INTERNATIONAL ATOMIC ENERGY AGENCY

COMISSÃO NACIONAL DE ENERGIA NUCLEAR

EMPRESAS NUCLEARES BRASILEIRAS SA.

INTERREGIONAL TRAINING COURSE

ON

EXPLORATION DRILLING AND ORE RESERVE

ESTIMATION FOR URANIUM DEPOSITS

APRIL 22 -MAY 16,1985POÇOS DE CALDAS, MINAS GERAIS

BRAZIL

INTERNATIONAL ATOMIC ENERGY AGENCYNUCLEBRÂSCOMISSÃO NACIONAL DE ENERGIA NUCLEAR

INTERREGIONAL TRAINING COURSE ON EXPLORATION DRILLING ANDORE RESERVE ESTIMATION FOR URANIUM DEPOSITS

POÇOS DE CALDAS - BRAZIL

APRIL 22 - MAY 16 / 1985

BRAZILIAN URANIUM DEPOSITS

L.C. SURCAN SANTOS

NUCLEBRÁS - BRASIL

BRAZILIAN URANIUM DEPOSITS

L.C. SURCAN SANTOS

NUCLEBRAS -BRAZIL

BRAZILIAN URANIUM DEPOSITSL.C. SURCAN SANTOSNUCLEBRAS - BRAZIL

For a period of about thirty years, since the creationof the Comissão Nacional de Energia Nuclear (CNEN) wich was su-perseded by NUCLEBRÃS, the systematic uranium exploration inBrazil led to the discovery of several uranium targets.

Many of them were developed to the stage of drillingand can be considered as promising uranium concentrations or de-posits like Amorinõpolis (Devonian sediments) Campos Belos / RioPreto (faulted and folded précambrian) and Alecrim (albitites) inGoias state; the quartz-pebble conglomerates in the QuadriláteroFerrTtero, Minas Gerais state (Gandarela and Gaivotas Projects);cretaceous sediments of Tucano Basin in Bahia and others.

Here it will only be considered the areas in wich de-tailed ore reserves calculations were made, in others words, theuranium ore deposits as such.

These are: Figueira, Itataia, Lagoa Real and Espinha-

ras.

Poços de Caldas that is under mining operation willbe discussed elsewhere in this course.

LOCATION OF URANIUM MINES AND ORE DEPOSITS

ITATAIACRE DEPOSIT

ESPINHARASORE DEPOSIT

FI3UEIRAORE DEPOSIT

LAGOA REALORE DEPOSIT

CERCADOMINE

URANIUM RESERVES (METRIC TONS OF U 3 0 8 )

ORE DEPOSITS/MINE

1 . CERCADO MINE (OSAMU UTSUMI}

2 . F I G U E I R A • • - - - •

3 . ITATAIA PHOS- URANIFEROUS PROVINCE "

4 . LAGOA REAL UP.AKiF-ROUS PROVINCE

5 . ESP1KHARAS A

6 . OTHER DEPOSITS

TOTAL

RESERVE CATEGORIES

Ri-ASO'JABLYASSURED

20.000

7.000

91.200

61.840

5.000

7.500

192.540

*::sTivi.TEDADDITIONAL

6.800

1.000

51.300

31.350

5.000

13.500

108.950

TOTAL

.26.800

8.000

142.500

23.190

10000

21.000

301.490

IAEA CUÍSIFlCiTIOM A N'JCLMI DECEI/3ER/84

FIGUEIRA DEPOSIT

The Figueira deposit is located in the north earstern PJJrani, about 5 km from the village with the same name. It coversan area of 3 knr along a north-south strip. (FIG. 1)

Mineralization is found in sandstones and carbonaceoussediments of the Rio Bonito sedimentary Formation (Per.nan).

1) EXPLORATION HISTORY

In 1956, during examinations of coal samples existing incollection of the Brazilian Geological Survey (DNPM), it was foundanomalous radiation in one sample that comes from the Rio do PeixeCoal Field in Par.nS.

During 1956 to 1959 a sistematic sampling of coal occu£rences in Parana was done looking for anomalous radiation .withoutsucess.

In 1969 prospection in the Parana Basin was restarted witha different; approach, looking now for favourable geological. en_vironments for uranium concentration.

The deposit was discovered following this systematic su£vey of the co3l basins of southern and southeastern Brazil. The

detailed work began in 1969, and environments favourable for uranium were determined from the interpretation of drill cores.

As a result, four areas (Ibaiti, CuriGva, Sapopema andFiqueira) were selected for exploration drilling.

During 1970 to 1971 a drilling programme with largespacing

was carried out (23.800m) and Figueira became the more promising

target.

During 1971 to 1972 50.000 meters of close spacing (400 x200 m) drilling was done in selected areas showing already thecontours of the Figueira deposit.

FIG. 1

THE FIGUEIRA ORE DEPOSIT

LOCATION MAP

200i

400i

600 800i

1000 Kmj i

1 6 ° - is;

20'

1 28°

54° 48° 42°

During the following years (1973-1974) a fill in drillingwas carried out in order to estimate the ore reserves (40.800 meters).

In 1977 a pre-feastbility study for mining and millingin the area was concluded, and underground workings (includingshaft and galeries) were done during 1978 and 1979 in order tosuply ore samples for processing plants of yellow cake productionand also as support for feasibility studies and mining planning.

2) GEOLOGICAL SETTTMG

The Figueira area lays on a paleotectonic structure ofthe Ponta Grossa arch.

The local stratigraphy consists of sediments of periqljicial, lacuster and marine environment represented by diamictites,shales and sandstones of Itararé Group.

Overlaying Itararé sediments occurs the Rio Bonito Fonnation.

The Rio Bonito Formation varies in thickness from 120 to130 m and was divided into three stratigraphic intervals basedon electric and lithological loqs. The basal interval (15 to 30 m)is composed of very fine grained to conglomeratic sandstones whichare light to dark grey in colour with intercalations of arkoses,siltstones, coal, dark shales and occasional beds of grey limestones. These sediments frequently possess a calcareous cement inaddition to pyrite. This interval has been interpreted to havebeen deposited in fluvial channels^on flood plains and in swamps.The middle interval (85 m - ) , consists of grey, green or yellowsiltstones intercalated with varieqated marls and light to mediumgrey limestones. White to red sandstones, characterized by paraj^lei lamination are also found in this interval. These sedimentswere probably deposited on a marine shelf below wave base. Theupper interval (- 20 m\ consists of very fine grained laminatedsandstones with intercalations of siltstones. These sedimentswere probably deposited on the shallow part of a shelf or closeto the shoreline. (FIG. 2).

FIG. 2

STRATIGRAPHIC COLUMN OF THE FIGUEIRA REGION

CHROCSTRA-

aw

1

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O

N

O

LU

<

d.

