S. HAMILTON                  GOVERNMENT OF INDIA              DEPARTMENT OF ATOMIC ENERGYATOMIC MINERALS DIRECTORATE FOR E...
PHANEROZOIC & PROTEROZOIC BASINS OF INDIA
CHINA                Meghalaya                     DomiasiatINDIA      Wahkyn        BANGLADESH                           ...
GEOLOGICAL CUM TECTONIC MAP OF MEGHALAYA, INDIA                     90°                                           91°     ...
STRATIGRAPHIC SUCCESSION OF THE MEGHALAYA PLATEAU, INDIA                                                                  ...
MAHADEK BASIN OF MEGHALAYA, INDIA1800 sq km28% area covered20,000 tonnes of uranium oxide12% of Indian reserves
A   B
URANIUM DEPOSITS OF MAHADEK BASIN, INDIA                              Tabular / pane-concordant                           ...
DOMIASIAT (KPM) URANIUM DEPOSIT
WAKHYN AND WAHKUT URANIUM DEPOSITWAHKYN NORTH                   WAHKYN SOUTH
UMTHONGKUT URANIUM DEPOSIT
PALAEO- CHANNEL MAHADEK BASINCross bedded Lower Mahadek sandstone                                                       PH...
PALAEO-CHANNEL, UMTHONGKUT                                          Uranium MineralisationPalaeo-flow direction perpendicu...
ARCHITECTURAL ELEMENTS, UMTHONGKUT              Channels (CH)              Sanddy Bedform (SB)              Sediment Gravi...
MEMBER         LITHOLOG      LITHO FACIES              INTEPRETATION                                         Proximal fan ...
MEMBER                                      LITHOLOG                                                      LITHO FACIES    ...
MEMBER                                  LITHOLOG                                           LITHO FACIES       INTEPRETATIO...
MAJOR LITHOFACIES OF MAHADEK BASIN LITHOFACIES       FACIES         INTERPRETATION                    PHOTOGRAPHS         ...
COMPARISON OF CHARACTERS OF DOMIASIAT AND UMTHONGKUT DEPOSITSl.   Characteristics                 Domiasiat               ...
GENERALISED LITHOFACIES OF MAHADEK BASIN                   8 KM           31.5 KM                 45 KM                   ...
SIMPLIFIED FACIES MODELS                                        VIS-À-VIS                             A     URANIUM DEPOSI...
BASEMENT CONTOUR MAP OF WAHKUT   PALAEO CHANNEL COURSE
BASEMENT CONTOUR MAP OF UMTHONGKUT                       Basement slope is on av.                       7.5˚ towards south...
ISOPACH CONTOUR MAP OF LOWER MAHADEK, WAHKUT                        IS O P A C H C O N T O U R M A P O F L O W E R M A H A...
ISOPACH CONTOUR MAP OF LOWER MAHADEK, UMTHONGKUT                            Av. thickness of Lower                        ...
3-D DIAGRAM SHOWING BASEMENT CONFIGURATION OF MAHADEK BASIN                           PJ           LDH                    ...
Rongcheng     NUmthongkut Wahkyn  Domiasiat
TECTONIC SETTING IN WAHKYN AND UMTHONGKUT SECTORUm                                                                        ...
UMTHONGKUT URANIUM OCCURRENCE, MEGHALAYA        Lower Mahadek sediments       U                          Basement granite ...
GEOLOGICAL SECTION RONGCHENG PLATEAURONGCHENG PLATEAU            BALAPHAKRAM PLATEAURONGCHENG PLATEAU             SOUTH OF...
RADIOACTIVE SANDSTONE OF LOWER MAHADEK                Medium-coarse grained & poorly sorted                 Arkosic to sub...
POLISHED CORE SAMPLE OF BOREHOLE, UMTHONGKUT                High order                radioactive thick                par...
URANIUM MINERAL IDENTIFICATION     FD        QZ63X,1N                                   500X,OIL          FD              ...
