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1.
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, α-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.  相似文献   

2.
The Bamianshan fluorite deposit is a super-large one recently discovered in Zhejiang Province of China. This paper presents an analysis of its geological background, orebody and ore characteristics, petrochemical characteristics of host rocks, rare earth elements (REE) of rocks and ores, fluid inclusions in fluorite and Sm-Nd isotopic features in an effort to study its sedimentary mineralization. The result shows that the super-large Bamianshan fluorite deposit is of hydrothermal sedimentation genesis, deformed by the later hydrothermal fluid. Integrated with host rocks and orebody characteristics, it is inferred that the deposit originates from the Cambrian sedimentary rocks. And the later magmatic activities deformed some orebodies in different degrees, forming steeply dipping vein orebodies in the tectonic belts regionally.  相似文献   

3.
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.  相似文献   

4.
Presented in this paper are some primary data on the well temperature, stratigraphical level and thickness of uranium mineralization in a certain uranium, ore deposit.Taking these data as the parameters.for the temperatures, pressures and geochemical conditions of uranium mineralization under ideal geological conditions, which constitute a finite variable series, in conjunction with the catastrophe theory developed by Rene Thorn (1968), we have proposed a swallow-tail model fitting to uranium mineralization.This model provide insights into the mechanism of uranium mineralization.The results of our study show that the uranium mineralizing process is a discontinuous or catastrophic event. Temperatures and pressures are considered important thermodynamic trap conditions which control the distribution pattern of uranium mineralization, and the principle of correspondence between the temperature and pressure conditions for uranium mineralization has been also derived, Geological bodies of minerogenetic importance serve as favourable geochemical media for capturing ore-forming materials. Uranium mineralization of industrial importance depends on a delicate coupling between temperature, prassure, and geechemical condition. The spurs of uranium mineralization in the model constitute the surface K, referred to as the surface of mineralizing enrichment on which minerogenetic dominance is expected.The model provides quantiatitively clnes to the process of uranium mineralization,i.e.,a process from quantitative change to qualitative change.  相似文献   

5.
试论天然有机质及其与铀矿化的关系   总被引：1，自引：0，他引：1  
王剑锋 《地球化学》1983,(3):294-302
Uranium is so intimately associated with carbonaceous matter in marine black shales and some sandstone-type uranium deposits that it is said to be “fixed” by organic substances. But different kinds sf organic matter are not of equal importance in the geochemistry of uranium. The nature and origin of organic substances in uranium deposits and the role that they plays in transporting and concentrating uranium are different from place to place. The reason why uranium is associated with certain types of organic matter (for example humus or bitumen) is described in this paper from geochemical viewpoint.  相似文献   

6.
The uranium deposit studied in this paper occurs in a Precambrian (Xuefengian)granite batholith. The emplacement age of the granite is 760 m.y. The average content of uranium in the granite is 7 ppm, but the yield of leachsd U is higher With an average of about 33.8%. The granitic rocks, contain; Some uraninite. Uranium mineralization mainly takes the form of siliceous veins With an age of 47 m.y. K-feldspar. present in the granite and pyrite associated with pitchblende were massspectrometrically analyzed for Pb isotopic compositious, characterized by anomalous lead. A reasonably linear array can be seen on the ^207Pb/^206Pb--^205Pb/^204Pb plot, implying a genetic connection between the rock and the ore, and a derivation of rock-forming materials from. a uranium-rich source. According to the continuous-growth model for anomalous lead, evolution, two isochrons give the. ages-of about 764 m.y. and 708 m.y.for ore-forming materials, close to the emplacement age of .the granite batholith. This indicates that the ore-forming materials came from the granite batholith. Eight granite samples collected from the mining .area were analyzed, but no uranium-lead ages could be worked out because of the pregressive destruction of the closed U-Pb isotopic system since granite emplacement, which resulted in the loss of uranium(78%). It can be imagined that in the period of continental weathering the surface water would infiltrate downwards, leaching out large amounts of uranium from the granitic rocks to form infiltration solution. The solution was heated at great depth and then found its way upwards, on which it dissolved constantly U from the rocks to form the uranium deposit.  相似文献   

