t ie / . , . i . . ' area soutfi Marievale HLne, -Rtiere the % la-Elrd a tra ta and
th e dyke ttave been retoOveg tiy- QrosLon.
fccttor^ing to E llis (3), the fracture occupied by tbe. iatru slo n »as salsly tbe. resu lt or internal tension due to ' suutetranestt subsidence. There Bre m si cat leas however that tbe coarse of tbe dyke ®as deterained to some extent by pre-..
ex lstlog trse tiires or fau lts. This is suggested by Us frequent cbanges of direction and elso by tbe S e t tbat tbe ayke, where t t transgresses tbe Main Beet Leader, frequently , 8 t$ s inwards,towards the downtbrown side. A teniiqa fraetig-e, due -to v e rtlo sl stresses t?oald have to dip outwards,.towards tbe Upttircmn side. In tbe nortihern/of toe "Old IM y * , t i SBTtflgs \. end Daggafanteln .Mines, there is Horizontal separation o t tbe. . "reef% on tbe: dyKe on tbe eastern Side, and overlapping pti tbe.. .western am* souttiem sides, m e racks inside the dome W e , ,v not only dropped vertically but have moved ttonaaftteUy -to a s iu tb -neste ti? a lrestlon , as would be easetie? I t tte aanten
* r U , D, direocioas oetweeo «est =04 so itii. mgi M U lasja tea tin s
point. n * u » . , W 4 i t r T . '
tee "OM ladr” tod tw Se« S tats Areas lotrosloo are im gb li i;
i . w « i n . w 9 0 .
. u w .* u w . f m i « , w m w " " 1 * « ^ * "
K U t w w fo r"
m tl0re6=l=s ’rar / m e j
They a t» ao t confined to any p a p tlc a ia r area and are tiuch tb ioner
; tbao .the upper s i l l phase' o f th e "Old Lady". Generally they
... s r e com pletely decomposed. . ,
Tffo examples air6 fcnown .underground of in tersec tio n s
. between narrow decoeposeS dykes, believed to be qu artz diabase, *
and normal sad reversed f a u lts devoid of igneous m ateria l, l a .'
bo th cases th e dykes are younger than tbe f a u lts an0 are net.:
d isp la ce s by them. TDls shows th a t the s t r a t a were frac tu red •
and fa u lte d before th e quartz diabase dykes and s i l l s were
in truded , Tbe,dykes fo llo ^ p re - e x is t in g planes- m. f ra c tu re or
f a u lt in g and in most cases suffered a g rea t d ea l-o f .shearing ;
ttsrougti renewed aovement on the fra c tu re s a t a l a t e r period* . .
g. PETROLOGY . /.-.> >
Quartz diabase is a tough, pale grey, fine-grained rock,
with a d u l l , non-lustrous appearance s im ila r to ilo e n ite ats&asev
In th in dykes and s i l l s and near tb e margins of th ick er in tro s -A
ions i t i s u sually sheared and completely decomposed. «ben sheared i t i s d i f f i c u l t to d is tin g u ish in hand-specimec frm - ,;,.
occasional specimens from the centres of th ic k in trusions ;
at,™ an o p h ttlc texture. » th in s e c tio n t t l g . IS ) , file
' - i r m f t * . y ;
w a .
m i w r r aK n o j; " W " . / largely.-
r " i
Qpartz Diabase from centre of "Old Lady" Dyke, E ast Oagga- footelQ Mine. Ordinary l ig h t. M agnification X21.
P la g io clase , s a u ssu rltlse d (pale grey la th s ) Remnants o f long prism atic c ry s ta ls o f A uglte, enclos­ ing P lag io clase la th s (darker grey, in d is t in c t)
This specimen is unusually coarse and fre sh . O pbttlc tex­ tu re Is c le a r ly v is ib le .
Quartz Diabase from "Old Lady" Dyke, Springs Mine.
Q iartz Diabase from "Old Lady" Dyke, Daggafonteln
Ordinary l l g b t . M agnification X19. No tra c e o f primary te x tu re .
O ra llte (sm all pale bladed c ry s ta ls ) C h lo rite , C a lc lte , Leucoxene e tc . (grey , in d is t in c t) Iron Ores (black) Q iartz (c le a r )
In f i g . 17 a v e ln le t o f q u artz , ep ldote and c a lc lte crosses centre of f i e ld .