URANIUM MINERAL IDENTIFICATION      COFFINITE                         PYRITE PITCHBLENDE        CARBONACEOUS              ...
Electron Microprobe data of Pitchblende, WakhynOxide                   Range                 Average (n=4) UO2            ...
ORGANIC MATTER                                                QUARTZ        ORGANIC        ORGANIC        MATTER        MA...
CARBON ISOTOPE COMPOSITION    Sl.    B.H. No.      Depth     Type of                      C                               ...
SULPHUR ISOTOPE COMPOSITION              Sl.      B.H. No.   Depth        34                                              ...
GEOCHEMICAL CLASSIFICATION(PETTIJOHN, 1972 WITH BOUNDARIES REDRAWN AFTER HERRON, 1988)                         A       B  ...
Discriminant function 1  DISCRIMINATION DIAGRAMS FOR TECTONIC ENVIRONMENT AFTER BHATIA 1983      - 0.0447 SiO2 - 0.972 TiO...
DIAGRAM SHOWING VARIATION OF Fe+3/Fe+2 RATIO WITHIN                            THE LITHO COLUMN,                          ...
CHEMICAL INDEX OF ALTERATION (after NESBIT AND YOUNG 1982)                       KAOLINITE                                ...
ORGANIC MATTER   RESIN
PETROGRAPHY OF BASEMENT ROCK                                                 ALT. PLAGIOCLASEMUSCOVITE                    ...
RADIOELEMENT BEARING ACCESSORY MINERALS IN GRANITIC ROCKS                                              7-110 ppm U  MONAZI...
VOLCANIC COMPONENTS IN SANDSTONE                  10 X TL-XN                                                10 -50 ppm U  ...
CONCLUSION Controls Sandstone-type Uranium deposits in Cretaceous Mahadek Basin,                             Meghalaya, In...
CONCLUSION Reductants           :     Organic matter /Biogenic pyrite Geochemical          :     Fe+3 /Fe+2 ratio 0.77 (Or...
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  1. 1. S. HAMILTON GOVERNMENT OF INDIA DEPARTMENT OF ATOMIC ENERGYATOMIC MINERALS DIRECTORATE FOR EXPLORATION AND RESEARCH
  2. 2. PHANEROZOIC & PROTEROZOIC BASINS OF INDIA
  3. 3. CHINA Meghalaya DomiasiatINDIA Wahkyn BANGLADESH MYANMAR
  4. 4. GEOLOGICAL CUM TECTONIC MAP OF MEGHALAYA, INDIA 90° 91° 92° 93° 94° F F F BARPUNG KO t & R. UTRA Faul BRAHMAP PIL IF JAMUNA F GUWAHATI SAMCHAMPI F E ON26° 26° KULSI F RZ DUDHNOI F EA T. SH A NI GA AP NA R JASRA BA SHILLONG F T DAP US SI T. SUNG VALLEY F T HR COMPLEX NG F DISA F 0 50Km F F25° DAUKI F F 25° F 90° F 91° F 92° 93° 94° ALLUVIUM JAINTIA GROUP CARBONATITE COMPLEX. INTRUSIVE GRANITE SHILLONG GROUP GARO GROUP & EQ. KHASI GROUP SYLHET TRAP KHASI GREENSTONE BASEMENT GNEISSIC COMPLEX (AFTER NANDY, D.R., 2001)
  5. 5. STRATIGRAPHIC SUCCESSION OF THE MEGHALAYA PLATEAU, INDIA (Modified after GSI, 1974)Geological age Group Formation LithologyMiocene Chengapara (700 m) Sandstone, siltstone, clay and marl.Oligocene Garo Baghmara (530 m) Feldspathic sandstone, conglomerate and clay. Kopili-Rewak(500) m Shale, sandstone and marl.Eocene Shella (600 m) Alternations of sandstone and limestone.Paleocene Jaintia Langpar (50-100 m) Calc shale, sandstone and impure limestone. Unconformity Upper: Coarse, arkosic sandstone and shale, 250m characteristic purple colour Mahadek Lower: Grey, coarse to fine grainedUpper Cretaceous Khasi feldspathic sandstone, arkose. 70m Sandstone-conglomerate alternations. Jadukata (235 m) Unconformity Basalt, alkali-basalt, and acid tuff. AlkalineLate Jurassicto Early Cretaceous Sylhet Trap and rocks of carbonatite complexes. Tectonic Coarse, porphyritic granite, pegmatite, aplite IntrusiveLate Proterozoic granites 479 -690 Ma and quartz vein. Epidiorite and dolerite.Lower -Middle Intrusive Quartzite with basal conglomerate.Proterozoic Shillong Barapani Meta phyllite sequences. TyrsadArchaean Unconformity Granite gneiss, migmatite, mica schist, sillimanite-quartz schist, granulite.
