01 - sodic pyroxenes - CMP 1978.pdf

8/11/2019 01 - sodic pyroxenes - CMP 1978.pdf

1/5

Contrib. Mineral. Petrol. 68, 7-11 (1978)

o n t r i b u t i o n s t o

ineralogy and

Petrology

9 by Springer-Verlag 1978

Sodie Pyroxen es From M etabas i tes in the as tern Medi terranean

A.I. Okay

Depart ment of Mineralogy and Petrology, Downin g Place, C ambridge, Great Britain

A bst rac t

The compositions of sodic pyroxenes from

blueschist metabasites in Northwest Turkey were in-

vestigated by electronprobe microanalysis. These are

compared with sodic pyroxenes from high-grade

blueschist terrains and eclogites with special reference

to the island of Syros in Greece. Pyroxenes from

lawsonite zone metabasites in Northwest Turkey are

chloromelanites, aegerine augites and aegerine

jadeites with the acmite contents ranging from 65%

down to 30%. Epidote-garnet bearing high-grade

blueschist metabasites of Syros on the other hand

contain omphacite with the acmite content less than

30%. All the analyzed sodic pyroxenes from eclogites

and high-grade blueschists in the literature are also

omphacites with low acmite contents. It is argued

that the acmite content of the sodic pyroxene de-

creases with ris ing temperature of metamorphism.

This is almost entirely related to the appearance of

epidote as an additional ferric ion bearing phase with

an increase in temperature.

Int roduct i on

Sodic pyroxenes are common minerals in the basic

rocks of the blueschist facies and related eclogites.

Their composi tions fall. within the ternary field of

acmite-jadeite-augite.

A considerable amount of new data on sodic py-

roxene compositions from blueschists and eclogites

has become available in the last ten years. Each batch

of new data has narrowed the miscibility gaps ,

based on the apparent absence of sodic pyroxene com-

positions over certain regions in the sodic pyroxene

ternary field (Dobretsov, 1962; Coleman and Clark,

1968), so that now almost the whole of the acmite-

jadeite-augite field is filled. The electron microprobe

analyses presented here demonstrate the widely vari-

able compositions of sodic pyroxenes. A new attempt

is made to relate the composition of sodic pyroxene

to the extensive, e.g., rock composition, and intensive

variables, e.g., pressure and temperature, of meta-

morphism.

Geol og i ca l E nvi ronment

In Northwest Turkey blueschists form a coherent, discontinuous

belt of about 20 km in width and 300 km in length. They flank

the margins of large ultramafic massifs in the Izmir- Ankara op hio-

lite zone (Brinkman, 1976). The rock types are domin antly metaba-

sites and metacherts. The eastern part of the blueschist belt in

the region o f Mihallicik was studied by Cogulu (1967) who dis-

tinguished three metamorp hic zones - lawsonite - albite, lawsonite

- crossite, epidote - crossite - with an increase in grade northwards.

The epidote zone truncates westwards. The studied areas, all

e n

t i r e l y in the lawsonite zone, lie in the central portion of the blue-

schist belt in t h e d i s t r i c t s of Tavsanli (area 1 in Fig. 1) and Gumele

(area2 in Fig. 1). In both areas metamorphism occurred during

a single event and retrogressive readjustment h as been minor. Pluri-

facial metamor phism, which complicates the inte rpretation o f min-

eral assemblages in the Alps, is absent.

M e t h o d

Sodic pyroxene compositions were determined for twelve elements

(Na, Ca, K, Fe, Mg, Mn, V, Ni, Cr, Ti~ AI, Si) using an electron-

probe microanalyzer With a Harwell Si(Li) detector and pulse

processor (Statham, 1976). The correction procedures are given

by Sweatman and Long (1969). Olivine and jadeite standards were

used throughout.

The analyses were recalculated to a four cation formu la unit.

As there is no substitution of silicon by tetrahedral aluminium,

the jadeite component equals to the aluminium in the formula

unit. Acmite component was calculated assuming Ac=fe rric ion =

(Na-AI) in the formula unit. The remainder of the cations were

included in the augite component. Transition elements such as

Ti, Mn, Cr o ccur in amounts less than 0.01 of the formula unit,

so that jadeite, acmite, dio psi de and hedenbergite components

make up 98% or more of the sodic pyroxene.

