Abstract:In this paper, through the analyses of sedimentary rock assemblages, structures and logging traces of twelve wells respectively from the north, east and south margins of the Junggar Basin, have been studied for classification, correlation and sequence stratigraphic framework of Jurassic Uraniumbearing Series. All researches indicate that the sequence stratigraphy have big differences in different positions. The sequence from Sangonghe Formation to Qigu Formation on the north margin of the Junggar Basin is three, including seven system tracts. The sequence from Badaowan Formation to Qigu Formation on the east margin of Junggar Basin is five, including twelve system tracts. And the sequence from Xishanyao Formation to Qigu Formation on the south margin of Junggar Basin is three, including seven system tracts. During the Badaowan and Qigu period, it had at least two lake formation. The whole experiences the process of retrogradation, progradation and then retrogradation again. Alluvial sand bodies of braided stream and delta fan are the main uranium reservoir. And the delta fan on the north margin also indicates uplifting events. The Jurassic in the study area mainly developed five kainds of deposition types, which are braided, braided viver deltas, lakes, lake deltas and delta fan, ten kinds of sedimentary subfacies types. The subfacies types of uraniumbearing series are braided channel, fan and lake delta plain. There were two parallel unconformities respectively up and under the coal bearing formation of Xishanyao period. The clay ground under the unconformaities have formed stratigraphic trap, the sand bodies on the two sides of the unconformaities are the most favorable exploration targets in the Junggar Basin. All the above results not only provide new constraints on increasing the precision of classification and correlation of Jurassic Uraniumbearing Series in the Junggar Basin, but also have great significance on the exploration of sand type uranium.

Abstract:MesoCenozoic intracontinental orogenic process in the Tianshan orogenic belt has a significant controlling effect on the sandstone type uranium deposits in the intramontane and bilateral basin. This study carried out the systematic analysis of the samples from Sawafuqi uranium deposit using thin section observation, α track radioactive graph technique, electron probe and scanning electron microscope. The results show that the Sawafuqi uranium deposit occur as tabular, lamellar, quasi lamellar, lenslike ore bodies, with high ore grade in the South Tianshan orogenic belt, which is different from typical interlayer oxidation zone sandstonetype uranium deposit. The three mineralization types have been identified in the deposit: preliminary sedimentary mineralization, interlayer oxidation zonetype uranium mineralization, and epithermal veintype uranium mineralization. Three uranium mineralization presents obvious formation sequence, with the preliminary sedimentary uranium mineralization forming early uranium enrichment, interlayer oxidation zone uranium mineralization forming the main orebodies, followed by late superimposed enrichment by the latestage epithermal uranium mineralization. Combined with previous study of the MesoCenozoic orogeny in South Tianshan, it can be concluded that preliminary sedimentary type uranium mineralization of the Sawafuqi uranium deposit was caused by Triassic Tianshan uplifting; interlayer oxidation zonetype uranium mineralization occurred in a relatively stable tectonic setting in the EocenceOligocene period; and since the Miocene, orogenic hydrothermal solution derived from strong folding and orogeny of South Tianshan reformed the former uranium ore bodies, thus resulting in the superimposed enrichment of epithermal veintype uranium mineralization.

Abstract:Honghaigou deposit is one of the large uranium deposits discovered in the southern margin of the Yili basin in recent years, which hosts not only sandstonetype Ubearing orebodies but also coaltype uranium orebodies. In this paper, we firstly studied the geological characteristics of the Honghaigou deposit, analyzed main controlling factors and then discussed the constraint of structure and sedimentation on the oxidation zone development and uranium spatial orientation. The study suggests that secondary uplifting along structural slope provides driving force for recharge and migration of fluid, with change sites of the slope being favorable for unloading of oreforming minerals. The main sandbody is channel for migration of oxidation fluid, which restricts the direction of the migration of the oxidation fluid. The change of sandbody resulted in pitching out of oxidation zone and spatial distribution of uranium orebodies. The diversity of the oxidized fluid zonation resulted in the diversity of orebody types and morphology, with the planes of interlayer oxidation zone controlling the occurrence of sandstonetype uranium orebodies and the vertical zonation of oxidized fluid controlling the spatial location of the coaltype uranium orebodies.