SYST

EM

Z

Ui

a.

tA

IK

inU

PP

ER

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LO

WE

R

UTHOSTFUTISRAPHY

GROUP

SlO

Q

«3V*

PA

S

o

a

=>

F0PVAT10N

SE3RA

ALTA

IRATI

PALERMO

RIO

90NI70

1 \Ur.U-il

THICK-NESS

50

4 5

SO

120

0

130

7 0 D

LITHOLOCY

I V I ' i 'r'i lr

• - .._-.._• . •

—

i • i i i ii i i i i i i

i , ; i . i

1 — • —

.

; i , . .

! • • 1 1 1

I I I i l l

' . . - • . • . • . ' < - . ' • ' . :

0 O D O O C

• • • . ' / ' ' . ' ' • • • ' • .

O O O O O OO C O C O

0 . 0 O C O> o o ' o ' o' c

* LITHOL03ICA4.

DESCRIPTION

ARGILLITE.DARK GREY

LIWiSTON- ,DARK GBEY , ARGIL

LITE, BLACK,SHALES,3ÍTU-

UINOUâ.

SASDSTOKE.FiNE 5RAiN£D,SIL-

TSTONE, SANDY .GREY- GREEN,

BI3TUS3ATEC WITH SILICE-

OUS K^IZONS.

SiNDS7CN-,WHIT!SK TOYEL-

LDW.FINE GRAINED .StLTSTO

NÍS ANO MAftLS.G^EEXSK TU

3r?0Wh * I T H IfcTERCALAT)-

C-fíS 0? GREY.LIUESTDNES

ÍSD SHALES , tAhSSTrNES,

tELLO«!Sh TCGftET.flHE

TO C0ARS3 GRASSED *iTH

HD»;r3»«5 OF CCAL AT THE

£ASE .

W^TUEí.AM, FrllTíiHÚ Ufc

t-sTÍNESiSHA-.ES.FíKcLV

AS" SMíTCSES

SEULC£>-

TAJty srntc

TURES

PARALLEL

LAKtKATOH

PARALLEL

LAUlhATlON

i^ECULAPLAW

SATION.atOTlR

««4LLELLA

UIKATIOM, -'LASER STKJC-

AND J B . I ^ C

TiOlk.

PARALLEL LA-

S H STRUCTU-

R E KiHKS,

W í STPJCTÜ-

RSS IN OiAMC-

1ITES

DEP0S-

TOMALEMW

ROHMEJiT

RESTRICTED

UAS:H£

RESTRICTED

KA8INE

RESTRICTED

MARINE

SIV Í .BAR;*

TRAXSGKESSI

TAi. FLJViAl

AIS DELTAIC

GLACIAL MAR)

KE WiVk TLi»-

6iWTES.CH-

TiSÍNTALrtU

VUL AHD lâ-

K i- »»*0- :»T4

3) URANIUM MINERALIZATION

Uranium mineralization occurs in the basal sediments ofTriunfo member of the Rio Bonito Formation, it has then a clearstratigraphic control.

The Triunfo Member wich has a thickness of 15 to 30 metersconsists of sandstones interlayred with shales, sil ts tones, arkosesand coal layers.

It is subdivided into there local units with the followingpredominant lithology (FIG. 3 ) :

Unit A - shales, siltstones with coalUnit B - sandstonesUnit C - shales, siltstones and limestones (including

a datum layer).

Uranium concentration is restricted to the level betweenthe coal layers of A unit till the calciferous layers of C unit.

Mineralization is associated to carbonaceous sandstones,siltstones and mudstones and also to coal itself. Uranium is pr£sent as uraninite in sandstones or linked to organo-mineral complexes.

Elements like molibdenum, lead, sulphur, zinc and copoerare found associate with uranium, in minor amounts.

The uranium of the Figueira deposit is thought to havecome from the reworked sediments of the Itararé Formation (PermoCarboniferous) which contains boulders of the precambriam basementwith anomalous concentrations of this element.

An important factor in the genesis of the Figueira mineralization was the local development of several types of depositionalenvironments in response to regional tectonic arching. Theseenvironments had distinct paieogeographic limits, sediment- typesand mineralization characteristics.

FIG. 3

THE FIGUEIRA ORE DEPOSIT

BASAL SECTION OF THE RIO BONITO FM.-DRILL HOLE 64/G

DEPTH 102,00 m

COO cpt - •

The m ine ra l i za t i on which occurred in the basal sediments

of the Rio Bonito Formation was the resu l t o f both syngenetic and

ep igenet ic processes. The syngenetic m inera l i za t ion occurred in

swamps conta in ing f i ne grained sediments r i c h in organic mater ia l

wh i le the ep igenet ic m ine ra l i za t i on developed in the f luv ia l -de l ta ic

environments in which the sedimentat ion was mainly of a sandy chaj*

ac te r w i t h i n t e r c a l a t i o n s of arg i l laceous and carbonaceous materj^

a l .

The formation of the epigenet ic uranium fo l lowed a sequeirc

ce of phases invo lv ing t ranspor t and deposi t ion which may have

occurred both before and a f t e r diagenesis of the host rocks.Ground

water of a s l i g h t l y a l ka l i ne nature nay have remobi l ized the U+

uranium t ranspo r t i ng i t in the U (ox id ized s ta te) to reducing

environments where i t was redeposited in geochemical c e l l s .

The main ore body i s l e n t i c u l a r in shape and accompanies a

nor th-south t rend ing paleochannel. The body is about 3000m long

and an average of 600 m wide (FIG. 4 ) .

In the mineral ized u n i t , uranium is associated w i th sanjd

s tones, s i l t s t o n e s , c lays , and carbonaceous sediments inc lud ing

c o a l . In the sandstones the uranium occurs in the form of uranini^

te in a calcareous cement in the i n t e r s t i c i a l spaces. In the s i H

stones, carbonaceous clays and coa ls , the uranium m ine ra l i za t i on

occurs in the form of organo-mineral complexes of phosphate, barium

and uranium, m inera log ica l l y c l a s s i f i e d as u r a n o c i r c i t e . In the

uran ium-r ich zones, the concentrat ions of I^Og vary from about 0.2

to 0.5? and average 1.5 to 3 .5m in th ickness. The p r i n c i p a l ac

cessory minerals include p y r i t e , j o rc is i ce , galena and cha lcopyr i te

along w i th sulphides of arsenic and thor ium- r i ch m inera ls .

Present reserves are 8,000 tonnes U30g from which 7,000

tonnes are reasonably assured.

