Characterization of U Sources in the Erlian Basin         (NE China): Implication for Sedimentary-Hosted U                ...
Framework         Central Asia          U Province5 major uraniferousdistricts in China.In NE China, the Yinshan-Liaohe di...
Geodynamic contextCrustal thickenning during the HercynianMongol Xing’an Orogeny.Mesozoic continental extension in EastAsi...
Location of the Erlian BasinIn NE China, Inner Mongolia.Mesozoic intracontinental basin.Oriented NE-SW    1000 km long    ...
Location of the study area             Study Area                                                                         ...
I. THE ROLE OF GRANITES  AS PRIMARY U SOURCE   Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Per...
Basement units                                                                                                       Hercy...
Granite geochemistry (typology)                                                                               Evolution of...
Granite geochemistry (magmatic source)                                                                                    ...
Granite geochemistry (U enrichment)                                                                                       ...
Granite petrographyMain mineral assemblage: quartz; K-feldspar; plagioclase; biotite; amphibole… chlorite; clinozoisite.  ...
Avaibility of uranium            Element mapping (SEM) + EMP profile on U-thoriteTechnical Meeting on the Origin of Sandst...
Metamictization of U-bearing accessory minerals                                                                      REE  ...
Evidendence of uranium leaching         Log du sondage            U & Th content (ppm)                        Th/U        ...
Age of U-rich granite                      U/Pb dating on zircon using ion microprobeU-rich granite   is Triassic (Indosin...
Geodynamic context for                                             Indosinian granites                                    ...
II. PERMEABLE SANDSTONE LAYERS      AS SECONDARY U SOURCE    Technical Meeting on the Origin of Sandstone Uranium Deposits...
Upper Cretaceous                                                               Erlian Fm                                  ...
The source of sediments Texture     Mainly granites                                                 Lithic fragment       ...
Intraformational U content / detrital accessory                   minerals                                                ...
III. SYN-SEDIMENTARY U CONCENTRATION:     SYN-          THE NUHETING DEPOSIT      Technical Meeting on the Origin of Sands...
The Nuheting deposit10 000t U @ 0.03-0.1% U                                                                               ...
EZK304-431                                                                                 Hosting                        ...
Distribution of Py and OM                                                                    High density minerals        ...
U oxide adsorbed to clay minerals                                                               U mineralization          ...
Model of the Nuheting depositTechnical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
ConclusionsIndosinian High K calc-alkaline granite are aninteresting primary U source.The permeable sandstone layers of th...
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04 bonnetti iaea 2012

  1. 1. Characterization of U Sources in the Erlian Basin (NE China): Implication for Sedimentary-Hosted U Deposits.C. Bonnetti1*; M. Cuney1; F. Malartre1; S. Bourlange1; X.Liu2; Y. Peng31 University of Lorraine (UDL)2 East China Institute of Technology, Fuzhou, China3 Geological Team No.208, BOG, CNNC, Baotou, China Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  2. 2. Framework Central Asia U Province5 major uraniferousdistricts in China.In NE China, the Yinshan-Liaohe district isdominated by sandstone-type uranium deposits(roll front and tabular)U deposits are hosted inMesozoic sedimentarybasins (e.g. Erlian Basin,Ordos Basin, SongliaoBasin).Study area: Erlian Basin. (After Dahlkamp 2009; Xingzhong and Weixun 1990; Cong 2009) Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  3. 3. Geodynamic contextCrustal thickenning during the HercynianMongol Xing’an Orogeny.Mesozoic continental extension in EastAsia: Geophysical data (gravimetry, Bassin d’Erlian Seismic tomography), enclaves geochemistry show a lithospheric thinning. 2 major events of granite injection: - Jurassic (190-150 My) - Lower Cretaceous (135-110 My) Mafic to felsic volcanisme (163-113 My in North China). Intracontinental sedimentary basins (initial deposition at about 155 My). Metamorphic core complexes (130- 110 My). (Charles, 2010) Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  4. 4. Location of the Erlian BasinIn NE China, Inner Mongolia.Mesozoic intracontinental basin.Oriented NE-SW 1000 km long 50-200 km wideComposed of several subbasinsshowing half-graben structure.Bordered by the East Gobi Basin tothe West, the Ordos Basin to the SWand the Songliao Basin to the East. (Meng , 2003) Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  5. 5. Location of the study area Study Area (After Nie, 2008; Wei et al., 2005)Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  6. 6. I. THE ROLE OF GRANITES AS PRIMARY U SOURCE Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  7. 