06 u mineralization hosted by paleozoic sandstones in sw sinai egypt
INTERNATIONAL ATOMIC ENERGY AGENCY Technical Meeting on The Origin of Sandstone Uranium Deposits: A Global Perspective 29 May – 1 June 2012, Vienna, Austria Uranium mineralization hosted by thePaleozoic sandstones in Southwest Sinai, .Egypt By Nuclear Materials Authority, El-Maadi, Cairo, Egypt
Outline Introduction. lithostratigraphy of the Paleozoic succession in Southwest Sinai. Geological setting of U-bearing sandstones in Southwest Sinai. Mineralogy and petrography of the radioactive sandstones. Radioactivity of the studied sandstones. Sandstone - type uranium deposits in the promising localities. Inferred U- resources in evaluated deposits. Summary and conclusions.
IntroductionThe Paleozoic clasticsexposed mainly along theNE Egypt (Eastern Desertand Sinai). SinaiThese clastics exposedalong the African platewhich related to the Arabo-Nubian massif.The Paleozoic success-ion in Sinai (up to 320m)form the basal units of thesedimentary sequenceunconformably overliesthe Precambrian basementrocks. Geological map of Egypt
….Introduction Cont The Paleozoic sandstones exposures in Southwest Sinai are distributed mainly as a strip extend from Um Bogma - G. Dhalal area, separating thecrystalline area of southern Sinaifrom Mesozoic and Tertiary rocks of El Tih and Egma Plateaux of central Sinai. Um Bogma G. Dhalal These exposures exist either as small bodies resting on the top of high, peneplained Ras basement rocks or as down- Millanfaulted blocks against crystalline basement mountains. Simplified geologic- geomorphic map showing the distribution of .Paleozoic rocks and the studied localities in Southwest Sinai
The studied localities (host to sandstone-typeuranium mineralization) in Southwest Sinai: W. El Sahu area (SE. Um Bogma) G. Adedia G. Um Hamd G. Abu Triefia G. Maghara G. Hemeyir area El Khamila G. Hemeyir G. Ghorabi Ramlet Hemeyir W. El Main area W. Qarqur W. Imlieh W. Um Gidy Ras Millan area W. Lethi .Geological map shows the studied localities in Southwest Sinai
Lithostratigraphy of the Paleozoic succession in Southwest Sinai Stratigraphic units included in this study
Lithostratigraphy of the Paleozoic succession in Um Bogma area (a) and annotated outcrop photographs showing in detail its Cambro-Ordovician and lower Carboniferous formations (b,c).
Lithostratigraphy of the Cambro-Ordovician succession in Ras Millan area (a) and annotatedoutcrop photographs showing in detail the radioactive sandstones of Araba Formation (b,c) and composite lithostratigraphic subdivisions of Adedia Formation (e) and detailed lithostratigraphic section of its radioactive uppermost part (f) and its annotated outcrop photographs (d,g) in south W. El Sahu area.
The radioactive basal conglomerate in Southwest SinaiThe anomalouspolymictic cong-lomerate lensesare well extend-ed in:W. El MainW. Qarqur,W. Um Gidy,W. Imlieh,G. NukhulG. Adedia.The lenses Thoriterange inthickness from60 cm to 2.0 m a. Polymictic basal conglomerate directly overlying the basement rocks at W. Qarqur b. Radioactive polymictic conglomeratic lens at the base of Araba Fm., W. El Main area. c. Rock fragments, xenotime and quartz cemented with carbonates (pointed by arrows), iron oxides and Fe-Ti cements in the conglomerate of W. Nukhul. (P.L., X=32).