FIG. i

THE FIGUEIRA ORE DEPOSITISOACCUMULATION MAP

LEGEND

. DRILL HOLE

ACCUMULATION'

< IOOO 1900 3300 ' 4300 *

ppm U3Q8XR1

0 100 200 300 «00• • » _J 1 •

ITATAIA URANIFEROUS PROVINCE

The I t a ta i a region is located about 170 km west of Forta

leza, in the central part of the State of Ceará,NE Brazi l (F IG . l ) .

The climate there is serai-arid a l l year round. I r regular r a i n f a l l

may occur from January to Apr i l and average r a i n f a l l is less than

500mm. Consequently, good and extensive fresh rock exposures are

a commom feature.

1) EXPLORATION HISTORY

Systematic invest igat ion of the Precambrian basement in

the State of Ceara began with a carborne radiometric survey in 1975.

This survey covered an area of 35 000 km in the north-central part

of that s ta te . The results of th is survey included the discovery

of 273 anomalies during 11 167 km of radiogeoloqical p ro f i l es

along roads and t racks. The equipament used included a portables

sc in t i l lometer SRAT-SPP-2 mounted on a four-wheel-drive vehic le .

Twelve anomalous areas (FIG. 2) were selected for further

study on the basis of commom qeoloaical factors, qeometry and chemi_

cal values. Al l twelve areas had hiqh values of UjOg (1000 to 3000

ppm U30g and 12% to 30% P2°5)» a n d w e r e related e i ther d i rec t l y or

i nd i rec t l y to vuggy, quartz-poor, fe.ldspathic rocks. The areal

d i s t r i bu t ion of th is unusual rock drew attention to the probable

regional character of the mineral izino event. The unusual rocks

were cal led a lb i te-syeni tes on the basis of the i r mineral content,

spec i f i ca l l y the absence of quartz. The mineral ization was conse_

quently related to alkal ine rocks. This approach was la te r shown

to be incor re t .

One of the anomalies discovered during th is "Tar- mounted

survey was no more than a single boulder lying on a dry stream bed.

The boulder was about 50 cm in diameter, reddish in colour, dens?,

massive cryptocrysta l l ine, and assaying 1500 ppm UjOg and 30% p£*V

This was considered to be of low p r i o r i t y in the schedule of follow

up studies on account to the form occurrence.

However, during a geological reconnaissance survey in

July 1976, NUCLEBRAS geologists discovered an extensive outcrop

FIG. 1

OL

THE ITATAIA ORE DEPOSITLOCATION MAP

200 400 600 800 lOOOKmJ 1 ! I I ! I ' i '

42° 36°

0°

ITATAIA ORE DEPOSIT

RIO GRANDE iDONORTE

-7

42

FIG. 2

oI í

SCALE90 k»

w*a0

+A + * + + © + * + IT*"* ++_ + + + +WAUCUM + +\ - K j - +/ i i + " + + + + + + V +\J^S

+ + + +K

+ 4 +

+ + + i''/+ + + + +

-»-+.,+

ITATIKA

e

+ + ' ^ /

+ + \+ +

+ +

I + + + I

BELT

S4KTA OUITCftIA tf£DIAN H l t t l F

FAULTS

r»*cTu*e«

STRUCTURAL TKEN9I

f - U

ITATAU

of such uranium-and phosphate-rich rock in an area about 1.5km to

the north of this anomaly. These rocks had radiometric value of

7000 to 10 000 cp* (SRAT-SPP-2) and, on chemical analysis, revealed

exceptionally high values for this type of association (2500 ppm

U,0g and 30% ^9^5^* P^"^ feldspathic, vuggy and radioactive rocks

were also found in the same place. This occurrence was referred

to as Anomaly 62 and later became know as the Itataia deposit.

2As the result of a preliminary reconnaissance, a 2- km

area was delimited to be investigated in detail. The usual ground

techniques of detailed radiometric and geological surveys were

adopted in view of the local features of the area, such as:

Topographic and radiometric surveys were carried Out on

a 1:1000 scale along north-south traverses with lines spaced at

50-m intervals. The mineralized bodies were perfectly contoured

by the isorads CFIG. 3}. -

Detailed geological map was made in early 1977 on ao

1:2500 scale in the 2-km area of the radiometric surveys. Thegeological mapping was carr ied out along the traverses used for

the radiometry. The mapping team consisted of two senior geoj^

og i s t s ( / IG . 4 ) .

Shallow test p i ts and trenches were opened concomitantly

with in areas of overburden. This geological in format ion, when

considered together with detai led surface radiometric character,

o f te r permitted favourable l i t ho log ies to be traced between areas

where bedrock information was lack ing . The general re lat ionships

show on the geological map confirmed the isorad contours. The £u£

face expression of the ore body suggested a thick dyke-l ike strujc

tu re , but th is in te rpre ta t ion was l a t e r shown to be mistaken.

VLF and e l e c t r o r e s i s t i v i t y were carr ied out in late

1977 in an attempt to trace the l a te ra l extension of buried stru£

tures and mineral ized bodies i d e n t i f i e d during the geological ma£

ping. These methods gave sa t is fac tory resu l t s ; they confirmed the

existence and preferred or ienta t ion of some buried mineral ized bod

ies fo l lowing a s t r i ke N70°N. Some fau l t s suggested by the geo1_

FIG. 3

ITATAIA DEPOSITRADIOMETRIC MAP

2 0 0

SCALE«OO «OO MK> I0OO»

RADIOMETRIC SCALE< SOO I2OO 41*00 > 7IOO

\ \

6,

ÍISORAO CONTOURSs

fSRAT/SPP-2)

PfiOJtCTtO * H t » t TRACEDO DWILL H O t l *

FIG. 4

- 120»

e V

£ 0 i

ISO

50C-

450-

403-

350-

-120»

CEGtND

FL.. - ~ J

MASSIVE OK

ZONES.

E3--I ~J Mi»ti . ES iHj CA'C?SIL'Ct-£D »CZf

fOLC ««IS

r» i i Man

FIG.5-GEOLOGICAL M6P AND CROSS SECTION OF THE I767AÜ CR£ DE POSIT

ogical mapping were also confirmed.

Dr i l l ing Programmes

The surface exposure of the I t a ta ia ore bodies was f u l l ydelineated by the geological/radiometric surveys.

The d r i l l i n g programme began in July 1977. Twenty- nineholes were d r i l l e d to a to ta l extend of 5000 m. Cores were takenthroughout the ent i re length of the holes and the recovery ratewas about 90% in each core withdrawal. The d r i l l -ho les were sitedon a wide-spaced grid that could be closed i f required.During thisprogramme the average of the holes was 150 m, following which theywere a l l logged with a Mount Sopris 2000 for natural gamma, resist i v i t y and s e l f - p o t e n t i a l . In 1979, a Mount Sopris 3000 logger wasused for this purpose, allowing a l l three logs to be recorded simultaneously during a single run. Mineralized rocks were interceptedin a l l 29 d r i l l holes, and the dike pat tern, as suggested by thegeological mapping, was shown to be incorrect.. Thick veins andlens- l ike massive bodies were defined up to 150 n depth.