Abstract:The Middle and Lower Jurassic in the southernYili basin is an important sandstonetype uraniumbearing sequence. This study carried out systematic analysis for lithological and geochemical features of the the Middle and Lower Jurassic clastic rocks in the southern Yili basin to understand its province features and tectonic environment. The results show that most sandstones are litharenite with low maturity, poor sorting and psephicity. Detritus consists mainly of siliceous and rhyolite fragments. It indicates the deposition of sandstone is close to the provenance. The finegrained clastic rocks has high SiO2 (ranging from 53.01% to 85.52%, Avg.71.22%) and Al2O3(ranging from 7.45% to 23.83%, Avg.13.96%), and low content of TFe2O3+MgO (ranging from 0.95% to 10.77%, Avg.3.64%) and TiO2 (ranging from 0.20% to 1.32%, Avg. 0.74%).The trace elements and rare earth elements characteristics of fine clastic rocks are similar to the upper crust. Light rare earth elements are enriched, the distribution model of heavy rare earth elements is flat. The anomalous value of Eu is negative. The trace elements and rare earth elements characteristics of fine clastic rocks suggest that the parent rocks were derived from felsic rocks in the upper crust and deposited in a tectonic setting related to continental arc. Combined with previous research data，it can be concluded that the clastic rocks in the lower and middle Jurassic in the southern margin of the Yili basin may be derived from the Carboniferous rocks in continental arc environment.

Abstract:Due to its large scale, favorablemetallogenic setting and condition sandstonehosted uranium deposit in the Yili Basin in Xinjiang is representative of uranium deposits of this kind. Study of mineralization is of great significance for future exploration and mining. Based on field investigation on sedimentary environment of regional Ubearing strata, with focus on orebearing country rocks, sedimentary sequence of typical sandstonetype uranium deposits in the Yili basin and orecontrolling sequences were analyzed to understand the constraint of clay minerals on uranium mineralization and spatial distribution of uranium mineralization. Systematic study was conducted to analyze clay minerals in orerich sandstone and their constraint on uranium mineralization using uranium geology, energy spectrometer, microscopic structure, scanning electron microscope, geochemistry, and H and O isotope. The results show that clay minerals are distributed widely within oxidation zone and redox zone of main orebodies, especially in strongly altered sandstone, all of which contain higher uranium contents than other sequence, reflecting an internal relation between clay minerals and uranium mineralization. Their relation can be further proved by SEM and energy spectrometer analysis. O and Ubearing fluids passing through sandstone can be absorbed by clay minerals with strong absorption capability and huge surface free energy, forming flake or clumpy clay minerals which contain high U content.Therefore, clay minerals play absorption role in uranium mineralization, facilitating the formation and positioning of orebearing space. Along with sedimentation, tectonic activities and latestage fluid mineralization, clay minerals and other oreforming lithology (orebearing sequence and sources) and structure all controlled uranium mineralization in this area.

Abstract:With the focus on the relationship between the organic matter and uranium minerlization of typical uranium deposits in the Ordos Basin, this study discussed the occurrence, characteristics and maturity of the coal. The results show that the evolution degree of organic matter is low and still in the low stage of mature, indicating it is favorable to the adsoption of uranium. Overall, organic matter in coal is closely related to the uranium mineralization,and positive correlation between the contents of uranium and organic matter coal suggest their adsorption form. The study of oilgas inclusions in this region indicates occurrence of multiple calcite cemetation,along with multiple development of oilgas inclusions,especially abudant latestage oilgas inclusions in late cementation calcite minerals.It can be concluded that it could have the migration and accumulation of oil and gas in this time, and the formation of uranium deposits is closely related to the filling and complexation of organic fluid or reducing gas in orebearing sandstone. Therefore, the organicrich fluid and reducing gases are of great importance for the uranium enrichment and precipitation.

