Studies on the analytical geochemistry of uranium and associated elements in the Hawks Crag breccia of New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry

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Copyright is owned by the Author of the thesis. Permission is given for

a copy to be downloaded by an individual for the purpose of research and

private study only. The thesis may not be reproduced elsewhere without

the permission of the Author.

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ANi�LYTICA.L GECYCHEMISTRY ASSOC!i .. TED ELEMENTS IN THE STUDIES ON THE

OF URANIUM AND

HAWKS ^CRAG ^BRECCI1� ^OF ^NEW ZEli.Ll'.ND

A thesis

presented in partial fulfil�ent of the requirements for the degree of Doctor of Philosophy in Chemistry

at

Massey Univer�ity

NOEL EDVU;.RD COHEN

1 969

M

All11r(lllil11i i flilii llli liif

1061960755 ^y

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ACKNOWLEDGEMENTS

The author wishes to thsnk his supervisors, Dr R. R. Brooks and Dr R. D. Reeves, for their enthusiasm and assistance

throughout the work undertaken. He is also indebted to Dr G. Coote of the Institute of Nuclear Sciences for his assistnnce in the Gammn Spcctrometry part of the studies; to staff of the Geological Survey for vnlunble advice, to

Mr Simon Nath�n, Mr John Foster and Mr Jock Braithwaite for assistance in the field work.

He also wishes to thank Mrs Barbara Sanderson for typing the thesis, Miss Doreen Scott for photographic assistance and Mr Peter Herbert for printing the figures.

The author is most grateful to the Mineral Resources Sub-Committee of the New Zenland ^Gr_ants Committee for the provision of funds to support this project.

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Tl,BLE OF CONTENTS ACKNOWLEDGEJviENTS

TABLE OF CONTENTS LIST OF T.r,BLES LIST OF FIGUHES ii.BSTRl�CT

GENER�L INTRODUCTION

P ^..RT I DEVELOPMENT OF i,N1\LYTIC1-1L PROCEDURES INTRODUCTIO^N

flN,.LYTICi,L PHOCEDUHES FOl\ THOHIUM , YTTRIUH ,i.ND THE R!.RE Ei.RTH ELEMENTS

( a) O p t imum SpectroGraphic Condi tions ( i ) Apparatus

( i i ) S ampl e Preparation ( i i i ) R e duct i on o f Background

I . Inve s tigation o f Carri ers

I I . Inves t igation of Gas Condi t i ons

i i

vi vii ix 1

4 1 0

10 1 0 10 1 0 10 1 1 (iv) Inve s t i gation o f S ens i t ivi ty Limi t s 13 ( v) The Volati l i sation Behavi our o f Y t tr ium , Thorium ,

Lanthanum , Cerium , Europium, Holmium , Palladium, and Zi rconium

( vi ) Final Spectrographic Operating Condi t i o ns ( b ) S tudies On The Interference O f Thorium , Y t trium

15 17

Ana Rare Earth �nalys i s Lines 1 9

t. Development o f an I on-Exchange S eparat ion 1 9 ( i ) S eparat i on by Use o f the Ace t ic/Nitric

Aci d �ni on-Exchange Sys t em 19 (ii) S eparati on by U s e of the Nitric Aci d

hnion-Exchange Sys tem 21

II. Mutual Interference o f Yttrium, Thorium and

Rare Earth �nalys is Lines 21

( c) The Us e of the Combined �ni on-Exchange

Spectrographic Procedure

( i ) Dissolut i on of rlOCk Sampl e s

(ii ) Analysis o f G-1, W-1 and CAAS Syeni t e ( i i i ) Evaluation o f Data

f,N4l.LYTICflL METHODS FOR URf>NIUH

(a) Spectrographic Procedur e for Macro Amo unts of Uranium

(b) Solution Fluorimetry ( c) Fusion-Bead Fluorimetry

25 25 27 27 33

33 33 35

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DISCUSSION

p;,JT II GEOCH;�tnc;,.L INVESTIG"TIONS IN THE Hi,V/I'::S CR,.G BRE^CCI.h.

INTRODUCTION

THE GEOLOGIChL ;�ND PHYSICi.L FE.c�.TURES OF THE UR.�,.NIFEROUS :.REf,

( a) Phys i cal Features ( b ) General Geology

37

39

( c ) The Pe trolo gy and Mineralogy o f the Uranium Depos i ts 44 ( i ) The North S i d e Depos i ts

(ii) The South Bank ^Deposit�

METHODS

(a) Sampl i ng P ro c e dures ( b ) An�lyt i c al Techniques

( c ) S tati s t i c al �nalysis of ^Data

ELEl'!ENTi,L ;�SSOCii,TIONS WITH UR!,^NIUM IN M^INERALS, SOILS riND SEDIMENTS

(a) C oppe r and ^Uraniu^m ( b) Beryllium and Uranium (c) Lead and Uranium ( d ) Zinc and Uranium ( e ) Rare Earth Elements