  6. 6. MAHADEK BASIN OF MEGHALAYA, INDIA1800 sq km28% area covered20,000 tonnes of uranium oxide12% of Indian reserves
  7. 7. A B
  8. 8. URANIUM DEPOSITS OF MAHADEK BASIN, INDIA Tabular / pane-concordant Low dipping flat ore body Palaeo Channel
  9. 9. DOMIASIAT (KPM) URANIUM DEPOSIT
  10. 10. WAKHYN AND WAHKUT URANIUM DEPOSITWAHKYN NORTH WAHKYN SOUTH
  11. 11. UMTHONGKUT URANIUM DEPOSIT
  12. 12. PALAEO- CHANNEL MAHADEK BASINCross bedded Lower Mahadek sandstone PHOTOMOSAIC OF THE SECTION Palaeo-flow direction perpendicular to the photograph
  13. 13. PALAEO-CHANNEL, UMTHONGKUT Uranium MineralisationPalaeo-flow direction perpendicular to the photograph
  14. 14. ARCHITECTURAL ELEMENTS, UMTHONGKUT Channels (CH) Sanddy Bedform (SB) Sediment Gravity-flow (SG) Downstream Accretion Macroforms (DA)
  15. 15. MEMBER LITHOLOG LITHO FACIES INTEPRETATION Proximal fan environment by braided river channel in Fluvial regime Sm, Sh, Sp, Fm rare Gmm; Top part of LM is relatively finer, rich in matrix. Fluvial braided channel systems Several small fining upward cycles Bottom part of LM Mineralisation dominated by Gmm, associated with the Sm and Sp; More of basal part of the coarser components cycles close to the basement. AHA MRE W L O Basement: Precambrian gneissic complex, Granite,WAHKUT gneisses/Migmatite
  16. 16. MEMBER LITHOLOG LITHO FACIES INTEPRETATION BH No UKT/C-5 Sm and minor Sh, Fm Mineralisation Mahadek GRAIN SIZE MUD SAND GRAVEL Upper & Gmm. associated with the 30.00 m si vf f m c vc gr 31.30 Sm basal part of the Lower Mahadek Several small fining cycles at the upper Sh Cm(<5%) upward cycles part of LM Radioactive Sm 37.00 bands Fm Sm Sm and Gmm at the basal part of LM 41.00 Gms Radioactive Sh Deposited under bands Sm Cm(<5%) braided fluvial 47.30 Sm regime by small Sh Py, CM (>5%) channels with Sm carbonaceous 53.25 matter under Relatively thicker reducing condition Py, Cm fining upward cycles Lower Mahadek Sm Proximal fan environment by AHA MRE W L O 59.60 braided river channel in Fluvial regime Sm Py, Coaly matter 65.55 66.45 Gms Basement, Granite Basement gneisses/Migmatite Migmatitic basementUMTHONGKUT 73.00
  17. 17. MEMBER LITHOLOG LITHO FACIES INTEPRETATION Fm, Sm (minor) Deposited as over bank facies under oxidizing condition Overbank & abandoned channel fill deposited in Meandering Fluvial Regime Shallow sandy Sm Sm braided system Sm Sm Sm Sm Sm Sm Fm Sm Sm Sm Sm Fm Sm Sm Fm Sm Fm Sm Fm under oxidizing condition Sm, Fm (minor) Shallow sandy AHA MRE PP U braided system 19.90m 48.50m Upper Mahadek under oxidizing condition with little development of Marker overbank facies at Horizon the end of the depositional cycleUMTHONGKUT
