BEPORT NO. IAEA-R-1866-F mü
TITLE
Uranium distribution in uranium ores and source rocks
PIKAL REPORT FOR THE PERIOD r 7"V-". '
1976-10-01 - 1981-09-30
9 AUTHOR(S)
G. Kurat
INSTITUTE
Naturhistorisches Museum Mineralogisch-Petragraphische Abteilung Vienna, Austria
INTERNATIONAL ATONIC ENERGY ACQfCT November 1981 f
FINAL REPORT
Contract Number : 1866/R3/RB
Title of Project : URANIUM DISTRIBUTION IN URANIUM ORES AND THEIR RESPECTIVE SOURCE ROCKS.
Institute Where Research is Being Carried Out : Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum Wien, Austria.
Chief Scientific Investigators : Univ.-Doz. Dr. Gero Kurat
Co-Investigators : Dr.F.Brandstatter Lisa Pabst
Time Period Covered : January 16 - October 15, 1981 n -2- Description of Research Carried Out :
A variety of uranium ore samples from different localities was processed in the usual way : samples were cut and auto- radiographed. On the basis of these pictures areas were se- lected for thin sections. These polished thin sections were investigated microscopically in transmitted and reflected light and the most typical or most important areas were photographically documented. Selected portions have then been routinely analyzed using an ARL-SEMQ electron microprobe under standard conditions (15 kV accelleration, 15 nA sample current) Most of the analyzed areas have also been documented by secon- dary electron scanning images and X-ray scans for the most imporant elements present.
In this report we deal with the following samples : A : Saskatchewan, Canada. Karin Lake (72-a), Charlebois Lake (682-c and 730-b), Cup Lake (374-b), Wollaston Lake (1010-c), and Black Lake (796-a). B : Argentina. La Estela Mine, San Luis (Arg-2). C : Peru. Macujani, Carabaya (U-Peru-4).
Following are brief descriptions and documentations of the above-mentioned samples : 1 -3-
A Saskatchewan Six samples of uraniferous pegmatoids were recieved from the University of Regina, Regina, Saskatchewan (Prof.G.Parslow, Mr.D.Thomas) for microprobe analysis of the uranium phases. The geological field work and petrological studies have been done by David Thomas and have been published in his thesis in 1978 at the university of Regina and in several reports to the Saskatchewan D.M.R.Geological Survey. A publication of the combined data of his and our work is under preparation. Therefore we will concentrate in this report on our work and include only brief descriptions of the samples without dis- cussing the geological occurrence. Locations of samples are shown on the geological sketch map (Fig.1) taken from Thomas (1979).
Sample 72-a Locality : Karin Lake Pegmatite unit in lower pelite horizon overlying older (Archean ?) granite gneisses. Preliminary thinsection examination : Abundant small euhedral uraninite ? within or in contact with biotite. Molybdenite present. Electron microprobe analyses : Six areas within sample 72-a were studied in detail : Area 1 (Figure 2) shows altered ura- ninite (light-grey) and monazite (dark-grey) in silicate ma-
trix (black). The monazite contains ~15 wt.% ThO2 and ^4% UO2. The rim of the monazite crystal is slightly enriched in U. Area 2 shows a large uraninite aggregate of uniform composi- tion in silicate matrix. Area 3 (Figure 3) shows uraninite (medium grey), silicate matrix (black, mainly quartz) and a veinlet (dark-grey) which consists of apatite (?), pyrite (?), and of a secondary U-phase. Area 4 (Figure 4) shows an irregu- lar intergrowth of three U-phases : (1) a Pb-rich uraninite (light-grey), a thorian Si-poor U silicate (medium grey), and coffinite (dark-grey). The Pb-rich uraninite is apparently -4-
the primary U-phase, while the U-Th silicates are alteration products. Both area 5 and 6 show large unaltered uraninite aggregates. Typical analyses are given in Table 1.
Sample 682-c Locality : Charlebois Lake Quartz-rich end phase (quartzolite) of pegmatite unit in basal pelitic assemblage overlying older (Archean ?) granite gneisses. Preliminary thinsection analysis : Small euhedral crystals (0.1 - 0.25 mm) associated with biotite clusters. Idenification not possible, but presumably a silicate. Electron microprobe analysis : The euhedral crystals mostly enclosed in biotite are an unknown Th-Fe silicate. A typical example is shown in Figure 5, where a large Th-Fe silicate shows uranium and lead mobilizations. Uranium in the main part is always below 10% by weight but is enriched at the rim and in lamellae to over 30%. Lead segregated into (mostly euhedral) PbS crystals. There is abundant molybdenite and rutile associated with the Th-Fe silicate. Typical analyses are given in Table 2.