The results obtained durino this f i r s t d r i l l i n o programme

were highly s ign i f icant . Allowing for an even distr ibut ion of the

mineral izat ion, i t was possible to infer the existence of at least

18 000 tonnes of U30g at I t a t a i a , wich j u s t i f i e d another d r i l l i n g

programme of a further 10 000 m.

In view of the promising resul ts , d r i l l i n g was r e i n i t i ated in mid-1978 and terminated in, January 1979. Forty-two holeswere d r i l l ed to a maximum depth of 300 m each and to a tota l of10 129 m durin-g-the programme. About 70% of the d r i l l i n g has asi ts objective the blocking out of reserves. The remaining 302 wascarried out for exploration purposes with specif ic reference to thela tera l extent of mineral izat ion. The holes were si ted on a 160msquare g r id , including those of the f i r s t d r i l l i n g programme.

At the end 1978, computer calculations based on the cor^

ventional method of blocks estimation, indicated reserves of 71 000

tonnes of UgOg of wich 34 000 tonnes were considered to be in the

category of measured and indicated reserves (reasonably assured)and 37 000 tonnes as in fer red reserves (addi t ional estimates).

Sampling and Analy t ica l Procedures

The cores from the mineralized horizons were f i r s t sampled according to geostatistical requirements using a support of0,25 m for homogeneous l i t ho log ic segments.

In addi t ion to l^Og, ThO2 and P2Og systematic analyses(delayed neutron and X-ray fluorescence), hundreds of analyses fortrace elements by emission spectrography were carr ied out to detej*mine the geochemical background and to look for other elements ofpotent ia l economic in terest (Pb, Zn, Mo, Ag). Concoraitantly, radj^oactive disequi l ibr ium studies were performed in core samples.These studies indicated equil ibrium between the chemical and gawnaray spectrometer values (correlat ion coef f ic ien t 0.96).

In 1979, support of the sampling was increased to 0.50min view of the regu la r i t y of the minera l izat ion, bearing in mindthe aspects of l i t h o l o p i c a l breaks and/or core recovery.

Routine analy t ica l procedures were established for theI ta ta ia ores. Each sample was automatically analysed fo r U3°8»P2°5* s i 0 2 ' A^2°3» Ca^ a n d Fe2°3 t o o b t a i n basic information formi l ing and dressing tes ts .

Airborne Survey

In late 1977, an airborne gamma-ray magnetometer surveywas carried out in view of the wide geographical d i s t r i bu t i on ofthe uranium minera l iza t ion. The main factor in the choice of a i rborne geophysics as a method of regional prospecting wasthe excejlent exposure, th in so i l cover, in termi t ten t stream network, d i ff i c u l t i e s of access and, p r inc ipa l l y , awareness that the mineral jzation was of a regional nature.

Two Norma-Britten Islander and one Douglas DC-3 aircrafwere used in the survey in three d is t i nc t areas, . to ta l l inp 38 00km . Operational character ist ics were uniform and included a i t i

tude of 150 m, speed of 220 km.h and north-south flight lines

spaced 500m apart. The geophysical equipament used included a

gammaspectrometer "Exploranium" OIGRS, Model 3001, containing nine

6 in. X 4 in. crystals as well as a "Geometries" Model 803 magneto

meter.

The data from 78 000 km of flight lines were recorded si

multaneously in analog form and digitally on magnetic tape. In the

processing, 441 anomalous records were identified which, on the

basis of essentially physical parameters, correspond to 42 anomaly

ous zones.

The data obtained during the airborne gamma-ray survey

were analysed in 1978 by NUCLEBRÂS personnel. Thirty new anoma^

ies were selected for verification. As a result, fifteen show

ings of phosphate-uranium mineralization were recognized., among

which four were coincident with the Itataia deposit and two have

been correlated with anomalies already discovered by the carborne

survey carried out in 1975. The remaining anomalies represented

new P-U areas.

2) GEOLOGY OF THE ITATAIA DEPOSIT

The I tataia deposit is situated in rocks attr ibuted to

the Caico Group. The principal country rocks are paragneisses with

a well developed planar fabr ic. Intercalated with these gneisses

is a large lens of carbonate rock at lest 10 km long. Lateral gna

dations are common and include graphite-marbles and calcosil icate

rocks.

Both the marbles and the gneisses are cut by several granite

and granite-pegmatite apophyses. These intrusive have been affecj:

ed intensively by deuteric processes, and d r i l l i ng has confirmed

ti i is at depth. The marbles and gneisses are very highly folded.

The latest axial planes are subvertical and the fo ld axes dip oein

t l y to the east (5° to 10°).

The I t a t a i a ore bodies are located on one of the regional

congressional release faults and, before the mineralization

sodes, the marbles uplifted on to the gneisses. The tectonicevent accounts for the local geomorphology whereby the marbleshave their topographic expression as a small hillock.

3) URANIUM MINERALIZATION

Two types of ore bodies have been recognized. The f i r s t con-s i s t s of uniform massive coiiophanite and the second of veinletand stockwork ores in marbles and "episyenit ic" rocks as well asin impregnations in gneisses. In fac t , impregnation is a generalfeature which affects al l the l i thologies in varying degrees.

Uranium and phosphorous show differente grades in thedifferent rock types:

In Collophanite 800 to 2000 ppm U30g and 122 to 30% P ^

In Marbles (Stockworks): 150 to 1100 ppm U30g and 2*to 15% P 20 5

In Episyenites: 300 to 1400 ppm U 30 g and 9% to 202 P2

The mineralization extends downwards 400 m below surface.

Uranium is evenly distributed in the collophanite, asshows by fission track and microprobe analysis. Two views havebeen proposed on the nature of the uranium in the collophane. Thefirst is that calcium has been isomorphously replaced by uraniumin the collophane structure. The second holds that the uranium isassociated with finely dispersed oxides or that it has been ad-sorbed by the collophane. However, it is significant that no discrete uranium species has yet been found.

" There" is convincing evidences that metasomatism was thekey process in the uranium mineralization at Itataia.

Related to metasomatic process Itataia shows the follow

ing features:

a) There is metasomatic alteration of different types of

rocks like granites, gneiss and marbles.

b) Compositional granitic rocks (granite and gneiss)were transformed trough desilicification, albitization, analcj[tization and chloritization into albitized rocks, in many caseskeeping the original structure.

c) Due to its chemical nature marbles went under deepalteration involving scapoiitization and strong dissolution withreplacement by a rock rich in phosphate (coilophanite).