Abstract:The northeastern Ordos basin is an important metallogenic area for sandstonetype uranium deposits in China. Field observation and microscopic identification for the Zhiluo Formation orebearing strata in the Daying uranium deposit suggest that pyrite occurs as several form and there is a certain correspondence relation between their macroscopic and microscopic occurrence. Sulfur isotope analysis of pyrite and study of alteration minerals indicate that δ4S values vary from -36.5‰ to -27.3‰, with an average of -32.28‰, suggesting an obvious biogenic process. Meanwhile, the discovery of framboidal pyrite and uranium minerals in biological debris cells also confirms biological effects on uranium mineralization. U6+ and Fe2 + reacted with light H2 32S in the groundwater, resulting in the paragenesis of pyrite closely and uranium mineralization.

Abstract:Based on the analysis for geological features of uranium deposits in the Dongsheng area of the Ordos Basin, this study conducted the acidolysisdesorbed hydrocarbon testing for 139 sandstone samples from Lower Section of the Zhiluo Formation in the Daying and Nalinggou deposits to understand the composition and origin of acidolysisdesorbed hydrocarbon and relationship of hydrocarbon fluids with sandstonetype uranium mineralization. The results show that the contents of CH4 and C2+ in the lower Zhiluo Formation sandstone are characterized by gradually decreasing from mineralized sandstone to gray sandstone and to graygreen sandstone, indicating close relation between uranium mineralization and hydrocarbon gas. Feature parameters, such as C1/ΣC, C1/C2+, C2/iC4, C2/C3, iC4/nC4, iC5/nC5, ln(C1/C2),ln(C2/C3) and δ13C CO2, of acidolysisdesorbed hydrocarbon gas show that hydrocarbon gas within the low Zhiluo Formation sandstone of the middle Jurassic is characterized by organic origin, with the gas at the stage of mature to high mature, and should be mixed gas consisting of cracked crude oil gas and associated gases. Based on the gassource correlation, it can be inferred that gas, developed in sandstone of Lower Section of Zhiluo Formation, may derive from sapropelic source rock of deepsemi deep lacustrine facies in the Triassic Yanchang Formation. The mixture gas of cracking gas of crude oil and associated gases migrates mainly into sandstone of the Zhiluo Formation along deep faulting, micro fracture and other pathways. Besides, alteration of migrated hydrocarbon gas on surrounding rock can be defined by fading alteration and greenish alteration in the Lower Section of the Zhiluo Formation. The redox transition zone between above alteration sandstone, adjacent to fracture, can be regarded as the favorable target of sandstonetype uranium prospecting.

Abstract:The north of Ordos Basin is found to have hosted a series of sandstonetype uranium deposits, which from east to west are Dongsheng, Hangjinqi (Nalinggou), and Daying uranium deposts, etc, suggesting it is China’s the largest and the most potential area for sandstonetype uranium deposits. The research shows that these uranium deposits are of similar geological characteristics and formation environment. Existence form of uranium and mineral characteristics of Ubearing minerals are the important contents in the study of mineralization process, because they provide not only the important basis for insitu leach mining of uranium but also key information on deposit formation mechanism or deposit formation environment of sandstonetype uranium deposits. This study investigates mainly the geological and geochemical features of uranium minerals in sandstonetype deposits (such as Daying and Nalinggou uranium deposits) and their genesis. By means of electron probe and high resolution scanning electron microscope, it can be concluded that the uranium mineral types of uranium deposits in the northern part of the basin are mainly coffinite, with minor brannerite, pitchblende, silicon water coffinite, thorium and uranium stone. Uranium minerals are often associated with pyrite and organic matter (soot) and calcite. The proportion of uranium minerals in the ores was quantitatively studied by sequential chemical extraction. The results show that the uranium minerals and adsorbed uranium account for about 50% of the existing forms of uranium. Uranium minerals of sandstonetype uranium ores were analyzed using insitu LA-ICP-MS REE test for the first time. Our results suggest that ΣREE is highly enriched in coffinite, which is the main carrier for rare earth elements in ores. Rare earth elements are useful components in uranium ores and REE standard curves show obvious rightdipping and LREE enrichment, LREE and HREE fractionation, weak negative δEu and δCe anomalies, indicating that the uranium mineralization formed in the exogenous environment. From the perspective of the above characteristics of uranium minerals, this study discusses the environment and genesis of uranium mineralization. Therefore, it can be concluded that uranium mineralization has experienced a low temperature fluid environment and the uranium deposits formed in the shallow crust, which is not related to the deep source, is the source of the deep crust.