ELEMENTII.L Ri,TIOS A S p:,THFINDERS FOR UH;�NIUM

DISCUSSION

PA.HT ^III

MINERf,LS BY EQUILIBRIUM ^STUDIES HIGH-RESOLUTION GAMMA

ON URi.NIUM

SPECTROMETRY

46 47

51

51 53 53

56 56 58 58 58 59 64 67

INTRODUCTION 73

INSTRUMENTATION 79

IDENTIFICATION OF SP^EC^TRA ⁸¹

( a) Calibration o f Puls e Heigh t Analys er 81

( b ) Analys is o f Spec tra ⁸¹

(i) 1 80-360 KeV Region 83

( i i) 30-180 KeV Region 84

EQUILIDRIUH STUDIES ON MINERJ,LS 87

( a ) Derivation o f th& Equilibrium Relationship 87 ( b ) The Is o topic Compos i t ion o f Uranium Minerals from

the Low er Buller Gorge ⁹¹

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D I SCUSSI ON

GEN:Z:Ri•L DISCUSSION HEFE .. n;;NCES

95 98 1 02

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LIST OF T;�BLES

p,·.RT I

I - 1 Effect o f Carr iers on Line- to-Background Raii o

of La4333 i n a Curbon Dioxide htmosphere 1 2 I-2 Times for Com�l�t e Vola t i l i suti o n o f Yt trium�

Thorium and Rar e Earths in Vari ous Matri ces 1 4 I-3 Line-to-Background R�t ios and Limi ts �f De tec tion

for Yttrium , Thorium and Rar e Ear ths 16 I - 4 Spe c trographic Ope r�t i ng C ondi t i ons 1 8

I-5 Analyt i cal Lines and Interferen c es 24

I-6 Recoveri es from Ion-Exchange Se��rati ons 28 I - 7 Compari son o f Spec trographi c , Neutron hCtivation 29

and He c omm ended Values for Thorium , Y t tr i um , Uranium and the Rare Ear ths i n G- 1 , W- 1 and ^C:\;·,S Syen i t e

I- 8 Rare Earth Abundance Ratios for G- 1 , W-1 and CAAS

II- 1 I I - 2 II- 3 II-4 I I-5

I I I- 1 I I I - 2

Syeni te ³⁰

PU1T I I

S t ratigraphi c S equen c e i n Lower Buller Gorge Analys i s of S tream S ediments as ^a Func t i o n of Mesh Size

45 52

Statistical Data for Various Elements in Minerals, 57 Soils and S tream S ediments

Rare E�rth Conc entrations i n Minerals , Matrix and 60 S tream Sediments

El emental rtat i os as Pathfi nders for Uranium in 66 S tream S e diments

I s o topes and Respe c t i v e Gamma Ray Energi es used 82 for Calibration of a Pulse Height Analys er

The Equilibrium S tate of Various U ranium Minerals 92 from the Lower Bull er Gorge

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LIST OF FIGURES

I - 1 Spec trograms o f Rare Enr th M ixtures ( CN b and pp 1 2- 1 3 region) Arced in Vari ous Atmospheres

I -2 Line- to-background R�t io as a Fun c t i o n o f pp 1 4- 1 5 :trc ing Current

I - 3 Volatili sation Curves f o r Rare Ear ths , pp1 8- 1 9 Yt trium , Palladium and Zir conium

I - 4 An.:1lysi s �l ement Intens i ty/Palladium Intens i ty pp 1 8- 1 9 as a Fun c tion o f the Coeffi c i en t o f Vari�tion

I-5 Elution curves for Analys i s Elements in Ni trate pp21-22 Sys tem

I- 6

I-7a

I-7b I-8

I - 9

I - 1 0

I-11 I - 1 2

I-13 I- 1 4

Reciproc al Di spersion Ci/mm) and Resolution Ci) pp22-23 as a Function o f Wavel ength (R) for the Hilger

E742 Quart z-Op t i c s Spec trograph

�orking Curves for Cerium ( 4040 ) in the pp25- 26 Presence o f various c onc entrati ons o f Neodymium

Working Curves for Y 3327 and ^La 3995 pp25-26 Neutron Ac t i vation Data from HASKIN and GEHL pp29-30 as a Func t i on o f Sp e c trograph i c Data from the

Author for G-1 and W- 1

Data from the Author as a Fun c t i on o f pp29-30 Spe c trographi c Data from TENN.' .. NT and FELLOWS

for CAAS Syeni t e

Rare Earth Dis tribution for an Average Bas i c pp31-32 Rock and CA�S Syeni t e

Spe c trographi c Working Curve for U ranium pp33-34 Uranium Fluor e s c e n c e I n t ens i ty as a Function pp34-35

of Per C ent Phosphori c Ac i d

Solution Fluorim e try Working Curve for Uranium pp34- 35 Fus ion-Bead Fluorime try Working Curve for pp36 -37 Uranium

Pf ^..RT I I

I I - 1 Map Show ing Dis tribution o f Hawks Crag Bre c c i a pp43- 44 on Nes t Coas t of Sou th Island

