provenance signatures of sandstone-mudstone

7/23/2019 Provenance Signatures of Sandstone-mudstone

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Chemical Geology,67 (1988) 119-139 119

Elsevier Science Publishers B.V., Amsterdam -- Prin ted in The Netherlands

[31

P R O V E N A N C E S IG N A T U R E S O F S A N D S T O N E M U D S T O N E

S U IT E S D E T E R M I N E D U S IN G D I S C R IM IN A N T F U N C T IO N

A N A L Y S IS O F M A J O R E L E M E N T D A T A

B.P. ROSER and R.J. KORSCH*

Department of Geology, University of Otago, Dunedin New Zealand)

Geology Department, Victoria University of Wellington, Wellington New Zealand)

(Received April 21, 1987; accepted for publication July 15, 1987 )

b s t r a c t

Roser, B.P. an d Korsch, R.J., 1988. Provenance signatures of sandstone-mudstone suites determined using discrim-

inan t funct ion analysis of major-element data. Chem. Geol., 67: 119-139.

Sandstones and argillites from selected New Zealand greywacke terranes represent four differing provenance groups:

P1 (mafic) - - first-cycle basaltic and lesser andesitic detritus, represented by the Maitai terrane and part of the

Caples terrane; P2 (inter mediate) m domi nant ly andesitic detritus (Waipapa and Pelorus terranes) ; P3 (felsie) - -

acid plutonic and volcanic detritus (Torlesse terrane ); and P4 (recycled) - - mature polycyclic quartzose detritus

(Greenland Group). Contrasts in major-elemen t composition occur between the groups due to differing provenance.

Si0~/AI~0:~ and K20/Na~O rat ios increase, and Fe20~ T+M g0 decreases from PI to P4, as a result of petrologic

evolution (P1- P3) and sedimentary matu ration (P4) . Some parts of oxide or ratio variation diagrams are distinctive

for each group, but considerable overlap occurs due to bulk composit ional variat ion with decrease in grain size. This

overlap is almost el iminated by dis criminant funct ion analysis using Al~03, Ti02, F%0:~T, MgO, CaO, Na~0 and K20,

and a plo t of the fi rst two functions gives effective separat ion between the four groups.

Tests of the functions with analyses of volcanic and plutonic rocks from New Zealand and the Lau volcanic arc,

additional sedimentar y terranes of New Zealand, and published data of sedimentary suites from Australia and the

Pacific margin give good results, suggesting tha t the method is a viable technique for provenance determination which

is largely independent of grain-size effects. The func tions are applicable only to rocks which lack signifi cant biogenic

fractions, or to those where analyses can be corrected for these inputs. A second set of funct ions using oxide/A120:~

ratios are designed for samples influenced by biogenic sedimentation. Although classification and test results are

adequate, results are mixed for suites of Tertiary and modern sediments with substant ial calcareous or siliceous com-

ponents from New Zealand, the Ja pan Trench and the Solomon Islands.

1. In tr od uc ti on QFL sytematics, has long been used as a tech-

nique for the de terminati on of the provena nce

Petrography of sandstones, and in particul ar of sedimentary units. It has also been suggested

tha t mudrocks should be used more extensively

for the same purpose Blatt, 1985). Lately,

*Present address:Division of Contin entalGeology, Bureau

of Mineral Resources, G.P.O. Box 378, Canberra, A.C.T. mu ch w or k ha s be en di re ct ed at de ri vi ng pe tr o-

2601, Australia.

graphic parameters suitable for assignment of

0009-2541/88/ 03.50 1988 Elsevier Science Publishers B.V.


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s e d i m e n t a r y u n i t s t o p l a t e - t e c t o n i c s e t ti n g s f e l d s p a r a n d a b u n d a n c e ( 8 0 - 9 0 } o f v o l ca n o -

( e .g ., C r o o k , 1 97 4; V a l l o n i a n d M a y n a r d , 1 98 1; g e n i c d e t r i t u s c o n s i s t i n g o f b a s a l ti c -4 n t e r ~

D i c k i n s o n e t a l. , 1 9 8 3 ) . T h e u s e o f g e o c h e m i s - m e d i a t e v o l c a n i c l i t h ic f r a g m e n t s , p l a g i o c l as e

t r y o f c l as t ic s e d i m e n t s f o r s i m i l a r p u r p o s e s i s a n d m a f i c m i n e r a l s ( L a n d i s , 19 74 , i 9 8 0 ) . ' F be

n o w b e c o m i n g m o r e p r o m i n e n t a s n e w d a t a b e - d e t r i t u s w a s p o s s i b ly d e r i v e d f r o m t h e la r g el y

c o m e a v a i l a b l e ( e .g . , M a y n a r d e t a l. , 1 98 2; B h a - b a s a l t i c v o l c a n i c r o c k s a n d v o l c a n o c l a s t i c s e d .

t i a, 1 98 3; B h a t i a a n d C r o o k , 19 8 6; R o s e r a n d i m e n t s o f t h e B r o o k S t r e e t t e r r a n e , c ~ m s i d er e d

K o r s c h , 1 9 86 ) . A s w i t h p e t r o g r a p h i c w o r k , g e o - t o b e a p r i m i t i v e t h o l e i i t i c t o c a l c - a l k a l i n e

c h e m i c a l s t u d i e s o f s e d i m e n t s a r e c o m p l i c a t e d o c e a n i c i s l a n d a r c ( C o o m b s e t a l., t 2 76 : W i l

b y m a j o r c o m p o s i t i o n a l v a r i a t io n s d u e t o t i a m s a n d S m i t h , 1 97 9; H o u g h t o n , 1 9 8 5 ). T h e

c h a n g e s i n g r a i n s iz e, a n d m o s t e f f o rt h a s b e e n K a y s C r e e k s a m p l e s a r e o f a n d e s i t ic p r o v e

d i r e c t e d a t s u i t e s o f l i m i t e d g r a i n - s i z e r a n g e . I n n a n c e , a v e r a g i n g Q s F2 oL v~ , ( T u r n b u l t , t.9 79 i .

a n e a rl ie r s t u d y w e e x a m i n e d K 2 0 / N a 2 0 - S i 0 2 H o w e v e r, t h e ir c h e m i s t r y is m o r e p r i m i ti v e t h a n

s y s t e m a t i c s o f s a n d s t o n e - m u d s t o n e s u i te s f r o m a ll o t h e r C a p le s t e r r a n e r o c k s ( s ee b eh ~w i , e s

t h r e e b r o a d t e c t o n i c s e t ti n g s , a n d / b u n d t h a t t h e p e c i a ll y t h e K 2 0 / N a 2 0 - S i O 2 r e l a ti o n s {R o s e r

c h e m i s t r y o f t h e f i n e r - g r a i n e d m e m b e r s , a n d t h e a n d K o r s c h , 1 98 6 ) a n d h e n c e t h e y h a v e b ee ~

t r e n d s i n s u i t e s a s a w h o l e , c a n b e a s d i s t i n c t i v e i n c l u d e d i n t h e P 1 c a t e g o r y ,

a s t h e s i g n a t u r e s o f s a n d s t o n e s a lo n e ( R o s e r

a n d K o r s c h , 1 9 8 6 ). I n t h i s p a p e r w e e x t e n d t h a t

2 2 P2

w o r k b y e x a m i n i n g c h e m i c a l v a r i a t i o n s b e -

t w e e n c l a s t i c s e d i m e n t s f r o m t b u r p r i m a r y

p r o v e n a n c e g r o u p s , a s t y p i f ie d b y e x a m p l e s o f P r i m a r i l y i n t e r m e d i a t e i g n e o u s p r o v e n a n c e ,

a n c i e n t N e w Z e a l a n d s e d i m e n t a r y t e r r a n e s o f r e p r e s e n t e d h e r e b y l i th i c v o l c a n o g e n i c g re y -

w e l l - e s t a b li s h e d p r o v e n a n c e , a n d u s e t h e d a t a w a c k e a n d a r g il li te f r o m t h e W a i p a p a a n d P e

t o d e r iv e d i s c r i m i n a n t f u n c t i o n s b a s e d o n m a - l o t u s G r o u p s o f t h e C a p l e s t e r r a n e . V o lc a n ic

j o r - e l e m e n t d a t a o f b o t h s a n d s t o n e s a n d m u d - l it h ic f r a g m e n t s a r e p r e d o m i n a n t l y a n de si ti c, ,

s t o n es . T e s t s w i t h a d d i t i o n a l a n d p u b l i s h e d d a t a a l t h o u g h m o r e e v o l v e d v o l c a n ic f r a g m e n t s

s h o w t h a t t h e f u n c t i o n s a r e a p p l i ca b l e t o P h a - ( d a c i te , r h y o l it e , t r a c h y t e ) a r e a l so p r e s e n t i n

n e r o z o ic s e d i m e n t a r y s u i te s e l se w h e r e , t h e s a n d s t o n e s . A v e r a g e f r a m e w o r k c o m p o s i-

t i o n s r e p o r t e d b y M a y e r ( 1 96 9 ) a n d S k i n n e r

2 .

P r o v e n a n c e g r o u p i n g s a n d e w

(1972 ) a re Q26F4oR24 an d Q~F2sR~.,~ re spec -

Z e a l a n d

t e r r a n e s

t iv e ly . S i m i l a r p e t r o g r a p h y a n d Q F L r a n g e o l'

Q~0_3~F~-,~oL~o-75 ha s be en re po r t ed by T u rn -

2 1 PI

b u l l ( 19 7 9 ) f o r t h e B o l d P e a k , U p p e r P e a k a n d

M o m u s / M t . C a m p b e l l f o r m a t i o n s o f t h e s o u th -

P r i m a r i l y m a f i c a n d l e s se r i n t e r m e d i a t e ig - e r n p o r t i o n ( C a p l e s G r o u p ) o f t h e t e r r an e .

n e o u s p r o v e n a n c e , r e p r e s e n t e d h e r e b y t h e v o l- K 9 0 / N a 2 0 a n d S iO 2 a r e h i g h e r t h a n i n t h e m o r e

c a n o g e n i c s e d i m e n t s o f t h e M a i t a i t e r r a n e , a n d p r i m i t i v e r o c k s o f t h e P 1 c a t e g o r y ( R o s e r a n d

a s m a l l n u m b e r o f s a m p l e s f r o m t h e K a y s C r e e k K o r s c h , 1 9 8 6 ). T h e C a p l e s t e r r a n e w a s p o s s b

F o r m a t i o n o f t h e C a p l e s t e r r a n e ( Fi g . 1 ) . T h e b l y d e p o s i t e d in a t r e n c h e n v i r o n m e n t o u t-

M a i t a i s e d i m e n t s a r e g r ey , g r e e n a n d re d t it h i c b o a r d o f t h e B r o o k S t r e e t v o l c a n ic a r c a n d t h e

s a n d s t o n e a n d s i l t st o n e , a l o n g w i t h c o n g l o m - f o re - ar c b a s i n e n v i r o n m e n t o f t h e M a i t a i G r o u p

c r a t e a n d m a f i c b r e c c i a. A i t c h i s o n (1 9 8 5 ) r e - ( C o o m b s e t a l. , 1 97 6; T u r n b u l l , 1 97 9; M a c -

p o r t s a v e ra g e c o m p o s i t i o n o f Q 2F26LT ~ f o r p a r t K i n n o n , 1 9 83 ) a l t h o u g h t i m i n g o f s e d im e n t a ~

o f t h e M a i t a i s e q u e n c e , a n d o t h e r p e t r o g r a p h i c t i o n m a y h a v e v a r i e d a l o n g t h e l e n g t h ( S p S r li ,

w o r k s t r e ss e s p a u c i t y o f d e t r i t a l q u a r t z a n d K - 1 9 7 8 ).


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[ ~ G reen land - P4

Torlesse - P3 I

Haast Schist

C ap les - P1 2 ~ NO~T.