  18. 18. MAJOR LITHOFACIES OF MAHADEK BASIN LITHOFACIES FACIES INTERPRETATION PHOTOGRAPHS CODE Massive deposited under sediment gravity sandstone Sm flow within a braided fluvial channel Horizontally deposited on large flood bar in channel deposits during the waning laminated Sh stage of flood events (possibly sandstone seasonal) deposited during low water level or Planar crossbedded sandstone Sp waning stage of flow under lower flow regime deposition from suspension of Massive Fm overbank sediments in flood plain mudstones setting rapid sedimentation from a high Massive, matrix energy flow, which are common insupported gravel Gmm the most active part of a fluvial channel sedimentation by rapid flowing clast Massive, Clastsupported gravel Gcm rich sediments deposited in a fluvial proximal fan setting
  19. 19. COMPARISON OF CHARACTERS OF DOMIASIAT AND UMTHONGKUT DEPOSITSl. Characteristics Domiasiat UmthongkutNo.1 Facies Gm, Gmm, Gt, PS, Sh, St, Fl & C Sm, Sh, St, Fm, Fl & Gmm Channel (CH), Sedimentary Gravity Channel (CH), Sandy bed form2 Architectural flow (SG), Gravel bar (GB), Sandy (SB) & Down stream accretion (DA) Elements bed form (SB) & Down stream accretion (DA) Depositional By gravel or sandy bed river proximal Sandy bed Braided river system3 to Fan environment environment Hosted by immature, poorly sorted, Hosted by feldspathic wacke, Sm grey arkosic to sub- arkosic pebbly facies4 Radioactivity quartz arenite and pebbly feldspathic wacke of PS facies Av. thickness of 40-50m 30-35m5 Lower Mahadek Basement Irregular, with highs and lows Irregular, with highs and lows6 topography Pitchblende and minor uranyl Pitchblende, Coffinite urano7 U - Minerology minerals organic complex and secondary uranyl minerals8 Ore body 10-15 above the basement 25-35m above the basement Depth of ore 25m, max up to 45m Min-15.45m & Max - 194.85m9 body
  20. 20. GENERALISED LITHOFACIES OF MAHADEK BASIN 8 KM 31.5 KM 45 KM 45.5 KM E D C B A Gmm Fm Gmm St U Sm Sm Sh Fm St Gmm Ps Sh U Sh U St St Sh Ps Ps Sm Fl Gcm Sh Sh PS U Sh Ps Ps Gmm St Gcm Sh Sm Sh Sh Sp Sh U Ps Laitduh Gmm U Sm Gmm Sh Ps Gmm Gt Gcm (1215m) Gcm U St U Sh Ps SmRongcheng (750m) U Sh Domiasiat Sm Gmm (750m) Umtryngai River (500m) Umthongkut (450m)
  21. 21. SIMPLIFIED FACIES MODELS VIS-À-VIS A URANIUM DEPOSITS DOMIASIAT an n Fa dF al & Mi xi m WAHKYNPro B l ma rgina e rin Ma GOMAGHAT
  22. 22. BASEMENT CONTOUR MAP OF WAHKUT PALAEO CHANNEL COURSE
  23. 23. BASEMENT CONTOUR MAP OF UMTHONGKUT Basement slope is on av. 7.5˚ towards south (varies between 5-10˚) The richer part of ore body is associated with NNE-SSW, NE-SW and NW-SE depression The basement low observed in the southern part is favorable for uranium mineralization.