The radioactive ferruginous sandstone of El Adedia Fm. in W. El Sahu area Wadi Sahu Wadi El Sahu 28o 58 33 " N 33o 22 39 " ELANDSAT of Wadi El Sahu, Southwestern Sinai. U- bearing ferruginous sandstone
….The radioactive ferruginous sandstones in W. El Sahu area Cont .G. Um Hamd
The radioactive ferruginous sandstones in G. Hemeyir area El Khamila G. Hemeyir 14E 32 33
U- bearing ferruginous sandstones in G. Hemeyir area.Photograph show the aeolian sands cover the exposures of U- bearing ferruginous sandstones
Ramlet Hemeyir Gaba l G ho rabi Ramlet Hemeyir Gabal Ghorabi 29o 03 53 " N 29o 00 59 " N 33o 29 03 " E 33o 30 19 " E.Radioactive localities in G. Hemeyir area mostly covered with aeolian sand
Map of airborne gamma ray spectrometry survey which carried out on the eastern side of the Gulf of Suez at Abu Zeneima-El Tor stretch )(4000 Km 2 ea yir ar eme G. H d an a m a a re B og ahu Um lS .E W S.
The radioactive Cambro-Ordovician sandstones in Ras Millan area Uc up to 1064ppm & 8359 ppm Th
The Lower Carboniferous Abu Thora Formation Abu Thora Fm. The lower Carboniferous Abu Thora Fm. exposed only in Um Bogma area and its vicinities. It is up to 242m in thickness.Three main lithofacies could be distinguishedfrom base to top; Ferruginous sandstone lithofacies. Varicolored siltstone and shale lithofacies. Milky white sandstone lithofacies .
The Lower Carboniferous Abu Thora Formation 33 22 33 23 33 24 P3 33 20 33 25 G . U m R in n a Q 29 a S IN A I 05Uranium within Abu Thora Formation B ab W . S e ih P3 W .S e ih ib a se W . 29 W . tN G. e 29 N as S a r a b it rr is controlled with major structure lines 04 P 2 Di P3 E l K h a d im Q P3 2 04 e ib P 2 a ab P3 2 .B P3 P A b u H a m a ta 29 W 1 2 such as: W U m B ogm a 00 5 km Q .M P 2 P3 W . 2 P3 W .A bu E l or K ey M ap N as P 1 ei P 3 2 P 1 2 2 P 1 2 d e ib P 1 Q a M o g h e ira t 2 Q B ab P 1 P 2 P 2 T a le t 1 2 2 P 1 2 P P 2 W . TS S e lie m 2 2 2 P 2 2 P 3 P3 NS N-S normal fault of W. El Kharig P 2 2 2 P1 P P P 1 3 2 2 AM 2 2 29 Q P P3 29 03 extending to Ras Nukhul and El 2 2 P1 W . P 3 2 P 3 2 Pc 03 N as P3 P3 P 3 2 P 2 2 P3 Khaboba localities. P e ib 2 2 P 3 P 3 2 P 2 2 Legend 2 Q W a d i D e p o s it s Q Pc A b u T h o ra F m . P 3 2 P3 P 1 2 P P 33 S a n d s to n e a n d C a r b o n a c e o u s c la y P 1 2 P 3 2 P3 P2 U m Bogm a Fm . P 2 2 P 3 U p p e r d o lo s to n e m e m b e r P P 3 P3 P 1 Q 2 3 P NW-SE normal fault of W. Naseib 2 2 2 2 P 22 M i d d l e i n t e r c a l a t io n m e m b e r 2 AT P 3 P 2 P3 P3 2 or u -T h 2 P 12 L o w e r d o lo s to n e m e m b e r 29 e tAb Pc P1 S a r a b it, A b u H a m a ta a n d D abb 29extending as a right limb of W. El Sahu 02 A d e d iy a F m s . S a n d s t o n e , p e b b ly S a n d s t o n e P P 1 02 3 2 P3 2 a n d S ilt s to n e P 1 2 B asem ent R ocks P 2 2 Pc P 2 P 2 graben. G r a n o d io r ite a n d d io r ite 2 2 P 2 2 Q D i p - S l ip F a u l t P P 1 P3 P 1 P3 1 2 Pc 2 2 L o c a t i o n o f l it h o s t r a t i g r a p h i c s e c tio n P3 P 1 2 P 3 2 P 29 3 2 0 .0 0 .2 0 .4 0 .6 k m P3 01 P 30" 1 2 P3 P 1 2 P 2 P 3 2 P 3 2 2 33 22 33 23 33 24 Geological) : mapl o ofi c Ump Bogmai Nareab (after BElb AassyS et t hal., s t e r n S i n a i . F ig .( 2 G e o g m a o f W a d a s e i - W a d i a a a r e a , o u w e 2006).