O010-7999/78/0068/0007/ 01.00


2/5

8 A.I. Okay: Sodic Pyroxenes From Metabasites in Turkey

- . -

Fig. 1. Map of Aegean and surrounding areas showing

major ophiolite occurrences black) and blueschist

outcrops in Northwest Turkey ruled). The ophiolite

outcrops in Western Turkey after Bingol 1976)

Mineral ssemblage and the Composition of the Sodic

Pyroxene

Blueschist Metabasites From Northwest Turkey

This group comprises thoroughly recrystallized, often

foliated, lawsonite bearing blueschist metabasites cor-

responding both in mineralogy and texture to Typ e

II I blueschists from California (Coleman and Lee,

1963).

The mineral assemblage in the metabasites is so-

dic amphibole (often crossite or glaucophane) + law-

sonite _+ sodic pyroxene + chlorite +_ quartz + phen-

gite + sphene . Sodic pyroxene is a common part of

the metabasic mineral assemblage in Northwest

Turkey making up approximately 5 to 25 modal per-

cent of the rock. Out of 86 thin sections of the metaba-

sites examined 50 contained sodic pyroxene that usually

occurred as small subhedral grains, occasionally

showing a reaction relationship to sodic amphiboles.

Sodic pyroxene is, along with the lawsonite, one

of the first metamorphic minerals to form in North-

west Turkish metabasites. As observed in the less

well recrystallized parts of the blueschist terrain in

Northwest Turkey, initialize spilitic dolerites are

transformed to an assemblage o f lawsonite, chlorite,

acmitic sodic pyroxene and quartz with incipient cros-

site. At this stage the original igneous texture is still

intact with plagioclase pseudomorphed by an assem-

blage of lawsonite, quartz and chlorite while augite

is largely replaced by an acmite rich sodic pyroxene.

With further recrystallization crossite forms at the

expense of sodic pyroxene, quartz and chlorite and

the rock loses its ghost texture with the development

of a distinct schistosity.

Sodic pyroxenes from ten blueschist metabasites

were analyzed by electlon-microprobe and plotted on

the jadeite-acmite-augite ternary diagram in Fig. 2.

Specimens with numbers starting with 93 come from

the area Gumele (area 2 in Fig. 1). Blueschists from

Gumele were studied, especially with regard to their

whole rock geochemistry, by Lunel (1967). The re-

mainder of the specimens with prefixed K come from

the districf north of Tavsanli (area 1 in Fig. 1). All

the analyzed rocks contain the assemblage lawso-

nite + crossite + phengite + sphene . Addit ionally

specimens K47, K75, K54, K29, 93163 contain pri-

mary chlorite, K47, K54 and 93180 contain quartz

and K33, K29, K114 contain calcite. However these

latter minerals occur in very small quantities, crossite,

lawsonite, and sodic pyroxene making up 90% or

more of the metabasites.

Compositions plotted in Fig. 2 demonstrate that

sodic pyroxenes with similar parageneses show a wide

range of compositions both within and between differ-

ent metabasites. Zoning in sodic pyroxenes, like most

other minerals with variable compositions from blue-

schist, is very common. The sodic pyroxenes from

Northwest Turkey using the terminology ado.pted for

sodic pyroxenes by Essene and Fyfe (1967), plot in

the fields of chloromelanite, aegerine augite and

aegerine jadeite with the acmite contents ranging from

65% down to 30%. Compositions of sodic pyroxenes

are apparently rather rare in this range, such that

a miscibility gap was proposed (Dobretsov, 1962;

Coleman and Clark, 1968), which the new analyses

fill at least in the ferric-rich portion.

High Grade Blueschist Metabasites

From Other Terrains

This group includes thoroughly recrystallized epidote-

garnet bearing blueschist metabasites and eclogites.

The mineral assemblage is glaucoph ane+epid ote

+ sodic pyroxene + garnet + white mica _+ quartz + ru-

tile . They grade into eclogites with the dominance

of sodic pyroxene and garnet in the mineral paragen-


3/5

A.I. Okay: Sodic Pyroxenes From Metabasites n Turkey 9

Fig. 2. Compositionsof sodic pyroxenes rom

lawsonite-bearing metabasites, Northwest Turkey

A c A c

O O o o . . 2

~ 1 7 6

o o

9 9 o o

9

ss

o 1(47

9 K~.I

AU Au Jd

Ac

097503

o @

A 97506

o o

I)97542 9 9

V V V V \

A u J d

Fig. 3. Compositionsof sodic pyroxenesfrom epidote-garnet bear-

ing high-grade blueschists, Syros

with numbers 97503 and 97667 have recrystallized

in plagioclase rich portions of the original coarse

grained protolith (Dixon, 1968). They represent an

unusually aluminous environment for a metabasic

rock.