7.
The Sanshenjiang gold deposit in southeastern Guizhou Province, China, is hosted by the Neoproterozoic metasedimentary rocks which experienced low-grade greenschist facies metamorphism. Gold mineralization occurs mainly in the ribbon chiltern slate of the first member of the Longli Formation and is controlled by both strata and faults. Ore bodies are characterized by abundant quartz-arsenopyrite-gold-pyrite-bedding veins, veinlets and small lenses within the shear zone. In this study, trace element and REE geochemistry was analyzed to constrain the origin and genesis of this deposit. The trace element signatures of wall rocks and veins display a basically similar tendency in the spider diagram, showing the genetic relationship. The values of Co/Ni, Y/Ho, Hf/Sm, Nb/La and Th/La reflect that the hydrothermal fluids of this deposit were derived from the mixture of multiple sources with marked enrichment of Cl and moderate to high temperature. There is a broad similarity in the chondrite-normalized patterns and REE fractionation between wall rocks and ore bodies, possibly reflecting their similar origin. Based on the difference in δCe and δEu, quartz veins and lenses can be subdivided into weakly negative Ce-anomalies (δCe=0.81 to 1.06) with slight Eu anomalies (δEu=0.81 to 1.06) type and the significant positive Ce-anomalies (δCe=1.13 to 1.97) with moderate negative Eu-anomalies type, probably suggesting physical-chemical changes in the evolution process of ore-forming fluids from the early to late stage. It can be concluded that the ore-forming process may have experienced three stages: formation of the original ore source bed, regional metamorphism and gold mineralization, on the basis of trace element and REE analysis and field observation.  相似文献   

8.
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.  相似文献   

9.
正Objective The Shangxu gold deposit is located in the south of the middle Bangong-Nujiang suture zone in northern Tibet.The origin of this deposit as an orogenic gold deposit is debatable.The study of the Shangxu deposit has a profound implication on gold exploration in the BangongNujiang metallogenic belt and can also improve our understanding of gold mineralization in northern Tibet.  相似文献   

10.
The Ordos Basin is well-known for the coexistence of oil, natural gas, coal and uranium. However, there has been little research to discuss the genetic relationship between them. In this paper, a case study of the Zaohuohao area in Dongsheng, Inner Mongolia, China, is conducted to investigate the genetic relationship between the natural gas and the uranium accumulation. Fluid inclusion data from the uranium-bearing sandstone samples indicate that the fluid inclusions formed in a gas-water transition zone. Using the homogeneous temperatures of aqueous inclusions coeval with hydrocarbon-bearing inclusions, combined with the buried history and paleo-temperature data, the gas-water transition zone reached the area at about 110 Ma. On the basis of this, the contents of Uranium （U） and Total Organic Carbon （TOC） of the samples were analyzed, and there was no obvious relation between them. With regard to the available data from both publications and this study, it is found that the U mineralization has a spatiotemporal accordance with the gas-water dispersal zone. Thus, it is believed that the natural gas in the gas-water zone is an effective reducer to the U-bearing ground water abundant in oxygen, which is the main factor to U accumulation. This result can be used as the reference to the U mines predicting and prospecting.  相似文献   

11.
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.  相似文献   

12.
The Shimen realgar deposit is characterized by the pipi-shaped orebody and the development of silica sinter and hydrothermal explosive breccia which are typical of hot spring activity.Very similar trace-element associations are noticed between the silica cap and the breccia and modern hot spring waters in the area.The chemistr of ore-forming solutions is also well comparable with that of modern hot spring.,The spring system that gave rise to the mineralization was charged by ground waters heated through thermal conducting systems in the deep crust and,to a lesser extent,by geothermal gradient.ΔD,δ^18O,δ^13CCH4andδ^13CH4andδ^13CCO2values and ^40Ar/^36Ar and 3^He/^4He ratios indicate that the spring system is of crustal derivation.The ore-forming metals were supplied by surrounding strata,particularly those underlying the ore deposits.The mechanim of ore deposition is thought to be hydrothermal explosion and accompanying boiling and abrupt changes in pH and Eh.Located in northwest Hunan,the Shimen realgar deposit is the leading arsenic producer in the country,However,regardless of its long mining history,the genesis of this deposit has long been a puzzle.It was considered to be postmagmatic epithermal in the leading arsenic producer in the puzzle.It Was considered to be postmagmatic epithermal in origin,but this is trongly challenged by filling(metasomatism)in karst environment proposed later by Zhou Zhiquan(1986)also encounters a number of difficulties.For example,why can the pipi-shaped orebody vertically extend up to several hundreds meters without any compatible development in the lateral dimension? A hot spring genesis is suggested in the present paper based on geological observations and laboratory studies conducted by the authors in recent years.  相似文献   