  24. 24. ISOPACH CONTOUR MAP OF LOWER MAHADEK, WAHKUT IS O P A C H C O N T O U R M A P O F L O W E R M A H A D E K , W A H K U T5600 15 C -1 7 11 C -2 1 17 0 200 400 600 m C -2 25400 C -1 4 21 9 18 C -3 3 C -2 4 C -1 0 C -3 6 2 0 C -2 7 14 19 C -2 9 C -6 33 C -2 35200 16 C -3 4 C -4 3 23 1 3C -1 8 A C -3 0 22 C -3 1 32 37 C -3 36 C -2 0 12 C -1 6 A 8 31 C -1 9 C -3 5 10 29 7A C -8 345000 6A 5 C -4 4 28 C -3 2 C -1 3 A C -1 24 C -2 6 35 30 3 C -7 38 27 C -2 5 4 2A C -4 5 C -3 7 26 C -3 9 25 C -2 8 C -1 2 C -2 C -1 1 1 C -1 54800 C -4 0 C -4 2 C -3 8 A C -4 1 39A C -5 A C -4 C -9 3600 3800 4000 4200 4400 4600 4800 5000 5200 5400 M IN E R A L IS E D B O R E H O L E S N O N -M IN E R A L IS E D B O R E H O L E S Av. thickness of Lower Mahadek is 52m
  25. 25. ISOPACH CONTOUR MAP OF LOWER MAHADEK, UMTHONGKUT Av. thickness of Lower Mahadek is 35m The thickness increases towards South
  26. 26. 3-D DIAGRAM SHOWING BASEMENT CONFIGURATION OF MAHADEK BASIN PJ LDH PDS RS TAR TRN PS DS GMG NOGRON UMT WKN ROD 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 TAR - TRANGBLANG, PDS - PDENGSHAKAP, PS - PHLANG SYENNAI, LDH - LAITUDH, TRN- TYRNAI, RS- RANGSPKHAM, PJ- PHUD JAD, GMG- GOMAGHAT, NOG- NONGJARI, WKN- WAKHYN UMT- UMTHONGKUT, RON- RONGCHENG, ROD- RONGDI
  27. 27. Rongcheng NUmthongkut Wahkyn Domiasiat
  28. 28. TECTONIC SETTING IN WAHKYN AND UMTHONGKUT SECTORUm N Po th rjr on iL gk ine ut am Fa en ul t t LOSTOIN CHIRA FAULT WAHKYN UMTHONGKUT Ri ng WAHKUT wa llu m fau lt Uranium Deposit Uranium Anomaly
  29. 29. UMTHONGKUT URANIUM OCCURRENCE, MEGHALAYA Lower Mahadek sediments U Basement granite gneiss Tertiary sediments
  30. 30. GEOLOGICAL SECTION RONGCHENG PLATEAURONGCHENG PLATEAU BALAPHAKRAM PLATEAURONGCHENG PLATEAU SOUTH OF BALAPHAKRAM PLATEAU Upper Mahadek Lower Mahadek Basement gneiss
  31. 31. RADIOACTIVE SANDSTONE OF LOWER MAHADEK Medium-coarse grained & poorly sorted Arkosic to subarkosic arenite – wacke 95 to 25 Ma
  32. 32. POLISHED CORE SAMPLE OF BOREHOLE, UMTHONGKUT High order radioactive thick part of carbonaceous matter LR film showing corresponding radioactivity
  33. 33. URANIUM MINERAL IDENTIFICATION FD QZ63X,1N 500X,OIL FD QZ PITCHBLEND 1250X,OIL
  34. 34. URANIUM MINERAL IDENTIFICATION COFFINITE PYRITE PITCHBLENDE CARBONACEOUS MATTER PITCHBLENDEWOOD CELLS REPLACED BY PITCHBLENDE PITCHBLENDE AS VEIN