Sodic pyroxenes from analyzed Syros metabasites

fall largely in the omphacite field with the acmite

contents ranging from 30% down to 2%. Omphacitic

pyroxenes of these compositions are characteristic of

eclogites and high-grade blueschists.

esis. These differ from the blueschist metabasites of

Northwest Turkey in the coarser grain size, the re-

placement of lawsonite and sphene by epidote and

rutile respectively and the occurrence of almandine

garnet. The eclogitic exotic blocks from the Francis-

can terrain in California, Type IV of Coleman and

Lee (1963), are a good example for these types of

rocks.

The blueschists from the island of Syros in the

Aegean provide another good example of high grade

blueschists. They were studied in detail by Dixon

(1967). The island consists of an alternating sequence

of pelitic blueschists z~nd marbles with rare intercala-

tions o f metabasic gneisses, metagabbros and serpen-

tinite (Dixon, 1976). The sodic pyroxene analyses

have been performed on the metagabbros and

gneisses. These sodic pyroxenes are currently under

study for their microstructure (Carpenter, 1978).

Sodic pyroxenes from four metabasic rocks from

Syros are shown in the acmite-jadeite-augite ternary

diagram in Fig. 3. All four rocks have the mineral

assemblage glaucophane + epidote + sodic pyroxene-

+ga rne t + white mica + qua rtz and all except 97506

contain rutile. Specimen 97542 also contains some

actinolite. The jadeite rich pyroxenes from specimens

i s c u s s i o n

Sodic pyroxenes from both terrains show a wide range

of compositions within a relatively uniform bulk rock

chemistry. In the metabasites the absence of albite

is reflected in the highly variable jadeite contents of

pyroxenes, even within a single rock, preventing any

geobarometric deductions. Although the jadeite con-

tents of pyroxenes from metabasites in Syros and

Northwest Turkey are similar the pressure has been

considerably higher in Syros as indicated by the pres-

ence of jade ite+ quar tz assemblages in rocks of ap-

propriate chemistry (Dixon, 1976).

However there is a distinct difference in the acmite

contents of the sodic pyroxenes between lawsonite-

bearing metabasites from Northwest Turkey and

other high-grade epidote-garnet bearing blueschists

and eclogites, including those from Syros. Such a

difference between lawsonite-zone metabasites on the

one hand and epidote-zone metabasites on the other

hand seems to be a general case (see Fig. 4). This

difference must lie in the intensive variables of meta-

morphism, e.g., pressure and temperature, as the bulk

rock chemistry is approximately the same in both

cases. Both oxygen isotope studies (Black, 1974; Tay-


4/5

1 0 A . I . O k a y : S o d i c P y r o x e n e s F r o m M e t a b a s i t e s i n T u r k e y

l o r a n d C o l e m a n , 1 96 8) a n d e x p e r i m e n t a l w o rk o n

the s tab i l i ty o f lawso n i te (Ni t sch , 1974) show tha t

ep ido te-garne t - ru t i l e bear ing b luesch i s t s have recrys -

t a l li z e d a t c o n s i d e ra b l y h i g h e r t e m p e ra t u r e s (38 0 ~

5 5 0 ~ t h a n l a w s o n i t e - s p h e n e b e a r i n g b l u e s c hi s ts

(2 7 0 0 -4 0 0 0 C ) . Th e l a w s o n i t e / e p i d o t e t r a n s fo rm a -

t ion , be ing a deh ydr a t ion reac t ion , ha s a s t eep slope

o n t h e P - T d i a g ra m , m a k i n g i t a g o o d g e o t h e rm o m e -

ter.

