geology and origin of the century zinc deposit · geology and origin of the century zinc deposit...
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Broadbent, Graeme Charles (1999) Geology and origin of
the Century Zinc deposit. PhD thesis, James Cook
University.
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Geology and Origin of the Century Zinc Deposit
Thesis submitted by
Graeme Charles BROADBENT BSc Vic
in 1999
Volume 3. Charts and journal reprint
For the degree of Doctor of Philosophy
in the Department of Earth Sciences
James Cook University of North Queensland
Economic Geology Vo!. 93, 1998, pp. 1264--1294
Geology and Origin of Shale-Hosted Zn-Pb-Ag Mineralization at the Century Deposit, Northwest Queensland, Australia
GRAEME C. BROADBENT, t
Rio Tinto Exploration, po. Box 175, Belrrwnt, Western Australia 6104, Australia
RUSSELL E. MYERS,
Key Centre in Economic Geology, School of Earth Sciences, James Cook University, Queensland 4811, Australia
AND JOHN V WRIGHT
Hoogstraat 50, 1381 W Weesp, Netherlands
r---. ..................... \ ----1 ----,--
I I I
{ I J I / I I I -
I I
I I I I I I I {
I I J I I I
0091 Ltl261 , I I!:l
1 ~ I ... 28000N + I
I I I DD91lH100
I I
I
LH113 • Tuff Marker bed
UnH.2
' ...... ...... , ...... -............
Tu!! Mark .... bed
Unit 4,2
LH120 •
Tu!! Marl<er bed
Un114,2
-.... ..............
LH82 •
Tu!! Marker bed
Unit 4,2
•
LH80 • Tull Mar1ler bed
Unft 4,2
•
-
LH107
":11
.... ------ j ...... -
Unt!4,2 - / ___ _
I f I I
Untt 4.2
LH168 •
Tuff
--.... 0091 LH164 "'"
UnU.2
Marker bed
~-~
Key:;
~ h .. .A :!I
Percentage of slllstone beds <100>50mm thick in _----'---:::~-'l:Tufi-Mai1<er-bed ~1 m logging Interval (Date in Appendix 8) ,
Percentage of sllt$lOnll beds>1 00mm thick in ~1m lOgging interval (Date in Appendix 8)
Zinc % (ore zone Intervals only)
LH154 •
Unit 4,2
0D90 LHeO
UnH2,
DD90LH60
LH115 •
--;;;~=::----~---~~~ ~, Vnft4,2 ........... ....
..... '\ \ \
---
\ \ \ \ \
"
' .... .......... .....
-----' ..... ~ { ApprOlCimate boundary of ore block$ (projected)
27000N
I I I t I I \
~
/ I
---".-..,."
"
ruff MarKer bed
~\ ~" . '.1----
LH168
I 1 I ~, I ~-~ .... I ; .... ". r ~ .... I ",'*M~bed
.... -/
_--- lH97 ----_ ..... ""'" . ----....... .,..... ------:3:: TuffMar1ler!le1l' .... - ___ -,-
~ Ltl170 ;-r _">- •
Unit 4 2
-::= .011 LH184 - . TulfMar~er bed
/ •
/ •
/ LH142
--~~- /' _=.!! ---.-.. _....r""'1 -- --_ ....... - ........ -• •
0091LH163 TuffMarl<erled .,d'---Marker bed ..- ....-;; -- ....... ...-............. ~;:-.------..
• ----- ...... ......... --------- .................
Vo114.2
Unll',2 UnR4.2
lH155 •
0091lH129 . UnU.2
---
Enclosure 1 . Relative abundance of >100mm and <100>50mm --~ - .- - --
Century Deposit. siltstone beds in rf~presentative drillholes. - ~ - -- - -.- - - ,,- - '- .-
, , "-
"\ \ . .\/
/, Tuff Mark .... be9 ,'/ \
LH110 I • I
•
Uni14,2
w '" '" '" ~
, + 28000N
w is o ." ... + 27000N
Scale 1:2500
Graeme Broadbent. PhD thesi&. Marct11999, Geology ano Origin of the Centuty Zinc Dep01lit. Enelo&ure 1.
DD91LH129 DD91LH164 DD90LH25 '
DD91~100 ~~ ______ • ____ --}-------~D~D9~O~L~H~40~--------~~J[~~----------~~--=:=::==:::::::===~~~::t:::~=--I ~~~ ______ ~-+~~~~----------~~~--__ ~ ____________________________ ~D~D9~~OLH54 v I- CLS
,CLS CLS
HWS
HWS
HWSSI
unit 1
FW FW
800Rl t----------------r-------r--------------------------------------
NW
125
130
135
140
145
150
155
165
46500E . . 28000N
o 10 20% 30% , .