I IS L N D

[ - ~ M aita i-P ] / ~ 1 ~ ~

iiiiiiii Murihiku

ECN I Miocene I ~

SOUT~q

I S L A N D

~ Brook St

Dun M t.

1 0 0 m

F i g . 1. P r e s e n t d a y d i s t r i b u t i o n o f N e w Z e a l a n d g e o l o g i c t e r r a n e s r e f e rr e d t o i n t h e t e x t .

2 3 P3 Average QFL compos itions f rom differ ing aged

pet rofaci es an d areas are in the range Q24F.~0L~6

Felsic igneous prov enance volcanic and plu- to QnoF43L17 MacKinnon, 1983; Korsch, 1984 ),

tonic) , represen ted by quartzofeldspathic and are considerably more quartzose and less

sandstone greywacke) and interbed ded argil- lithic than the more mafic and primitive P1 and

lite of the P ermi an-Cr etac eous Torlesse ter- P2 sediments on p.120. Torlesse sediments plot

rane. Nume rous petrographic studies have in the transit ional to dissected magmatic arc

concluded th at the Torlesse sediments were de- fields of the QFL plot of Dickinson et al. 1983),

rived from a silicic crystalline plu- and are considered to have been derived from

ton ic-meta morphic ) terra in with a lesser an active continental magmatic arc and depos-

inte rmed iate -aci d volcanic comp onent e.g., ited in a tre nch or submarine fan setting at the

Reed, 1957; MacKin non, 1983; Korsch, 1984). New Zealand strike -slip /subduc tion margin

Compositions of th el at er Torlesse rocks reflect MacKinnon, 1983; Korsch and Wellman,

cannibalistic reworking MacKinnon, 1983). 1987).


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2.4. P4 f o r t h e m o r e m a t u r e P 3 a n d P 4 g r o u p s , w h ic l l

h a v e p a r a l l e l a n d o v e r l a p p i n g t r e n d s . T h e

Q u a r t z o s e s e d i m e n t s o f m a t u r e c o n t i n e n t a l r a n g e s i n P I a n d P 2 a r e s m a l le r , a n d s a m p l e s

p r o v e n a n c e , r e p r e s e n t e d b y s a n d s t o n e a n d a r - c l u s t e r a t l e s se r S iO 2 a n d g r e a t e r o x i d e c on ~

g i ll it e o f t h e O r d o v i c i a n G r e e n l a n d G r o u p . t e n t s , in d i c a t i v e o f l o w e r Q a n d g r e a t e r

S a n d s t o n e s a r e q u a r t z - r ic h a n d a r e p o o r in m a f i c - i n t e r m e d i a t e v o l c a n o g e n ic c o m p o n e m .

f e l d s p a r a n d r o c k f r a g m e n t s , a v e r a g i n g Q s0 Fs R,2 L i n e a r i t y o n N a e O , K 2 0 ( F i g . 2 ) a n d ( ; aO p l o t s

( L a i r d , 1 9 7 2 ) , a l t h o u g h f r a m e w o r k Q v a lu e s is m a r k e d o n l y i n t h e P 3 a n d P 4 s u i t e ~ T h e P ]

m a y h a v e b e e n e n h a n c e d c o n s i d e r a b l y b y f o r- a n d P 2 g r o u p s o c c u p y d i ff u s e f ie ld s a n d se g re -

m a t i o n o f s e c o n d a r y m a t r i x ( M c L e n n a n , 1 98 4 ) . g a t i o n o f s a n d s t o n e a n d a r g il li te is c o n s i d e r a b l y

M o s t o f t h e r o c k f r a g m e n t s a r e q u a r t z i te o r i n- p o o r e r , p r e s u m a b l y a c o n s e q u e n c e o f ~h e r e l a -

t r a f o r m a t i o n a l s e d i m e n t ( L a i r d , 1 9 72 ) , a n d t iv e i m m a t u r i t y o f t h e s e d i m e n t s . C ( m l e n t s o f

G r e e n l a n d s e d i m e n t s w o u l d p l o t i n t h e c r a t o n t h e m i n o r o x id e s M n O a n d P~O~-, a r e v a r i a b le

i n t e r i o r o r r e c y c l e d o r o g e n f ie l d s o f D i c k i n s o n a n d s h o w l it tl e c o n t r a s t b e t w e e n ~ he t b u r

e t a l. (1 9 8 3 ) . L a i r d c o n s i d e r e d t h e s e d i m e n t s t o g r o u p s , w i t h M n O r a n g i n g o v e r a l l t o ~ ).:~ w t ~'i

b e d e r i v e d f r o m a d e e p l y w e a t h e r e d g r a n i - a n d P 2 0,~ f r o m 0 .0 5 t o 0 .3 5 w t,[~ i.

t i c - g n e i s s i c t e r r a i n , b u t N a t h a n ( 1 9 76 ) i n - S a n d s t o n e s f r o m t h e f o u r g r o u p s o c c ~ p y re ~-

f e r r e d t h e s a n d f r a c t i o n t o b e p o l y c y c li c , a n d a t i v e ly d i s c r e te f ie l d s o n p l o ts o f t h e r a t i o s

t h u s f a v o u r e d d e r i v a t i o n f r o m a p r e - e x i s t i n g A I 20 3 /S iO ,) a n d K 2 0 / N a ~ O a g a i n s t F e ~ O : ~

s e d i m e n t a r y t e r r a n e . + M g O ( F ig . 3 ) . T h e s e i n d ic e s a r e a m ~ g t h o s e

T h e p r o v e n a n c e g r o u p s o u t l in e d a b o v e t h u s t o u n d t o b e t h e m o s t d i s c r i m i n a t in g f b r t e c to n i c

c o v e r a w i d e Q F L / Q F R r a n g e , f r o m v i r t u a l l y s e t t i n g i n s a n d s t o n e s ~B h a t i a . 1 98 3 J. A s t b r t h e

n o n - q u a r t z o s e t o r e l a t i v e l y q u a r t z r ic h , a n d H a r k e r d i a g r a m s , o v e r l a p i s i n c r e a s e d w h e n t h e

r e p r e s e n t a p r o g r e s s i o n f r o m p r i m i t i v e v o l c a n i c a r g i ll it e s a r e i n c l u d e d , a n d n o a r e a s o n t h e p l o t s

a r c t h r o u g h a c ti v e c o n t i n e n t a l m a r g i n t o r e c y - a r e d i s t i n c t iv e f o r a ll s a m p l e s f r o m a n y t e r r a n e .

c l e d o r o g e n . I n o r d e r to e x a m i n e t h e v a r i a t i o n s M o s t o v e r la p , h o w e v e r , c o n s i s ts o f a r g it li te f r o m

i n c h e m i s t r y o v e r t h i s r a n g e o f p r o v e n a n c e a n d o n e g r o u p w i t h s a n d s t o n e o f a n o t h e r , lt'~ h e f u ll

e n v i r o n m e n t w e h a v e a s s e m b l e d 2 4 8 a n a l y s e s g r a i n - s i z e s p e c t r u m i n s u i te s is s a m p l e d , a m b i -

o f g r e y w a c k e s a n d a r g il li te s f r o m t h e N e w Z e a - g u i t y c a n b e m i n i m i s e d , a n d s o m e i n d ic a t i o n o~

l a n d t e r r a n e s . O f t h i s n u m b e r , 15 2 a r e u n p u b - p r o v e n a n c e g a i n e d f r o m s i m p l e c h e m i c a l p lo t s.

l is h e d a n a l y s e s u s e d b y R o s e r a n d K o r s c h S a n d s t o n e s f r o m t h e

P1 P3

g r o u p s p k ) t n e a r

( 1 9 8 6 ) , a n d t h e r e m a i n d e r a r e d r a w n f r o m t h e t h e c o m p o s i t i o n o f a p p r o p r i a t e a v e r a g e ,~ Ji

r e f e r e n c e s c i t e d in F ig . 2 . C o p i e s o f t h e u n p u b - c a n i c r o c k s ( F i gs . 2 a n d 3 ~. s u g g e s t i n g t h a t t h e i r

l i s h e d a n a l y s e s m a y b e o b t a i n e d f r o m t h e a u - c h e m i s t r y l a rg e l y r e f l e c ts t h a t o f t h eH ~ s o u r c e

t h o r s o n r e q u e s t . F o r a ll a n a l y s e s t h e m a j o r a n d t e r r a n e s . T h e P 1 t o P 3 t r e n d o v e r a l l r e s e m b l e s

m i n o r o x i d e s w e r e r e c a l c u l a t e d t o 1 00 % v o l a ti le t h e d i f f e r e n t i a t i o n t r e n d o f t h e l i n k e d a v e r .

o r l o s s o n i g n i t i o n - f r e e a f t e r t o t a l i r o n h a d b e e n a g e s ( e . g ., M g O , F i g. 2 ) . a l t h o u g h s o m e d e v i a -

r e c a l c u l a t e d a s F ee O3 T . t i o n s d o o c c u r . P 1 s e d i m e n t s a r e e n r i c h e d i n

A l.~O 3 a n d d e p l e t e d i n C a O a n d K 2 0 r e l a t i v e to

3 . B u l k

c h e m i c l v r i t i o n s

t h e r a n g e b a s a l t - a n d e s i t e , a n d P 2 r i c h e r in Ti O ,,

a n d N a 2 0 a n d p o o r e r i n C a O r e l a t i v e t o a n d e -

H a r k e r v a r i a t i o n d i a g r a m s f o r T iO 2 , A 1 2 0 3 , s i t e - d a c i t e . I n t h e P 3 s a n d s t o n e s T i 0 2 , Fe20 :~ .,.

F e 20 3 T a n d M g O s h o w l i n e a r t r e n d s f r o m a r - a n d M g O a r e e n r i c h e d a n d K ,~ O d e p l e t e d . P [

g i lt it e t o s a n d s t o n e w i t h i n e a c h g r o u p , r e f l e c t- a n d P 2 a rg i ll it e s d o n o t c o n t r a s t g r e a t l y w i t h

i n g d e c r e a s i n g p r o p o r t i o n s o f m a t r i x - s i z e d t h e i r s a n d s , w h e r e a s P 3 a r g i ll it e s d i v e r g e c o n -

d e t r i tu s ( F ig . 2 ) . T h i s is p a r t i c u l a r ly m a r k e d s i d er a b ly f r o m t h e m a g m a t i c t r e n d l in e . T h e P 4


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Symbols:

s q ua re s = P ] ( M a i -

t a i a n d K a y s C r e e k ) ;

d i a m o n d s

= P 2 ( W a i p a p a - P e l o r u s ) ;

ci rc les

= P 3 ( T o r l es s e ) ;

t r i ang les

= P 4 ( G r e e n l a n d ) .

Open sym

bols

a re a rg i l l i t e s ,

f i l l ed

s ands . A l l da ta r ec a l c u la ted t o 100% LO l - f r ee . Le t t e r s A , D , R and G a re av e rage andes i t e , dac i t e ,

r h y o l i t e a n d g r a n i t e r e s p e c t i v e l y f r o m

L e M a i t r e ( 1 9 7 6 ).

