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Author Hofmann, H.; Pearce, J.K.; Hayes, P.; Golding, S.D.; Hall, N.; Baublys, K.A.; Raiber, M.; Suckow, A. url  openurl
  Title Multi-tracer approach to constrain groundwater flow and geochemical baseline assessments for CO2 sequestration in deep sedimentary basins Type Journal Article
  Year 2023 Publication International Journal of Coal Geology Abbreviated Journal  
  Volume Issue Pages 104438  
  Keywords CO geological storage, Great Artesian Basin, Groundwater chemistry, Isotopic tracer, Surat Basin  
  Abstract Geological storage of gases will be necessary in the push to net zero and the energy transition to reduce carbon emissions to atmosphere. These include CO2 geological storage in suitable sandstone reservoirs. Understanding groundwater flow, connectivity and hydrogeochemical processes in aquifer and storage systems is vital to prevent risk and protect important water resources, such as the Great Artesian Basin. Here, we provide a ‘tool-box’ of geochemical assessment methods to provide information on flow patterns through the basin’s aquifers (changes in chemistry along flow path), stagnant versus flowing conditions (cosmogenic isotopes and noble gases), inter-aquifer connectivity and seal properties (major ions, Sr and stable isotopes), water quality (major ions and metals) and general assessments on residence times of groundwater (cosmogenic isotopes and noble gases). This information can be used with reservoir and groundwater models to inform on possible changes in the above-mentioned processes and serve as input parameters for CO2 injection impact modelling. We demonstrate the use and interpretation on an example of a potential CO2 storage geological sequestration site in the Surat Basin, part of the Great Artesian Basin, and the aquifers that overly the reservoir. The stable water isotopes are depleted compared to average rainfall and most likely indicate greater contributions from monsoonal rain events from the northern monsoonal troughs, where amount and rainout effects lead to the depletion rather than colder recharge climates. This is supported by the modern recharge temperatures from noble gases. Inter-aquifer mixing between the Precipice Sandstone reservoir and the Hutton Sandstone aquifer seems unlikely as the Sr isotope ratios are distinctly different suggesting that the Evergreen Formation is a seal in the locations sampled. Mixing, however, occurs on the edges of the basin, especially in the south-east and east where the Surat Basin transitions into the Clarence-Moreton Basin. Groundwater flow appears to be to the south in the Precipice Sandstone, with a component of flow east to the Clarence-Morton Basin. The cosmogenic isotopes and noble gases strongly indicate very long residence times of groundwater in the central south Precipice Sandstone around a proposed storage site. 14C values below analytical uncertainty, R36Cl ratios at secular equilibrium as well as high He concentrations and high 40Ar/36Ar ratios support the argument that groundwater flow in this area is extremely slow or groundwater is stagnant. The results of this study reflect the geological and hydrogeological complexities of sedimentary basins and that baseline studies, such as this one, are paramount for management strategies.  
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  ISSN (up) 0166-5162 ISBN Medium  
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  Call Number THL @ christoph.kuells @ hofmann_multi-tracer_2023 Serial 165  
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Author Robin, V.; Beaufort, D.; Tertre, E.; Reinholdt, M.; Fromaget, M.; Forestier, S.; Boissezon, H. de; Descostes, M. url  openurl
  Title Fate of dioctahedral smectites in uranium roll front deposits exploited by acidic In Situ Recovery (ISR) solutions Type Journal Article
  Year 2020 Publication Applied Clay Science Abbreviated Journal  
  Volume 187 Issue Pages 105484  
  Keywords Dissolution, In situ recovery, Ion exchange, Post mining, Remediation, Smectite  
  Abstract In Situ Recovery (ISR) is the most important process of uranium production in the world (50%). It consists of an injection of a leaching solution into a permeable mineralized aquifer (sandstone), pumping of the solution after dissolution of the ore minerals and recovery of the uranium from the pregnant solution in a surface plant. In this context, the fate of swelling clay minerals such as smectites is of main importance due to their role in the mobility of cationic elements by diverse geochemical processes such as ion-exchange reactions or dissolution. The present study details analysis of dioctahedral smectites before and after in-situ leaching by acidic (H2SO4) ISR solutions. Samples were collected from two sedimentary basins hosting some of the main uranium roll front deposits exploited by acidic ISR (Tortkuduk deposit, Shu-Saryssu basin, Kazakhstan, and Dulaan Uul and Zoovch Ovoo deposits, Sainshand basin, Mongolia). Scanning Electron Microscope and X-Ray Diffraction analysis revealed that dioctahedral smectite is a ubiquitous mineral in all analyzed samples, before and after acidification, and revealed a difference of crystal chemistry of the smectites between deposits of Kazakhstan (beidellite type) and Mongolia (montmorillonite type). Chemical analysis and semi-quantification of the smectites before and after acidification also revealed a difference in chemical reactivity, with a higher dissolution of montmorillonite layers compared to beidellite ones, and the importance of ion-exchange reactions. These findings are consistent with literature data obtained on model systems. The persistence of dioctahedral smectites after several years of acidification is crucial for the understanding of geochemical processes during uranium production or remediation of the aquifers. Finally, based on the analysis of samples from U-deposits hosted in both sedimentary basins, a schematic model of the impact of acid solutions on dioctahedral smectite was proposed.  