Sample 730-b Locality : Charlebois Lake Migmatite; tonalitic-granodioritic neosomal material Preliminary thinsection examination : Altered uraninite (?) associated with biotite seams. Electron microprobe analysis : Primary uranium minerals are desintegrated and altered to fine-grained complex intergrowths of U-Th oxides-hydroxides and silicates. They occur in nodules within biotites. There is also abundant uranophane present which is partly associated with the Th-U nodules and partly fills cracks within the biotite. A typical situation is shown in Fi- gure 6. Analyses are given in Table 2. Except for the uranophane, which occurs in fresh crystals and which is apparently very young, the analyses all have very low sums which is probably due to ex- tensive oxidation and hydratization.
-18- Figure 7 Secondary electron scanning image (SE) and X-ray scans fn-r n. Ph. anri Th of at-«aa A in samnle 374— b from CUD -5- Jt* J> ,_g 1 i-3 I^OW^tJS^^^o^C4 O > 3 iQ O P 1 O PPPO VQ(DK) 3* O H- H- U O (D U rtK) OOOOO'OOtoOO (D • CT P PO CO K) K) K) P O |— i •*"*> M Hi (D 3 (D • 3 P . — & 3 ? ^ P •• - I * C > H < P (D _h VD -» -J G 3 ^ LO UIOO ** O CO IO O O I^ H- P» -J • • • I* i* !•••• Ul £) P C IQ CTt Ul -» K) IO O OOOOO 3 3 (D *• '-» Ul -J *. -J H- p. 3 O H- U p rt- (D 3 -A VD . -* -J O pi CO Ul OO *» O O -4 U> O O Ol
P H- -^l Ul_t Qj 0 CTt -> K)OOOCOCnOCO *• ^ P 3 CO OO K) CO *>-OCTt-»COtO^-» Co CT OO K) *» CO •£>. O O (D P H- OO Ul -» 3 K) O -> -»OOOCT1VOO-» *^ IO "* VO VO CO CTtOUlOOOOO*. 3 -i -J K> Ul *. Ul OO H- 3 • (D Hf -4 Ul -» P Ul -A OOO COiUO*> l— t CTt * 1» !••• I*««« ^^ Ol _A ' O CO *. -i Ul K) -J -» CTt ^K^> ^k CO VO -» CO *>• VO K) H> K O 3 -6- 1 l P > i-3 3 OWQ!S 4
Ul -» OJ Q W OO K( -J (Tt O OJ tOO->O->*>.O-i X , P Nl O I OO 9 I *»1J O OJ DJ S •O O ojo -> H- Ol -20- Figure 21: Secondary electron scanning image (SE) and X-ray scans n -7- Sample 374-b Locality : Cup Lake Quartzolite; quartz rich and phase of granitoid pegmatite in graphite pelite assemblage directly overlying older (Archean ?) granite gneisses. Preliminary thinsection investigation : Uraninite-like (altered) phases associated with biotite and secondary U minerals. Electron microprobe analysis: Two types of U mineral associations occur in this sample which are illustrated in Figures 7 and 8. Area A (Figure 7) shows a typical complex intergrowth of Pb-rich U-Th oxide and Th-U silicate enclosed in biotite. Area B (Figure 8) shows the association of uranophane and an Fe-U silicate with pyrite. Typical analyses of all phases are given in Table 3. Sample 1010-c Locality : Spurjack Island, Wollaston Lake Mafic pegmatoid phase with coarse-grained hornblende, diopside, and scapolite in calc-silicate unit. Preliminary thinsection examination : Uraninite (?) associated with molybdenite (?); abundant secondary yellow U-mineral. Electron microprobe analysis : The most common U phase is urano- phane which is intimately intergrown with diopside and hornblende, and commonly also with other U and Pb phases. A typical associa- tion of uranophane, U-Ca silicate, and an unknown Pb-X mineral is shown in Fig.9. A kasolite-like mineral tends to occur iso- lated. Analyses of all phases are given in Table 3. Sample 796-a Locality : Pluto Bay, Black Lake Honzogranite Preliminary thinsection examination : Tiny uraninite crystals in biotite grains; radioactive zircons and monazite (?). Electron microprobe analysis : The major U bearing phase is urani- nite which has variable amounts of Th and Pb and also appears to be altered to variable degrees. Minor amounts of U reside in a Ql ^* i~3 23 ^O W ("5 S ^J ^3 i"3 *~r 1-3 0} tn 25 v ^q " ij^ (^J o oi ty DI Oi vQ (D 10 ff o H- H- Ql Q ff Ol (D *Ö rt (O OOOOOO Oto O O D* PJ 0> O OJ to 10 10 •d O o) H l«j M M1 (D (D —3 (KD (D • 3 Oi OJ i< rf 3 • Oi • • * O > *0 (D _». OO -» CTl O G CO U •b (O OIO OOOOOO-»OO > X t **^ — * H- VO OO O -J OOCTIOOO-»O CTl PJ 1O IV (D OUl UICTlVOib ib —J (D H1 (D PJ (D Oi . tn ^ U> 0> 3 -J IO -» IO H- ff -J 3 PJ •b OJ OOOOOIOOOOU1OOJ H» I ib DJ / ON (O OJ OJ -iVOOOOOOVOOOJibCTlN) O I I O) (D -JIOibtO^OUlVDOO O Oi rl- c" g (D (D •Ö O H« rt to OO CTl-* (O frj (D (D IO VOOib O O O O OJOVO (D OO . - . I .... I ... W *> E l .^ ^A -jooo (o -» ~j o ooovo G o oi CTl ib -J OJ ib OO O i -» 3 rl- O Oi (D O •< OO CTl -» •O G D) ib O O O Ul O -» O ibOM 1 Mi (D BJ to ^S ^S CO OO OOOtOOJOJO OO -i OO 3 3 O VOVDUlUl Ul-Jib ib (D O g o O C VO -J -» »a G CO MM, -»O OCTlOOO (OOOJ Ol M P /Sl M ^ 3 »J* t-> OO (O O O O -» O OJ O -» 3 ö •O1 B) H- -JO CTl Ul O OJ OJ (D O H rt HI I (D O (D 1 -J lb -» £ ' o r c -1 OJ OOOibOOJOOCTIOOO —» Ol O) H- o? O^cr«« O i 1 O ibOO-»IOIOOOOJOUl Ol (D O OibOOIO -J UlIO IO _L I - ff (D Oi lit O CO O) 0 (D OO (O ib -» H- = O) (O Ul O*^]OOOOO CT1O«1 W IvK*I mVl? *-*fr • QCl Ol H- OJ (OOOMOibO (O O -» (D O) rt 3 -^O OJ ib OJ —» Ul Ul sO O I P1O) (D Ol OJ OJ P 1U cn o oj o o oo (oo-> 'U. 3 M I « .... i*. !••« &. _j, Cr ^ (D U) -» O O *. ibib CTlOO _ ib ~^ OO fb ib OO CTI **J CTl DO) O^J P3l *>I• OM O" • Ml O 3 . - Karin Lake, Sample 72-a/Area 1 -9- U-silicate which typically fills cracks and in small zircons which are rich in Th and U. Large zircons are free of Th and contain very little U. A typical occurrence of uraninite and zircons is shown in Fig.10. A detailed picture of uraninite small zircon association is given in Figure 11. Typical analyses are given in Table 4. Summary All analyses of U bearing phases encountered in our-six samples from Saskatechewan are plotted in Figures 12-15. Apparently, there is a variety of U bearing phases present, the analyses of which do not always correspond to known uranium minerals. The large variety is, however, mostly due to degradation of a few primary phases and formation of secondary silicates thereof. This relationship shows up clearly, if the apparent U-Pb ages are calculated (Fig.16). The most common primary U: mineral is uraninite. Except for the dubious Fe-U-silicate in sample 374 ("age" 2.300 m.y.) the urani- nites appear to be the oldest uranium 'minerals encountered. In three different samples they show U-Pb ages around 1.400 m.y. (samples 72 granodiorite, 374 quartzolite, and 796 monzogranite). Although degraded to somewhat different degrees, the uraninites are chemically similar in all three rocks. Among the elements we looked for only ThO, is constantly present in appreciable amounts (7-8% by weight). In sample 796 (monzogranite) there are three genera- tions of uraninite or pitchblende present which have different Th contents and different apparent U-Pb ages : ThO, 8%,1460 m.y.; ThO2 9%, 940 m.y.; ThO2 11%, 700 m.y.. Monzogranite 796 is the only example encountered where U-Th oxide has been formed during later than the 1.400 m.y. events. In general, later events are marked by the formation of U-Th silicates. In granodiorite 72 U-Th silicates with ThO2 contents between 3 and 17% formed from around 1200 m.y. up to almost present time. Karin Lake, Sample 72-a/Area 3 V. -10- P > ,.g V tu Tl < )-3 G t3 (Ii & & Quartzolite 374 has a 460 m.y. (uncorrected for Th content !) Th-U silicate, indicating a U mobilisation and depletion event, and apparently recent formation of uranophane. The monzogranite 796 has in addition to the dubious