Mineralogy of the polymictic basal conglomerate Thorite Uranothorite ZirconThorite is the most abundant Th-bearing mineral associated with other detritalheavy minerals; including abundant uranothorite, thorianite, monazite, zircon,xenotime besides cheralite (Th, Ca, Ce)(PO4, SO4), chevikinite (Ca, Ce, Th)4(Fe, Mg)2(Ti, Fe)3O22 and thorutite (Th, U, Ca) TiO2.
.Mineralogy of the ferruginous sandstones of El Adedia FmThe principal minerals Xenotime Xenotimeresponsible for the radioactivity: The refractory xenotime,apatite, allanite, euxenitezircon, monazite as well assecondary U minerals; XenotimeSaleeite and becquirelitein W. El Sahu area.Uvanite and threadgolditein G. Hemeyir area. The gangue minerals Uvanite mainly are iron oxides;magnetite, goethite, ilmenite in addition to barite and galena.
.Mineralogy of the Araba sandstones at Ras Millan area Autunite Allanite Sodium meta-autunite MonaziteThe minerals responsible forradioactivity are zircon, allanite,thorite, xenotime, monazite, davidite Zirconand secondary U minerals; saleeite,johannite and sodium meta-autunite.The aluminium phosphateminerals; goyazite, florencite, Zircon grains cemented with Fe-Ti oxidesplumbogummite were associated inthe anomalous sandstones.
Black sand lenses in El Adedia and Araba formationsThe black sand lenses occur within the radioactive horizons of El Adedia and Araba formations.Meander loops and channels with deep scours appear to be the most favourable sites for these lenses.It consist of heavy minerals concentrate include zircon, monazite, xenotime, ilmenite, ilmenorutile and rutile. Well rounded monazite and zircon are the most abundant minerals.The framework grains coated with iron and titanium oxides cement.The cement materials occur as fibrous, radial and acicular forms.
Mineralogy of the radioactive Abu Thora sandstones Graphite The anomalous U content in Abu Thora Fm. (Uc up to Sphene 380 ppm) is controlledmainly by the presence of U- bearing detrital grains. These detrital minerals are Apatitesphene, apatite, euxenite, Zirconzircon and monazite. The leached U hosted in the interbeded mudstones and siltstones is captured bythe iron oxides, clay minerals and organic matter contents. U occurs as spots within other minerals as graphite. Euxenite
Radioactivity of basal conglomerate lensesThe basal conglomerate lenses have anomalous eU and eTh contents(reach up to 157 ppm eU and 2379 ppm eTh).The eTh/eU ratio for these sediments ranges from 1.3 to 18.2 with anaverage of 5.3.The chemical uranium (Uc) is depleted in this lithofacies (reach up to 40ppm at W. Qarqur). It ranges from 14 to 40ppm with an average of 23.2ppm.The high Th content is attributed to high concentration of Th and Th-Ubearing minerals such as thorite, chevikinite, cheralite, thorutite, thorianite,zircon, monazite and xenotime.These radioactive minerals essentially exist as inclusions in the rockfragments (framework components) or through detrital matrix and/or cementmaterials.
Radioactivity of ferruginous sandstones in south W. El Sahu areaThe ferruginous sandstones has anomalous Uc; upto 3000 ppm in south W. El Sahu area; G. Abu Triefia The anomalous sandstones in G. Um Hamd, G. Abu Triefia and G. Um Karasy show high radiometricmeasurements and are enriched in radionuclides; eU, eRa and K%. Wadi Sahu G. Um eU content reached 2040 ppm with an average of Hamd506 ppm. Ra content reached 1528 ppm, with an average of G. Um Karasy396 ppm. The high uranium and radium contents are attributed mainly to the presence of tongues and lenses of secondary U-mineralization. The Uc/eU ratios of these sandstones ranges from 0.41 to 5.1 with an average of 1.51. G. Um The eU/eRa ratios for most of the mineralized Hamdsamples exceed unity, reﬂecting a state of radioactive disequilibrium between uranium and its daughters. G. Um Karasy G. Abu The above ratios indicates the enrichment of Uc in Triefia these sandstones in the form of secondary uranium mineralization such as saleeite and becqurelite.