D ashed l i ne

c onne c t s av e rage bas a l t ( o f f - s c a le a t 48% S iO~)

t h r o u g h r h y o l i t e . D a t a f o r t h i s

s t u d y s u p p l e m e n t e d b y a n a l y s e s

d r a w n f r o m

R e e d (1 9 5 7 ) , N a t h a n ( 1 9 7 6 ) , W o o d ( 1 9 7 6 ) ,

Eggers (1978), Landis (1980), Rowe (1980), Reid (1982), Foley (1984), Orr (1984) and Graham (1985).

g r o u p p l o t w e l l a w a y f r o m a v e r a g e r h y o l i t e o r l e s s e ) a r g i ll it e s, a n d 6 2 a n d 6 0 f o r t h e P I a n d

g r a n i t e , i n k e e p i n g w i t h i t s p o l y c y c l i c c h a r a c - P 2 s u i t e s , r e s p e c t i v e l y .

t er . S i g n i f i c a n t w e a t h e r i n g o f t h e G r e e n l a n d T h e d i s c r e p a n c i e s s e e n w i t h i n i n d i v id u a l

G r o u p s o u r c e t e r r a n e i s i n d i c a t e d b y v a l u e s f o r g r o u p s w i t h r e s p e c t t o t h e ir a p p r o p r i a t e v o l-

t h e c h e m i c a l i n d e x o f a l t e r a t i o n C I A ) o f N e s - c a n i c p r e c u r s o r d o n o t i m p l y d e r i v a t i o n f r o m

b i t t a n d Y o u n g 1 9 8 2 ) , w h i c h a v e r a g e s 7 0 .2 d i s t i n c t m o n o l i t h l o g i c p r o t o l i t h s , h o w e v e r . I n

r a n g e 6 4 - 7 5 ) i n t h e P 4 a r g i ll it e s . T h i s c o n - a s t u d y o f s e d i m e n t s d e r i v e d f r o m t h e S o l o m o n

t r a s t s w i t h a n a v e r a g e o f 6 4 f o r t h e P 3 T o r - I s l a n d s v o l c a n i c a r c, C r o o k e t a l. 1 9 8 4 ) n o t e d


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, t ~ F e, 20 :, T 1 . 0 27 - 0 . 3 3 8 .... i . 2 2 9

, , R - ~ " M g O - 1 . 0 8 5 - 0 . 8 2 7 0 . 4 8; ~

A

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0 1 " ~ , N a,,O o 0 . 3 9 2 1 A 3 ~ 0 . 3 8 t

. _ , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K , :O - 1 . 1 4 2 1 . 3 3 :i LS 0 S

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3 , 9 4

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.. oO . ) . . , c a t e g o r i e s b a s e d o n t h e N e w Z e a l a n d t e r r a n e s

. . . ~ d e s c r i b e d i n p p . 1 2 0 - 1 2 2 ) . T h e t e c h n i q u e i s d e -

II / ~ s c r i b e d b y K l o v a n a n d B i l l i n g s ( 1 9 67 ) ~ a n d h a s

o

5 )o ~s b e e n a p p l i e d p r e v i o u s l y t o g e o c h e m i c a l d a t a

F e 2 0 3 T +M g O ( M i d d l e t o n , 1 9 62 ; C h a y e s a n d V e l de , 1 96 5 ;

P e a r c e a n d C a n n , 1 9 71 ; B h a t i a , 1 98 3; S u g i s a k i ,

F i g .

3. Plots of

A 1 2 0 3 / S i 0 2 a n d

K 20 /N a2 0 v s. 1 9 8 4 ) . T h e a n a l y s i s f o r t h i s w o r k w a s m a d e u s -

F e 2 0 a T + M g O . D a t a , s y m b o l s a n d s o u r c e s o f a n a l y s e s a s i n i n g t h e d i s c r i m i n a n t p r o c e d u r e s a v a i l ab l e i n t h e

F i g . 2 .

S P S S - ~ p a c k a g e ( N o r u s i s , 1 9 8 5 ) ( ) n a V A X '~

t h a t t h e c h e m i c a l t r e n d s m i m i c t h o s e o f t h e 11/780 P 2 0 5 a n d M n O w e r e n o t i n c l u d e d in t h e

s o u r c e v o l c a n i c s , b u t c o n c l u d e d t h a t d e p a r t u r e s a n a l y s i s , a s c o n c e n t r a t i o n s a r e l o w a n d a n al yt .-

i c al p r e c i s i o n p o o r e r t h a n f o r t h e m a j o r o x i d e s.

f r o m t h e m a g m a t i c t r e n d w e r e th e p ro d u ct : o f

c h e m i c a l d i f f e r e n t ia t i o n d u r i n g w e a t h e r i n g a n d T h e r e m a i n i n g o x i d es w e r e s c r e e n e d b y s t e p ,

t r a n s p o r t , r a t h e r t h a n e v i d e n c e o f d i s c r e t e w i s e s e l e c t io n , a n d a ll e x c e p t S iO 2 w e r e i d e n t i ,

f le d a s d i s c r i m i n a t i n g v a r i a b l e s.

s o u r c e s f o r i n d i v i d u a l s a m p l e s .

4 D i s c r i m i n a n t f u n c t i o n a n a l y s i s

4 1

Class i f i ca t ion resu l t s

A l t h o u g h s o m e p o r t i o n s o f t h e v a r i a t i o n d ia -

g r a m s d i s c u s s e d a b o v e m a y b e p r o v e n a n c e d is - S t a n d a r d i s e d d i s c r im i n a n t f u n c t i o n c o e ff i-

t i n c t iv e , w e h a v e e x a m i n e d t h e d a t a u s i n g c i e n t s a n d a l li e d s t a t i s t i c s a r e g i v e n i n T a b l e 1:

d i s c r i m i n a n t f u n c t i o n a n a l y s i s i n a n a t t e m p t t o L a r g e e i g e n v a l u e s a n d c a n o n i c a l c o r r e l a t io n s f o r

i m p r o v e s e p a r a t i o n b e t w e e n t h e g r o u p s . T h e t h e f i rs t t w o f u n c t i o n s ( F 1 a n d F 2 ) s u g g e s t t h e y

o b j e c t o f t h i s a n a l y s i s is t o d e r i v e a s e t o f l i n e a r a r e p o t e n t i a l l y g o o d d i s c r i m i n a t o r s , a n d t o i l e t -

f u n c t i o n s b a s e d o n m u l t i p l e v a r i a b l e s , d e s i g n e d t i v e l y t h e y a c c o u n t fo r 9 8 ,6 % o f t h e v a r i a b i l i t y

t o a c h i e v e b e s t s e p a r a t i o n b e t w e e n p r e - d e f i n e d i n t h e d a t a . A t e r r i to r i a l p l o t ( F i g. 4 ) O f t h e F [


7/21

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8 . . . . , u n e x p e c t e d , a s t h e p r o g r e s s i o n P 1 P 3 m i m i c s

P ~ H ~ ' ' p'2 t h e e v o lu t io n a ry t r e n d o f t h e v o lc an ic r oc k a v-

e r a g e s ( F ig . 4 ) . C o i n c i d e n c e w i t h a p p r o p r i a t e

4 ~ R . G v o l c a n i c a v e r a g e s su g g e s t s t h a t t h e b u l k c h e m -

, .c ,. ' ~ , ~ * . ~ " t - - ~ i s t r y o f t h e s e d i m e n t s r e f le c t s w e ll t h a t o f t h e i r

p r o p o s e d p r o t o l i t h s . T h e t e r r i t o r i a l p l o t a l s o

F2 o ~ / ' ~ ' ~ " ~~" , ~'~# D . s h o w s t h a t a l t h o u g h g r a i n - s i z e e f f e c t i n e a c h

~ g r o u p is r e d u c e d i t is n o t e l i m i n a t e d . I n t h e P 3

" ~ J . ." a n d P 4 g r o u p s s a n d s t o n e a n d a r g il li te o v e r l a p ,

4 ~nl

~, .~ . . b u t a r e s l i g h t l y d i sp l ace d . T h e d eg ree o f d i s -

: ~B p l a c e m e n t , h o w e v e r , is m u c h r e d u c e d c o m -

p a r e d w i t h t h e v a r i a t i o n d i a g r a m s .

-8 P4 p l U s i n g t h e t e r r i t o r i a l p l o t i t s e l f t o b ac k c l a s -

' ' ' ' ' s i fy e ac h i n d i v i d u a l s am p l e , 9 5 . 2 % o f t h e c l a s -

8 4 0 4 8

s i f i c a ti o n c a s e s a r e a s s i g n e d t o t h e c o r r e c t g r o u p .

F 1

A r a t e o f 8 5 .1 % i s g a i n e d f o r a s e t o f 3 88 a d d i -

F i g . 4 . C l a s s i f ic a t i o n p l o t o f f u n c t i o n 1 ( F I ) a n d f u n c t i o n

2 ( F 2 ) f o r t h e N e w Z ea l an d s ed i m e n t s ( n = 2 4 8 ) . Open t io n a l T o r l e s s e ( P 3 ) a n d C a p l e s - P e l o r u s t e r -

symbols are argil li tes f iUedgreywackes . Sq ua res = PI ;di a-

r a n e ( P 2 ) s a m p l e s ( B . P . R o s e r a n d R . J .

monds=P2; c i rc les=P3; t r iang les=P4. B ou nd ar ie s f r o m K o r s c h , u n p u b l i s h e d d a t a , 1 9 8 6 ) n o t i n c l u d e d

S P S S - - s o f t w a r e .

Crosses

a r e g r o u p c e n t r o i d s , a n d

solid

i n t h e o r i g i n a l a n a l y s i s .

l ines

m a r k g r o u p b o u n d a r i e s . L e t t e r s

B A D R R H

a n d G

T h e r e s u l t s a b o v e s u g g e s t t h a t t h e f u n c t i o n s

a r e a v e r a g e c o m p o s i t i o n s o f b a s a lt , a n d e s i t e , d a c i t e , r h y o d -

a c i te , r h y o l i t e a n d g r a n i te , r e s p e c t i v e l y , f r o m L e M a i t r e

d e r i v e d m a y b e e f f e c t i v e i n e s t a b l i s h i n g t h e

( 1 9 7 6 ) .

Dotted l ine

j o in s t h e a v er ag e s f ro m b a sa l t t h ro u g h b r o a d p r o v e n a n c e o f g r e y w a c k e - a r g i l l it e s u i te s .

r h y o l i t e . T o e x p l o re t h e r e l a ti o n s h i p b e t w e e n p r o t o l it h

a n d s e d i m e n t w e h a v e e x a m i n e d d a t a f o r se v -

a n d F 2 s c o r e s o f t h e c l a s s i fi c a t io n s e t s a m p l e s , e r a l s u i te s o f v o l c a n i c a n d p l u t o n i c r o ck s , a n d

c a l c u l a te d f r o m t h e u n s t a n d a r d i s e d d i s cr im i - t e s t e d t h e v i a b il it y o f t h e d i s c r i m i n a n t w i t h

n a n t f u n c t i o n c o e f f i c i e n t s ( T a b l e I I ) , s h o w s a n a l y s e s o f s e d i m e n t a r y s u i te s o f w e l l - e s ta b -

r e l a t iv e l y g o o d s e p a r a t i o n b e t w e e n t h e p r e - d e - l i s h e d p r o v e n a n c e f r o m e l s e w h e r e i n t h e w o r l d .

f i n e d gr o u p s w h e n c o m p a r e d w i t h t h e v a r i a t io n

d ia g ra m s . S e p a r a t i o n is m a r k e d f o r t h e r ec y - 5 . V o l c a n i c a n d p l u t o n i c s u i t e s

c l e d P 4 g r o u p , b u t s l ig h t o v e r l a p r e m a i n s b e -

t w e e n P 1 a n d P 2 , a n d P 2 a n d P 3 . T h i s is n o t T h e p o s i t i o n s o f t h e v o l c a n i c r o c k a v e r a g e s

i n F i g . 4 i n d i c a t e t h a t t h e d i s c r i m i n a n t f i e l d s

T AB LE II r e f l e c t t h e c h e m i s t r y o f a p p r o p r i a t e p r o t o l i th s .