Abstract:The southeastern Erdos Basin presents strong phenomenon of oil and gas development. It seems that regional uranium mineralization is closely related with fade alteration. This study carried out study of organic geochemical feature of the Zhiluo Formation and its relationship with uranium mineralization in the extensively mineralized Huangling area. The gas chromatography analysis of saturated hydrocarbons shows that the peak carbon number of nalkanes in organic matter belongs to C15~C22;,with C21+ C22）/（C28+C29）from 0.72 to 26.08; ∑C21-／∑C22+of 0.88~6.39; Pr/Ph of 0.47~0.85; OEP of 0.87~1.08 and CPI of 1.04~1.22. All this data indicate that hydrocarbon source rocks are in the stage of maturation, with oil and gas organic matter mainly from lacustrine sedimentary parent material in the Triassic Yanchang Formation. The hydrocarbon generation peak of lacustrine source rocks in the Triassic Yanchang Formation in the study area is in agreement with the time of missing strata hosting uranium mineralization since the formation of Ubearing sequences. The generated oil and gas can not only provide the reduction ability for uranium mineralization，but also can make the formed uranium ore bodies avoid reconstruction by the late oxidation.

Abstract:Based on outcrop, drilling data and seismic sections, and along with the study of lithology, lithofacies and facies sequence, this study defined the sequence stratigraphy of the MiddleLower Jurassic Yan’an Formation and Zhiluo Formation in the northeastern Ordos Basin. Five sequences have been recognized in the Yan’an Formation and four in the Zhiluo Formation. Each sequence is composed of low accommodation systems tract and high accommodation systems tract. Occurrence features of coal sequences and uranium ore deposits and their positions in the sequence column, it can be deduced that the coal of the Yan’an Formation occurs mainly in peat swamp environment of delta plain and the uranium of the Lower Zhiluo Formation occurs mainly in braid river deposit, which respectively represent the high accommodation systems tract and low accommodation systems tract, according to the characteristics and the position in sequence stratigraphic framework of CoalUranium distribution. In combination to geological, geochemical and paleontological data, the paper also discussed restriction of paleclimate and structure on coaluranium mineralization.

Abstract:The primary gray sandstone of the Middle Jurassic Zhiluo Formation in the northern Ordos Basin is characterized by high uranium content. Uranium extracted from the syndepositional Urich sandstone through oxidation was the key source for uranium mineralization. In this paper, UPb detrital zircon geochronology, heavy mineral analysis and paleocurrent analysis were used to document sediments sources of the Middle Jurassic Zhiluo Formation in the northern Ordos Basin and to understand the origin of the Urich sandstone. The results show that UPb ages of the detrital zircons from the Zhiluo Formation concentrate on four groups: 251~308Ma, 322~354Ma, 1529~2182Ma and 2200~2632Ma. Heavy mineral assemblages of Mnrich ilmenite, zircon, apatite and titanite suggest intermediatefelsic magmatic rocks were the main source rocks. Comparative study of potential sources shows that the Zhiluo Formation in the study area was derived mainly from NeoarcheanPaleoproterozoic magmatic and metamorphic rocks and late Paleozoic magmatic rocks in the WulashanDaqingshan area and the eastern Langshan area. Statistical analysis of uranium contents from source rocks shows that the late Paleozoic intermediatefelsic magmatic rocks are extremely enriched in uranium than other types of rocks, which caused the formation of the primary Urich sandstone in the northern Ordos Basin. Late Paleozoic magmatism was related to the subductioncollision evolution of the PaleoAsian Ocean. The distribution of the late Paleozoic magmatic rocks possibly controlled the distribution of preore uranium concentration and formation of the uranium deposits in the Central Asia uraniferous province and can be an important factor for the uranium exploration of other basins in this uraniferous province.