Radioactivity in G. Hemeyir area a Gabal Hemeyir 29o 01 36" N 33o 32 38 " E 2400 ppm G.Hemeyir b El Khamila c 29o 01 38 " N a 33o 32 32 " E > 550 ppm b c G. Ghorabi 29o 01 38 " N 33o 32 32 " E > 400 ppmLANDSAT of Gabal Hemeyir, southwestern Sinai.
….Radioactivity in G. Hemeyir area Cont Chemical uranium (Uc) in the ferruginous sandstones reach up to 2400ppm with anaverage of 399.6 ppm. Uc/eU ratios for the ferruginous sandstones in G. Hemeyir area ranges from 0.49 to27.5 with an average of 7.7. The eTh/eU ratio ranges from 0.12 to 0.44 with an average of 0.36. The radioactive sandstones at G. Hemeyir area are related to three successivehorizons include; The ferruginous sandstone at the topmost part of El Adedia Formation. The lateritic soil directly overlying the first and is represented by ferruginous siltstone (~ 1.5 m in thickness). The third horizon is the violet and mottled white S.S. at the base of Abu Thora Fm., with Uc reach up to 212 ppm. The enrichment of uranium in these sandstones under conditions where uranium was removed from its source and re-deposited in permeable fault zone with continuous recharge and a basic dyke act as a barrier to U-bearing solutions.
Radioactivity of Araba Formation in Ras Millan area The anomalous sandstones are highlyradioactive along the fault zone (extend ~12 km); its activity is variable along this extension. The radioactive horizons are: The basal quartzite of Araba Fm. (Uc up to 102ppm and Th up to 7433 ppm). Ras Millan areaThe very fine sandstone at the topmost part ofAraba Fm. (Uc up to 1016 ppm and Th up to8359 ppm).The high eTh/eU ratios range from 1.68 to 25.6with an average of 9.08. This ratios reflect the presence of detrital radioactive Th and Th-U bearing minerals like . xenotime, allanite, monazite, thorite, zircon and Fm davidite. a ba r A
….Radioactivity of Araba Formation in Ras Millan area Cont The highest radioactive measurements were located at the downstream of W. Lethi (eTh = 8359 ppm and eU = 450 ppm) in Araba very fine sandstones. The sandstones far from the fault zoneare slightly enriched in uranium than thorium (Uc ~ 100 ppm in average). U liberates from the lattice of refractory hi Let W. minerals during the hydrothermal alteration Cam bro processes along the permeable fault zones -Or dov and re-precipitated as secondary uranium i ci a ns and (e.g. saleeite, johannite and sodium-meta- Ca st o mb nes ro- autunite) in the overlying sandstones. This Ord ovi explains the high value of both Uc and cia ns and eTh/eU ratio in the same time in these s ton es sandstones.
Radioactivity of Abu Thora Formation S. No. Lithofacies eU eTh Ra K% eTh/eU The Uc/eU ratio in most of Ferruginous the mineralized and non 1 sandstones 13.4 10.4 16.2 0.62 0.81 mineralized samples greater Coal bearing 2 9.72 19.78 6.61 0.36 2.12 than 1. It ranges from 0.09 to black shales 58 with an average of 12.7. 3 Varicolored 24.72 37.09 18.0 0.24 1.91 siltstones 4 White sandstones 6.0 2.83 1.16 0.035 1.5 There is negative relationbetween the eTh/eU ratios andUc indicates some enrichment of U relative to Th (U was enriched during secondary processes). Uc in White S.S. Uc in ferruginous S.S. 1 Uc in Shales Uc in Siltstones The close spatial correlationbetween U-bearing sandstones and major structures in the area suggested that the 50 51 52 53 54 55 56 57 58 59 60 supergene enrichment of U in Average U concentration in ppmthese clastics was facilitated by tectonic movements.