U /
Typical quartz diabase
decomposed than the specii
o p n ltlc texture are s t i l l (
renaln :xcept possibly qu
the rock a characteristic
scope. Iron ores occur
A lb lte is sometimes consp
snowing cneracterlstic li
z o l s i t e , ca lc lte , ru^ lle , <
p re sen t.
iro n ores, quartz, calctti
o f a primary texture. M
epldote and ca lclte are f
tn e re are occasional rell*
tiOT.ewr the rock is sSiean
destroyed. Egsential Minet
Plagioclase - * ptienoer 6056 An I or compi replace
la rg e ljF .a ite rea to u f a l t t e and c b lt ir t te . . ' .
: ’ESptcel fitaBase i s f in e r in g ra in end atmft more - aecdopdseti tfean th e specimen sbown In f ig . 15. R elios o f
o p b it ie te x tu re a re s t i l l v ts itile but no p ris is tf stijierals / , ; •
. recdaia ax&ept posaibly Quartz, ( t i g , 15), u r a l i t e i s abunaaot and acdiira 1b th in blasefl c ry s ta ls and long f in e needles, .giving
tb e rock- a tiia ra tt^ ris tic ^ irea ttie ry 11 appearance under tbe •jntct'o-
scope. ' Iron Ores, oceur In sm all g ra in s and spebfcg. Quartz • : .
occurs i e minute e le a r pools ana occasionally as m .lcropegaatlte,-•
A lb lte is. sometimes, conspicuous a s sm all sca tte red c ry s ta ls k shoeing c h a ra c te r is t ic lam ellar tw in n in g .. A l i t t l e ep ldo te , : . v-
z o i s i t e , c a lc l te , r a t l i e , p y r i te ana p y r r h o tl te :8re oeeasionai^y
present.. '
F requently th e rock i s in a very advanced s t a t s o f alterMtlo9% ( f ig . 17), i t co n s is ts of a contused mass rif u r a i l t e , c h id r i te ,- ; '
I ro n o re s , q u ar ts , c a lc l te and o th e r m inera ls, f l th o u t any-tratid •
o f a Brimary te x tu re . Minute v e in le ts ol' o a lo r i te , quartz ,
ep iao te and c a lc l te are f a ir ly ebomoc. Sear in tru s iv e eontacts ...
th e re are occasional re lic s of a p o rp h y ritic -texture., GenersCLtx
boisever th e rock i s sheared .and a l l i t s primary fe a tu re s are .
d e s tro y e d .' ' '
S o l An ta n d e sin e -M ira d d n te ) . gaussu rltlsetv o r completely decomposed, occasionally - replaced by a lb l te .
fptiene a f te r llm e n lte ,
- " • S S J S i w S S ® ^
^ - . 3 3 %
.. SLU enas I>°
'iRe. wQl:d tn tru d ed .e itti^ r before a r a f ts r , but - %
not W in g , tBe ^ ^ s W v O f the 'vec tersdors .lavas, since th# :
magna fitd' ttot reaob ib e . s a r fsc e (3 ) . Tbe magma s tiH d if lea ;.
near t to -g u rfa s e anfiyMOti g re a t depth, since, tbe diabase, i s :.
s im ila r , a p a rt tji# absence o r a m y g a e le a to tb e lavas Of .
tbe Teiitersiloi'p^ th e Bird S e rie s . The bigbest
stra ^ lg ^ 6iBt$l5 . tioriaon•.reabhed by the "Old Lady" Is the
Kimberley .S tiale | :n6t f a r beL .. tb e pre-Ventersfiorp .surface but a c o ^ i s e r a m -dsptb belo s tfte top of tbe- Yectersdorp
% stem . Qiiarta diabase dykes and s i l l s ibtrtifle tb e lower Blsburg beds bu t are not known to penetrate th e Ven#ters&>r$>
lav a s. 4 .x- The above evidence poin ts to th e q uarta diabase in th is ions
being o lfler tbao th e VentersdorB la v a s , th e i r age bAlng ea riy ;
Ventersdorp or la te witwatersrand.
S e le s i s s siuBEary o f th e pltncsteal c h a ra c te r is tic s o r tbe f lv e g ra ip s o f In tru s iv e rocks described above*
V e rtle a l dykes trend ing Ntr-SE to B-w.
S i l l s a t o r n ea r p resent su rface .
Ho v e r t ic a l displacement o f s t r a t a on £
Fresh d a rk b o lo c ry s ta llln e ro c is .