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  ISSN (up) 0169-1317 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ robin_fate_2020 Serial 179  
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Author Hall, S.M.; Gosen, B.S.V.; Zielinski, R.A. url  openurl
  Title Sandstone-hosted uranium deposits of the Colorado Plateau, USA Type Journal Article
  Year 2023 Publication Ore Geology Reviews Abbreviated Journal  
  Volume 155 Issue Pages 105353  
  Keywords Colorado, Plateau, Uranium, Vanadium  
  Abstract More than 4,000 sandstone-hosted uranium occurrences host over 1.2 billion pounds of mined and in situ U3O8 throughout the Colorado Plateau. Most of the resources are in two distinct mineral systems with deposits hosted in the Triassic Chinle and Jurassic Morrison Formations. In the Chinle mineral system, base metal sulfides typically accompany mineralization. The Morrison mineral system is characterized by V/U ratios up to 20. The uranium source was likely volcanic ash preserved as bentonitic mudstones in the Brushy Basin Member of the Morrison Formation, and lithic volcanic clasts, ash shards, and bentonitic clay in the lower part of the Chinle Formation. Vanadium originated from two possible sources: iron–titanium oxides that are extensively altered in bleached rock near deposits or from similar minerals in variably bleached red beds interbedded with and beneath the Morrison. In Chinle-hosted deposits, in addition to volcanic ash, a contributing source of both vanadium and uranium is proposed here for the first time to be underlying red beds in the Moenkopi and Cutler Formations that have undergone a cycle of reddening-bleaching-reoxidation. Transport in both systems was likely in groundwater through the more permeable sandstones and conglomerate units. The association of uranium minerals with carbonate and more rarely apatite, suggests that transport of uranium was as a carbonate or phosphate complex. The first comprehensive examination of paleoclimate, paleotopography, and subsurface structure of aquifers coupled with analysis of the geochronology of deposits suggests that that there were distinct pulses of uranium mineralization/redistribution during the period from about 259 Ma to 12 Ma when oxidized mineralizing fluids were intermittently rejuvenated in the Plateau in response to changes in tectonic regime and climate. Multiple lines of evidence indicate that deposits formed at ambient temperatures of about 25 °C to no greater than about 140 °C. In both systems, deposits formed where groundwater flow slowed and was subject to evaporative concentration. Stagnant conditions allowed for prolonged interaction of U- and V-enriched groundwater with ferrous iron-bearing reductants, such as illite and iron–titanium oxides, and more rarely organic material such as plant debris. Paragenetically late in the sequence, reducing fluids introduced additional organic matter to some deposits. Reducing fluids and introduced organic matter (now amorphous and altered by radiolysis) may originate from regional petroleum systems where peak oil and gas generation was from ∼ 82 to ∼ 5 Ma. Our novel analysis indicates that these reducing fluids bleached rock and protected affected deposits from remobilization during exposure and weathering that followed uplift of the Plateau (∼80 to 40 Ma).  