  35. 35. Electron Microprobe data of Pitchblende, WakhynOxide Range Average (n=4) UO2 89.33-91.35 90.3ThO2 0.00-0.04 0.03 P2O5 0.02-0.23 0.09 SiO2 1.95-2.75 2.42 TiO2 0.03-0.92 0.32Al2O3 0.19-0.21 0.20 FeO 0.58-1.56 1.16 MgO 0.03-0.04 0.04 CaO 2.08-2.56 2.25 PbO 0.00-0.09 0.06La2O3 0.03-0.07 0.05Ce2O3 0.19-0.39 0.25Pr2O3 0.02-0.06 0.04Nd2O3 0.07-0.25 0.15Sm2O3 0.05-0.08 0.07Gd2O3 0.02-0.10 0.06Yb2O3 0.04-0.06 0.05 Y2O3 0.11-0.39 0.20Total 95.96-98.53 97.68REE2O3 0.51-0.98 0.65
  36. 36. ORGANIC MATTER QUARTZ ORGANIC ORGANIC MATTER MATTER ORGANIC MATTER OM AS INCLUSION IN VEIN QUARTZ CLASTMIGRATORY NATURE - OM
  37. 37. CARBON ISOTOPE COMPOSITION Sl. B.H. No. Depth Type of C 13 No. (m) organic ( ‰) matter 1. DS-237 16.65 Lump -23.4 2. DS-198 19.20 Lump -22.2ALGAL FEATURE (?) REPLACED 3. PITCHBLENDE BY DS-21/1 Pit Lump -20.1 4. DS-21/2 Pit Lump -23.1 5. DS-53 45.65 Disseminated -18.8 6. DS-251 25.20 DisseminatedLab. -19.8 Total Carbon Organic Carbon Total No. % % %S 7. DS-192 52.40 Disseminated 508 -17.1 0.3 0.30 0.22 509 0.37 0.36 0.07 8. RG-99 05.10 Banded 510 -21.4 1.02 0.99 0.06 WOOD CELLS REPLACED 511 1.14 1.09 0.17 BY PITCHBLENDE 512 0.11 0.11 0.05 514 7.75 6.30 0.45
  38. 38. SULPHUR ISOTOPE COMPOSITION Sl. B.H. No. Depth 34 s No. (m) ( ‰) 1. DS-212 37 +2.9 2. DS-249 17.90 -25.0 3. DS-249 30.90 -23.7FRAMBOIDAL PYRITE IN ORGANIC MATTER 4. DS-195 22.40 -7.6 5. DS-21 Pit -2.6 6. DS-21 Pit -9.7 7. RG-109 14.60 0.00 8. RG-99 05.10 -21.4 9. PHLAGDILION PHNG-1 -36.3 WOOD CELLSREPLACED BY PYRITE PHLAGDILION 10. PHNG-2 -1.1
  39. 39. GEOCHEMICAL CLASSIFICATION(PETTIJOHN, 1972 WITH BOUNDARIES REDRAWN AFTER HERRON, 1988) A B D E F C A Greywacke B Litharenite C Arkose D Subarkose E Sublitharenite F Quartz Arenite
  40. 40. Discriminant function 1 DISCRIMINATION DIAGRAMS FOR TECTONIC ENVIRONMENT AFTER BHATIA 1983 - 0.0447 SiO2 - 0.972 TiO2 + 0.008 Al2O3 - 0.267 Fe2O3 + 0.208 FeO - 3.082 MnO + 0.140 MgO + 0.195 CaO + 0.719 Na2O - 0.032 K2O + 7.510 P2O5 + 0.303 Discriminant function 2 - 0.421 SiO2 + 1.988 TiO2 – 0.526 Al2O3 – 0.551 Fe2O3 – 1.610 FeO + 2.720 MnO + 0.881 MgO + 0.907 CaO – 0.177 Na2O – 1.840 K2O + 7.244 P2O5 + 43.57 A B C D A Passive Margin B Oceanic island-arc C Continental island-arc D Active continental margin.