Texture o p b ltlc to aub-opb ltlc .
Margins c h il le d , w ith p o rp b y rltlc texture*
E sse n tia l m inera ls; p lag ioclase (jpradorlte-by tow nlte),
a u g lte (d lo p s td lc ).
A ccessories: o liv in e (conspicuous In s i l l s , ra re in dykes),
iro n o res , b to t l t e , quartz ( in 6ykes, absent in s i l l s ) .
A lte ra tio n
Very l i t t l e . P lag ioclase and au g lte generally fresh*
O livine serp en tln lse d .
4sa L ate Karroo.
Type o f In tru s io n . S i l l s In tb e Transvaal dolomite. A few narrow Inclined dykes in th e ffltwetersrand System;
K o lo cry sta llln e rocks, dark o r m ottled (Green Syenite) and /p a le
W / (Lie redaiab (Bed syeaite). T exture bypidtosbtpbie-granulBr (g ran ito id ) . t a r g lo s e M lise , p o rp b y rltic . E sse n tia l M lnersla.
(a ) Green Syenite: p lag ioclase (andesine, la rg e ly
a l te re d to a l b l t e ) , a u g lte , u r a l i t e ( a f te r aug lte)
(u) Bed S yenite: a lb l te (90# o f rocic).
A ccessories.
(a ) Green S yenite: iron o res , q u artz , b lo t l te . (B) Red Syenite: b lo t l t e , quartz (much micropeg-
m a tlte ) , iron o res .
A lte ra tio n
(a ) Green sy en ite . Moderate to In tense . Andesine a lte re d to a lb l te , aug lte
to u r a l i t e and e b lo r i te . Secondary ep ldo te, quartz
and c a lc l te .
(b j Bed S yenite . Moderate, A lb lte cloudy, b lo t l t e cb lo ritlsed *
M s Pre-Karroo. Bushveld o r post-Watertergr.
I r r e g u la r v e r tic a l dykes trending NB-SW.
Rnpw s i l l s and narrow in clin ed dykes.
l i t t l e v e r tic a l displacement o f s t r a t a on dykes.
D un grey a lte re d rock, f in e t o medium grained.
| 76 Ifexture o p b itlc ( r e l i c s ) .
M argins e b ll le d anfl deccmposefi, occasionally shearmii
E sse n tia l m inerals: p ieg ioclase (andesine-labradorLte, decomposed), u r a l i t e ( a f te r a u g lte ) .
A ccessories: Ilmen t t e , quartz?, various secondary m inerals.. A lte ra tio n
in tense* P lag io clase rep laces by c h lo r i te and o ther min­
e r a ls . Auglte o ra ll t la e d . Ilm enlte leucoxenlsedi
Secondary ep ldo te, q u artz , a lb l te , c a lc l te , t a lc .
£gg Pre~Transvaal, post^Ventersdorp.
4 . THE mRITE-msANOPKYRE
Troe o f In tru s io n Tblcjt s i l l s of n o rl te overla in by granophyre. In the
Kimberley Shale, Bird G&iartzlte and Jeppestosn Series*
T ransgress ive dyte phase d isp lac in g the Maln-Blrd s t r a ta
v e r tic a l ly atitait 300 f e e t .
A few narrow dykes and s i l l s .
P e tro lo g ic a l Features
(a ) B o rlte . D ull greenlsb-grey rock, medium to coarse grained.
T exture hypldiontorphic to panldltXQOz*pl5ic.
M argins c h il le d . e s s e n tia l m inera ls: e n s ta t l te and d lopslde (a lte red to
serp en tin e and u r a l i t e ) . A ccessories: p lag ioclase (by tow nlte-anortb lte , decoo-
posed), quartz ( l i t t l e mlcropegmaUte).
: : - (tf) Gr^flOJ&yre.
t t t t l s fe y rodk, medium to coarse grained. Texture g ra n itic*
Contact e l t t t sbale g ra d a tio n a l, con tac t w ith q u a r tz lte
Sbaitier. E s se n tia l m inera ls: o rthoclese (deccxnposad), q uarts (cucb
m lcropegmattte), hornblende.
A ccessories: i la e n l te , e b lo r i te .
A lte ra tio n
(a ) N o rlte . In ten se . Pyroxenes a l te re d t b serpen tine and u r a l l t e t
P lag ioclase decomposed.