Fe-U silicate {which could also be a late product but because of the possible acceptance of Pb into the lattice gives a very high apparent U-Pb age) and the three generations of uraninite an apparently recent high-Ca and Th-free U silicate. Interestingly, the small zircons present in this rock apparently have the same age as the oldest uraninite ( 1.500 m.y.) which very probably is the crystalliza- tion age of the rock. The large zircons are too poor in ü {and Pb) for an age determination via microorobe analysis. The remaining three samples of our. suite from Saskatchewan do not contain uraninite and (probably consequently) are dominated by younger U bearing phases. Migmatice 730 contains an unknown U- Th-X oxide (770 m.y.), Th-U silicate (460 m.y.) and recent urano- phane. Quartzolite 682 contains only two young phases, a 340 m.y. (?) Th-U-Fe silicate and a recent U-Th silicate. The mafic pegmatoid 1010 contains only phases of recent age : uranophane, kasolite,and an unknown Pb-X mineral. In summary, the Saskatchewan samples appear to be of super- metamorphic origin and were formed in such events around 1.400 to 1.500 m.y. ago. Subsequent mobilization and recrystallization events which probably took place around 750 and 450 m.y. ago led to the formation of a variety of U-Th-Fe silicates. Even younger events lead to the formation of mainly uranophane and minor amounts of U-Pb-Fe phases. Since all samples come from within the Cree Lake Mobile Zone (compare Lewry and Sibbald, 1978) it is nou surprising that the primary uraninites still preservered are of late Hudsonian age. Thus, the mineralizations in mobilisates of the Hudsonian oro- geny (pegmatoids, granites, quartzolites) are apparently syngene- tic and document the effectivity of uranium mobilization and reprecipitation during ultrametamorphic events {low degree anatexis in wet environment). The lower ages of approximately 1.000, 750, and 450 m.y. thus could represent lower temperature tectonism within the Cree Lake Mobile Zone. Charlebois Lake, Sample 682-c/Area A -12- References Beck, L.S.(1969) uranium Deposits of the Athabasca Region Saskatchewan. Sask.Dept.Min.Resources Rept, 126. Lewry, J.F., and T.I.I.Sibbald (1978) A review of pre-Athabasca basement geology in northern Saskatchewan. In : Uranium Exploration Techniques (G.R.Parslow, ed.), Saskatchewan Geol.Soc., Spec.Publ. no.4,pp 19-53. Thomas, D.J.(1978a) Uranium metallogenetic studies : Charlebois Lake and Cup Lake. In : Summary of Investigations 1978, Christopher, J.E. and Macdonald, R.(eds.); Sask.Geol. Surv., pp 66-73. Thomas, D.J.(1978b) The geology of the Compulsion River area, Saskatchewan. Thesis, University of Regina- Thomas, D.J.(1979) Uranium metallogenetic studies, "pegmatite" prospect geology. In : Summary of Investigations 1979, Christopher, J.E., and Macdonald, R.(eds.), Sask. Geol.Surv., pp 86-95. -13- B Argentina One sample of a rich U ore from "La Estela" mine, San Luis Province, Argentina, was provided by Dr.P.Stipanicic, IAEA (Sample Arg-2). The sample is a core sample of a brecciated syenite, consisting mainly of red K-feldspar and grey plagioclase, which contains a • brown-black striated "vein": This "vein" (mineralized shear zone or mini-fault?) is highly active. Autoradiography shows abundant bright ' spots within a lower cloudy activity. There is no detectable acti- vity outside this zone. According to Dr.Stipanicic, the syenite is of metasomatic origin and is located within Hercynian granite. The mineralized zone consists of fragments of feldspar, euhedral pyrites and bent strings of uranium minerals embedded in a