13.
Sedimentary rock-hosted disseminated gold (SRHDG) deposits in the Youjiang-Nanpanjiang Basin,southwestem Guizhou Province are commonly hosted by the same fold crests that commonly contain a remarkable amount of organic material. The total organic carbon (TOC) contents of the ores and host rocks are usually less than 1%. The reflectance of vitrinite and pyrobitumen in the ores and the host rocks ranges from 1.5% to 4.5%, often in the range of 2% to 3%. In the Lannigou deposit, the reflectance of vitrinite and pyrobitumen in the ores is usually somewhat higher than those within the host rocks, indicating a hydrothermal impact on the organic matter in the altered host rocks. On the contrary, the estimated maximum paleotemperatures of the Getang and Zimudang deposits are higher than the homogenization temperatures of the fluid inclusions in the ores, signifying that the organic matter maturation predated Au mineralization. No correlation between the organic matter contents and Au concentrations were recognized in the ores.However, the most striking observation is that there is a positive correlation between the $2 (a parameter of Rock-Eval analysis), Au and As contents of the ores in the Lannigou deposit. Organic matter maturation and migration is apparent from the TOC vs. HCI diagram. Furthermore, group analysis of the dichloromethane extractable organic component of the ores and host rocks shows that the maturation degree of the organic matter in the ores is slightly higher than that of the host rocks in the Lannigou gold deposit. However, the compositions of their alkanes, steranes and terpenes, which serve as biomarkers, are quite similar; this suggests that the organic matter found in the ores and host rocks has a common marine source. Organic matter probably contributed to the preconcentration of Au in the host rocks. Hydrocarbons in the system,on the other hand, clearly contributed to the emplacement of the gold mineralization through thermal sulfate reduction.Organic matter in the solution might have increased the potential of the hydrothermal solution to transport Au.  相似文献   

14.
The Xiaotongjiapuzi gold deposit occurs in a Palaeoproterozoic rift accretionary terrane in eastern Liaoning and is hosted by a carbonate formation of the Dashiqiao Formation, Liaohe Group. The metamorphic grade of the host rock is low amphibolite-high greenschist facies. Gold, which is mainly invisible, is distributed in pyrite and arsenopyrite. The grains of Au-bearing sulphide minerals are fine, ranging from 0.0 n to 1 mm. The wall-rock alterations are characterized by low-temperature silification, hydro-sericitization, sericitization and carbonatization. The homogenization temperatures of the fluid inclusions in quartz closely associated with gold mineralization range from 140 to 240° C. The metallogenic age represented by the Ar-Ar isotopic age of sericite is 167 Ma. Comparisons and studies show that the Xiaotongjiapuzi gold deposit can be classified as the submicron-sized disseminated deposit (analogous to the Carlin-type) hosted in metamorphic rocks.  相似文献   

15.
The Baoshan Cu-Pb-Zn polymetallic deposit is lied in the central Nanling mineralization zone,and belongs to the junction area of the Chenzhou-Linwu fault zone and the Leiyang-Linwu fault zone.It is a significant part of Nanling polymetallic deposit belt.The outcropping stratas consist of upper Devonian Shetianqiao,Xikuangshan Formation,Lower Carboniferous Menggong'ao,Shidengzi,Ceshui,and Zimenqiao Formation.Igneous rocks in the Baoshan ore area mainly comprise granodiorite porphyry.Furthermore,the radio ...  相似文献   

16.
The ductile shear zone-type gold deposit is a kind that both the ore-forming mechanism and ore-controlling factors are closely related to the ductile shear zone and its evolution. Ductile shear zone develops in Beishan area, Gansu of Northwest China, and develops especially well in the south belt. The controls of the ductile shear zone on gold deposits are as follows. (1) The regional distribution of gold deposits (and gold spots) is controlled by the ductile shear zone. (2) The ductile-brittle shear zone is formed in the evolution process of ductile shear zone and both are only ore-bearing structures and con- trol the shape, attitude, scale, and distribution of mineralization zones and ore-bodies. (3) Com- presso-shear ductile deformation results in that the main kind of gold mineralization is altered mylonite type and the main alteralization is metasomatic. (4) Ore-bearing fracture systems are mainly P-type ones, some D-type and R-type ones, but only individual R’-type and T-type ones. (5) Dynamic differen- tiation and dynamic metamorphic hydrothermal solution resulting from ductile deformation is one of the sources of ore-forming fluid of gold mineralization, and this is identical with that ore-forming ma- terials are mainly from metamorphic rocks, and ore-forming fluid is mainly composed of metamorphic water, and with the fluid inclusion and geo-chemical characteristics of the deposit. (6) There is a nega- tive correlation between the gold abundance and susceptibility anisotropy (P) of the altered mylonite samples from the deposit, which shows that the gold mineralization is slightly later than the structural deformation. All above further expound the ore-forming model of the ductile shear zone type of gold deposits.  相似文献   