(b) Granophyre. In ten se . O rthoclase s e r le l t l s e d , hornblende e b lo r i t ls e d ,
Ilm en lte leucoxenised. Secondary c a lc l te and occas-
lonal ep iao te .
MSS. L ate Ventersdorp.
Thick s i l l s in tb e B ird S eries and Jeppestosn S e rie s , a i tb
tran sg ressiv e dyke phase forming a closed rin g sM
d isp la c in g the s t r a t a v e r tic a l ly abcait 850 f e e t (the
"Old Lady"). Numerous th in n er s i l l s and inc lined dykes w ith no p a r t ic ­
u la r tre n d , d isp lacing th e s t r a t a v e r tic a lly ,
D ull grey a lte re d rock , f in e g ra in ed .
: dpblttd . toccBsiooal r e l t c s ) .
M argins sheared and decomposed»
S M en titi . m tnara lst p lag io cla se (andesine-labrB dorlte ,
6ec<a®oseS), u r a l i t e ( a f t e r a u g lte ) .
A ccessories: Iron o re s , q uartz ( l i t t l e m lcroBegnatlte),
various secondary minerals*
A lte ra tio n Extreme. B enerally no- p rlsa ry te x tu re . P lag ioclase toeomr
posed aM seldom recogn isab le. .4 4 Augite u ra il t l s e d i :
Secondary e b lo r i te , q u artz , ep ldo te , z o l s i t e , a ib ltS
c a lc l te , leucoxene, tu tU e .
a s s E arly V entersdorp o r L ate W ltwatersrand.
My thanks are fitie to D r,J.A .Bancroft, Cohsuitlng Geologist,
Aaglo-*fi6riean corporation o f Scutb A frica L td ., f o r Bermlaalyf
t o w r ite t h i s tb e s ts .
1 am u y eb te d t o o ther members, p a s t and presen t, o f the
s t a f f o f tb e Anglo-American Geological Laboratory, sp rin g s , fo r
moat o f tb e underground geologica l mapping on whicb th i s fiorSt
I s based, ana f o r tb e prepara tion o f most o f th e tb ln 's e c tio n s
I examined; I thank Dr.B.B.Broek, A ssis tan t Constiltlng G eologist, fo r
b i s in te re s t and c r it ic ism s , Mr.H.C.H.Ubltesiae and Mr.P^i.
Stiydom f o r many h elp fu l suggestions in the course o f th e woM*; and !£r.C.S.Beugger fo r advice In drawing th e plans and sections*
Springs, T ransvaal.
BOth Novea&er 1949.
G > * r r * l . «.W.: o f rM n M m T . ^
L M .. M0Q. (2 ) m m t , A .L .: - I t e aw ftcor s m th * m o a * . c a i w m a
B oja , 1939.
(3) sails, J .: "M ratmal"” °* * « « ' Mertto “ « w * r — » — . W M i " . M ' » * '
VOL. s a i l . 1S40- „ ,
- - : = = = - = -
t r a n s . s e o l^ o c .s u i . . Vol. Z O . l94S- •
$ rans .s«< il.soc .s .A ., Vol* l * 19to-
1
:
i - I / t i t 5 £ S 3 5 t W l - F i c H g
" ' i r V 'v t W v - : ••
i .
-I •
i k :
,4 ;U
f: li i" f. 1 ' il* i k L M i M'S4: 'k
f
P L A T E M E
P O S S I B L E STRAIN RELATIONSHIP BETWEEN THE 1 LMEN ITE DIABASE
DYKES AND OTHER STRUCTURES S C A L E I : I 0 0 , 0 0 0
S E C T I O N O F
S T R A I N E L L I P S OI D R E F E R E N C E
A X E S O F F O L D I N G I N T H E M A I N R E E F L E A D E R
— - A n t i c l t v n
T E A R F AULTS
RttjVvC- Ko-hviieol —. . . . . . . L « f t -
\ /
Vo,
S C A L E Vrko*s«n. «l3 Of f e « t )
3 0
' r .