---- - _ - :;!l" --
- - ' ...... -_. +.-.... ----
-
4700tlE
Key: ;;:::¥:ll-Tuff Marker bed
~~~r--tlllnIY I>edCled 1lI1tstol1elmSte TaCleS
-E;ly!o,liticsiltstone faCies
'::::::::::-- SIM/e fac:ies
l) 10% 20% 30% (Y I
-- - - - ------ - -- Tuff marker t*l - - _ 190 - - - - - - - -- - ---- - - - -- - --- - - - - - - -
unit 1
210
-~-- - - -
---unit 2
-- --unit 3.1
unit 3.2 225 ~---L:-=1 - - _. - -
unit 4.1
-... - -- _ 230
HWS
FW
275001'1
10% iI!O% 30% ,
• . - •
........ ,"'" % (ore zone intervals only)
~ %
o 10% 20% 30% f •
o 10% 20% 30% I I
It-~
-- - --
-
CLS
HWS
47500E
Cambrian Limestone
Hanging Wall Sandstone
HWSS' Hanging Wall SlItstone
FW Footwall Sequence
= = ;:::;; = ::::c::: -=------ -- --- - - --
- -- - -- - -
- - -- - - ,.....,... -
170 unit 4.2 ------ - --unit 4.3 1---=-"'- -'-
175 - -1-_"--.., - -- --- --- --- -
unit 4.514.6 ---180 -- -.. --. - -.. -- - --- 240 - - -. -- -- - ---- - - 235 --
. DD91LH261 DD91LH10. 0D91LH54 DD90LH46 DD91LH164
HWSS
, unit ~\::::::::-::;:::::--
CLS
CLS
~~. ----------------------------------------~--------------------------------~~RL
..
J
130
9lZ6---1i
Sample fIlcations fOr siderite analyslll, projllCled to .approximate plane of transect
a 10% 2G% :!;J% I j
- --- -- - -
- - -- ..- -
--- -
D090LH25
270001'1 48Q.OflE
Pie diagram of averaged composition of IIlderite laP analyses) a$ determined by microprobe analysi$. Analytical
data are in Appendo< 3, SE
G 10% 20% 30% I I
Iffdiwdual driJlholes have tJeer, .~ to correct for appaf&"l.t th .::k~ v,atiatict'j: ~lJSed by dAnmt ""'" '0 ~$ns BI!g''', ToIa me:", <»nIlm: has alSo bftn re~scaled - reWer u;ale bars tOT individual ~
D091LH129
Vertica.· se" 'e 1 ~250
Enclosure 2. Century Deposit. Geological cross section and assay· profiles, SE-NW transect
Graeme Broadbent. PhD thesis. March 1999. Geology and Origifl cf the Century Zinc Deposit. Enclosure 2 .
l~oRl---------------------------------------1--------------·i---------------------------------------------------------------t---------------------------~-----------------------L--~----~--------------J I 1200R
1-________ -""'----------~D~D:91L_H_1~~~~---------D-D-91LL~~1n~.~--~--~:-__ --~:_----__ ----------~D~D~9:1~LH~1~~~----J~----------~~-D-OO-OLHOO . - _____ ~D~D~990 LH90
• CLS -. ----1....-------HVVS ClS
CLS HWS
HWS~------__ +_~ FW
1000RL
FW unit 1 FW
FW
800RLj-----------------------------------t-------------f-----------------------------------------------------~~ r--------------------------------------------4--------------------~~RL
. 27000N 47JOOE
~~~==:~TUff Ma.rker bed thinly bedded siltstonelshale facias
~~- stylolllic siltstone facies sw Key: !---':'sihale facles
(I 10% 200£ 30% 1 •
- -~ ::::::: ____ :0_ --_ Turf marker bed - --- --::::---145 -----------.......,---- se 155
unit 1
160 235
165
7(; - - - -- -- -170 - - ...... ~ unit 2
- - - - -- - -unitU
- -- - - - - -- - - -115§;5 - - - ....... -unin.! - - -- - - -- - -- - -unit 4.1
4----,..1 _ _ - - - --unitU - --- - - - - -\lnitiU unit 4.4:= - - -- -- - -- -- - - - -f-...s...",,- - - '-- ""-
195 .95 -- - - - - - - -
0D91 LH163 DD91 LH177
. 215000
o tlW> 20% 3O'If. t I
J::;:J--:ZiOC % (ore zone intervals only)
---
0091 LH164
- - ""*' ... --- -
- -
- - --- - - ~
- - - '- ,,,-,-
-- --- -1245 ----
CLS Camblian Limestone
HWS Hanging Wall Sandstone
HWsS Hanging Wall Siltstone
FW Foatwsll Sequence
_ ... _- 1 .. .....