Th e e f f e c t o f p r e s s u re o n s o d i c p y ro x e n e c o m p o s i -

t ions in metabasa l t s i s more d i f f i cu l t to as sess . The

a b s e n c e o f p r i m a ry a l b i te a n d t h e p r e s e n c e o f j a d e i t e -

+ quar tz as semblages in Syros (Dixon , 1968) ind ica te

cons iderab ly h igher p ressu res (12 to 15 kbar ) fo r

b l u e s c h is t s f r o m S y ro s t h a n t h o s e f ro m e p i d o t e z o n e

b l u e s c h i s t s i n N e w C a l e d o n i a , w h i c h s h o w a v e ry

s i m il a r m i n e ra l p a r a g e n e s is w i t h t h e e x c e p t i o n o f t h e

s tab i l i ty o f a lb i t e (Bro the rs , 1974) , ind ica t ing lower

p re s s u re s o f r e c ry s ta l l iz a t io n . H o w e v e r t h e r a n g e o f

o b s e rv e d a c m i t e c o n t e n t i n t h e e p i d o t e - z o n e s o d i c

p y ro x e n e s f ro m t h e b l u e s c h i s t m e t a b a s i t e s i n N e w

C a l e d o n i a i s n e a r l y t h e s a m e a s t h o s e f ro m S y ro s ,

30 dow n to 5 (Black , 1974) , sugges t ing tha t t em-

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

t e n t o f t h e s o d i c p y ro x e n e .

Th i s t r e n d o f d e c re a s i n g a c m i t e c o n t e n t i n t h e

s o d i c p y ro x e n e w i t h r is in g t e m p e ra t u r e m a y b e r e l a t e d

e i t h er t o t h e fo rm a t i o n o f a n a d d i t i o n a l f e r r ic b e a r i n g

p h a s e o r t o r e d u c t i o n d u r i n g t h e p ro g re s s i v e m e t a -

m o rp h i s m . O m p h a c i t i c p y ro x e n e is n o t t h o u g h t t o

b e i n h e re n t l y u n s t a b l e i n t h e l a w s o n i t e - z o n e c o n d i -

t i o n s a s i n d i c a t e d b y i ts p r e s e n c e i n s o m e p a r t i a ll y

r e c ry s ta l l iz e d b a s i c r o c k s (C a rp e n t e r a n d O k a y , i n

prep.) .

B l u e s c h i s t m e t a b a s i t e s g e n e ra l l y d o n o t c o n t a i n

any i ron ox ides , as fe r r i c ion has a l t e rna t ive s i tes

i n t h e s o d i c a m p h i b o l e s a n d s o d i c p y ro x e n e s . Th e re -

fo r e t h e m a j o r f e r r i c i r o n b e a r i n g m i n e ra l s i n l a w s o -

n i t e - z o n e b l u e s c h i s t s a r e s o d i c p y ro x e n e s a n d s o d i c

a m p h i b o l e s . I n t h e e p i d o t e - z o n e b l u e s c h i s t s , e p i d o t e

i t se l f i s an add i t iona l F e 3+ bear ing ph ase . Th us the

fo rm a t i o n o f e p i d o t e in th e t e m p e ra t u r e i n t e rv a l o f

3 5 5 -4 0 0 C w o u l d b e e x p e c t e d t o a f f e c t t h e f e r r i c i r o n

c o n t e n t s o f t h e a s s o c i a t e d s o d ic p y ro x e n e a n d s o d i c

a m p h i b o l e .

La w s o n i t e a n d f e r r i c i r o n r i c h e p i d o t e a r e e x p e c t -

e d t o c o e x i s t o v e r a c e r t a in r a n g e o f t e m p e ra t u r e a n d

p re s su re . S o d i c p y ro x e n e s c o e x i s t in g s t a b l y w i t h l a w -

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

a c m i t e c o n t e n t o f a ro u n d 3 0 a n d p l o t i n t h e a c m i t e -

j a d e i t e - a u g i t e t e rn a ry d i a g ra m i n t h e i n t e rm e d i a t e r e -

g i o n b e t w e e n l a w s o n i t e a n d e p i d o t e z o n e m e t a b a s i c

p y ro x e n e s (F i g . 4 ). U n fo r t u n a t e l y t h e s c a r c i t y o f p y -

ro x e n e a n a l y s e s o v e r s u c h t r a n s i t i o n a l t e r r a i n s p ro -

h ib i t s the t es t ing o f th i s hypo thes i s .