Abstract:Trace elements and rare earth elements (REE) of sedimentary rocks, especially argillaceous rocks, have high sensitivity on hydrological changes of sedimentary environment, therefore, they can be used as an effective method to study paleoclimate and paleoenvironment and trace the source province and tectonic settings during deposition period. In this paper, twentyeight argillaceous rock samples collected from the Jurassic Yan’an and Zhiluo formations in the northern margin of Ordos basin were analyzed for REEs, trace elements and clay minerals by means of ICPMS and SEM analysis to investigate the effect of redox conditions of the Yan’an and Zhiluo formations and structural setting and paleoclimate change of provenance on uranium mineralization. The results shows that (1) the characteristic values and ratios of trace elements and REE such as (B, Sr/Ba, B/Ga), (U/Th, V/V+Ni, V/Cr, Ni/Co) suggest that the bottom water was fresh and oxidation environment during the whole time Yan’an and Zhiluo Formation deposition. Fe2+/Fe3+ ratio suggests that the diagenesis environment of Yan’an Formation was regional reduction block. However, the upper Zhiluo Formation was in a strong oxidized background. (2) The sedimentary sequence from the Lower Jurassic Yan’an Formation to Middle Jurassic Zhiluo Formation represents a complete sedimentary cycle and the sedimentary facies, including fluvialalluvial fan facies(Lower Yan’an Formation), lacuserine deltaswampy facies (Middle and Upper Yan’an Formation),braided stream facies (Lower Zhiluo Formation), meandering river facies(Upper Zhiluo Formation). The Sr, Cu,Sr/Cu, FeO/MnO, Al2O3/MgO ratios and the clay mimerals’ vertical variety indicate that the paleoclimate and paleoenvironment experienced a changing process from warmhumid climate to drywet alternation, arid and semiarid climate. (3) Chemical Index of Alteration (CIA) indices and Index Chemical Variation (ICV) indices reflect that the Yan’an Formation was in relatively stable geotectonic background during middle Jurassic Zhiluo period, until tectonic activities of the margin of Ordos basin started to quickly increase. (4) LaThSc, La/YbΣREE and F1F2 discrimination diagrams indicate that the provenances of Yan’an Formation and Zhiluo Formation were derived mainly from the upper crust (felsic rocks), with a certain amount of alkali basalt addition. The geotectonic background was dominated by continental margin (active continental margin, passive continental margin), and part of material shows a continental island arc setting. The above research results reveal that the transformation of paleoclimate and the oxygencarrying ancient water played an important geological role in formation of coal and sandstonetype uranium mineralization.

Abstract:The Nalinggou uranium deposit in the northern Ordos Basin has obvious late hydrothermal features. Spatial distribution of the ore bodies is mainly controlled by the greengray sandstone transition interface, and closely associated with chloritization of alteration sandstone. Detailed petrographic and electron microprobe chemical analysis was conducted to chlorite from the Nalinggou uranium deposit. Based on the relationship between chlorite genesis and paragenetic minerals, three types of chlorite have been identified: fillingtype chlorite, flakes chlorite intergrowth with pyrite and chlorite altered from biotite. FeSi diagram of chlorite also determines that chlorite in different color sandstones can be divided into two types: brunsvigite and pycnochlorite. The diagram of Al/(Fe+Mg+Al)Mg/(Fe+Mg) shows that chlorite in different color sandstone is of two origins: femic constituents fluid and pelitopsammite. On the basis of the relation between major cations and magnesium in chlorite, our calculation suggests that chlorite resulted from multiple medium to low temperature hydrothermal fluid effect. Comprehensive studies have shown that chlorite in the Nalinggou uranium deposits experienced at least two fluid activities, a slightly high temperature reducing fluid activity and a slightly low temperature oxidizing fluids activity. It can be concluded that the former played an important role in mineralization. The hydrothermal fluid that associated with chlorite formation not only brought part of uranium but also promoted the activation and migration of uranium.

Abstract:Erlian Basin includingthe Manite Depression is characteristic of episodic rifting in the Early Cretaceous. Different stages of rift episodes control the vertical distribution of uranium reservoir and sandstonetype uranium deposits. In the western Manite Depression, advantageous orebearing sequences and uranium reservoir and the forming process of sandstonetype uranium deposits are all closely related to the episodic rifting in the Basin. Saihan Formation is the advantageous uranium reservoir bearing sequence which is in the transition stage from fault depression to sag;Late of episodic rifting usually accompany with weak episodic tectonic inversion.Multiepisodes weak tectonic inversion result in structural slope which contol the paleohydrogeology and the mineralization;Unconformity surface and denudation between different rifting episodes are control factors of the development of the oxidized zone and sandstonetype uranium deposits; Different stages with different features of episode rifting decide the space and time disposition of oilgas,coal and sandstonetype uranium deposits,which participate in sandstonetype uranium mineralization.According to different structural and depositional features of different stages of episodic rifting,we can determine key exploration sequences and prospecting types and favourable prospecting areas.