17.
福建钟腾斑岩铜（钼）矿床根带的蚀变矿化特征   总被引：1，自引：0，他引：1  
  相似文献   

18.
The Kengdenongshe deposit is a newly discovered large Au-Ag-Pb-Zn polymetallic deposit in the eastern Kunlun metallogenic belt, and the genetic relationship between Pb-Zn-rich ore bodies and Au-rich ore bodies in this deposit is controversial. Therefore, comparative studies of mineralization, alteration, and fluid inclusions in the two types of ore bodies were carried out with the statistical analysis of the correlation among ore-forming elements of Au, Ag, Pb and Zn. The results show that, from north to south, the mineralization changes gradually from Pb-Zn-rich to Au-rich with the wall-rock alteration from silicification-epidotization to baritization-marbleization-silicification. In addition, the structures of Pb-Zn-rich ores indicate a hydrothermal sedimentary origin with the late hydrothermal superposition, while those of Au-rich ores show features of hydrothermal origin. Besides, based on the study of fluid inclusions in this mining area, the ore-forming fluid of Pb-Zn-rich ores is low temperature (focus on 150-170°C) and low-medium salinity (1.74%-10.24% NaCleqv), while that of Au-rich ores displays low-medium temperature (manily 130-250°C) with low-medium salinity (0.35%-10.24% NaCleqv). Pb-Zn and Au-Ag show positive correlation (correlation coefficient r>0.25), but Au is poorly correlated with Pb and Zn (correlation coefficient r<0.15). However, to due to the late stage hydrothermal superimposition, Au is rather well correlated with Pb in high grade ores. In summary, there may exist two epochs of mineralization in the Kengdenongshe polymetallic deposit. The early one is Pb-Zn mineralization stage with characteristics of hydrothermal sedimentary origin, and the ore-forming fluid may be derived from the mixture of magmatic water and seawater. While the later one is Au mineralization stage, having characteristics of hydrothermal origin with subsequent hydrothermal superimpositions, and the ore-forming fluid is mainly derived from magmatic water that mixed with meteoric water. © 2018, Science Press. All right reserved.  相似文献   

19.
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.  相似文献   

20.
The Dongsheng sandstone-type uranium deposit is one of the large-sized sandstone-type uranium deposits discovered in the northern part of the Ordos Basin of China in recent years. Geochemical characteristics of the Dongsheng uranium deposit are significantly different from those of the typical interlayered oxidized sandstone-type uranium ore deposits in the region of Middle Asia. Fluid inclusion studies of the uranium deposit showed that the uranium ore-forming temperatures are within the range of 150–160℃. Their 3He/4He ratios are within the range of 0.02–1.00 R/Ra, about 5–40 times those of the crust. Their 40Ar/36Ar ratios vary from 584 to 1243, much higher than the values of atmospheric argon. The δ18OH2O and δD values of fluid inclusions from the uranium deposit are -3.0‰– -8.75‰ and -55.8‰– -71.3‰, respectively, reflecting the characteristics of mixed fluid of meteoric water and magmatic water. The δ18OH2O and δD values of kaolinite layer at the bottom of the uranium ore deposit are 6.1‰ and -77‰, respectively, showing the characteristics of magmatic water. The δ13CV-PDB and δ18OH2O values of calcite veins in uranium ores are -8.0‰ and 5.76‰, respectively, showing the characteristics of mantle source. Geochemical characteristics of fluid inclusions indicated that the ore-formation fluid for the Dongsheng uranium deposit was a mixed fluid of meteoric water and deep-source fluid from the crust. It was proposed that the Jurassic-Cretaceous U-rich metamorphic rocks and granites widespread in the northern uplift area of the Ordos Basin had been weathered and denudated and the ore-forming elements, mainly uranium, were transported by meteoric waters to the Dongsheng region, where uranium ores were formed. Tectonothermal events and magmatic activities in the Ordos Basin during the Mesozoic made fluids in the deep interior and oil/gas at shallow levels upwarp along the fault zone and activated fractures, filling into U-bearing clastic sandstones, thus providing necessary energy for the formation of uranium ores.  相似文献   

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