- --
--
"" 12011if
-
-
47500E
NE
Q 10% 20";; 30% 1 __ j
I
1"0_.1-' _ belIn .. ..::aIed 10 COtIiId. 'l:t.pparef'IC thidlness varial\aa _ by_ c~'" \0 _1nQ ang!fs. Total meIaI et)1'I!tel1tlln aIao teen re_ - relerscale _ fC! iIi~ log$.
DD90LH60 DD90LH90
'Enclosure 4. Century Deposit. Geological cross.section and assay profiles, SW-NE transect
GraemEI Broadoont PhD thesis. March 1999. Geology and Origin of the Ce.ntury Zinc Deposit. Eoc\Qsure 4.
i I
sw
180
183
184
185
· .... · ' .. ' . · ' ... ~.
::/', ' ... ~ ,. , ... . · .... -
, • ' , 'f .•
· " ~ . , ... ~ . , " '. .". · .. ' . .. . . . . - . · . . .
DDW LH163
py sp1 sp2 gn
• • • " '"
81
85
I-l
.~.:t:". . ..' ,. : : :., . , ' , .. : : .: .. ' . , ., ,
DD9QLH1n I
unit 3.2
/"
py sp1 sp2 9n
unit 4.1
T
I
unit 4.2 ,
- - ----- -DD90 LH177
251
252
... -.
I," i '<
I,':"" [-',:=: L' ' , ' ,', .. , - ., :. " .. , I,' ':', , ' , . : : .. ; ',-. . . ,
DD90LH164
py sp1 sp2 90
_._- -0090 LH164
234
'-.., /
""\Qeo LH60
,v /
/
/
'-.., ....... 1/ PY sp1 sp2 gn
--
235~
238
239
240
· " . .. . ~ '. ~
, · .
· . . ·
• • • .. . ,
- ·
. · ' ,
. -
. . , .'
~'- DD90LH6Q
160
/' /
161
163
164
,-
165
. ,
· -. , , . · ' .. '" , , . ' .
· . , · . . , . ..- .. '.' .
"" . -.. ~ . ' . , -
· , -
.' , · . , '
, ,
, ' . '
, . . .
D090 LH90
py sp1 sp2 gn
0090 LH90
Enclosure 5. Century Depo$it NE - SW detailed core logging transect. Lithology
Fine shale partings. 1·3 mm sclJ!e
FInely bedded silllShalelshale laminae 3.2Omm scale
MBiSlve sill beds
Inten&e sty101ite d_lopment
Moderate IItylo1ite ~Iopment
Weak stylotilesJundulose bedding, compac;lion feature8
SIlolI'$iIWins
. :.~.:.~.:.: ... .... . . , "'" ~
1--..
Siderite Alt~ration
Intense dissemina,on I •
medium di$$emin_
weak dissemination
Nodulelllboudins i
Di$$eminations along IarJIlJllae
• Siderite altElrf is supenmpose on lihology col n.
,
!
I I
-$~
'if (,f
Pyrite (py)
Richly pyriilk: ZOl\eli
Pyrite rich laminae
~seontinuo\llllaminae
Transgressive to di&&emlnatecl
Veins and crackles
Grey Carbonaceous sphalerite (sp1)
Rich laminae, approaching rnaSllil/e
Well developed lami!lae
Sparse diseontinuouslamlnae
1&..:::::1 . Atoll texturelifreptacement fronts
1L...._sl~ilve:ale Slit} SedlmentGl'llilt$ize
'---shale
Vertical_le .. 1: 10. Individual graphic logs tuI1Ie been rlMlclJ!ed to correct for ap~ lIIickne$$ variallon caused by dlfferent core to bedding angleS. OrigInal dIif hole Il1Blr'IIaQe8 are as Shown on Individual lOgIi.
White noncarbonaceous sphalerite (sp2)
Rich laminae, approaching massiv .... ultra.flne grainslze
Well defined laminae Ultrafirle gralnslze
~~ Discontir«JQUS laminae a~ r: dillseminated !lne «Q,3mm) sreins along bedding
Disseminated rned grained (O,S·1.0mm) bands and patches ("awiliy"exlufes)
Coar&e (;>1.Qmm) sugary leJdured granular aggregates
VlIlns and crackles
.',. ~ .. ~"');I;w. ...... .. ,
,,' " . .. , ... " ..
~ 'r !¥ {} \{" , "
Galena (gn)
EuhedraJ cryst~1 dispersed along layering
Weak disseminations
Bands along layering
Irregu!ar replacive masses stylolile ionus. i:jeddlng_ ' parallel layers .
Veins and cracldes
I
Graeme Broadbent. PhD theala. March 1999. Geology and Origin of the Century linc D&~it. Enclosure 5,
,
i I -,