Abstract:Ages and tectonic implications of the Eraly Cretaceous rhyolites in the west of the Songliao Basin and Da Hinggan Mountains were obtained using zircon UPb dating, petrography analyses and geochemical researche methods. The zircon UPb dating by LAMCICPMS and SHRIMP techniqu, indicate that the crystallizing age of the rhyolites, was from 131.6±06Ma to 123.9±1.7Ma, which belongs to Early Cretaceous. Geochemical researches indicate that the rhyolites from Manduhu area are rich in silica (SiO2＝69.08%~79.58%), alkali (K2O＋Na2O 5.93%~9.76%, average＝8.14), K (K2O/Na2O＞1.0, average＝2.14), poor in calcium (average＝0.60), magnesium (average＝0.27) and have high FeOT/MgO (average＝6.77) ratio, which is a typical highK calcalkaline to shoshonitic series with the character of metaluminous (A/CNK＝1.35~1.78). Early Cretaceous rhyolites are classified as two major types in terms of rare earth element and trace elements geochemistry: I type rhyolites and II type rhyolites. The rocks have high contents of rare earth elements with ∑REE＝149.04×10-6~213.18×10-6(average＝172.35×10-6), enriched in LREE \[(La/Yb)N＝4.89~11.87\], LILEs (Rb, Ba, Th, K) and depleted in HFSE, especially Nb, Ta, Sr, P and Ti. The δEu values vary from 0.54to 0.88 (average＝0.70) and most rocks have moderate negative Eu anomalies. Similar REE distribution pattern imply that the rhyolites come from the same magma source. Compared with I type rhyolites, the II type rhyolites, with strong negative Eu anomalies (δEu＝0.05~0.46, average＝0.27)，have lower ∑REE(average＝142.60×10-6) and depleted in HFSE (Nb, Ta, Sr, P and Ti). The types (I, II) rhyolites with the characteristics of postcollision granites, have lower Sr(＜206×10-6), high Yb(＞2) and well geochemical correlation. Combining with previous studies, we suggest that the rhyolitic magma, which caused by Mongolia Okhotsk postcollisional action, was ogigrinated from partial melting of crustal materials and suffered fractional crystallization, and the rhyolites formed in the interpolateextending settings. The conclusions have most important significance for studying the volcanic action and tectonic settings of Early Cretaceous volcanic rocks.

Abstract:There are increasing evidence showing that microorganisms in interlayer oxidation zone sandstone type uranium deposit have involved in uranium metallogeny, indicating that China should focus on study of important role of microorganisms in the formation of interlayer oxidation zone sandstone type uranium deposits. Through molecular biology, living bacterium cultivating and laboratory simulation method, this study discussed microbial relationship with uranium mineralization in the Shihongtan and Mengqiguer sandstone type uranium deposits of Xinjiang. The results show that the microbial groups have different distribution characteristics in the different geochemical environments and present distinct biogeochemical zonation. From oxidation to reduction zones, the number of anaerobic bacteria increases while the number of aerobic bacteria number decreases. The distribution of bacteria in each zone is controlled by organic carbon content, iron occurrence and content and dissolved oxygen and sulphate content in groundwater. Microbial effects on uranium mineralization are comprehensive and restricted by various environmental factors. There are kinds of relationship occurring in microorganism, such as symbiosis and mutualism, and competition and antagonism, all of which affect the development of uranium deposits. The microorganism enrichment mechanism of uranium deposits is dominated by indirect metabolic biosorption, followed by enrichment of metabolic mechanism.