There was widespread replacement of cal cite by phosphatein the marbles.

d) During a final staqe phosphate was deposited inlarge quantities both b> replacing of marbles or filling fractures and cavities.

e) Granite bodies of brazilian age (400 to 500 n- y.)has been affected elsewhere by the same mineralizing processwich clearly indicates that uranium mineralization is younger.

f) One of the chemical alterations undergone in theoriginal rocks was the liberation of Fe + of mafic minerals(mainly biotite) and oxidation of ferrous into ferric iron pn>ducing a pervasive hematiti zation wich appears as minute crystalsgiving a reddish or pinkysh colouration to the metasomatisedrocks, including the newformed collophanite.

All these evidences indicates a close relationship be_tween uranium mineralization and the metasomatism.

During the final stage, cryptocrystalline hydroxy-apatite was extensively deposited from saline heated fluids('vl30°C,_and approximately 22* equivalent CaCl2) which impregnatedthe pore-spaces and cavities formed before.

Transport of large quantities of calcium phosphatewould have been possilbe only in acid medium (low-pH fluids).Movement of these fluids in the host marbles provoked an increasein pH, the alkalinity favouring rapid deposition of uraniferouscollophane. Such conditions of rapid deposition are apparentlyconfirmed by the cryptocrystalline fabric of the collophane andthe absence of uranium minerals. The uranium would have been

adsorbed by the collophane with, possibly, some replacement ofCa -'n the apatite.

Fluid inclusions in the apatite indicate formation temperjures of the order of 136°C and high salinity (VI9.5X to221 equivalent Ca Cl^J, while quartz filings in cavities in thecol rshane indicate temperatures of 50°C and low salinity (% 5%equivalent CaCl2), evidence of a distinct decrease in salinitydurfnc deposition of the late minerals. The low CO* contentsuggests low pressure deposition.

It is believed that the brazilian orogem'c cycle hadstructurally affected the original metasedimentary rocks andalorg zones of congressional release associated with regionalfaulzs ascendent fluids had caused metasomatic alteration ofrocks.

Phosphate and uranium present in the original metasedj^rcentiry rocks has been remobilised and concentrated during themetasomatic process by replacement or by impregnation and fillingof cavities.

Marble has played a. leading role in the deposition ofuranium and phosphate at Itataia, making it a large deposit di£tinct from the other occurrences were marble is missing.

Finally the entire region went through a deep erosionalprocess during a long period of time, atested by tho presenceof detrital fragments of U-P mineralized rocks in sandstones ofDevonian age in the Parnaiba Basin (Serra Grande Formation) anda laroe amount of residual collophanite in low lands at Itataiaarea.

Also weathering has affected the setting of mineralizedzones in marble by its dissolution and argilisation, changingthe original pattern after mineralization.

Exception made for aspects resulting of role played by

the marble, the remaining features in Itataia are common to

others metasomatic uranium

LAGOA REAL URANIFEROUS PROVINCE

The Lagoa Real Province is located in h i l l y country of the

central-southern part of the State of Bahia, some 20 km northeast

of the town of Caetité" (FIG. 1 ) .

The Lagoa Real Project covers an area of 4.540 sq.km.

Uranium mineralization occurs in a l b i t i t i c bodies para l l e lto i ts fo l i a t ion wich lays on metasomatised and cataciastic rocksof Archaean basement.

1) HISTORICAL BACKGROUND

Due to the presence of uranium bearing quartz-pebble cojnglomerates in the ferr i ferous quadrangle (Minas Gerais) and alsoin Jacobina (Bahia) a carborne survey was launched in 1971, toinvestigate the Northern Espinhaço region. No uraniferous congl£me rate was found but from the result ing anomalies an airborne

survey was suggested.

During 1974/1975 the Espinhaço Setentrional Project (a i£

borne gammaspectrometric survey) covered an area of 60 000 sq.km

with 4 km spacing l ines .

In 1976/1977 another airborne survey-Diamantina Project-

wich covers an area of 145.000 sq.km with spacing lines of 2 km

was carried out.

The l imi ts between both projects was the paral le l of 14°

wich cross-cut the Lagoa Real re-qion. Needless to say that both

surveys detected uranium anomalies at the same region wich corre_

sponds to the Lagoa Real area.

Another airborne survey done by CGA-DNPM in 1976 wich was

mainly magnetometry but with gammaspectrometry, also detected ura_

nium anomalies in the same area.

The f i r s t ground-check of these anomalies (1977) had shown

large extensions cf aligned structures (about 3.000 meters) of

FIG. 1

THE LAGOA UEAL DISTRICTLOCATION MAP

Oi

200»

400 600j

BOO 1000 Kmi i

PERNAMBUCO \ ( ~ {

LAGOA REAL DISTRICT

a l b i t i t i c rocks wi th radiometr ic values between 5.000 to 15.000

c/s .

Detai led ground-check of some of the more promising anoma

l i e s had shown the presence of high grades of uranium in a l b i t i

t es .

On March 1978 a programme of evaluation of the anomalies

was s tar ted and f i ve new anomalies were found.

Af te r these resu l ts a detai led airborne gammaspectrometri c

survey (São Timóteo Project) was done in 1979 wi th close spacinç

f l i g h t l ines (500 m) g iv ing t o t a l covearaqe resu l t i ng in 33 anc

mal ies, inc luding those already knew.

Ground-check of the above mentioned anomalies star ted i r

1980 resu l t ing in 30 anomalies selected fo r evaluat ion wich cons

t i t u t e s the Lagoa Real D i s t r i c t .

From these, f i ve anomalies were considered as p r i o r i t i e s

and since 1980 are being under evaluation wi th de ta i led radic

met r i c , topographic and geological mapping, trenching and systen

a t i c d r i l l i n g . ( F I G . 2 ) .

Ore dressing tests showed hiah s o l u b i l i z a t i o n of uraniur

wi th low acid consumptions.

2) GEOLOGICAL SETTING

Uraniferous anomalies are found i n a zone Archaean basemen

consist ing of ca tac las t ic g ran i to ids , augen gneisses, microcl ine

gneisses, grànodicfritès and a l b i t i t e s (FIG. 3) .