fluorite- rich matrix (Fig.17). Figure 18 shows in detail the uranium minerali- zation from within the central portion of Fig.17. The only uranium mineral present is a U silicate with varying U/Si ratio, which is either approximately 5:1 of 3:1 (Table 5, Figure 19). The chemical composition apparently is in between pitchblende and coffinite but could represent two different silicate phases (note the clusters in Fig.19). In figure 20 very similar U silicates are documented which occur together with fluorite and pyrite. Analyses are given in Table 5 and projected in Fig.19. In Figure 21 an intergrowth of U silicates with fluorites enveloped by silicates is shown. Summary : The principal U mineral present at La Estele mine can be defined as a SiO2~rich pitchblende or a 5:1 to 3:1 (U:Si) silicate. This U mineral is generally very low in Pb and therefore very young. There are some indications of older ages, although also very young, which, however have to be taken very cautiously. The low Pb contents and the absence of Th indicate a supergene origin. -14- 1 Table 5 s Averaged and selected electron microprobe analyses of uranium silicates from sample ARG-2, La Estela Mine, Argentina (in weight-%). Area A/1 A/ 1/4 A/1 A/1/7 A/2 B/1 No. of anal. 2 1 2 1 6 6 SiO2 4.1 4.2 7.3 7.7 5.0 5.6 fi°2 0.29 0.28 0.24 0.33 0.32 0.89 UO2 77.2 76.2 72.4 77.3 79.0 79.0 ThO2 - - - - — — V - 0.03 2°3 — — — — MgO 0.06 0.09 0.07 0.09 0.07 0.04 FeO 1.15 0.97 0.84 1.13 1.20 0.80 CaO 3.6 3.2 2.65 2.8 2.94 1.97 BaO 0.05 0.06 0.03 0.11 0.06 0.05 - PbO 0.24 0.06 0.04 - 0.02 Na2O 0.14 . 0.13 0.10 0.10 0.14 0.27 Total 86.83 85.19 83.63 89.63 87.73 38.64 Apparent age (m.y.) 24 6 O 4 O 2 -15- C Peru Several samples of uranium ores from Carabaya, Peru, were provided by Dr.P.Stipanicic, IAEA. The rock is a volcanic tuff which is very richely impregnated by a yellow mineral. Autoradiography shows abundant strong but diffuse activity. In thinsection (sample U-Peru-4) the highly glassy tuff shows U phosphate filling many of the abundant voids. Figure 22 gives a typical example. The U-phosphate is coarse grained and has a somewhat variable compo- sition throughout the thinsection. Thre is a K-rich and a Ca- rich variety. Analyses are given in Table 6. All analyses are plotted in Fig.23. The U mineral present in U-Peru-4 apparently is not a common autunite as was suggested by the geologists from Peru. It is a related mineral, with a (1/2 K + Ca)/U ratio of 0.72:2.07. The K-rich mineral has a (1/2K + Ca)/U ratio of 0.56: 2.16, very similar to the Ca-rich phase. The Ca-rich phase has a Ca deficit as compared to stoichiometric autunite and in addi- tion has a surplus of U. It threrefore is probably an autunite with part of the Ca being replaced by K and U. The U surplus and the (Ca + K) deficite is even more pronounced in the K-rich variety. We have to conclude, that U is present mostly in the oxidized (+6) state but partially also in the reduced (+4) state. Thus the environment must have been more reducing that that in which autunite normally forms. All phases are Pb-free and there- fore of recent age. WoHaston Lake, Samote 1010-c/Area R I I -16- Table 6 : Averaged electron microprobe analyses of U phosphate from sample U-Peru-4, Macujani, Carabaya, Puno, Peru (in weight-%). Phase U phosphate K-rich Ca-rich No.of Anal. 8 5 SiO2 1.25 1.22 TiO2 0.02 0.06 UO2 65.3 62.4 ThO2 MgO 0.05 0.06 CaO 2.00 4.1 PbO CuO BaO 0.36 0.03 Na2O 2.60 0.64 Total 71.58 68.51 -17- Figure captions Figure 1 Geological sketch map of the Cree Lake Mobile Belt, northern Saskatchewan (from Thomas, 1979) Figure 2 : Secondary