U s e o f a v e r a g e s , h o w e v e r , c o n v e y s n o i m p r e s -

Unstandard iseddiscr iminantfunc tioncoeff ic ien ts s ion of t h e va r i a b i l i t y w i th in ea ch vo lca nic

F1 F 2 l i t h o t y p e o r o f v a r i a t i o n i n c h e m i s t r y d u e t o d i f-

f e r i n g m a g m a s e r i e s , f a c t o r s w h i c h m a y i n f l u -

T i O , - 1.773 0.445 en ce t h e co m p o s i t i o n o f' d e r i v e d se d i m en t s .

AI=,O:~ 0.607 0 . 0 7 0 C e n o z o i c v o l c a n i c r o c k s o f t h e c u r r e n t l y a c -

Fe=,O:~T 0 .760 - 0 . 250

M g O - 1. 50 0 - 1.1 4 2 t i v e T a u p o V o l c a n i c Z o n e w e r e e r u p t e d i n a

C aO 0.616 0 . 4 3 8 m a r g i n a l b a s i n r e l a t e d t o t h e N e w Z e a l a n d s u b -

N a 2 0 0.509 1 . 47 5 d u c t i o n m a r g i n . L a v a s r a n g e f r o m b a s a l t

K,O - - 1.224 1 . 4 26 t h r o u g h t o r h y o l i t e , a n d a l l a r e c a l c - a l k a l i n e i n

C o n s t a n t - 9 . 0 9 0 - 6 . 86 1

c o m p o s i t i o n ( C o l e , 1 9 7 9 a ) . A p l o t o f d i s c r i m i -


8/21

126

n a n t s c o r e s c a l c u la t e d f r o m t h e u n s t a n d a r d i s e d D a t a f r o m t h e lo w - t o m e d i u m - K L a u V ol-

c o e f f i c i e n t s ( T a b l e I I ) s h o w s a r e l a t i v e l y c a n i c G r o u p , r e p r e s e n t i n g e a r l y a n d m a t u r e a r c

o r d e r l y p r o g r e s s i o n f r o m b a s a l t a n d b a s a l t i c s t a g e s ( C o l e e t a l. , 1 9 8 5 ) f o l lo w a s i m i l a r a r :

a n d e s i t e ( P I ) t h r o u g h a n d e s i t e s a n d d a c i t e s c u a t e p a t t e r n t o t h e T a u p o V o l c a n ic Z o n e calc--

( P 2 ) t o r h y o l i t e s a n d i g n i m b r i t e s ( P 3 ) i n a a l k a l i n e r o c k s a n d p r o g r e s s f r o m b a s a l t t o d a c -

b r o a d a r c u a t e t r e n d ( F ig . 5 A ) . A n u m b e r o f

s a m p l e s , h o w e v e r , h a v e l a r g e n e g a t i v e F 1 a n d ~A~

T A U P O V O L C A N I C Z O N E

F 2 s co re s a n d o v e r la p t h e P 4 f ie ld i n a r e g io n 8~ . . . . . ' - - ~ T . . . . . . . . . . . . . . . .

d e n o t e d p I E X T

d u e t o h i g h s c o r e s o n M g O a n d P3

F e 2 0 3 T . T h i s s u g g e s t s t h a t t h e s a m p l e s u s e d t o 4 ~ o ~ w i . o

d e f i n e t h e P I p r o v e n a n c e f i e l d d o n o t f u ll y, c o v e r ~ i ,~ ~ -~

t h e c o m p o s i t i o n a l r a n g e o f m o r e m a g n e s i a n ~ 0 ~ ~ ,~

..........

v o l c a n i c r o c k s , a n d s e d i m e n t s s o d e r i v e d m a y o " . . "-

t h e r e f o r e p l o t i n

p 1 E X T

i f b u l k c h e m i s t r y i s

~ ~ ~

i n h e r i t e d w i t h l i tt le a l t e r a t i o n . T h e p o s s i b i l i ty _ ~ . , ?>.

o f c o n f u s i o n w i t h P 4 s e d i m e n t s p r o p e r s e e m s ~, . , . " .

s m a l l , h o w e v e r , a s n o n e o f th e r e c y c l e d se d i- . . . : ~ ' O ~ o % .

~ o oo c ::q

m e n t s o f t h e c l a s s i f i c a t i o n s e t o r t h o s e e x a m - -~ . oO ~ 'i o

p 1 E X T o [

i n e d b e l o w f a l l i n t h e o v e r l a p z o n e ( P I ~ X T ) . " ' " ' ' ~ ' "o . .. .. .. .. .. .. .. .. .. .. .. .

( ~ L A U & M A G O V G .

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Fig . 5 . D i s c r im in an t p lo t s o f igne ous rocks an d ave rages . TVZ . . . ~::~

A . C a l c - a l k a l i n e v o l c a n i c r o c k s f r o m t h e T a u p o V o l c a n i c 4 t ~ * / / , .' * ' .~

Z o ne (T V Z ) , N e w Z e a l a n d ( d a ta o f C o le , t 9 7 9b ) ( n = 2 3 5 ) . S H ' ,' ,: ~ ' , -

S y m b o l s : f i U e d c i r c l e s = b a s a l t s ; o p e n c i r c l e s = l o w - S i a n - i / ~ , ~ ' . i ~

des i t e s ;

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o b s i d i a n s . Dotted l ine d e n o t e s g e n e r a l t r e n d ( f i t t e d b y e y e ) , h ~ i ~a -o~.* * ,

solid lines a n d crosses a r e b o u n d a r i e s a n d g r o u p c e n t r o i d s , i / ~, ~ -, I ~

r e s p e c t i v e l y , f r o m F i g . 4. A r e a b e t w e e n t h e dashed l ine a n d - 4 " ' ~ ~ *

t h e P1-P4 b o u n d a r y ( d e n o t e d p i ~ ' x T ) e n c l o se s T V Z r o c k s i . '

p l o t t i n g i n t h e P 4 f i el d . S o m e d a t a p o i n t s h i d d e n o r o m i t - - 8 l P4 , . ' . . . , . . . . P~ ,

t e d f o r c l a r i t y , b u t s c a t t e r o f l i t h o t y p e s f u l l y r e p r e s e n t e d . / ~

B . V o l c a n ic ro c k s f r o m t h e L a u a n d M a g o V o l c a n ic G r o u p s ,

F i j i ( d a t a o f C o le e t al ., 1 9 8 6 ) , a n d a v e r ag e s o f h i g h - K a n d

PAPAROA

s h o s h o n i t i c b a s a l t s t o a n d e s i t e s ( E w a r t , 1 9 8 2 ). L a u G r o u p

( l o w - in t e rm e d i a t e K ) ( n = 1 3 9 ) : f i l led circles=basalts; ~ I ~ T / . . . . . . . . . . . . . . . . . . . I

open circles=basal t ic

a n d e s i t e s ;

f i l led tr iangles=

a n d e -

P 3 - - - i t ? , i ~

s i t e s ;

ope n s quar es

= dac i t e s ;

f i l led d iamonds

= rhyo l i t e s . ~

, ' 1 I ' T 6

/

D a sh ed lin em a rk sb ro ad tre nd (fitte db ye ye ).M a g oG r ou p 4 i ~ ~ . .. . /

( a l k a l i c ) ( n = 8 ) : inver ted tr iangles=basal ts . ( 3 a r e o f f- % 0 GD . .

sca le in p1EXT.)

Dottedl ineis for theTaupoVolcanicZone F2 0 J ' . . .. . . .. . . i

s c o re s o f b a s a l t s ( B ) t h r o u g h b a s a l t i c a n d e s i t e s ( b ) t o a n - / / ' o

d e s i te s ( A ) o f t h e h i g h - K

( H K )

a n d s h o s h o n i t ic

( S H )

4

v o l c a n i c s e ri e s ( a p p e n d i x I V o f E w a r t , 1 9 8 2 ) .

C . G r a n i t o i d s f ro m t h e P a p a r o a R a n g e , N e w Z e a l a n d ( P . J .

W h i t e , u n p u b l i s h e d d a t a , 1 9 8 7 ) a n d a v e r a g e p t u t 0 n i c r o c k s

- s P ~.~

( Le M a i t re , 1976 ) ( n = 32 ) . Filled circles= g r a n i t e s ; ope n / G~

circles= g r a n o d i o r i t e s . GA = ave rag e gabb ro ; D - d io r i t e ; -8 - 4 1~ ~

GD

= g r a n o d i o r i t e ; G = g r a n i t e . ~


9/21

127

i t e / r h y o l i te , a l t h o u g h n o n e p l o t i n p 1E XT ( F ig . b o u n d a r i e s m u s t b e e x p e c t e d d u e t o m a g m a t i c

5 B ) . T h e o v e r a ll t r e n d i s h o w e v e r d i s p l a c e d t o e v o l u t i o n a n d t h e s e d i m e n t a r y p r o c e s s e s t h a t

t h e ri g h t ( g r e a t e r F 1 ) . I n c o n t r a s t , i n t r a p l a t e p r e s e r v e a r e c o r d o f t h a t e v o l u t io n .

a l k a li o l i v in e b a s a lt s f r o m t h e M a g o V o l c a n ic

G r o u p i n t h e s a m e a r ea (C o l e e t a l., 1 9 85 ) p l o t 6 . S e d i m e n t a r y s u i t e ~

p a r a l le l b u t l e ft o f t h e T a u p o V o l c a n ic Z o n e l in e

a n d across p1EXT A v e r a g e d a t a f o r h i g h - K a n d

S e v e r a l p r e v i o u s l y p u b l i s h e d g e o c h e m i c a l

s h o s h o n i t i c b a s a l t s t o a n d e s i t e s a l so p l o t t o t h e

d a t a - s e t s o f s e d i m e n t s o f d i f fe r i n g ag e s f r o m

l e ft o f t h e T a u p o t r e n d , a n d s p r e a d i n t o P 3 f o r

t h e s h o s h o n i t e s , d i f f e r e n t t e c t o n i c s e t t in g s a r o u n d t h e w o r l d

h a v e b e en c o m p a r e d w i th t h e d i s c r i m i n a n t

T h e p a t t e r n f r o m th e l o w - K 2 0 L a u t r e n d t o

f u n c t i o n p l o t s d e v e l o p e d h e r e .

h i g h - K 2 0 s h o s h o n i t e t h u s r e f l e ct s a n e v o lu -

t i o n a r y s e q u e n c e i n o r o g e n i c la v a s , a n d h a s s e v -

e r a l i mp l i c a t i o n s t o t h i s w o r k . F i r s t l y , i t s u g g e s t s

6 . I . A u s t r a l i a

t h a t s e d i m e n t s d e r i v e d f r o m t h e m o r e b a s i c

s h o s h o n i t i c o r h i g h - K r o c k s a r e l ik e l y t o b e Q u a r t z - p o o r v o l c a n o g e n i c s a n d s t o n e s f r o m

m i s c l a s s i f i e d . T h u s , f o r

P I P 3

s e d i m e n t s t h e t h e L a t e D e v o n i a n B a l d w i n F o r m a t i o n o f N e w

p r e s e n t d i s c r i m i n a n t i s t h e r e f o r e a p p l i ca b l e S o u t h W a l e s a r e o f a n d e s i t i c p r o v e n a n c e

o n l y t o l o w - K o r c a l c - a l k a l i n e s o u r c e t e r r a n e s , ( C h a p p e l l , 1 9 6 8 ) , a n d r e p r e s e n t f o r e - a r c b a s i n

a n d to t h e m o r e s i li c e ou s h i g h - K a n d s h o s h o n - d e p o s i t s d e r i v e d f r o m a c a l c -a l k a li n e i s l a n d a rc .