I I - 2 II-3a

Pho to Show ing Dense B e e ch Fores t i n H . C . B . Area pp43- 44 Aerial Photograph of Lower Bul l er Gorge

inc luding H . C . B . area pp43-44

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II-3b II-4 II-5

II- 6

II-7

I I - 8

I I - 9

I I- 1 0

I I-1 1

III-1 III-2

III-3 III-4

I II-5

I I I - 6 III^-7

I I I - 8

Aerial Photograph o f H . C . B. Area from Fig . II-3a pp43-44 De tai l e d Geologi cal Map o f th8 H . C . D . Area pp45- 46 Pho tosraph and ,:,u toradi ograph of itrkos e pp48-49, containing Uranini te

El emental Relati onships in Minerals , Soils ^pp57-5

�

and S tream S edim ents

Cumulat ive Frequency Plots for Various El ement s pp58-59 i n Soils and Str eam S ediments

Rare Ear th Distribu t i on i n Uranium Minerals ^pp59-60 and in Stream Sediments Draining H . C . B . Areas

Triangular Plot for C onc entra t i on Rat ios of Copper , Lead and Uranium in Minerals, Soils and Stream S e diments

Map of Buller Gorge hrea of New Z ealand showing Radioactive Horizons and Sampling P oints for Soils and S tream Sediments

Triangular Plot for C oncentrati on Rat ios o f Lanthanum , Ytt rium and Thorium from S tream S e diments i n Drainage Areas; Ohika-Nui Riv er , O tu tu tu River and Hawks Crag Bre c c ia

Pi'.RT III

Decay S c hemes for

u238, u235

^and^Th232

Comparison o f Uranini t e Sp e c trum Recorded wi th Nai( Tl ) and Ge ( L i ) Detec tors

Gamma S p e c t ro s c opy ; Schemat i c D iagram

Computer-As s i s t ed Analysi s o f Gamma Spec tra;

S chemat i c Diagram

Calibration Curve , KeV as a Fun c t i on o f Channel Numb0r

Gamma Spe c tra of Uranini t e , Ra226 and Th232 Gamma Spe c tra of Uranyl N i t rate , Extrac ted Uranium Frac tion and Extrac ted Thorium Frac tion

. C(1 85 )

Theore t�cal Curve o f _c(295) as a Func tion o f the "Perc entage Equil i b rium Radium"

pp64-65

pp71 -72

pp74- 75 pp7 6 - 77

pp79-80 pp79- 80 pp81 - 82

pp83-84 pp85- 86

pp 90- 91

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hBSTRACT

Part I

S tudi es were carr i ed ou t on the opt imum cond i t ions for the suc cess ful use o f a lnrge quar t z spe c trograph for the d e t ermin�ti on o f thor ium , yttr i um and the rare ear ths in s i l i c at e ro cks . The b e s t l i ne - t o-background ratios were achieved by arcing samp l e s in a m�trix of 4% s odium chloride in carbon p owder . An atmosphere o f 20% argon and 80% oxygen w�s us ed to r e duce background and eliminat�

cyanogen band int erferenc e . An ani o n- exchange pro c e dure was used to s eparate the rare earths from other elements . The resul t ing enr i chment allowed use to be made of less s ensi tive rare earth

lines in the ultraviolet end o f the spe c trum where the sp e c t rograph i c dispersion i s greater . Line interferences w e r e studi ed and

ne c es s ary corre c t i ons for thes e interferenc e s were cal culat e d . The t echni que was tested b y analysi ng the s t andard rocks , G- 1 , W-1 and CAhS syeni te . Depending on i ts c onc entratio� uranium was analys e d by e i ther fluoram e t r i c o r spe c trographi c te chniques . Good agreem0nt w i t h the recommended values for the s tandard r o cks was ob taine d .

Par t I I

An inve s t i gation o f the known areas o f uranium

minerali zation in the Lower Bul ler Gorge o f New Zealand was carr i e d out to i nves tigate the suitab i l i ty o f s tr eam- sediment

analysis for geochemi cal prosp e c ting for uranium . General analys i s o f t h e minerals r eveal ed certain el emental as s o c i at i ons . The

distribution of these elements in the weathering sequence, minerals,

soils , s t ream-sediments , was s tudied in an a t t emp t to di s cover

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sui tabl e p3.thfinders for ure.nium. ,.11 rcsul ts were tre3.ted s t�t i s t i cally . Rare ear th analys i s of s tream sadimants provided new in form�t ion concerning the p^os sible ori�in of the Hawks Crag Brc:c c ia.

P<1.r t I I I

Us e was made o f ^a high- resolu t i o n gamma spcc trometer t o s tudy the gamma radi at ion o f uranium minerals in the low energy r egion of the spec trum , 30-360 KeV . Ident i fi c ation ^{o f} the gamma radiat ion , in thi s region , was achi eved by u s e of chemi c al

s ep3.raticns and s tandard sourc e s . This provided the bas i s for the development , and s u c c e s s ful us e , o f ^a new me tho d for the deter

mination of "perc entage equ i libri um radium" . The s i gni f i can c e o f the values for the "p erc entage equil ibrium radi um" o f the m i nerals s tudied is di s cus s e d .