electron scanning image (SE) and X-ray .scans for U, P, and Th of area 1 in sample 72-a, Karin Lake, Saskatchewan. Strongly altered uraninite and monazite in silicate matrix. Figure 3 : Secondary electron scanning image (SE) and X-ray scans for U, Fe, and Si of area 3 in sample 72-a, Karin Lake, Saskatchewan. Formation of secondary uranium phases on surface of a large uraninite crystal (high U) and at sites where partly oxidized sulfides (mostly pyrite) are located. Figure 4 : Secondary electron scanning image (SE) of area 4 in sample 72-a, Karin Lake, Saskatchewan, uraninite (white) is transformed into thorian coffinite (light gray) and marginally into Si-rich coffinite (dark grey). Black .are silicates. Figure 5 : Secondary electron scanning image (SE) and X-ray scans for U, Th, and Pb of area A in sample 682-c from Charlebois Lake, Saskatchewan. Uranium and lead phases apparently exsolved from uraniferous thorite. Figure 6 : Secondary electron scanning image (SE) and X-ray scans for U, Si, and Th of area 1 in sample 730-b from Charlebois Lake, Saskatchewan, Canada. Finegrained intergrowths of Th-U oxides-hydroxides and silicates rimmed by albite and enclosed in biotite. The most U-rich phase is uranophane which typically fills cracks within the biotite. I UHtYVMIN -18- Figure 7 : Secondary electron scanning image (SE) and X-ray scans for U, Pb, and Th of area A in sample 374-b from Cup Lake, Saskatchewan, Canada. Thorian uranium oxide (white) with Th-U silicate (grey) in biotite (dark). Note the high Pb contents of the U oxide phase. Figure 8 : Secondary electron scanning image (SE) and X-ray scans for U, Fe, and Si of area B in sample 374-b from Cup Lake, Saskatchewan, Canada, Uranophane (white) intergrown with pyrite and an apparent Fe-U silicate forming around the sulfide. Figure 9 : Secondary electron scanning image (SE) and X-ray scans for U, Si, and Pb of area 5 in sample 1010-c from Wollaston Lake,Spurjack Island, Saskatchewan, Canada. Uranophane (light grey) partially mantled by Si-rich U-silicate (grey) and an unknown Pb mineral (white). In places the phases are intimately intergrown. Figure 10: Euhedral zircon (left edge) and uraninites (black) in mica of sample 796-a from Black Lake, Pluto Bay, Saskatchewan, Canada. Transmitted light; width of picture is 2 mm. Figure 11: Secondary electron scanning image (SE) and X-ray scans for U, Si, and Th of area B3 in sample 796-a from Pluto Bay, Black Lake, Saskatchewan, Canada. A small zircon (dark grey) is attached to an uraninite (grey; the smaller uraninite in Fig.10). Note the in- homogeneous U distribution in uraninite and the similar Th contents of uraninite and zircon. Figure 12: Projection of analyses of U-bearing phases from samples from Saskatchewan, Canada., onto the U-Si-Ca plane (in atomic proportions). The most important clusters are indicated by the most common phase name. L -19- Figure 13: Projection of analyses of U-bearing phases from samples from Saskatchewan, Canada, onto the U-Si-Th plane (in atomic proportions). Names as in Fig.12. Figure 14: Projection of analyses of U-bearing phases from samples from Saskatchewan, Canada, onto the U-Si-Pb plane (in atomic proportions). Names as in Fig.12. Figure 15: Projection of analyses of U-bearing phases from samples from Saskatchewan, Canada, onto the U-Si-Fe plans (in atomic porportions). Names as in Fig.12. Figure 16: Apparent U-Pb ages of U-bearing phases in .U ore samples from Saskatchewan, Canada. Numbers are sample numbers. Figure 17: Photomicrograph of a typical area within the minera- lized "vein" in syenite from La Estella