i ti c l i th o t y p e s . T h i s r e s t ri c t i o n m a y n o t b e t o o C h e m i s t r y o f t h e s a n d s t o n e s is c o m p a r a b l e w i t h

s e v er e , h o w e v e r , a s t h e f r e q u e n c y o f t h e l a t te r t h a t o f a v e r a g e a n d e s i t e a p a r t f r o m e n r i c h m e n t

r o c k s i n o r o g e n i c r e g i o n s i s g r e a t e s t i n t h e r a n g e i n N a 2 0 ( C h a p p e l l , 1 9 6 8 ) . T h i s i s c o n f i r m e d

a n d e s i t e - r h y o l i t e ( E w a r t , 1 9 8 2) . S e c o n d l y , a n d b y t h e d i s c r i m i n a n t ( F i g . 6 A ) , w i t h s a m p l e s

m o r e i m p o r t a n t l y , t h e p a t t e r n m a y i n f u t u r e l y in g a l o n g t h e

P I P 2

b o u n d a r y . C l a s s i fi c a t io n

p e r m i t t h e i d e n t i f i c a t io n i n s e d i m e n t s o f t h e i n t o P I o r P 2 r e fl e c ts d i f fe r e n c e i n S iO 2 c o n t e n t

m a g m a s e ri e s o f t h e p r o t o l i t h s , i f t h e s t e p f r o m a s b e t w e e n lo w - a n d h i g h - S i a n d e s i t e .

s o u r c e t e r r a n e t o s e d i m e n t h a s b e e n c o n s e r v a - I n c o n t r a s t t o t h e B a l d w i n r o c k s, q u a r t z o s e

t iv e g e o c h e m i c a ll y . O r d o v i c i a n a n d S i l u r i a n g r e y w a c k e s a n d a s so -

P a t t e r n s f o r a v e r a g e p l u t o n i c r o c k s a r e s i m - c i a t e d s h a l e s f r o m t h e S n o w y M o u n t a i n s p l o t

i l ar t o t h o s e o f t h e v o l c a n i c s . V a l u e s f r o m g a b - i n t h e P 4 f i e ld (F i g . 6 A ) . S o m e g r a i n - s iz e e f f e c t

b r o t o g r a n i t e p l o t i n a n a r c f r o m P 1 to P 3 ( F i g . i s a p p a r e n t , a s i n b o t h s e t s s a m p l e s w i t h > 7 0

5 C ) i n p o s i t i o n s c o m p a r a b l e t o v o l c a n ic e q u iv - S i 0 2 ( g r e y w a c k e e n d ) a r e d i s p l a c e d f r o m t h o s e

a l en t s. In d i v i d u al s a m p l e s f r o m a n e x a m p l e w i t h l es s er S iO 2 ( s h a l e e n d ) . T h e s e g r e y w a c k e s

s u i te ( g r a n i t o i d s f r o m t h e P a p a r o a R a n g e o f a r e t h o u g h t t o b e t h e p r o d u c t s o f s u c c es s iv e r e-

N e w Z e a l a n d ; P . J . W h i t e , u n p u b l i s h e d d a t a , c y c l in g e p i s o d e s o f o l d e r s e d i m e n t a r y r o c k s o f

1 9 87 ) p l o t i n P 3 , w i t h g r a n o d i o r i t e s d i s p l a c e d t h e L a c h l a n F o l d B e l t ( W y b o r n a n d C h a p p e l l ,

f r o m g r a n i t e s . 1 9 8 3 ) , a n d t h i s i s p e r h a p s r e f l e c t e d b y r e s p e c -

R e s u l t s f o r th e v o l c a n i c a n d p l u t o n i c r o c k s t iv e p o s i t i o n o f t h e g r o u p s o n t h e p l o t. T h e m o r e

c o n f i r m t h e p r o v e n a n c e s a t t r i b u t e d b y in d e - m a t u r e S i l u r i a n s a m p l e s p l o t d e e p e r o v e r a ll i n

p e n d e n t s t u d i e s t o t h e c l a s s if i c a ti o n d a t a t h e P 4 f i el d ( m o r e n e g a t i v e F 1 a n d F 2 s c o r e s)

g r o u p s. T h e p a t t e r n s i n t h e T a u p o a n d L a u d a t a , t h a n d o t h e i r O r d o v i c i a n p r e c u r s o r s . T h e O r -

h o w e v e r , e m p h a s i s e t h a t c h e m i c a l c o m p o s i t i o n d o v i c i a n r o c k s f al l n e a r e r t h e g r o u p c e n t r o i d o f

i s a c o n t i n u u m , a n d t h e b o u n d a r i e s b e t w e e n t h e G r e e n l a n d t e r r a n e c l a s si f ic a t io n s e t, w h i c h

p r o v e n a n c e g r o u p s s h o u l d b e v i e w e d a s g u i d e s t h e y c l o se l y r e s e m b l e g e o c h e m i c a l ly ( W y b o r n

r a t h e r t h a n r i g id d i v i s i o n s . O v e r l a p s a c r o s s a n d C h a p p e l l , 1 9 8 3 ) .


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128

~ ) A U S T R A L I A ( ~) 8 O L O M O N $

P 3 / P 2

~ \

F 2 0 " / ~ ~ ' J / F 2 0 , ~ :; . t " f . .. .

/ ~ / ~ o ~

u

/

P4 ~ a

- 8 P } - 8 ~ / P ;

/l ........................... PIeX: /I

- 8 ~- 4 0 .J. 8 - 8 - 4 0 4 B ,

@ A L A S K A ~ .~ C A L I F O R N I A

F o ~ / -

~ i F ~

- ~ / o o~..i t

+ . . ~ . . o o

o

' ~ o 0\ / % . ~ " ....

4 o

- P 4 P l - 8 P 4 P l

- S - 4 0 4 8 - 8 - 4 0 , 1 8

F I F I

Fig. 6. Dis criminan t plots for sedime ntary suites.

A. Austra lian sedimenta ry rocks. Baldwin Formation sandstones ( ChappeU, 1968);

f i l l e d s q u a r e s

= < 57 Si02;

o p e n

s q u a r e s = > 57 (n = 10). Silurian (triangles) an d Ordovician (circles) greywackes and shales (Wy born and Chappeik

1983 ) ; o p e n s y m b o l s = < 70 Si02, f i l l e d = > 70 SiO~ ( n = 25 ). C r o s s e s are the group centroids from Fig. 4.

B. Sea-floor sediments from the Solomon Islands and Woodlark Basin (carbonate-free data of Crook et al., 1984 ) (n = 47 )

F i l l e d s q u a r e s = sands; o p e n s q u a r e s = muds. Eight samples plot off-scale, 4 in the P1 and P2 fields, and 4 in P t ~>:~'. Letters

B, A and G are average New Georgia basalt, low-Si andesite and glass, respectively, also from Crook et aL (19841. Average

picri tic basalt plots off-scale i n p/EXT.

C. Alaskan sandstones (data of Connelly, 1978). F i l l e d d i a m o n d s =Kodiak Formation and Kodiak Slivers; .~pen d i~ l

m o n d s = Uyak Complex and Cape Curre nt terrane.

D. Californian arkoses and shales (data of Van de Kamp et al., t976; carbonate-free).

F i l le d c i r c l e s = S a n t a

Ynez arkoses:

o p e n c i r c l es = shales; f i l l e d t r i a n g l e s = Salton sands. M = average of Mojave Dese rt-Transverse Ranges granit ic rocks. Two

shales in which calculated carbonate CaO exceeds CaO present are not plotted.

6 2 S o l om o n I s l a n d s d e s i te p r o v e n a n c e F i g . 6 B ) . A n u m b e r o f M g -

r i c h s a m p l e s s p r e a d i n t o t h e P 1 E xr r s e c t i o n d e -

S e a - f l o o r s e d i m e n t s f r o m v a r i o u s te c t o n i c l i n e a t e d b y t h e T a u p o V o l c a n i c Z o n e d a t a. A s

s e t t i n g s o f t h e S o l o m o n I s l a n d s a n d t h e W o o d - d e s c r ib e d a b o v e , C r o o k e t a l. 1 9 8 4 ) c o m p a r e d

l a rk B a s i n C r o o k e t a l. , 1 9 8 4 ) p l o t m a i n l y i n e l e m e n t a l c o n t e n t s o f t h e s e s e d i m e n t s w i t h a v -

t h e P 1 fi e ld , i n d i c a t i v e o f b a s a l t - b a s a l t i c a n - e r a g e v a l u e s f o r p o s s i b l e i g n e o u s p a r e n t s f r o m


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29

the New Georgia Island group picritic basalt, iments differs from that of the source. Van de

basalt, low-Si andesi te and glass). Discrimi- Kamp et al. 1976) recognised tha t Na and Ca

nant scores for these averages correspond well were lesser in the sediments than in the source,

with the sediments Fig. 6B). Although close and that Fe, Mg and Ti were enriched in the

relationship of sediments to any particul ar par- shales compared with the arkoses and sands, due

ent does not imply selective contribut ion from to precipitation in clay minerals. The patte rns

tha t source, the discriminant results accurately on Fig. 6D are compatible with these changes,

reflect the bulk provenance of the suite as a but the results overall still identify a P3

whole, provenance.

6 .3 . A l a ska 6 .5 . N ew Z ea l a n d

Arkosic greywackes from the Uyak Complex, Quartz-poor volcanogenic sandstones and

siltstones of the Triassic to Jurassic Murihiku

Cape Current terrane, and Kodiak Formation

terrane of southern South Island were derived

of Kodiak Island were derived from an active

from a mature active arc and deposited in a fore-

volcanic arc, deposited in a trench and later in-

arc basin envi ron men t Coombs et al., 1976;

corporated into an accretio nary prism Con-

MacKin non, 1983). Rec ent work suggests tha t

nelly, 1978). Using petrographic criteria,

some Proterozoic basement may have been

Connelly interpreted the provenance of the

prese nt beneat h the arc Coombs, 1985). Us-

Uyak and Cape Curren t rocks as andesitic, ing various lines of evidence, Boles 1974)

whereas higher quartz content s and the chem- identified temporal variations in provenance.

istry of the Kodiak wackes reflected a greater Detritus was andesitic in the lowermost North

cratonic input. Discriminant results Fig. 6C) Range Group Lower-Middle Triassic ), be-

support an andesitic source, as Uyak and Cape came more felsic dacit e-rhy olit e) for the

Current rocks are conce ntra ted in P2 and along greater part of the Taringatu ra Group, and re-

the

P 1 P 2

join. There is little evidence of a turned to andesitic in its upper part latest

greater cratonic influence in the Kodiakwackes, Triassic ). Andesitic detritus remained pre-

although the displacement of the data towards dominant throug h the Jurassic part of the se-

P4 relative to the other groups may be a result

quence. These changes are reflected in the

of such a contribution, discriminant plot Fig. 7). North Range sam-

ples cluster in P2 nea r the composition of an-

6.4. Cal i fornia desite, whereas the more evolved Taringatura

rocks fall in the P3 field Fig. 7A). Samples

Eocene and Oligocene arkoses and shales from the uppermost part of the terr ane spread

from the San ta Ynez Mounta ins, and Holocene back into P2 Fig. 7B ). Although there is some

sands from the Salton Basin were derived from scatter, the bulk of the data lies along the Taupo

a calc-alkaline plutonic and metamorphic ter- Volcanic Zone trend, confirming previous sug-

rain with a lesser volcanic compo nent Van de gestions tha t the source terr ane was calc-alka-

Kamp et al., 1976). The arkoses and Holocene line in nature Boles, 1974), and supporting

sands generally plot in the P3 field consisten t proposed matu rity of the arc.

with such a provenance, but grain-size effect is Psammi tic and pelitic schists of the Haast

shown by the shales, which are displaced into Schist ter ran e Bishop, 1972) span the

P2 and P4 Fig. 6D). The data overall lies to- greenschist and amphibol ite facies, and hence

wards P4 with respect to the composition of av- original detrital mineralogy has been largely or

erage Mojave /Transverse Range granite, completely destroyed. The schist has grada-

indicating tha t the bulk composition of the sed- tional boundaries with the quartzofeldspathic


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130

( ~ M U R I H I K U - T R I A S S IC H A A S T S C H IS T

8 . . . . i / e 8 i

I / /

. . . . oJD ~ P 3

/ /

P2

~ ~ 4 ~

4

/

o

~ . . m , ~ . oo f

i o ~

i f J

I 4

/

. ~ - 8 P / ~ i

Fl

J U R A S S I C

Fig. 8. Q uartzofeldspathic schists fr om the Ha dst Schist

8 P 3

' ' ' ' ' / " P2 ' 1 terrane , New Zealand.Data drawn from Wiltiamson (t939),

, , . , t Grapes et al. (1982) and this work. n=6 9.