  41. 41. DIAGRAM SHOWING VARIATION OF Fe+3/Fe+2 RATIO WITHIN THE LITHO COLUMN, MEGHALAYA, INDIA Fe+3/Fe+2 10.56 UKT/C-5 UKT/C-6 WKT/C-27 WKT/C-29 0.00m 0.00m 0.00m 0.00m 3.10 MAHADEK UPPER MAHADEK MEMBER UPPER 11.50 3.10 2.65 28.29 DEPTH (m) 1.90 20.65 3.25 31.30 1.66 0.53 1.99 1.15 MAHADEK Fe+3/Fe+2 1.07 LOWER 10.66 0.59 0.71 2.39 0.48 4.74Fe+3/Fe+2 0.88 LOWER MAHADEK MEMBER 0.45 0.94 (Non Radioactive zone) 66.45 m 0.45 0.84 0.42 LOWER MAHADEK MEMBER 0.27 (Ore zone) 0.26 98.00 m 98.00 m INDEX 100.35 m UPPER MAHADEK MEMBER LOWER MAHADEK MEMBER Fe+3/Fe+2 0.77 RADIOACTIVE BAND BASEMENT Fe+3/Fe+2 RATIO 1.74
  42. 42. CHEMICAL INDEX OF ALTERATION (after NESBIT AND YOUNG 1982) KAOLINITE KAOLINITE SMECTITE ILLITE SMECTITE ILLITEPLAGIOCLASE K-FELDSPAR PLAGIOCLASE K-FELDSPAR Mol.% Al – K- Ca+Na MINIMUM AND MAXIMUM FOR LOWER (n=26) AND UPPER MAHADEK ( n=13)Mol.Al2O3 % 0.050 – 0.225 0.036 – 0.113Mol.K2O% 0.001– 0.045 0.010 – 0.054Mol. CaO + Na2O 0.001 – 0.013 0.003 – 0.012
  43. 43. ORGANIC MATTER RESIN
  44. 44. PETROGRAPHY OF BASEMENT ROCK ALT. PLAGIOCLASEMUSCOVITE MICROCLINE POTASH FELDSPAR GARNET BIOTITE CHLORIT E MUSCOVITE COMPOSITION SYENOGRANITE TO QUARTZ MONZONITE Alteration: SERICITISATION, CHLORITISATION, S-TYPE SIGNATURE GOETHITISATION, LEUCOXENISATION
  45. 45. RADIOELEMENT BEARING ACCESSORY MINERALS IN GRANITIC ROCKS 7-110 ppm U MONAZITE XENOTIME ALPHA TRACKS POTASH FELDSPAR POTASH FELDSPAR POTASHFELDSPAR ZIRCON UNIDENTIFIED REE MINERAL METAMICT ALLANITE
  46. 46. VOLCANIC COMPONENTS IN SANDSTONE 10 X TL-XN 10 -50 ppm U Embayed Quartz Qtz Needle shape Quartz Qtz Wedge shape Quartz Qtz Embayed Quartz Qtz DOMISIAT WAKHYN UMTHINIANG RONGCHENG 10 X TL-XN
  47. 47. CONCLUSION Controls Sandstone-type Uranium deposits in Cretaceous Mahadek Basin, Meghalaya, India.Lithological : Lower Mahadek ( Upper Cretaceous)Sedimentological : Proximal Fan environment Braided river channel in fluvial regimePalaeo- channel : Primary Control Palaeo-current direction southBasement configuration : Gentle slope (<5˚)Thickness of host rock : Optimum thickness of 40mTectonic : Up-liftment / Tilting / Rotation Cont…
  48. 48. CONCLUSION Reductants : Organic matter /Biogenic pyrite Geochemical : Fe+3 /Fe+2 ratio 0.77 (Ore Zone) Diagenetic : 3 Physico-chemical conditions Acidic / Alkaline/ Reducing Palaeo-environment : Arid & Humid Source : Granite & Gneisses ( 7-110 ppm) Volcanic (10-50 ppm)Mahadek Basin 1800 sq km, 72 % area remained to be explored
  49. 49. Thanks

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