PLATE YU S E C T I O N O F N O R I T E - G R A N O P H Y R E
A N D "OLD LADY' HNTRUSIONS S C A L E I : 5 0 , 0 0 0
KARAOO
T n x r u r z z a . ul u a zz
S C A L E ( T h o u s a n d s of f e e t )
R E F E R E N C E
W IT WA T E R S ft A N D S Y S T E M
V77T777J K i m b e r l e y S h a l e
rv v v v d B i> "d A m y g d o lo ic l
KXWWvS Te.ppeb^-iwn Series
1 N T R US I V E S
( M o n t e - G r a n o p h y r e
Q- ua r bz D i a b a s e
£. D
». g<
P L AT E 3ZE
PLAN OF NORITE - GRANOPHYRE AND "OLD L A D Y ' INTRUSIONS
S C A L E I : 100 ,00 0
R E F E R £ N C E
D Y K E S DI SPL ACI NG THE MAIN RE EF LEADER
fv Jo rL C ft - G r o vi o p K y v a.
O l A U»oLij’' ( c^K arka d. L a b a 9 « -) •
S I LLS IN T H E B I R D S E R I E S OR T H E KI MB E R L E Y S HAL E
X * x x N e v i t* . - G r * « .o p k - j r c .
F A U L T S D I S P L A C I N G T H E M A I N H E E F L E A D E R
&-—g--------- N o r m a l
=----; ---------- ReV «.y54.el
. - 0 -------- T e a r
--------------------------L I N E OF S E C T I O N I N P L A T E VTT
L : . . I ' L ' ' ' j i , 1' h . I I
P L A T E m C
P O S S I B L E STRAIN RELATIONSHIP BETW EEN THE I LMEN ITE DIABASE
DYKES AND OTHER STRUCTURES S C A L E I : I 0 0 , 0 0 0
R E F E R E N C E
A X E S OF F O L D I N G I N T H E M A I N R E E F L.« A P E R
— | r — S y n- c l i ni xl -------- ^----Ah. t i t . l i . r - . al
T E A R F AULTS
........ L e f t - tvo.>t.cle.cL
I L M E N I T E D I A B A S E D Y K E S
S C A L E (JU < m s* n ..L s o f f e e t )
3 0
PLATE YU S E C T I O N O F N O R I T E - G R A N O P H Y R E
A N D "OLD LADY' HNTRUSIONS S C A L E f ; 5 0 , 0 0 0
g g a a g a Z k Z > Z % Z Z Z : ^ 2 Z ^ Z Z 7 Z X 2 Z ? Z X Z Z 7 2 ^ K x ^
R D S e r i e s ^<<V n n
; W ^ ^ X \ X \ x x x ^ s X t
R E F E R E N C E
S C A L E ( T h o u s a n d s of f e e t )
W I T W A T E R S R A N D S Y S T E M
77777772 K i m b e r l e y S h a l e
rv v v v a B i r d A m y g d a l o i d
K^VvYnX^ Te . p p e s t o w n Se r ve
t N T R US I V ES
N o r t t e - G r a n o p h y r e
Q- ua r b z D i a b a s e
T
NEV STATE AREAS f NTR usi ON
PL AT E m PLAN OF NOR IT E-GRAN OPHYR E A N D
"OLD LADY" INTRUSIONS S C A U £ \ •, ioo^ooo
R E F E R E N C E
D Y K E S D I S P L A C I N G T H E MAI N R E E F L E A D E R
3a®&aB^^8SS5B N oi-C t* - G rA T io p k g y *
"OIA. L a <i y '* ( c L t a b a S e . )
S I L L S I N T H E B I RT> S E R I E S OR T H E KI MB E R L E Y S H A L E
V X X X N o v 'l t - G Y fcH.O p k ^ r c.
C?i*a»-Ca eLLttbixae.
F A U L -’" ' - D I S P L A C I N G T H E M A I N %EEF L E A D E R
± T----------- Noiri tvt t .1
—~ — j---------- R c v e r s A e l
^ --------- T e a - v
------------------------- L I N E OF S E C T I O N I N P L A T 't7XE
2 . 5 0
S C A LE
Author Brandt R T Name of thesis The Geology Of Certain Igneous Intrusive Rocks In The Far East Rand, Transvaal, South Africa.
PUBLISHER: University of the Witwatersrand, Johannesburg ©2013
LEGAL NOTICES:
Copyright Notice: All materials on the U n i v e r s i t y of t h e W i t w a t e r s r a n d , J o h a n n e s b u r g L i b r a r y website are protected by South African copyright law and may not be distributed, transm itted, displayed, or otherwise published in any format, without the prior written permission of the copyright owner.
Disclaimer and Terms of Use: Provided that you maintain all copyright and other notices contained therein, you may download material (one machine readable copy and one print copy per page) for your personal and/or educational non-commercial use only.