Fil led c , i r

i c l e s = p s a m m i t i c schists; o p e n c i r c l e s = p e l i t i c schists

~ , f " ~ s i m i l a r t o t h a t s e e n i n t h e T o r t e s s e c l a ss i fi c a :

F2 ( i t i o n d a t a (F ig . 4 ) a n d s o i s a r e l i c g r a i n - s i z e

e f f e c t r a t h e r t h a n e v i d e n c e o f m e t a m o r p h i c s hi f~

-4 -f o r P 2 p ro v e n a n c e .

.... Pl C l a s s i f i c a t i o n r e s u l t s i b r t h e d a t a - se t s d i s -

c u s s e d ab o v e a r e s u m m a r i s e d i n T a b l e I [I . T h e

- 8 P 4 . . . . / ]

, ~ . ' " L " ] , , , i p r o v e n a n c e s i n d i c a t e d f o r t h e s e d i m e n t a r y

- 8 - 4 o , 8 s u i t e s u s e d a s t e s t d a t a a r e g e n e r a l l y in a c c o r d

F1 w i t h t h e p r i o r a n d i n d e p e n d e n t a s s e s s m e n t s

Fig. 7. Sandstones and sil ts tones from the Murihiku ter- ba se d on o th e r te ch ni qu es .

rane, New Z ealand (B oles, 1974; B.P. Roser, unpublished

data, 1986) n = 110. O p e n s y m b o l s = s i l ts t o n e s ; f i ll e d s y m -

b o l s = s a n d s . D o t t e d l i n e is the calc-alkaline Ta up o Vol-

7 . E f f e c t o f b i o g e n i c s e d i m e n t a t i o n

canic Zone ren d from Fig. 4.

A. Triassic d i a m o n d s = N o rth R an g e G ro u p ; c ir-

c l e s = Kaihikuan-Otamitan T aringatura Group.

B. Otapirian and Jurassic (inverted

t r i a n g l e s .

T h e f u n c t i o n s d e r i v e d a b o v e a r e a p p l ic a b l e

o n l y t o s e d i m e n t s w h i c h l a c k s i g n i f i c a n t b i o ~

T o r l e s se t e r r a n e t o t h e n o r t h a n d w i t h t h e v o l- g e n ic c o m p o n e n t s , t h e m o s t i m p o rt a n ~ o f w h i c h

c a n o g e n i c C a p l e s t e r r a n e t o t h e s o u t h . A n a l - a r e C a C O 3 a n d S iO 2. A d d i t i o n o f b i o g e n ic C a O

y s e s f r o m t h r e e a re a s c l u s te r i n P 3 ( F ig . 8 ) i n c r e as e s F I a n d F 2 s c or e s, p u s h i n g c o m p o s i

s u g g e s t iv e o f P 3 ( T o r l e s s e ) p r e c u r s o r ( c o m - t i o n t o w a r d s P 2 . A l t h o u g h S iO 2 i s n o t u s e d d i -

p a r e w i t h F ig . 4 ) . S i m i l a r c o r r e l a t i o n i s s h o w n r e c t l y i n t h e f u n c t i o n s , d i l u t i o n e f f e c t is i m p l ic i t,

b y K z O / N a z O - S i O 2 p a t t e r n s ( R o s e r a n d a n d a d d i t i o n o f b i o g e n i c s il ic a w i ll d e c r e a s e b o t h

K o r s c h , 1 9 8 6 ) . T h e d a t a u s e d c o v e r t h e f u ll F I a n d F 2 s c o r e s a n d p u s h s c o r e s t o w a r d s P 4 .

r a n ge in m e t a m o r p h i s m , a n d n o c o n s i s te n t I n m o d e r n o r s e d i m e n t s o f lo w m e t a m o r p h i c

c h a n g e s i n d i s c r i m i n a n t s c o r e c a n- b e a t t r i b u t e d g r a d e b i o g en i c c a r b o n a t e c a n b e e s t i m a t e d f r o m

t o c h a n g e i n m e t a m o r p h i c g r a d e , P e l i ti c s c h i s t s C O2 c o n t e n t , b u t b io g e n i c s i li c a is m o r e p r o b -

a r e d i s p l a c e d r e l a t i v e t o p s a m m i t i c , b u t t h i s i s l e m a t i c ( e .g . , M u r d m a a e t a l. , 1 98 0; C r o o k e t


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TABLE III

Classification summary

Data-s et n PRI OR ( % )

P 1 P 2 P 3 P 4 P 1 v ~ r

Classification set

Mait ai- Kay s Creek 27 P1 88.9 11.1 -- -- --

Pelor us-Wa ipapa 60 P2 3.3 86.7 10.0 -- --

Torlesse 117 P3 -- -- 100.0 -- --

Greenland 44 P4 -- -- -- 100.0 --

Additional Torlesse 247 P3 -- 7.3 92.7 -- --

Caple s-Tu apek a Group 141 P2 6.4 73.0 20.6 -- --

Vol c an i c s , p l u t on i c s :

Taupo Volcanic Zone

basalt, basaltic andesite 56 P1 69.6 -- -- -- 30.4

andes ite, dacite 105 P2 25.7 62.9 7.6 -- 3.8

rhyolite, ignimb rite 74 P3 -- 1.4 98.6 -- --

Lau Volcanic Group

basalt, basaltic andesite 67 P1 97.0 3.0 -- -- --

andes ite, dacite 68 P2 26.5 69.1 4.4 -- - -

rhyolite 4 P3 -- 100.0 -- -- --

Mago Volcanic Grou p 8 P1 12.5 - - - - -- 87.5

Paparo a granitoids 32 P2, P3 -- -- 100.0 -- --

S e d i m e n t a r y s u i t e s :

Baldwin For matio n 10 P2 60.0 40.0 -- -- --

Snowy Mountains 25 P4 -- -- -- 100.0 --

Sol omo ns- Woo dla rk 47 P1 68.1 12.8 - - 4.3 14.9

Kod iak Islan d 22 P2 27.3 68.2 4.5 -- - -

Santa Ynez 38 P3 -- 7.8 55.3 36.8 --

Salton Basin 9 P3 -- -- 77.7 22.2 --

Murihiku terrane

Nor th Range Group 42 P2 4.8 90.5 4.8 -- --

Taringa tura Group 25 P3 -- 24.0 76.0 -- --

Otap irian -Jur assic 41 P3 ~ P2 4.9 63.4 31.7 -- --

Haas t Schis t terran e 69 P3, P2 -- 15.9 84.1 -- --

n- -n um ber of analyses; PRIOR- -pr ove nanc e classificat ion from ind ependent references ci ted in the text .

a l ., 1 9 8 4 ) . E s t i m a t i n g d e t r i t a l S i O z c o n t r i b u - N a 2 0 a n d K z O t o A 1 20 3 . A l t h o u g h t h e s e r a t i o s

t i o n b y a s s u m i n g a f i x e d S i O z / A l e O a r a t i o a n d a r e n o t i m m u n e t o d i s t u r b a n c e , e f f e c t s s h o u l d

h e n c e d e r i v i n g e x c e s s s i l i c a ( M u r d m a a e t a l ., b e s m a l l g e n e r a l l y w h e n c o m p a r e d w i t h t h o s e

1 9 8 0 ) d o e s n o t a c c o u n t f o r c h a n g e i n t h e r a t i o o f s u b s t a n t i a l a d d i t i o n s o f C a O a n d S i Q .

d u e t o s e d i m e n t a r y d i f f e r e n t i a t i o n p r o c e s s e s U n s t a n d a r d i s e d d i s c r i m i n a n t f u n c t i o n c o e f -

a n d d i f f e r i n g p r o v e n a n c e ( F i g . 3 ) . f i c i e n t s f o r t h i s a n a l y s i s a r e l i s t e d i n T a b l e I V .

I n a n a t t e m p t t o c i r c u m v e n t t h e i n f l u e n c e o f T h e f i r s t t w o f u n c t i o n s a c c o u n t f o r 9 8 . 3 % o f t h e

b i o g e n i c C a a n d S i w e h a v e d e r i v e d a s e c o n d v a r i a n c e , b u t e i g e n v a l u e s ( 4 . 6 6 , 1 . 5 3 ) a n d c a -

d i s c r i m i n a n t u s i n g t h e s a m e c l a s s i f i c a t i o n d a t a , n o n i c a l c o r r e l a t i o n s ( 0 . 9 1 , 0 . 7 8 ) d e c r e a s e f r o m

b u t b a s e d o n t h e r a t i o s o f T i O 2 , F % O 3 T, M g O , t h e p r e v i o u s a n a l y s i s , i n d i c a t i n g p o o r e r d i s -


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132

T AB LE IV o v e r l a p z o n e i n P 4 . A n a l y s i s o f t h e s e d i m e n t a r y

t e s t d a t a s e t s g i v e s r e s u l t s c o m p a r a b l e t o t h o s e

Unstandardised discriminant function coefficients fbr the

ana ly sis u sin g o xid e/A 12 0~ r at io s d e t e r m i n ed o r i g i n a l l y ( c o m p a r e T a b l e s V an d

I I I ) . A l t h o u g h p e r c e n t a g e s i n le a d i n g c a ~ e

F I F 2 g o r i e s a r e g e n e r a l l y l o w e r , m a i n t v ~ h r o u g h

m o v e m e n t o f P 2 s a m p l e s i n t o P I o r P & p ro v e .

TiO~/AI~Q 30.638 56.500

Fe20:~T/A120.~ - 12.541 .... 10 .87 9 n an ce c h a ra c te r i sa t i o n re m ai n s in go od ag ree -

MgO/A120.~ 7 .329 30.875 m en t w i th th e pr io r c l a s s i f i ca t io ns . 'F~ fu r th er

Na~O/A120:, 12 .031 -5 .404 t e s t th e d i s t i nc t iv en es s o f th e r a t io s as p rov e-

K20/A120:~ 35.402 11.112

n a n c e i n d i c a t o r s , w e h a v e e x a m i n e d s e v e r a l e x

Co nstant - 6.382 - 3.890

I r a d a t a - s e t s i n w h i c h b i o g e n i c s e d i m e n t a t i o n

i s s i g n i f i c an t .

c r i m i n a t i o n . T h e t e r r i t o r ia l p l o t f o r t h e c l a ss i - M i o c e n e f l y s c h a n d m a s s i v e m u d s t o n e s f r o m

f i c a t io n s e t ( F ig . 9 ) s h o w s c o n t r a c t i o n o f t h e t h e e a s t c o a s t o f N o r t h I s la n d , N e w Z e a l a n d

P 2 f ie ld , i n c r e a s e d o v e r l a p , a n d a m a r k e d g r a i n - ( R o s e r a n d K o r s c h , 1 9 8 6 J w e r e d e p o s i t e d m

s iz e t r e n d i n t h e P 3 d a t a . A l t h o u g h t h e fi e ld s t r e n c h s l o p e b a s i n s a t t h e H i k u r a n g i s u b du e -.

a r e i n v e r t e d , t h e p r o g r e s s i o n f r o m P 1 t o P 4 r e - t i o n m a r g i n ( V a n d e r L i n g e n a n d P e t t i n g a .