This zone is about 80 km long and varies in width from 3i

to 50 km. To the south, east and north there lays large areas o

low r e l i e f which are underlaid mainly by gneisses and greenshist

of Archaean or Low Proterozoic age. Along i t s western margin, th

massif i s frenquently fau l ted against the metasediments and meta

olcanics of the Espinhaço Super Group. The region may have bee

subjected at least to three tectonic cycles during which the rod«

FIG. 2

THE LAGOA REAL URANIFEROUS DISTRICT-ANOMALY LOCATION MAPO 2 4 Ski»

GRAPHIC SCALE

« i ' " . " ° > - " " > SÃO -n-í

j ^ 5

LEGEND

•D I 5 0 0 0 SCOlt t,r

0í \ Winuonò ore-alies

0 Aiotroly t£.iC4f,ler

r in/»stiço1ion

Town /Form

LoV.e/Dtoinoge

CAETUE PROJECT

FIG.

43

IS*

• * • V V • :

* * * * "' * ^

l»T£f»"T{ »ND/O» SMOT COVEÍS

v Vv v J;.'-ivJ ;j»

>:R F?OT£RCZOIC

TÇNI BUT

i X I -J* j :isii,;lfsit»»*50l0»iTtS,T?f*ltTt5 ,IIC t,»E?tTf ÍI11S i1»; wi*»;7ITC$

L»60»l»l»l UMKWK O»ST»iCTtMODI»lfDr»O» »3»

were rejuvenated. These include the Guriense (3,000 m.y.+).Trans

amazonian (1,800 - 2,100 m.y.) and the Braz i l i an (1,800 - 500

m.y.) cycles.

The microcl ine-plagioclase-augen gneisses are the host

to the a l b i t i t e s wich often are minera l ized. They always exihibit

strong catac las is and granoblast ic texture(FIG. 4 ) .

The s t ruc tu ra l evolut ion of these rocks is important f o r

the emplacement of a lb i tes and consequently as a guide for uranium

mine ra l i za t i on .

The main regional s t ruc tu ra l pat tern is re la ted to tensio

nal t ranscurrent domains wich produces long lineaments in a north

south d i r e c t i o n .

There is evidence of th rus t f au l t s wich a f fec ts the Espinhi

ço rocks.

At least two deformational phases has be?n recognised:

During Archaean times a low angle duc t i le shearing zone

has been developed, resu l t i ng from the th rus t ing of a basemeni

bloc over another in a mobile b e l t .

At Transamazonian times ( * 2.000 m.y.) he l i co ida l tors ior

wi th dextra l r e l a t i ve motion, inc luding l oca l l y ro ta t iona l comp<

nents, were developed without intense shearina.

Loca l l y , a l b i t i c rocks emplacement re f l ec ts the regiona

s t r u c t u r a l pa t te rn .

T ' p.re is two main arch surfaces, whose trend varies f ro

NE in the south i n f l e c t i n g to NW in the no r th .

A l b i t i t e s dips to the west in the southern area being a

most v e r t i c a l in the middle changinq to a eastern dip in the nor

ern area, l i ke an "S " , character iz ino a lonq sigmoidai s t ruc ture

resu l t i ng from he l i co ida l t o r s i on .

FIG. 4

THE LAGOA REAL DISTRICTANOMALY-03

•A PYROXENE ALBITITE

ALBITITE

ALBITE-WICROCUNE-QUARTZ -

MiCROCLINE-ALBITE-OUARTZ - METASOUATITE

4C SO 120 ISO 200j t i r t

The predominant foliation is cataclastic. This foliationcontrols the mineralized albitites and is superimposed to a lowangle pre-existing foliation (1 to 15°).

In the intersections zones between these two foliationscataclastic zones were developed. These intersections zones holdsthe richest mineralized bodies.

The geological sections made upon drilling show many descontinous tabular albititic ore bodies wich are concordant withthe regional cataclastic foliation CFIG. 5).

The pinch and swell of the mineralized bodies may be a resuit of the stress composition but it cannot be clearly definedin the field yet.

The albitites bodies varies from few meters to kilometerswith width varying up to hundred meters.

3) URANIUM MINERALIZATION

The uranium mineralization occurs in a l b i t i t e s . They arecharacterized by the presence of sodic plagioclase (a lb i te ) ancaegerine-augite. The country rocks are invariably microlineortho-gneisses. The fo l i a t i on of these oneisses is essent ia l l )para l le l to the regional t re i id, wich within the massif inscribesan arch. The fractures which also fol low the s t r i ke are often calaclast ic and the i r dip d i rect ions, as well as that of the f o l ja t ion , are hel ico idal from south to north. The mineralized bodieof metasomatic a l b i t i t e s surrounded by microline gneiss are fusjform and likewise accompany the regional st ructural trends. Th<length of these varies from 20 to 100 times the width.

The uranium enrichment is of braz i l ian age which is sujported by absolute age dating (U/Pb) of uraninite at 820 m.y. Silut ions r ich in sodium chloride and methane (found in f l u i d incl jsions) ascended pre-exist ing fracture planes and zones of weakneswithin the microd ine gneisses causing sodium metasomatism and tfi

7f

FIG. 5

THE LAGOA REAL DISTRICT

S*1040 n

1000 -

960 -

920 -

680 -

840 -

800 -

AN3/ALY-03

0 2C

1 1

'OVERBURDEN

PYROXENE AL31TITE

ALBÍTITÊ

ALBITI-KICROCUKE

yiCROCLlF£-AL3ITE

» 40 (0 tOmi » j

• -

-OL'iRTZ - METASOMATITE

-«UARTZ - UcTfeSOMATITE

formation of the albi te-pyroxene-rocks. The uranium was mobilisedand concentrated as f ine disseminations in the mafic bands ofSodic pyroxene.

The uranium mineral is u ran in i te . B-Uranophane can be observedon f racture planes at surface. The grades of ikOg are qui te highand may reach 3.503» in exceptional cases. The average grade ofthe mineral ized zone is about 0.3 to 0.2£ U30g. The concentrationsof thorium are low (<100 ppm).

Simi lar deposits and metaiogenetic models have been describedby Kazansky and Laverov (1977) in the U.S.S.R.

Besides the evident s t ruc tu ra l ore control uranium also foj_lows a l i t h o l o g i c a l control as i t is res t r i c ted to a l b i t i t e s .

But there is non mineralized a l b i t i t e s mineralogicaly andchemical s im i la r to the mineralized ones. The only conspicuosdif ference i s the greater proportion of mafic minerals in minera^ized a i j i t i t e s .

Uranini te is associated with f ine bands of mafic and opaqueminerals (aeg i r ina-aug i te , arnphibole, b i o t i t e , garnet, epidot andmagnetite).

During a l b i t i z a t i o n of gneisses there is a re la t i ve loss ofSiO- and K O and a gain in Na^O, Al2^3 and Fe.

Oxygen isotope analyses of quartz, a lb i te and magnetite fromgneisses and a l b i t i t e s indicates that the metasomatic f l u i d s wereof ground-water nature.