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  ISSN (up) 0169-1368 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ hall_sandstone-hosted_2023 Serial 111  
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Author Su, X.; Liu, Z.; Yao, Y.; Du, Z. url  openurl
  Title Petrology, mineralogy, and ore leaching of sandstone-hosted uranium deposits in the Ordos Basin, North China Type Journal Article
  Year 2020 Publication Ore Geology Reviews Abbreviated Journal  
  Volume 127 Issue Pages 103768  
  Keywords Geochemical composition, leach mining, Mineralogy, Ordos Basin, Sandstone-hosted uranium deposit  
  Abstract The Nalinggou–Daying uranium metallogenic belt is situated at the northern Ordos Basin, China. Petrographical, mineralogical and geochemical techniques were used to study the ore-bearing sandstones and host rocks in the Nalinggou–Daying uranium metallogenic belt. The present study shows that uranium minerals, i.e., coffinite, pitchblende, and brannerite, are mostly disseminated around pyrite and detrital particles. The ore-bearing sandstones are enriched in organic matter, with which this reductive environment influenced uranium leaching. The carbonate concentration of the uranium ores is markedly higher than that of the host rocks, and intense carbonatization occurs in the ore-bearing sandstones. In this case, the usage of the classical in-situ leach uranium mining technique by injecting H2SO4 + H2O2 solution produces calcium sulfate precipitate, which can lead to blocking of the ore-bearing strata. For this reason, laboratory and field uranium mining tests were conducted using CO2 + O2 in-situ leaching technology and were demonstrated to be successful, illustrating that this approach is technically feasible. Inhibiting ore bed blockage and increasing the amount of injected O2 are important for uranium leaching in this setting.  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ su_petrology_2020 Serial 120  
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Author Hall, S.M.; Gosen, B.S.V.; Paces, J.B.; Zielinski, R.A.; Breit, G.N. url  openurl
  Title Calcrete uranium deposits in the Southern High Plains, USA Type Journal Article
  Year 2019 Publication Ore Geology Reviews Abbreviated Journal  
  Volume 109 Issue Pages 50-78  
  Keywords Calcrete, Carnotite, Finchite, Geochemistry, Uranium, Vanadium  
  Abstract The Southern High Plains (SHP) is a new and emerging U.S. uranium province. Here, uranyl vanadates form deposits in Pliocene to Pleistocene sandstone, dolomite, and limestone. Fifteen calcrete uranium occurrences are identified; two of these, the Buzzard Draw and Sulfur Springs Draw deposits, have combined in-place resources estimated at about 4 million pounds of U3O8. Ore minerals carnotite and finchite are hosted in dolomite at the Sulfur Springs Draw deposit, with accessory fluorite, celestine, smectite/illite, autunite, and strontium carbonate. Host carbonate at the Sulfur Springs Draw deposit is ∼190 ka and mineralization mobilized as recently as 3.8 ka. Ash collected near the deposit is 631 ka and erupted from the Yellowstone caldera complex. The Triassic Dockum Group that contains sandstone-hosted uranium deposits throughout the region and underlies the SHP is a potential source for uranium and vanadium. Regional uplift and dissection reintroduced oxygenated groundwater into the Dockum Group, mobilizing uranium. Additional uranium may have been contributed to groundwater by weathering of volcanic ash in Pliocene and Pleistocene host rocks. The locations of the uranium occurrences are mostly in modern drainage systems in the southeast portion of the SHP. Modelling of modern groundwater in the SHP carried out in a parallel study shows that a single fluid could form carnotite through evaporation, and that fluids of the requisite composition are more prevalent in the southern portion of the SHP. The southeastern portion of the SHP hosts more uranium occurrences due to a variety of factors including (1) upward transport of groundwater and connectivity between source and host rock, (2) higher uranium and vanadium content of groundwater, (3) higher rates of groundwater recharge in this region to drive the mineralizing system, and (4) shallower groundwater facilitating surface evaporation. Ongoing erosion of host rocks challenges preservation of deposits and may limit their size.  
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  ISSN (up) 0169-1368 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ hall_calcrete_2019 Serial 124  
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