Abstract:Asone key national strategic resource, sandstonetype uranium deposits are one of the most important types in the modern world. This paper decribes in great detail the distribution and ratios of sandstonetype uranium ore deposits at home and abroad, discussed interlayer permeability sandstone type and submerged permeability sandstone typeuranium deposits formed by supergene fluids. The results show that distinct redox zoning of interlayer permeability sandstone typeuranium deposit occurs in terms of surface color, mineral combination and geochemistry, and moreover, bacteria zoning phenomenon. Color zoning show remarkable different characteristics among oxidized zones, redox transitional zones and reduced zones; mineral combination differs among the different zones; geochemical zoning is also defined by U, TOC contents and Fe2+/Fe3+ and Th/U ratios. In addition, the quantities of bacteria, such as sulfate reducing bacteria (SRB), thiobacilli, ferrobacteria, and nitrobacteria, vary considerably among the different zones, and there is conspicuous positive correlation between the magnitude of SRB and TOC. By analysis of carbon and sulfur isotope in the mineralization belt, we find that SRB has involved in the metallogenic process and infer that SRB may be the dominant factor causing carbon and sulfur isotopic fractionation. As a whole, color, mineral, geochemical, and bacteria zonings all have coupling relationship with the redox zoning. This study proposes the mechanism of sandstonetype uranium deposits involved by bacteria and geochemical reactions, and a number of key scientific problems needed to be solved urgently through summarizing metallogenic model of interlayer permeability sandstone type and submerged permeability sandstone typeuranium deposits. The exceptional responses of typical sandstone typeuranium deposits to geophysical, geochemical, prospecting exploration and remote sensing have great guiding significance to searching for sandstone typeuranium deposits.

Abstract:Interlayered oxidation type sandstonehosted uranium deposit is one type of the uranium deposits. It is totally blind or concealed, which makes it is difficult to be detected. As one branch of the deeppenetrating geochemistry, the electrogeochemical prospecting has become an important and effective method and accomplished a lot of achievements in exploration for deepburied uranium orebodies. Many studies indicate that there are existing electrogeochemical anomalies over known sandstonehosted uranium deposits. The physical and chemical formation conditions of interlayered oxidation type sandstonehosted uranium deposit are summarized and analyzed. Electrogeochemical characteristics of U is introduced over known uranium deposits. Formation mechanism of electrogeochemical anomaly is introduced based on the known migration mechanisms and field results. The U ore body is manifested as jumping U electrogeochemical anomaly of U detected directly above, which can be regarded as prospecting indicator for concealed sandstonehosted uranium deposit.

Abstract:To study themigration kinetics of uranium driven by dissolved ferric iron in acid solution, a group of leaching tests on the sandstonetype uranium ore taken from the Yili Basin had been carried out with sulfuric acid solution containing different contents of ferric iron. Results show that uranium, oxidized by ferric iron, can migrate from ore to the solution within 10 hours. The migration rate declines rapidly so that it makes uranium dissolution process gets to an equilibrium stage. The rate of uranium dissolution positively correlates with that of the transformation between ferric iron and ferrous ironas exponential functions. While the transformation rate of ferric iron to ferrous iron approaches zero, the uranium oxidation process stops and then leads to an uranium dissolution equilibrium. It also shows that ferric iron concentration of 2g/L is sufficient to induce a strong dissolution of uranium migration from ore. The increasing of the solution acidity weakens the relationship between uranium dissolution rate and Fe3+conversion rate. However, when acidity changes from 2g/L to 4g/L (pH value of 1.65~1.33), the uranium leaching effect does not change significantly. So, the solution with Fe3+concentration of 2g/L and the acidity of 2g/L (pH value of 1.65) is economical and effective for uranium leaching.

Abstract:The formation of sandstonetype uranium is closely related to humic acid，and uranium mineralization is restrained by many chemical factors. Adsorption experiment was designed to investigate the adsorption effects of humic acidparameters such as solution Ph, adsorption time and humic acid dosage on uranium (VI). The results show that pH value has great effect on adsorption of humic acid, and adsorption rate reached the maximum when pH value was 6. A small amount of humic acid dosage could make the U (Ⅵ）adsorption rate to 98.79 %. With adsorption rate increasing, the amount of humic acid increase，and finally tended to balance. Adsorption achieved a basic balance in a short time. In the binary system of humic acidclay and humic acidsandstone，mixed adsorption increases with the increasing amount of humic acid. In the ternary system of humicclaysandstone，the similar adsorption result was also obtained.