ESPINHARAS DEPOSIT

The Espinharas uranium occurrence is located at the smalltown of São Jose de Espinharas and from there extends in a NEand SW direction. São José de Espinharas is situated 25km northof the city of Patos in the State of Paraíba, NE-Brazil (FIG. 1).

1) EXPLORATION HISTORY

The radiometric anomaly at Espinharas was discovered inthe course of a regional carborne survey by CNEN in 1972. Lowuranium values at high thorium/uranium ratios in surface samplesdiscouraged detailed follow-up work.

In 1976, as part of a prospecting programme carried outby NUCLAM the anomaly was looked at more closely. A systematicground radiometric survey was done, the first trenches and pitswere dug. The mineralized rock was believed to be a steeplydipping, old intrusive dike (according to current thinking nolonger holds true) but the mineral composition and texture werecorrectly described and albitization was recognized.

In the second half of 1977 limited diamond drilling was

carried out to probe the possible depth continuation of the su£

face mineralization. The drilling approach was based on the ajs

s u m p t i o n of a s t e e p dip a n g l e f o r the m i n e r a l i z e d z o n e .

After the completion of 13 holes it was indeed concluded

that the dip was mainly steeply to the north but in places also

vertical or steeply to the south.

At the centre of field activities in 1978 was a second-phase diamond drilling programme totaling 36 holes. This drijling was designed to improve the knowledge of the deposit, dete£mine the average grade of the mineralization with greater accuiracy and explore the anticipated downward continuation on the mj^neralization. Based on the results of this drilling, conventional reserve estimates on vertical longitudinal sections were made.

4 n f 1 ii<

THE ESPINHARAS ORE DEPOSIT!LOCATION MAP

4 4I I i i

176 kmI l

FIG. 1

38°_ j

CEARA M c » W

/

/

RIO GRANDS DO NORTE

Acu

Augusto Severe

yCurrais Novos

ESPINHARAS ORE DEPOSIT

<.

í

J.PESSOA

) PARAI3ACampino G'ortde

PERNAMBUCO RECIFE

SITUATION

of uranium.

The year 1979 was spent studying geological data gatheredpreviously wi th the purpose to gain a bet ter understanding of thegeology and mineral izat ion and simultaneously carry out concep_tua l mining (open p i t and underground), me ta l l u rg i ca l , engineering and in f ras t ru tu re studies wi th regard to the v i a b i l i t y of amin ing /mi l l ing venture at Espinharas.

By the time the second d r i l l i n g stage had been completedear ly in 1979 in had been concluded that the Espinharas "ore body" has an average dip angle of 50° to the NW - a considerable mo<ii f i c a t i o n to the i n i t i a l assumption of a near-ver t ica l d ip .

When rep lo t t ing of surface and basic d r i l l hole data ond r i l l sections had advanced far enough to commence wi th the geol£g ica l i n t e rp re ta t i on , the impression gained was that

a) the ore was not a continuous body of mineral izat ion butwas made up of discint inuous , l e n t i c u l a r , i r regu la rbodies whose long axes pa ra l l e l the regional fol iat ion,

b) these len t i cu la r bodies were arranged en- ichelon,

c) the plunge angle ot these bodies was not 50° but only20-30 and the plunge d i rec t ion not perpendicular tothe base l ine (N30°W) but the same as the dip directionof the regional f o l i a t i o n , viz N70°W (TIG. 21 .

For the year 1980 the t h i r d diamond d r i l l i n g campaign ofthe Project was proposed. The or ig ina l aim of i t would have beento probe the in ferred down-plunge continuation of the major oreshoots postulated in "the new in te rp re ta t ion by means of a row ofve r t i ca l holes arranged in a fence- l ike fashion across the plunged i rec t i on .

The d r i l l i n g results obtained in 1980 have confirmed

a) the concordant a t t i tude of the main ore shoots

b) the extension f racture ore emplacement model as beingthe best choice"to explain the s t ruc tu ra l control ofthe minera l i za t ion , and

^Sr::«à->:^::.V

TACTITES ;

1 MINERALIZED EPISYENITES

AMPHIBOLITE

I^V. ' j UtTRABASIC ,

CNEIS3E5

GEOLOGIC MAP OF THE ESPINHARAS ORE DEPOSIT

«0 160 220 100 }60 4(0 i«0I I 1 I I 1 I

c) the continuation, at depth, of the numerous aplogranite dikes mapped on surface.

A new finding has been the lithological control of themineralization exercised by these aplogranites. This constitutesa second order ore control and accounts for the extremely shallowdip angels (10-15°) of the shoots known since tlie re'iinterpretationof 1979 but hitherto unexplained.

As for the economic aspects, the 1980 drilling has producedthe best ore intersections.

2) GEOLOGICAL SETTING

a) Lithology

From the surface observations and drilling data combinedwith petrographical and geochemical analyses it can be concludethat the process of metasomatic alteration, to wich the uraniummineralization is closely associated, it is one of the latestgeological events in the are, being younger than all rock types.

This conclusion came from the simple fact that metasomaticprocess has afected all existing lithologies.

Being so, there is not a single mineralized rocks type assuch, all rocks may show their metesomatised equivalents.

It is possible, both on trenches and drill-cores, tofollow a gradational change from a country rock like a biotite-amphibole-gneiss into a mètasomatised and mineralized gneisswith the same structure.

In order to distinguish among the several rocks types a

microscopic criterium was used to recognise metasomatic altera

tion.

This distinction was confirmed by mineralogical and

Metasomatised rocks show a typical pink color due to hematitization of feldspars and also a typical vuggy texture wichallows distinction between mineralised and norr mineralized rocks.

The present thinking is that the mineralizing event formspart of a metasomatic process post-dating all rock and affectingthem in varying degrees near a mineralizing structure.

What the now metasomatised rocks were before metasomatismcan still readily be determined visually in drill core and outcropthanks to the perfect preservation of original rock textui..s andstructures.

Common to all radioactive rocks is thus a replacemencprocess that has individually changed the original rocks dependentupon their respective mineralogical/chemical composition andinternal texture.

It was possible then to characterize the existingological types into two main groups.

lith

LITHOLOGIC TYPES

Pre-metasomatic Country Rock

1) Biotite-Ajiiphibole Gneiss2) Granite-gneiss3) Aplogranite

Mineralized equivalent

1) Albitised gneiss2) Layered Albitite3) Massive Albitite

Regional (Country)Rocks

1) Biotite-Amphibole Gneiss

This texturally and compositionally wery variable group o

rocks is by far the most plentiful country rock in the mineralize'

area. It usually forms long, monotonous, uniform intersections 1i

the drill holes and trenches but, on account of its low resistenceto weathering does not usually make large outcrops.

This group of rocks comprises porphyroblastic gneisses,

schistose gneisses and amphibole schists which may have either

sharp or qradationai contacts with each other.