Mine, Argentina. A : Transmitted light. B : Relfected light : Uranium mineralization in center (light grey) in fluorite plus silicate matrix (dark grey). Abundant pyrite (white). Width of pitures is 2 mm. Figure 18: Secondary electron scanning image (SE) and X-ray scans for U, Ca, and Si of area A/1 (central portion of Fig.17) in sample ARG-2 from La Estela Mine, Argentina. Massive uranium mineralization is situated at the inter- face between fluorite (high Ca) and silicates (feldspars, mica, and quartz). Figure 19: Projection of electron microprobe analyses of U minerals from sample ARG-2, La Estela Mine, Argentina, onto the U-Si-Ca plane (in atomic proportions). Figure 20: Secondary electron scanning image (SE) and X-ray scans for U, Ca, and Si of area A/2 in sample ARG-2 from La Estela Mine, Argentina. Uranium silicates are intergrown with quartz and feldspar and accompanied by fluorite (high Ca) and pyrite (medium grey in SE picture). -20- Figure 21: Secondary electron scanning image (SE) and X-ray scans for U, Si, and Ca of area B/1 in sample ARG-2 from La Estela Mine, Argentina, uranium silicate is inter- grown with fluorite (high Ca). Figure 22: Secondary electron scanning image (SE) and X-ray scans for O, K, and Si of area 1 in sample U-Peru-4 from Macujani, Carabaya, Puno, Peru. Uranium phosphate fills voids in glassy tuff. Figure 23: Projection of U-phospha.te analyses from sample u-?eru-4, Macujani, Carabaya, Puno, Peru, onto the U-Si-Ca plane (in atomic proportions). L_ FIs. ' Geological sketch rap of -he Cree Lake Mobile E=It, northern Saskat- chewan. Areas investi- gated during the project zre shown by stars. Kerned in 1979: l, Karin Lake; 2, Pipewrench Lake; 3, Pluto Bay, Black Lake. Sapped in 1978: 4, Char- lebois Lake; 5» Cup Lake. 1010-C CMC IA« HOM.E MtT WESTCWf GHMHM.TC I LAtC /*O»tK*MEMATtCMUPiONiAN KUTONS mmWTOhE DOMMN. WATHMMHMTHQLnH 1U*-««C»U5TM. HOCK* (AMCMMTI MWlUlAlU-GNf«AS ANDIMSCi HOCK3 —i UhDKFEMNTtATH)CN WiTOWS AND MCMUTlf CS OfIMVTC AOCKS W(TM MPtOB SUTMCMMTMS r Figure 1 LA ESTELA Karin Lake, Sample 72-a/Area 1 Fig. Sample- ARG-2, Area A/1 Karin Lake, Sample 72-a/Area 3 100 pm Fig.3 SASKATCHEWAN Sample 72-a/Area 4 Karin Lake 100 Fig. 4 Sample ARG- 2, Au-f! A Charlebois Lake, Sample 682-c/Area A U 100 Fig. 5 Sample- ARG--2, Aren B/1 Charlebois Lake ,Sample 730-b/Area 1 100 F L q . 6 Cup Lake, Sample 374-b/Area A 100 Fiq.7 Cup Lake, Sample 374-b//Area B Fig.8 Wollaston Lake, Sample 1010-c/Area 5 SASKATCHEWAN Black Lake, Sample 79R-r Fiq. 10 i untvv AN Black Lake, Sample 796-a/Area B 3 L_ LH SASKATCHEWAN -f Ü72R 57336 UlGlC < U37L-B 7. U5CS2 * C79BR / «r uranopiiane \ Pitchblende/* * x "'"*$a ' *-*x \ • f*~Jr- ••" "* * "- -* ? A\ r TlT-^n i ni 1-<3 ^M*1* »., „ * ., t ., *" + -L^ .tJV..** ." "- $•,"^" *~"~'^' r •'--iÄ*^" • „y.- \S Th silicates U U-Silicates 51 Fig. 12 TH SASKATCHEWAN U?2? =-> •-- -- £2 S /^uD UlSlS Ü371B US682 U796H Th silicates Pitchblende + Uraninite U U silicates SI + Uranophane Fig.13 SASKATCHEWAN U720 S732B UiGi1S iJ37 U-Pb-silicate *>'••••., ''- üraninite pitchblende: ,-^ -w JE Th silicates U-silicates + U uranophane 51 Fig.14 SASKATCHEWAN * Ü72P, X- 573SB ^ ÜiSl© s US6S2 •> U79SR Th-Fe-silicate Pitchblende Üraninite LJ U Silicates SI Fig.15 (O O) . O (O O LU CM jQ o> Q. C I OI ? if (O Z ccco (O £o CO IT3t Su. V- •+•* < a CO < (O CO 0 MXMX Figure 1 T »< LA ESTELA Sample ARG-2, Area A Sample ARG-2, Area A/1 100 r111 Fig.3 1 L/—- h,'-, LA ESTELA U SI Fig. Sample ARG- 2 U A . 100 pm Fdg.: Sample- ARG-2, Aren B/1 100 Fiq.6 Sample LJ-Peru-4, Area 1 Xti^f.%*-:^-- ': "^rVi*4i*w-** Pb 100 Fiq.7 . h MACUJANI U SI Fig.