7. Basement units Hercynian granites (wu et al. 2005) and/or yanshannian granites; Jurassic-Cretaceous (Deng et al. 2007; Wu et al. 2005a): Biotite granites K feldspar-rich Weathered at surface EBND06,17 Metasediments: EBND07 Paleozoic ZK2011-1 Metamorphosed and foldedEBND10A-B EBND21 Marble, schist… Jurassic volcanic rocks: EBND21 EBND22 At the basis of the basin Rhyolite breccia Trachyte Basement sample map Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  8. 8. Granite geochemistry (typology) Evolution of the relative proportions of quartz and feldspars High K Calc-alkaline granites (rich in K-feldspar) Alteration is mainly argilization Na-Ca leaching (kaolinization)Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  9. 9. Granite geochemistry (magmatic source) Altered granite is Slightly peraluminous (Al > Na+K+2Ca; feldspar alteration) Preserved granite is metaluminous (Al < Na+K+2Ca) in accordance with the presence of Ca-rich, Al-poor mineralsMagmatic source derives from a mafic source (amphibole, epidote…) Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  10. 10. Granite geochemistry (U enrichment) Magmatic differentiation: Th>U U leaching by Granite weathering Th/UTechnical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  11. 11. Granite petrographyMain mineral assemblage: quartz; K-feldspar; plagioclase; biotite; amphibole… chlorite; clinozoisite. 200 µm 200 µm 200 µm Amphibole (NL) Chlorite (NL) Clinozoïsite (NLAccessory mineral assemblage: titanite; allanite; U-thorite ; zircon (±apatite). 200 µm 500 µm Titanite (APL) Allanite (APL) U-thorite (SEM Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  12. 12. Avaibility of uranium Element mapping (SEM) + EMP profile on U-thoriteTechnical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  13. 13. Metamictization of U-bearing accessory minerals REE Zr-rich thorite carbonate 0m Iron oxide Thorite 25,8 m Thorite Thorite 60,5 mDepth (m) Iron oxide U-Thorite Thorite U-Thorite U oxide inclusion 92,3 m U-Thorite UO2 116,5 m Allanite Allanite 137,0 m REE Allanite U-Thorite carbonate 152,0 m Zircon 176,5 m REE carbonate 180 m Paragenetic U-bearing accessory mineral succession Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  14. 14. Evidendence of uranium leaching Log du sondage U & Th content (ppm) Th/U U leaching ZK2011-1 0m Strong fracturation Strong alteration Th/U=4 U ; Th Th/U Leaching 82 m Weak fracturation Weak altération U et Th Th/U = Leaching140 m Average U & Th/U in granites180 m Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  15. 15. Age of U-rich granite U/Pb dating on zircon using ion microprobeU-rich granite is Triassic (Indosinian) Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  16. 16. Geodynamic context for Indosinian granites S N (After Lin et al., 2008)Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  17. 17. II. PERMEABLE SANDSTONE LAYERS AS SECONDARY U SOURCE Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  18. 18. Upper Cretaceous Erlian Fm Swamp: OM & Py-rich silty mudstoneUpper Calcareous Unit mudstone Crevasse splay: Siltstone with floatting gravels Fine grained sandstoneLower Unit Braided channel: Sandstone with ripples Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  19. 19. The source of sediments Texture Mainly granites Lithic fragment Sericitized K-feldspar Microcline Feldspathiccomposition Plagioclase Kaolinite Chlorite trend Chlorite trend Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  20. 20. Intraformational U content / detrital accessory minerals U-bearing minerals = in situ U release In reduced sandstone:the same accessory minerals as observed in granites U-thorite (NL) Zircon Epidote Pyrite Apatite U-thorite Titanite Monazite U-thorite (SEM) Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  21. 21. III. SYN-SEDIMENTARY U CONCENTRATION: SYN- THE NUHETING DEPOSIT Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  22. 22. The Nuheting deposit10 000t U @ 0.03-0.1% U (After Dahlkamp 2009)Tabular ore bodyMainly hosted by OM & Py-rich silty mudstoneU is adsorbed to clay minerals or mineralized as pitchblende and coffiniteThe main ore body is very shallow (about 30m depth) Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  23. 23. EZK304-431 Hosting sedimentary facies Upper unit OM & Py- rich Lower Swamp unit Silty mudstone Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  24. 24. Distribution of Py and OM High density minerals along the bedding XR tomographyTechnical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  25. 25. U oxide adsorbed to clay minerals U mineralization Coffinite on phytoclast Coffinite on Qtz thrombolite Coffinite on pyrite Py Botrhyoidal Coffinite on quartzMineralization along the bedding Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  26. 26. Model of the Nuheting depositTechnical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012
  27. 27. ConclusionsIndosinian High K calc-alkaline granite are aninteresting primary U source.The permeable sandstone layers of the Erlianformation are reflecting the U-rich granitemineralogical composition.The « reservoir » can be considered as a secondaryU source.The mineralization of the Nuheting deposit ismainly hosted in swamp dark grey silty mudstonewith a high Py and OM content.The Nuheting deposit correspond to asynsedimentary U concentration.Technical Meeting on the Origin of Sandstone Uranium Deposits: A Global Perspective, IAEA 2012

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