2) Granite Gneiss

Concordantly intercalated in the amphibole-biotite gneissesare quartzo-feldspathic layers ranqing in thickness from a fewcentimetres to 30 m and exhib i t ing a gneissosity para l le l to thatof the sourrounding amphibole-biotite gneisses. More commonly i tpinch end swell over shorts distances. This rock unit is l i gh tcolored and granular and consists of quartz, mi crocl ine.plagioclaseand some b i o t i t e .

3) Aplogranite

Extremely widespread in the deposit area and beyond arequartzo-feldspathic dikes or sheets ranqinq in thickness betweena few centimetres and several metres (exceptionally 15 m) whosemost peculiar feature are their shallow dip angles (0-20 ).Hundreds of structural readings on surface and in drill core showthem to be clearly intrusive, forming discordant contacts withthe gneissic foliation. The aplogranite is a light coloured(pinkish, yellowish, whitish) rock.

The aplogranite is the youngest- rock in the area, intrju

ding all other lithological units. It frequently carries xemj

liths, usually displaced and rotated, of country rock and is thou[

ght to have intruded along well developed fracture zones created

during orogenic stage.

Mineralized Rocks

1) Albitised Gneiss

At first glance, albitised gneiss differs from the unaj[tered gneiss only by the pinkish colour of the feldspars and thesmall vugs. In some parts, however, common, hornblende in theamphibole-biotite gneiss was replaced by riebeckite and arfvedsonite

(sodium-rich amphiboles) giving the rock a distinctly bluish tint.Other minerals constituting this gneiss include plagioclase, hornblende, chlorite, titanitü, apatite, opaque minerals, carbonate,cummingtonite, biotite and epidote.

2) Layered Albit i te

Layered Albitite is the metasomatically altered equivalentof Granite Gneiss whose original foliation is well preserved andeven accentuated by biotite flakes partly epidotized and by thealignment of pore space owing to the dissolution of the free quartz.

3) Massive Albit i te

This is the metasomatic equivalent of aploqranite. It isporous owing to the removal of most of the fr&e quartz.

Some of the pore space is filled with small crystals ofsecondary quartz and more commonly with calcite. Most characte£istic is the strong pinkish-reddish colouration common to allradioactive rocks at Espinharas. Albitite and/or oligoclase,forms up to 90* of the rock, followed by orthoclase and somebiotite. Other minerals found include apatite, pyrite,: chalcopy .rite, sphene, monazite, hastingsite and glaucophane.

3) GENETIC MODEL FOR THE ESPINHARAS MINERALIZATION

There is convincing evidence that metasomatism has playeda leading role in the deposition of the uranium mineralization atEspinharas. Fractures are know to form starting-places for suchreplacement, and for Espinharas the hypothesis is advanced thattension fractures provided channel ways for ore bearing solutions.The metasomatic process started to affect the adjacent rocks fromsuch tension fractures created under the influence of a couple offorces in a local stress field. Extension fractures opened upessentially along zones of weakness, parallel to foliation rlanesin the gneisses and also parallel to the numerous aplogranite dikeswich thenselves were previously emplaced along fracfjre planes (FIG. 3) .

The development of such an extension fracture 2one stoppedthrust fault. The termination

FIG. 3

ESPINHARAS DEPOSITMINERALIZATION MODEL

E-56 E-57 E-59 E-65

/ T"~íCÍ_

• DIRECTION OF GRANITIC BODIES

REGIONAL FOLIATION

MINERALIZED ROCK

of the development of a fault zone at such an early, rudimentarydeformational phase may even have been favourable to the fracture-controlled metasomatism.

The metasomatic process appears to have been the last major geological event in the area, accompanying the movements thattook place during the formation of the huge Patos lineament andassociated structures some 30 km to the south of EsDinharas.

BIBLIOGRAPHY

This text was based mainly upon the following references:

ANGEIRAS, A .6 . ; NETTO, A.M. and CAMPOS, M. de (1978) - Phosphoro-

uraniferous mineralization associated with sodium epysie-

nites in the Ceara Precambrian I n : "Uranium Deposits in

Latin America: Geology and Exploration" - IAEA, Vienna.

BALLHORN, R.; THAKUR, V.K.; FONTE, J.E.C. and SUCKAU, V . . ( 1 9 8 1 ) -

The Geology of the Espinharas Uranium Deposit, Paraíba ,

Braz i l . (AG. 162/27) IAEA. In Advisory Group Meeting on

Uranium Geology in Latin America (1978). Lima, Peru.

FORMAM, J.M.A. and ANGEIRAS, A.G. (1981) - "Poços de Caldas and

I t a t a i a : two case histories of uranium exploration in Bra

z i l " (IAEA - AG. 250/14) I n : Uranium Exploration Case Hi£

tor ies . Proceedings of an Advisory Group Meeting. Vienna,

26-29 - November 1979.

FORMAN, J.M.A. & WARING, M.H. (1981) - "L'Uranium en Amerique du

Sud et plus specialement dans la province uranifêre bre-

s i l ienne". Chronique de la Recherche Miniére n9 461 pp.

5-47.

FUCHS, H.D.; FONTE, J.da; SUCKAU, V. and THAKUR, V. (1981) - "The

Espinharas uranium occurrence, Braz i l " (IAEA-AG-250/2) I n :

Uranium Exploration Case Histor ies. Proceedings of an AjJ

visory Group Meeting, Vienna, 26-29 - November 1979.

LOBATO, L.M.; FORMAN, J.M.A.; FUZIKAWA, K; FYFE, W.S. and KERRICH,

R. (1982) - "Uranium enrichment in Archaean basement: La-

goa Real Braz i l " . In tern . Symposium on Archaean and Early

Proterozoic Geologic Evolution and Metaliogenesis, Salva-

dor, Bahia, B raz i l . (Rev. Bras. Geociincias, v. 12, n°s 1

a 3, pp. 484-486.

OLIVEIRA, A.G.; FUZIKAWA, K.; MOURA, L.A.M.; RAPOSO, C. C1984) -Província UranTfera de Lagoa Real, Bahia. Intern. Re-port NUCLEBRÃS.

SAAD, S. (1974) - Aspectos da mineralização uranífera em Figueira,Paraná. Boi. 8 - CNEN, Rio de Janeiro.

SURCAN SANTOS, L.C. & ANACLETO, R. (1983) - Jazida de Urânio deEspinharas, Paraíba. NUCLEBRÃS. Intern. Report.

SURCAN SANTOS, L.C. (1984) - "Mineralização de Urânio ligada a m£tassomatismo sÕdico, Espinharas, Paraíba. Revista Brasilej.ra de Geociincias (In press).