m a i n s . B a c k - c l a s s i f i c a t i o n r a t e f a ll s t o 8 6 . 7 % , 1 9 8 0 ) . P r o v e n a n c e i s m i x e d ~ G h e n t a n d H e n

l a r g e ly t h r o u g h c l a s s i f i c a t io n o f m a n y P 3 a r gi l- d e r s o n , 1 9 6 6 ) , w i t h d e r i v a t i o n f r o m I 'o r le s se

l it e s i n t o P 4 . ( P 3 ) s e d i m e n t s , p l u s f e ls ic v o l c a n i c d e t r i t u s

T h e v o l c a n i c r o c k a v e r a g e s p l o t i n t h e i r re - f r o m t h e C o r o m a n d e l v o l c a n i c a r c. M a n y o f t h e

s p e c t i v e f i e ld s ( F ig . 9 ) a s b e f o r e , a n d t h e i n d i- s a n d s t o n e s c o n t a i n b i o c l a s t s a n d c a r b o n a t e c e -

v i d u a l v o l c a n i c a n d p l u t o n i c s u i t e s h a v e s i m i l a r m e n t , a n d m u d s t o n e s a r e r i c h i n c a l c a r e o u s m r-

c l a s s i f ic a t i o n r a t e s ( T a b l e V ) a n d a n a r c u a t e c r o f o s si l s. S t r o n g g r a in - ra z e t r e n d i s s e e n o n a

t r e n d , a l t h o u g h d i f f e r e n c e s b e t w e e n t h e T a u p o r a t i o d i s c r i m i n a n t p l o t ( F ig . 1 0 A }. S a n d s t o n e s

V o l c a n i c Z o n e a n d L a u t r e n d s a r e n o t a s f a ll i n P 3 n e a r t h e p o s i t i o n o f i n t e r b e d d e d t u fl ~

m a r k e d . T h e T a u p o d a t a a g a i n d e f i n e a p IE X T a n d t r e n d t o t h e f i n e r- g r a in e d m e m b e r s a t t h e

P 2 P 3 P 4

j u n c t i o n . A l t h o u g h e f fe c t s m a y b e

. . . . ~ m a s k e d t o a n e x t e n t b y t h e P 3 v o l c a n o g e n ic d i-

U

B ~ \ p~,~., t r i t u s , i t s e e m s t h a t t h e M i o c en e s ed i m en t s h av e

\

, \ / ,~4 i n h e r i t e d a T o r l e s s e s i g n a t u r e w i t h o u t m a j o r

" - ~ ~ J i / '"~ ~ ~:~' ~ f r a c t i o n a t i o n o f t h e r a t i o s d u r i n g r ecy c l i n g ,

~ t1 ~ A r g i l la c e o u s h e m i p e l a g i c s e d i m e n t s t r o m I n

. ~ o ~ ~ , t t e r n a t i o n a l P h a s e o f O ce a n D r iU in g

F2 o . ~ ( I . P . O . D ) / D e e p S e a D r i ll i n g P r o j e c t

% 0 o . * ; ~ . . , , , ,

/ o -D -~ .~ , ." ( D . S . D . P . ) s i t e s o n t h e w e s t s l o p e o f t h e J a p a n

-4 / ~ t r e n c h a r e g r e a t l y e n r i c h e d i n b i o g e n i c s i li c a .

~i w it h a n h y d ro u s S iO 2 r e a c h i n g 8 5 .3 % , S u g b

/ ~ s a k i, 1 9 8 0 ) . T h e s e d i m e n t s h a v e c o m p l e x

-8 / P2 P 3 t p r o v e n a n c e , b e i n g d e r i v e d f r o m t h e t i t h o lo g i -

, , t a l l y d i v e r s e g e o l og i c b e l t s o f n o r t h e r n H o n s h u

-; -,

o ;

,~ a n d H o k k a i d o , a n d v o l c a n i c l a s t i c d e t r i t u s b e -

F~

c o m e s m o r e i m p o r t a n t i n t h e u p p e r p a r t s o f t h e

Fig. 9. Territorial plot

fo r th e ra t io

discriminant. Classifi-

c o r e s ( V o n H u e n e e t al ., 1 9 80 : A r t h u r e t a t. .

c a t i o n d a t a a n d s y m b o l s l e t t e r s B t o R n d G a n d o v e r l ap

field pi~xT defined by d a ta fo r T V Z v ol canic ro ck s a s in 1 9 8 0 ) . M o s t s am p l e s p l o t i n t h e P 2 f i e l d i n d i c -

F ig s. 4 a nd 5A , a t i v e o f i n t e r m e d i a t e b u l k p r o v e n a n c e ( F i g


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133

T A B L E V

S u m m a r y o f c l a s s i f ic a t i o n re s u l t s f or p r e v i o u s d a t a - s e t s , u s i n g r a t i o d i s c r i m i n a n t

D a t a - s e t n P R I O R ( )

P1 P2 P3 P4 p i1~ :x 'r

C l a s s i f i c a t i o n s e t

M a i t a i - K a y s C r e e k 27 P 1 1 0 0 .0 . . . .

P e l o r u s - W a i p a p a 6 0 P 2 6 . 7 8 1 .7 1 0 .0 1 .7 - -

T o r l e s s e 1 1 7 P 3 - - 5 .1 8 1 . 2 1 3 .7 - -

G r e e n l a n d 4 4 P 4 - - - - - - 1 00 .0 - -

A d d i t i o n a l T o r l e s s e 2 4 7 P 3 - - 1 3 .8 8 1 . 8 4 . 4 - -

C a p l e s - T u a p e k a G r o u p 1 41 P 2 1 4 .2 6 9 .5 1 3 .5 2 .8 - -

Volcanics, plutonics:

T a u p o V o l c a n i c Z o n e

b a s a l t , b a s a l t i c a n d e s i t e 5 6 P 1 6 7 .9 - - - - - - 3 2 .1

a n d e s i t e , d a c i t e 1 0 5 P 2 3 2 . 4 4 6 . 7 2 . 9 9 . 5 3 . 8

r h y o l i te , i g n i m b r i t e 7 4 P 3 - - - - 1 0 0. 0 - - - -

L a u V o l c a n i c G r o u p

b a s a l t , b a s a l t i c a n d e s i t e 6 7 P 1 9 8 . 5 - - - - - - 1 .5

a n d e s i t e , d a c i t e 6 8 P 2 5 4 . 4 3 3 . 8 1 1 .8 - - - -

r h y o l i t e 4 P 3 - - - - 1 0 0. 0 - - - -

M a g o V o l c a n i c G r o u p

b a s a l t 8 P I . . . . 10 0 .0

P a p a r o a g r a n i t o i d s 3 2 P2,P3 -- - - 1 0 0 .0 - - - -

Sedimentary suites:

B a l d w i n F o r m a t i o n 1 0 P 2 9 0 .0 1 0 .0 - - - - - -

S n o w y M o u n t a i n s 2 5 P 4 - - 1 6.0 - - 8 4.0 - -

S o l o m o n s - W o o d l a r k 4 7 P 1 7 4 .5 4 .2 - - 4 .2 1 7 .0

K o d i a k I s l a n d 2 2 P 2 5 0 .0 5 0 .0 - - - - - -

S a n t a Y n e z 3 8 P 3 2 . 6 2 3 .7 3 9 . 5 3 4 .2 - -

S a l t o n B a s i n 9 P 3 - - - - 2 2 .2 7 7 .8 - -

M u r i h i k u t e r r a n e

N o r t h R a n g e g r o u p 4 2 P 2 2 1 . 4 6 9 . 0 2 . 4 4 . 8 2 .4

T a r i n g a t u r a G r o u p 2 5 P 3 - - 1 2. 0 8 0 .0 8 .0 - -

O t a p i r i a n - J u r a s s i c 4 1 P3--*P2 4 . 9 4 6 . 3 3 6 . 9 1 2 .2 - -

H a a s t S c h i s t t e r r a n e 6 9 P3,P2 -- 2 7 . 5 7 1 . 0 1 .4 - -

n = n u m b e r o f an a l y s e s; P R I O R - - p r o v e n a n c e c l a s s i f ic a t i o n f r o m i n d e p e n d e n t r e f e r e n c es c i te d i n t h e t e x t.

1 0 B ) . I n v i e w o f t h e r e s t r i c t e d g r a i n - s i z e r a n g e o f s l i g h t l y m a t u r e a r c c o m p o s i t i o n ( F u j i o k a e t

h o w e v e r , a P 3 c h a r a c t e r i s a l s o p o s s i b l e ( c o m - a l . , 1 9 8 0 ) .

p a r e w i t h f i n e - g r a i n e d s e d i m e n t s i n F i g s . 9 a n d S u r f i c i a l c o n t i n e n t a l m a r g i n s e d i m e n t s f r o m

1 0 A ) . C l e a r e r i n d i c a t i o n o f P 2 p r o v e n a n c e i s s h e l f a n d s l o p e e n v i r o n m e n t s o f f W e s t l a n d , N e w

g i v e n b y d a t a f o r l o w e r M i o c e n e t u r b i d i t e s a n d Z e a l a n d , c o n t a i n u p t o 7 0 C a C O 3 ( S t o f f e r s e t

q u a r t z - i n t e r m e d i a t e O l i g o c e n e s a n d s f r o m a l . , 1 9 8 4 ) a n d h e n c e c a n n o t b e a p p l i e d t o t h e

H o l e s

4 3 8 B

a n d

4 3 9 F i g .

1 0 B ) . T h e s e w e r e d e - f i r s t d i s c r i m i n a n t ( F i g . 4 ) . T h e w e s t e r n m a r -

r i v e d f r o m a m i x e d c l a s t i c s e d i m e n - g i n o f t h e S o u t h I s l a n d i s a n a c t i v e c o n t i n e n t a l

t a r y - v o l c a n i c s o u r c e ( t h e O y a s h i o l a n d m a s s ) s t r i k e - s l i p m a r g i n b e t w e e n t h e A u s t r a l i a n a n d


16/21

134

~ ) E A S T C O A S T N I ( ~ J A P A N T R E N C H

8 8

4 4

F2 F2 0 ~ . . . .. .

/ / /

l P 2 P 3 P 1 P 2 P 3 t

- 8 i 8

-8 -4 0 . . . .. . . . .. 4 . . . . .. . . . .. . . . 8 . . . . -8 -4 0 ,~ 8

C ~ WE S T L A N D

D )

S O L O M O N S ( r a w d a t a ~

F 2 0 ' '~ . . . . ~ -~ - - . . . . . . F 2 0 . . .. . .. . .. . . ~ . . .. . ..

[

4 ~ /

i P l P2 F : 3

P 1

P 2 P 3 [ L

- 8 - 8

- ~ - ~

o ~

- ~ - ~ o . . . . . . . . . . .

T

. . . . . . .

F 1 F I

Fi g . 1 0 . Ra t i o d i s c r i m i na nt p l o t fo r s e d i m e nt a r y s u i t e s .

A . M i o c e n e s e d i m e n t s , e a s t c o a s t N o r t h Is l a n d B . P . R o s e r , u n p u b l i sh e d d a t a , 1 9 8 4 ) n = 2 0 8 ) F i l l e d c i r c l e s = s a nds t o ne s :

o p e n c i r c l e s =

m u d s t o n e s a n d s i l ts t o n e s ;

t r i a n g l e s =

i n t e r be dd e d r hy o l i t ic t u f t s .

B . J a p a n t r e n c h s e d i m e n t s . O p e n t r i a n g l e s = a r g i l l a c e o us s e d i m e nt s , S i t e s 4 3 4 , 4 3 5 , 4 3 8 , 4 4 0 , 4 4 1 Su gisak i , 198 0) r~= 1 7 0 ) ;

f i l l e d , o p e n s q u a r e s =

s a n d s t o n e s a n d s i l ts t o n e s , r e s p e c t iv e l y , l o w e r M i o c e n e a n d u p p e r O l i g o c e n e U n i t s 4 a n d 5 , H o l e s

4 3 8 B

a n d

4 3 9

M ur d m a a e t a l ., 1 9 8 0 ; Sug i s a k i , 1 9 8 0 )

n =

1 8 ) .

