Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences),the Ministry of Education(No.TPR-2019-08)the Fund of Outstanding Talents in Discipline of China University of Geosciences (Wuhan)(No.102-162301192664)
文摘Carbonaceous debris(CD),common dispersed organic matter(i.e.,DOM),is widely disseminated in sandstones from uranium-bearing strata from the Dongsheng uranium ore field of the northern Ordos Basin.Compositions of maceral,element and biomarkers of CD were investigated through a series of methods with optical microscope,elemental analyzer and gas chromatography-mass spectrometry analyses(GC-MS)to study origin of CD.The results show that CD,centrally distributed nearby channel erosion surface,decreases with the increased distances to channel erosion surface,which indicates the CD might be related to the coal seam from the upper unit of the J2y Formation or synsedimentary plant from the J2z Formation.Macerals of CD are composed of vitrinite(i.e.,V),inertinite(i.e.,I),and minerals,including that V is primary.Compared with the coals from the J2y Formation classed into vitrinertite-V(V+I>95%,V>I),CD is grouped into vitrite(V>95%).Although,CD and coal are similar in element composition,the former is of lower organic carbon,H,N,and higher S.The(C27+C29)/(C31+C33)ratios of n-alkanes biomarkers indicate that the percentage of woody plants accounting for vegetation composition of CD predominate over that of coal,which is also evidenced by the higher C/N ratios and oleanane contents of CD.The evidence is also supported by plant branch buried in sandstones.The distribution characteristics of CD and differences in vegetation types between CD and coal suggest that CD might be not from the coal seam from J2y.The tissue preservation index,gelification index,ground water level index,and vegetation index reflect that the paleoenvironment of CD is controlled by fluctuating water,which is also supported by the existences of round CD.Compared with peat,sedimentary paleoenvironment where CD deposits is of weaker reducibility,higher salinity by analyzing Pr/Ph ratios and gammacerane index.Distributions of n-alkanes carbon number of CD with the presence of unknown complex mixtures show that microbial activities exist in sand bodies.Differences in hydrodynamic intensity,redox condition,and microbial activity intensity between sedimentary paleoenvironment of CD and peat,show that CD is born in synsedimentary sandstone environment not in peat.Hence,it comprehensively draws conclusions that immature‘non-peatborn’CD is formed from the trunk,stem,branch,root fragments buried in sandstones,depositing in(micro)allochthonous positions by the influences of fluctuating water.The DOM from synsedimentary plant debris might play more roles in adsorption and complexation,and microorganisms may participate in uranium mineralization,which could provide certain guidance for uranium exploration and mining.
基金supported by the National Key Research and Development Program of China (No.2018YFC0604202)the National Science Fund Project (No.42172128)the International Geoscience Programme (No.IGCP-675)
文摘Large quantities of metal sulfides are widely distributed in uranium ores from the Middle Jurassic Zhiluo Formation of the Shuanglong uranium deposit,southern Ordos Basin,providing a convenient condition to study the relationship between metal sulfides and uranium minerals.The morphology and composition of uranium minerals and metal sulfides are illustrated to study uranium mineralization and mechanisms of metallogenesis.Uranium minerals can be broadly categorized as pitchblende,coffinite and brannerite.Metal sulfides associated with uranium minerals are pyrite,sphalerite,chalcopyrite and galena.Some assemblages of various metal sulfides and uranium minerals indicate that they are coeval,but the order of formation is different.Based on mineralogical observations,paragenetic sequences for mineral assemblages are discussed.Alteration of Fe-Ti oxides forms Ti oxides,brannerite and pyrite.The formation of chalcopyrite was later than that of pyrite.Clausthalite(Pb Se)replaces sphalerite or shows isomorphism with galena.There are three genetic types of galena,of which typeⅠis related to tectonic thermal events and can interact with uranyl ions to form uranium oxides and Pb;.When sulfur activity is relatively high,Pb;can form new anhedral galena,that is,typeⅡ.TypeⅢof galena is related to the decay of uranium minerals.The genetic order of the main minerals was determined as follows:Fe-Ti oxides>Ti oxides/sphalerite/pyrite>clausthalite/galenaⅠ/chalcopyrite>galenaⅡ/uranium minerals>galenaⅢduring the diagenetic stage.Hydrogen sulfide(H;S)is a decisive factor in the interaction between metal sulfides and uranium.Metal ions can react with H;S,accompanied by precipitation and enrichment of uranium minerals.