Sandstone–type uranium deposits in the promising localitiesThe studied Paleozoic sandstones in southwest Sinai host two types of uranium:mineralization 1. The syngenetic continental/littoral paleoplacers; include mainly refractory minerals which are detrital from nearby source rocks. Two types of placers can be recognized on the basis of depositional environment; stream and beach placers. The stream placers hosted mainly in the basal polymictic conglomerate lens directly overlying the basement rocks and in black sand lenses exist in the sandstones of El Adedia and Araba formations. The refractory minerals concentration is depositional controlled and its
…Sandstone–type uranium deposits in the promising localities Cont2. The tectolithologic sandstone- type uranium deposits It formed by the epigenetic enrichment of uranium within the sandstones unconformably overlying the Precambrian granitic basement rocks or faulted against it. The present U deposits are related to the permeable fault zones and stacked as discordant bodies through more than one stratigraphic horizon. The sandstones enriched in secondary uranium minerals include uranium phosphates and vanadates in addition to detrital mineral grains; xenotime, sphene, apatite, zircon, monazite, euxenite, fergusonite and allanite. The concentration of xenotime (YPO4) and associated authigenic Al-phosphate minerals may have been formed by dissolution of the detrital minerals by
Estimation of inferred U resources in uraniferous blocks of G. Um Hamd- W. El Sahu area. Average Ore Metal Density, Average S. No. Block No. Area, m 2 thickness, amount, amount, g/cm3 grade, % m ton ton SH333F- 1 708.77 2.8 2.639 5237.25 0.054 2.83 VC1 SH333WC 2 733.2 2.56 2.739 5141.08 0.075 3.86 2 SH333V- 3 5986.78 1.2 2.498 17946 0.014 2.51 FD1 4 SH333FD2 2500 1.2 2.712 8136 0.014 1.14 5 SH333FD3 2500 0.6 2.712 4068 0.014 0.57 SH333V- 6 2500 1.8 2.359 10615.5 0.014 1.49 FD4 7 SH333FD5 1909.38 1 2.712 5178.24 0.018 0.93 SH333F- 8 9920.55 1.77 2.716 47691.3 0.023 10.97 WD6
I. The inferred U resources in G. Um Hamd - W. El Sahu area. No. of No. of No. of Estimated Locality excavated excavated evaluated U metals .No Shafts trenches blocks in tons 1 G. Um Hamd 19 3 8 24.3 The inferred U resources in G. Um Hamd locality is 28.7 ton U 3O8 or 24.3 ton U metal. The area south W. El Sahu; G. Abu Triefia, G. Um Karasy and G. Maghara are still under preliminary evaluation stage.
El Khamila locality G. Hemeyir W . El Kh am ila
Inferred U resource estimation in El Khamila locality Volume determination of ore-deposits = 170m X 140m X 2.0m = 47600m3 U- grade % = 0.024% U-ore tonnage = 111860 t ferruginous sandstone U- metal tonnage = 26.85 t U3 O8 – tonnage = 31.7 t 3 8
Summary and ConclusionsThe tectonic history of southern Sinai is considered to be one of the most important factors in the formation of the present tectonic-lithologic type uranium deposits. The uranium deposits hosted in fluvial sediments, which generally consist of a sequence of conglomerates-sandstones-mudstones (fining upward sequence). The refractory minerals in the basal conglomerates and upper parts of Adedia and Araba formations represent the primary source of uranium and its associated metals in the Paleozoic sandstones. Another source of primary uranium is considered to be either the surrounding uraniferous granitic provenance, or detrital granitic and/or felsic volcanic rock fragments in the host sandstones.
Summary and Conclusions The tectonic-lithologic stack type deposits are in part considered the product of redistribution of uranium in permeable hosts along structures took place by younger tectonic processes. The uranium mineralization are rarely located far from fault zones and are stackedup along different horizons of these permeable localities. The tectonic-lithologic sandstone-type uranium deposits occur in significantquantities in the Cambro-Ordovician sandstones of G. Hemeyir, W. El Sahu and Ras Millan areas. The large extension of the hosted sandstones indicates significant U-resources in these localities in Southwest Sinai. Results point to the necessity for further exploration in detail.