Geology Reference
In-Depth Information
Fig. 11.6 Subsolidus phase
assemblages in the join
Ak
75
Ab
25
-Lc
75
Ab
25
-
(SiO
2
)
75
Ab
25
at 1 atm (after
Gupta and Gupta 1997)
Qz
Ab
75
25
Mel + Di
+ Wo
+ Lc
ss
ss
ss
30
Di
+ Wo
+ Tridy + Felds
ss
ss
28
27
23
29
c
d
25
Di
+ Wo
+Felds
21
ss
ss
a
b
Di
+ Wo
+ Lc
ss
ss
ss
33
32
31
26
24
Lc
Ab
Ak
Ab
75
25
75
25
Fig. 11.7 Subsolidus phase
assemblages in the join
Lc
60
Ab
40
-Ak
60
Ab
40
-
Qz
60
Ab
40
at 1 atm (after
Gupta and Gupta 1997)
Qz
Ab
60
40
7
9
6
5
8
Di
+ Wo
+ Tridy + Felds
ss
ss
e
2
f
Lc
+ Di
+ Wo
+ Felds + Mel
s
s
ss
3
1
10
13
12
Lc
Ab
Ak
Ab
60
40
60
40
the leucite-akermanite-SiO
2
system, its natural occurrence in K-rich volcanic rocks
is extremely rare. An exceptional example is an occurrence of modal wollastonite in
katungite, mafurite and uganditic rocks, in which wollastonite is associated with
modal diopside, melilite and leucite (Stoppa 1988).
The
flowsheet diagram (Fig.
11.8
) shows that a wollastonite-melilite leucitite (i)
can be derived from either a wollastonite melilitite (b-i),
i), wollastonite-melilite-
-
italite (a
(l-i). Likewise a
wollastonite-pyroxene phonolite (j) can be obtained from a wollastonite leucitite
(L
(l-i). or a melilite leucitite (c-i)
(l-i). or a wollastonite leucitite (l-i).
-
-
-
j), a wollastonite-leucite phonolite (d
j), a pyroxene-leucite phonolite (e
j) or a
-
-
-
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