A

A u _ _ I d

Fi g . 4 . C o m p o s i t i o n s o f me t a m o rp h i c so d i c p y ro x e n e s ; f i l le d t r i a n -

g l e s : P y r o x e n e s f r o m i r o n - r i c h m e t a s e d i m e n t s a n d m e t a c h e r t s ;

f i l l e d c i rc l e s : p y ro x e n e s f ro m l a w so n i t e b e a r i n g me t a b a s i t e s ; o p e n

c i rc l e s : p y ro x e n e s f ro m e p i d o t e -g a rn e t b e a r i n g b l u e sc h i s t me t a b a -

s i t es a n d e c l o g it e s , o p e n t r i a n g l e s : p y ro x e n e s f ro m a l u m i n u o u s

b l u e sc h i s t s ; f i l le d sq u a re s : p y ro x e n e s f ro m m e t a g re y w a c k e s t h i s

p a p e r , M u i r W o o d 1 9 7 7 ) ; E rn s t 1 9 76 ) , B l a c k 1 9 7 4 ) ; A b ra h a m

e t a l . 1 9 7 4 ) ; K e r r i c k a n d C o t t o n 1 9 7 1 ) ; E rn s t e t a l. 1 9 7 8 ) ; O n u k i

a n d Ern s t 1 9 69 )

I t i s k n o w n t h a t t h e e p i d o t e c o m p o s i t i o n a l f i e l d

ex tends towards lower fe r r i c con ten t s wi th r i s ing t em-

p e ra t u r e d u r i n g p ro g re s s i v e m e t a m o rp h i s m (M i y a s h -

i ro and Sek i , 1958) , such tha t ep ido tes f rom ec log i tes

u s u a l l y h a v e l o w p is t a c it e c o m p o n e n t s . Th i s i m p l i e s

a c e r ta i n a m o u n t o f r e d u c t i o n d u r i n g m e t a m o rp h i s m ,

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

o m p h a c i t e - e c lo g i t e . S u c h a p ro g re s s i v e r e d u c t i o n w i t h

i n c r ea s i n g g r a d e h a s b e e n o b s e rv e d i n s o m e h i g h p r e s -

s u re m e t a m o rp h i c t e r r a in s , e . g ., in H o h e T a u e rn w i n -

dow ( Ab rah am e t a l . , 1974) .

A l t h o u g h r e d u c t i o n m a y b e o f im p o r t a n c e i n h ig h -

g rade b luesch i s t s and ec log i tes , the regu lar and sharp

b re a k i n s o d i c p y ro x e n e c o m p o s i t i o n s b e t w e e n t w o

t y p e s : o f m e t a b a s a l t s , i n d i c a te t h a t t h e t e m p e ra t u r e

r e l a t e d la w s o n i t e / e p i d o t e t r a n s fo rm a t i o n i s m a i n l y r e -

s p o n s i b l e fo r t h e o b s e rv e d d i f f e r e n c e b e t w e e n l a w s o -

n i te a n d e p i d o t e -g a rn e t b e a r i n g m e t a b a s i t es .

9 Compositional Range of Sodic Pyroxenes

From Blueschists

S o d i c p y ro x e n e a n a l y s e s f ro m b l u e sc h i s ts a n d r e l a t e d

ec log i tes a re show n in acm i te - jade i te -aug i te t e rnary

d i a g ra m i n F i g. 4. Th e r a n g e o f s o d i c p y ro x e n e c o m -

pos i t ions ' fo r d if fe ren t majo r ro ck type s , i ron -r ich

ro c k s , m e t a b a s a l t s a n d m e t a g re y w a c k e s , a r e a l s o i n d i-

ca ted .


5/5

A.I . Ok a y : So d i c Py ro x e n e s Fro m M e t a b a s i t e s i n Tu rk e y 1 1

Acmite and aegerine have a very wide pressure-

temperature stability field. They are found in iron-rich

rocks and metacherts from both lawsonite and epi-

dote zone blueschists in Northwest Turkey, California

and other blueschist terrains. The occurrence of aeger-

ine in igneous rocks is a further testimony of its large

P T

stability field. Most of the analyses of sodic py-

roxenes from iron-rich rocks come from Muir-Wood

1977) who also reports Mn as a major component

in some of the aergerines.

Metabasites on account of their calcium and ferro-

magnesium rich character do not contain any jadeite

or jadeite-rich pyroxenes either in lawsonite or epi-

dote zones. However lawsonite is stably associated

with jadeite rich pyroxenes in some metagreywackes

from the Franciscan terrain in California Ernst et al.,

1970). The occurrence o f jadeite in appropriate bulk

rock composi tions depends on the prevailing pressure

of metamorphism.

