Mineralogy,Fluid Inclusion and H-O-C-S Stable Isotopes of Mengqiguer Uranium Deposit in the Southern Yili Basin,Xinjiang:Implication for Ore Formation

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.

Genesis of green sandstone/mudstone from Middle Jurassic Zhiluo Formation in the Dongsheng Uranium Orefield, Ordos Basin and its enlightenment for uranium mineralization

The middle Jurassic Zhiluo Formation in the Dongsheng is comprised of a big set of green sandstone/mudstone with most of uranium orebodies occurring in close proximity to its footwall.By synthesizing field observations,region analysis,data collected from previous coal and uranium borehole,a regional north-south geological profile across the entire orefield is conducted.Experiments on sandstone/mudstone including rock mineral identification,clastic micromorphology and element geochemistry were carried out.Information from the geological profile indicates that green sandstone/mudstone is widely present in a stable horizon with clear boundaries to the country rock.Microscopic observations and geochemical data on sandstone/mudstone exhibit similar mineral composition with almost identical slightly flat,minor Eu enriched,Ce depleted chondrite-normalized REE patterns.Furthermore,the green clay membrane of the clasts has a complex composition containing chlorite/smectite,green smectite,chlorite,and green kaolinite,with elements including Fe,Mg,Si,and Al.These above results indicate that the green sandstone/mudstone underwent resemble sedimentary diagenetic processes as the country rock without transformation by large-scale regional fluid,while the existence of Fe2+-rich membrane is the main factor to the green sandstone/mudstone.Further concentration of the pre-enrichment uranium during diagenetic process led to the final formation for uranium deposits.The above studies are conducive to enrich the metallogenic mechanism of sandstone type uranium deposits and could provide certain reference for uranium exploration and deployment.

Ammonium Dissociation for Swine and Dairy Cattle Manures

The dissociation of ammonium (NH4+) into ammonia (NH3) in wastewaters is a key factor governing atmospheric nitrogen volatilization. Relatively rich in total ammoniacal nitrogen (TAN or NH4+ plus NH3), livestock manures are most susceptible to NH3 volatilization, although indirect measurements report 5 times less NH4+ dissociation as compared to theoretical values. The objective of this study was therefore to directly measure NH4+ dissociation of two standard NH4Cl solutions (1750 and 3500 mg TAN/L), and of swine and dairy cattle manures at various dilutions and temperatures using a ammonia selective electrode (hydrogen and silver-silver chloride electrode couple) at various pH and temperatures. All solutions demonstrated NH4+ dissociation varying from theory, especially because of dissolved compounds such as atmospheric CO2. At a neutral pH, ratios of theoretical to measured [NH3-N] ranged from 1.5 to 3.5, with higher ratios corresponding to higher TAN levels. At a pH below 6, NH3 volatilization was enhanced by the shift of HCO3- to H2CO3 and CO2. With previous research projects reporting 5 times less NH3 volatilization as compared to theory, the present indicates that dissociation activity account for half of this drop with gas diffusion accounting for the other half.