C . Sur f i c i a l s he l f a nd s lo pe s e d i m e nt s , W e s t l a nd , N e w Ze a l and . F i l l e d t r i a n g l e s = sands; o p en t r i a n g l e s= m u d s a n d s i l t s

S t o ff e r s e t a L , 1 9 8 4 ) , n = 3 0 ) .

D . S o l o m o n s - W o o d l a r k s e d i m e n t s , r a w d a t a o f C r o o k e t a l. 1 9 8 4 ) ,

F i l l e d s q u a r e s =

sands;

o p e n s q u a r e s =

m u d s . N i n e s a m -

p l e s p l o t o f f - s c a l e in t he p1 EXW f i e ld h i g h F2 ) .

P a c i f ic p l a t e s. T h e h i n t e r l a n d o f t h e a r e a s a m - c o n t r i b u t i o n s . T h e d a t a a r e, h o w e v e r , a lm o s t

p l e d b y S t o f f e r s a n d c o w o r k e r s c o n s i s t s o f a c i d e v e n l y s p l it b e t w e e n P 2 a n d P 4 F i g . t 0 C ) . T h i s

p l u t o n i c s a n d b a n d e d g n e i s s a s i n F i g . 5 C ) , s e e m s t o b e p r i m a r i l y a g r a i n - si z e e f fe c t , a s

q u a r t zo s e G r e e n l a n d G r o u p m e t a s e d i m e n t s c o a rs er s a m p l e s s a n d ) f al l m a i n l y i n P 4 , a n d

P 4 ) , a n d s c h i st o s e m e t a s e d i m e n t s o f t h e P 3 f in e r m u d ) in P 2 . T w o s a n d s p l o t t in g d e e p i n

T o r l e s s e - H a a s t S c h i s t t e r r a n es . S e d i m e n t s d e - t h e P 1 a n d P 2 f i e ld s a r e e n r i c h e d i n a u t h i g e n i c

r i ve d f r o m t h i s t e r r a n e s h o u l d t h e r e f o r e h a v e a n d r e li c t g l a u c o n i t e - g o e t h i t e p e l l et s , g iv i n g

P 3 o r P 4 c h e m i s t r y d e p e n d i n g o n t h e r e l at iv e l ar g e F e 20 ~ T / A 12 0 .~ r a t io s a n d c o n s e q u e n t l y


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negative F1 and F2 scores. The results overall, relat ed ter ranes and within suites themselves is

however, indicate a net t P4 provenance consis- of more significance.

ten t with the lithologies available in the source Incorporat ion of argillite data in the discrim-

region, inan ts has exte nded the lithological range

As an example of sediments of basic prove- available for use. Although variation related to

nance, we have again utilised the Solo- grain size has been reduced compared to that

mons-Woodla rk data of Crook et al. (1984),but seen in the varia tion diagrams (Figs. 2 and 3)

have analysed the raw data rather than that some contrast remains between sandstone and

which is carbonate-corrected. The results (Fig. argillite in the more fractionated P3 and P4

10D) are in good agreement with those from categories. In some cases (e.g., Santa Ynez, New

the first discriminant and using the ratios of Zealand Miocene, Japa n Tre nch data; Figs. 6D,

the carbonate-corre cted data (Fig. 6B, Tables 10A and B) provenance type cannot be identi-

III and V), except that numbers in the p1EXT fled clearly using data for the finer -grained sed-

overlap category are increased due to larger iments alone. Nevertheless, sa nd- mud trends

MgO/A1203 ratios. PI -type provenance is still in these two categories differ. For the first set

clearly identified, of funct ions P3 argillites have greater F1 and

The results from the sets above indicate tha t lesser F2 scores tha n the ir companion sands,

the oxide/A12Q ratios are useful as provenance whereas both F1 and F2 scores tend to be greater

guides in sediments rich in biogenic detr itus in P4 argillites compared to thei r sands, plot-

where it is not possible to apply the firs t dis- ting near the P3-P 4j oin (Figs. 4, 6A, D and 8).

criminant. However, discrimina tion is poorer It is preferable therefore for sampling to span

than that using the first disc riminant , espe- the full available range in grain size, as the

cially for fine-grained samples tha t fall about trends themselves in these two categories can

the P2 P3 P4 join. be used to resolve ambiguities. Such sampling

also gives a bet ter impression of the bulk chem-

8. Di sc us si on ical composition of individual terra nes (Roser

and Korsch, 1985; Sawyer, 1986).

Apparent retention of P3 chemical charac-

The good agreement seen overall between in- teristics by greenschist- and amphibolite-facies

dicated and previously postulate d provenances rocks of the Haast Schist terr ane (Fig. 8) sug-

for the test sets (Tables III and V), and the gests tha t provenance signatures can survive

comparability of volcanic, plutonic and meta- relatively high-ra nk metamorphism. This is

morphic lithotypes with the classificat ion cat- suppor ted by subsets of the 141 Caples ter rane

egories suggest that the funct ions developed samples used as additional test data (Table III)

here are viable tools for deter mina tion of bulk for the first discriminant. Of 56 Pelorus Group

provenance. However, it must be emphasis ed sands tones and argillites in this set, 49 (88 )

tha t the change in sediment composition from are classed as P2 by their discrimina nt scores.

P1- P4i sa com ple x syst emin fiue nced bype tro- A very similar rate (89 ) is given by 27 more

logic evolution and magma character istics of the metamo rphosed ( chlorite zone ) Pelorus Group

source terranes, coupled with sedim entary ma- semi-schists and schists from the same area.

turation, weathering and diagenesis. Unique The discriminant may hence be useful for char-

classifications within single fields may there- acterising bulk provenance (mafic, intermedi-

fore be the exception rat her than the rule, and ate, felsic, or recycled) in metamorphic terranes

should not be presumed. The general distribu- where recrystallisation has obscured or de-

tion of data with respect to the fields, potential stroyed original detrital mineralogy. In less re-

parent s (e.g., appropriate rock averages), any consti tuted rocks results should be interpreted


18/21

136

in conjunction with petrography, as the nature Several rece nt studies Mayna rd et al.. 1982:

of detri tus volcanic, plutonic, met amorph ic) Bhatia, 1983, 1985; Roser and Korsch. 1986:

cannot be diff eren tiat ed using the chemist ry. Bhati a and Crook, 1986) have examined sedi-

The discriminants discussed here should be re- ment chemistry as an indicator of tect~mic set-

garded as a comple ment to established methods ting. The present dis criminant categories are

for determining provenance rather than as an themselves broadly related to tectonic setting

alternative, in tha t sediments from each category are likely

The possibility of being able to identify, in to be more common in particular plate-tectonic

sediments, the magmatic series of volcanic environments. Imma ture oceanic island arc

source terr anes is an interest ing aspect worthy sediments are likely to concent rate m l)l and

of future work. Before this can be furthered, p1EXT, nd detritus from mature island arcs and

comprehensive data are nee ded for high-K, immature contin ental margin magmatic arcs in

shoshoni tic and alkalic magma source ter ran es P2. P3 classifications are probable {or sedi-

and derived sediments, along with improved ments at mature continental margin arcs and

character isation of P1 provenances by inclu- continenta l transfo rm boundaries pull-apart

sion of more samples from basic Mg- and Ti- basin s), whereas suites at passive cont inental

rich protoliths, margins, intracra tonic sedimentary basins an ]

Centra l to the above and to chemical dis- recycled orogenic provinces wilt commo nly ex~

criminat ion of sediments in general is the need hibit P4 signatures. Such interpre tat ion should

for more data from sediment s of known prove- be made with caution, however, given t h petro-

nance, which may be compared with the pro- graphic anomalies possible in transitional or

tolith, so tha t the nature and magnitude of unusual plate-tectonic settings ~Valloni and

chemica l frac tion ation between the two can be Maynard, 1981; Mack, 1984: Pott er. 1984: Vel-

assessed. Studies such as that of Crook et al. bel, 1985) and petrological evolution m mag-

1984) are impor tan t in this context. While matic source ter ran es iFigs. 5A. B and 7, ol

source-sediment comparisons are most easily single setting, and the need to integrate chem~

accomplished in modern situations, and the ef- istry with geologic and petrographic studies

fects of weathering can be more readily evalu- remains.

ated, data from older lithified suites are also

desirable, as the chemistry of modern sedi-

cknowledgements

ments may differ in some respects from tha t of X-ray fluorescence analyses were made in the

ancien t cou nterp arts Bhatia, 1983). Pro- Analytical Facility, Victoria University of Wel-

cesses of chemical different iation operating lington, with the assistance of K. Palmer and

during and subsequent to sedime ntation have H. Roe. Financial support was provided by a

reached comple tion in the older suites, and if N.Z.U.G.C. Postdocto ral Fellowship B.P.R..).

provenance is well established using indepen- and internal research grants of the University

dent criteria their chemical characteris tics pro- of Otago and Victoria University of Wellington.

vide a direct basis of compar ison for enigmatic Our tha nks to P.J. White for the use of his Pa-

suites of similar history. An approach which paroa data, to J.N. Ashby and K. Palmer ibr

may be of special value in examining helpful discussions, and to C.A. Landis and D.S

source-se dime nt relations in anci ent sequences Coombs for comments on the manuscript.

is analysis of conglomerate clasts to evaluate

evolutionary stage of contributing arcs e.g., Re fe re nc es

Leitch and Willis, 1982), combined with com-

Aitchison, J.C,, 1985. Steph ens Subgroup upp er Ma itai

p a r i s o n o f t h e c h e m i s t r y o f t h e c o n g l o m e r a t e G ro up ) i n t h e C o un te ss R an g e-M a ra ro a R iv er a re a. N .Z .

m a tr ix . J . Geol. Geophys. , 28:767 abst rac t ) .


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A r t h u r , M . A . , V o n H u e n e , R . a n d A d e l s e c k , J r . , C . G . , 1 98 0. i t o r s ) , M o d e r n a n d A n c i e n t G e o s y n c l i n a l

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p o s i t i o n o f s a n d s t o n e s . J . G e o l . , 9 1: 6 1 1 - 6 2 7 . B a s i n . U n i t e d N a t i o n s C o m m . C o o r d . J o i n t P r o s p e c t .

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A u s t r a l i a n P a l e o z o i c g r a y w a c k e s a n d m u d r o c k s : p r o v e - S . O . P . A . C . ) , T e c h . R e p . 3 4: 2 7 5 - 3 1 2 .

n a n c e a n d t e c t o n i c c o n t r o l . S e d i m e n t G e o l ., 4 5 : 9 7 - 1 1 3 . D i c k i n s o n , W . R . , B e a r d , L . S . , B r a c k e n r i d g e , G . R . , E r j a v e c ,

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c h a r a c t e r i s t i c s o f g r e y w a c k e s a n d t e c t o n i c s e t t i n g d i s - b e r g , F . A . a n d R y b e r g , P . T . , 1 98 3. P r o v e n a n c e o f N o r t h

c r i m i n a t i o n o f s e d i m e n t a r y b a s i n s . C o n t r i b . M i n e r a l . A m e r i c a n P h a n e r o z o i c s a n d s t o n e s i n r e l a t io n t o t e c -

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p r e h n i t e - p u m p e l l y i t e t o g r e e n s c h i s t f a c ie s i n t h e D a n - H i l l m o l y b d e n u m o c c u r r en c e , B u l l e r d i s t r i c t , w e s t N e l -

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im en t . Pe t ro l . , 55 : 69 -75 . e rence t o t he and es i t i c -b a sa l t i c com pos i t i on a l r ange . In :

B o l e

provenance signatures of sandstone-mudstone

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