There is an apparent lack of sodic pyroxene com-

positions in a small region between jadeite and om-

phacite. A much larger area extending towards more

ferric-rich compositions and including this region was

interpreted by several workers as a miscibility gap

in the sodic pyroxene system Dobretsov, 1962; Cole-

man and Clark, 1968). However from the extensive

range of compositions plotted in Fig. 4, it is likely

that the apparent lack of sodic pyroxene compositions

in this region is due to the absence of suitable rock

compositions. Immiscibility, as demonst rated in exso-

lution, in such low temperature minerals as sodic py-

roxenes, is likely to be on a submicroscopic scale.

As a result, microprobe analyses should not be

expected to reveal the limits of immiscibility in the

sodic pyroxene ternary system.

Acknowledgements. Th i s wo rk wa s c a r r i e d o u t wh i l e i n re c e i p t

o f a g r a n t f r o m t h e M i n e r a l R e s e a r c h a n d E x p l o r a t i o n I n s t i t u t e

o f Tu rk e y (M T A) w h i c h is g ra t e fu l l y a c k n o wl e d g e d . Th e a n a l y se s

o f so d i c p y ro x e n e s f ro m t h e h i g h -g ra d e b l u e sc h i s t s o f Sy ro s a n d

f r o m i r o n r i c h m e t a s e d i m e n t s w e r e k in d l y p r o v i d e d b y M . A . C a r -

p e n t e r a n d R . M u i r W o o d r e s pe c ti v el y . I t h a n k R . M u i r W o o d ,

M .A. C a rp e n t e r , a n d S .O. Ag re l l fo r c r i t i c a l c o mme n t s o n t h i s p a -

per.

e f e r e n c e s

A b r a h a m , K . , H o r m a n n , P . K . , R a i t h , M . : P r o g r e s s iv e m e t a m o r -

p h i s m o f b a s i c r o c k s f r o m t h e s o u t h e r n H o h e T a u e r n a r e a ,

Ty ro l (Au s t r i a ) . N . Jb . Ab h . 1 2 2 , 1 -3 5 (1 9 7 4 )

B i n g o l , E . : Ev o l u t i o n g e o t e c t o n i q u e d e l An a t o l i e d e l Ou e s t . B u l l.

Soc . Geol . France . Ser . 7 , 18 , 431-450 (1976)

B l a ck , P . M . : M i n e r al o g y o f N e w C a l e d o n i a n m e t a m o r p h i c r o c k s

III . Pyroxenes. Cont rib . Minera l . Pet ro l . 45 , 281-288 (1974)

B l a c k , P .M . : Ox y g e n i so t o p e s t u d y o f me t a mo rp h i c ro c k s f ro m

t h e Ou e g o a d i s t r i c t , Ne w C a l e d o n i a . C o n t r i b . M i n e ra l . Pe t ro l .

47 , 197-206 (1974b)

B r i n k m a n , R . : G e o l o g y o f T u rk e y . A m s t e r d a m : E l s ev i er P u b .

Com pany . 158 (1976)

B ro t h e rs , R .N. : Hi g h -p re s su re sc h i s t s i n n o r t h e rn Ne w C a l e d o n i a .

Cont rib . Minera l . Pet ro l . 46 , 109-127 (1974)

C a rp e n t e r , M . : Ki n e t i c c o n t ro l o f o rd e r i n g a n d e x so l n t i o n i n o m-

phaci te . Cont rib . Minera l . Pet ro l (1978 , in press)

C o g u l u , E . : E t u d e p e t ro g ra p h i q u e d e l a r e g i o n d e M i h a l l ic c i k (Tu r -

quie) . Schweiz . Minera l . Pet rogr. Mi t t . 47 , 683-824 (1967)

C o l e ma n , R .G. , C l a rk , J .R . : Py ro x e n e s i n t h e b l u e sc h i s t f a c i e s

o f C a l i fo rn i a . Am . J . Sc i. 266 43-59 (1968)

C o l e m a n , R . G . , L e e, D , E . : G l a u c o p h a n e - b e a r i n g m e t a m o r p h i c

ro c k t y p e s o f t h e C a z a d e ro a re a , C a l i fo rn i a . J . Pe t ro l . 4 , 2 6 0 -3 0 1

(1963)

Di x o n , J .E . : Gl a u c o p h a n e sc h i s t s o f Sy ro s , G re e c e (a b s t ra c t ) . B u l l.

Soc . Geol . France . Ser . 18 , 280 (1976)

Di x o n , J .E . : Th e me t a mo rp h i c ro c k s o f Sy ro s , Gre e c e .

Ph .D. Th e s i s (u n p u b l i sh e d ) , Un i v e rs i t y o f C a mb r i d g e (1 9 6 8 )

Do b re t so v , N .L . : M i sc i b il i t y l i mi t s a n d me a n c o m p o s i t i o n s o f

j a d e i t e p y ro x e n es . Do k l . Ak a d . N a u k . SSSR 1 4 6 , 1 1 8-1 20

(1962)

Ern s t , W.G. : M i n e ra l c h e mi s t ry o f e c l o g i t e s a n d re l a t e d ro c k s

f ro m t h e V o l t r i g ro u p , We s t e rn L i g u r i a, I t a l y . Sc hwe iz . M i n e ra l .

Pet rogr. Mi t t . 56 , 293-343 (1976)

Ern s t , W.G. , Se k i , Y . , On u k i , H . , Gi l b e r t , M .C . : C o mp a ra t i v e

s t u d y o f l o w - g r a d e m e t a m o r p h i s m i n t h e C a l i f o r n i a C o a s t

R a n g e s a n d t h e o u t e r me t a mo rp h i c b e l t o f J a p a n . Ge o l . So c .

Am. Mem. 70 , 259 (1970)

Esse n e , E . J. , Fy fe , W.S . : Om p h a c i t e i n C a l i fo rn i a n m e t a m o rp h i c

rocks. Cont rib . Minera l . Pet ro l . 15 , 1 -23 (1967)

Ke r r i c k , D .M . , C o t t o n , W.R . : S t a b il i t y re l a t i o n s o f j a d e i t e p y ro x -

e n e i n F ra n c i sc a n me t a g re y wa c k e s n e a r Sa n Jo se , C a l i fo rn i a .

Am. J . Sci . 271 , 350-369 (1971)

Lu n e l , T . : Ge o l o g y o f Sn b r e n -K a ra a l a n a re a , Esk i se h i r (Tu rk e y ) .

Ph .D. Th e s i s (u n p u b l i sh e d ) , Un i v e rs i t y o f B r i s t o l (1 96 7 )

M i y a sh i ro , A. , Se k i, Y . : En l a rg e m e n t o f t h e c o m p o s i t i o n f i e ld

o f e p i d o t e a n d p i e mo n t i t e wi t h r i s i n g t e mp e ra t u re . Am . J . Sc i.

256 , 423m30 (1958)

M u i r W o o d , R . : I ro n r i c h se d i me n t s i n b l u e sc h i s t f a c ie s me t a m o r-

p h i sm. Ph .D . Th e s i s , Un i v e rs i t y o f C a mb r i d g e (u n p u b l i sh e d )

(1977)

Ni t sc h , K .H. : Da s P-T-Xc o 2 S t a b i l i t /i t s fe ld y o n La wso n i t . C o n t r i b .

Minera l . Pet ro l . 34 , 116-134 (1972)

On u k i , H . , E rn s t , W.G . : C o e x i s t i n g so d ic a mp h i b o l e s a n d so d i c

p y ro x e n e s f ro m b l u e sc h i s t f a c i e s me t a mo rp h i c ro c k s . M i n e ra l .

Soc . Am. Spec . Paper 2 , 241-250 (1969)

S t a t h a m, P . J . : A c o mp a ra t i v e s t u d y o f t e c h n i q u e s fo r q u a n t i t a t i v e

a n a l y s i s o f t h e X- ra y sp e c t ra o b t a i n e d w i t h a S i (L i ) d e t e c t o r .

X-ray Spect rom. 5 , 16-28 (1976)

Swe a t ma n , R .R . , Lo n g , J .V.P . : Qu a n t i t a t i v e e l e c t ro n p ro b e mi -

c ro a n a l y s i s o f / o c k fo rmi n g m i n e ra l s . J . Pe t ro l . 1 0 , 3 3 2 -3 7 9

(1969)

Ta y l o r , H .P . , C o l e m a n , R .G. : O1 8 10 1 6 ra t io s o f c o e x i s ti n g mi n -

e ra l s in g l a u c o p h a n e - b e a r i n g me t a m o rp h i c ro c k s . Ge o l . So c .

Am. Bul l . 79 , 1727-1756 (1968)

Ac c e p t e d Oc t o b e r 1 2 , 1 9 7 8

Documents

01 - sodic pyroxenes - CMP 1978.pdf