366 
PACIFIC SCIENCE, VoL XV, July 1961 
TABLE 3 
Probable Parent Magma and Material Added to or Subtracted from It to 
Obtain Other Rocks 
1 
2 
3 
4 
5 
6 
7 
8 
SiCL 
46.9 
40.6 
51.4 
49.2 
49.0 
45.4 
45.1 
40.5 
ai 2 o 3 
12.9 
5.0 
9.1 
12.9 
13.2 
10.7 
9.2 
8.0 
Fe.Os 
2.1 
0.9 
2.5 
1.8 
1.7 
2.8 
3.8 
3.5 
FeO 
9.6 
11.7 
1.7 
8.8 
9.6 
6.0 
6.4 
8.0 
MgO 
14.6 
38.1 
15.7 
10.0 
9.3 
22.7 
22.6 
30.5 
CaO 
9.9 
3.1 
17.7 
12.2 
11.6 
11.1 
11.1 
7.5 
Na 2 0 
1.5 
0.0 
2.0 
2.2 
2.2 
0.7 
0.7 
0.0 
k 2 o 
0.4 
0.0 
0.0 
0.5 
0.6 
0.0 
0.0 
0.0 
Ti0 2 
2.3 
0.6 
0.0 
2.3 
2.6 
0.6 
0.6 
1.5 
norms 
ne 
2.6 
or 
2.2 
2.8 
3.3 
ab 
12.6 
12.0 
19-5 
18.3 
5.8 
5.8 
an 
27.2 
13.6 
15.8 
23.9 
24.5 
26.1 
22.0 
21.7 
f wo 
8.8 
0.7 
30.0 
15.0 
13.5 
12.1 
13.5 
6.5 
di v en 
1 fs 
6.1 
0.5 
25.4 
9.7 
8.4 
9.5 
10.4 
5.1 
2.0 
0.1 
0.7 
4.2 
4.2 
1.2 
1.6 
0.7 
hy Ifs 
11.9 
2.9 
7.0 
8.5 
5.9 
7.5 
3.5 
4.0 
0.7 
3.2 
4.4 
0.8 
1.1 
0.4 
, ffo 
ol { 
Ifa 
13.0 
64.3 
13.8 
5.8 
4.4 
29.3 
27.0 
47.3 
5.0 
14.5 
0.4 
3.0 
2.8 
4.3 
4.1 
6.3 
mt 
3.0 
1.4 
3.7 
2.6 
2.6 
4.2 
5.6 
5.1 
il 
4.4 
1.2 
4.4 
5.0 
1.2 
1.2 
2.9 
plagioclase 
Per cent wo in 
Anes 
An 5 7 
Anss 
An 5 7 
An 8 2 
An 7 8 
pyroxene 
27 
53 
38 
35 
41 
39 
40 
Per cent of 
crystallization 
50 
75 
90 
25 
50 
17 
1. Average of analyses 2 and 3, Table 1. 
2. Least amount of material that added to Pele’s hair (Table 1, analysis 1) yields the picrite-basalt (Table 1, analysis 4). 
3. Least amount of material that subtracted from Pele’s hair yields the composition of sample 10 (Table 1) . 
4. Material that subtracted from Pele’s hair yields sample 10, assuming 75 per cent crystallization. 
5. Material that subtracted from Pele’s hair yields sample 10, assuming 90 per cent crystallization. 
6. Least amount of material that subtracted from column 1 of this table yields sample 10. 
7. Material that subtracted from column 1 yields sample 10, assuming 50 per cent crystallization. 
8. Least amount of material that subtracted from column 1 yields sample 8 (Table 1) . 
particular differs greatly in alkali: silica ratio 
from typical tholeiitic rocks, containing half 
again as much alkali as rocks with the same 
silica content lying on the main trend line, such 
as sample 8. 
If we assume that the liquid phase of the 
parent magma had the composition of the Pele’s 
hair (Table 1, analysis 1), the composition of 
the material that must be removed from it by 
crystallization to yield magma of the composi- 
tion of sample 10 can be calculated. Columns 3, 
4, and 5 of Table 3 indicate the composition of 
the material, assuming respectively 50, 75, and 
90 per cent crystallization of the parent liquid. 
Column 3 appears to represent an impossible 
situation, because the plagioclase is considerably 
richer in sodium (Ab-ts) than it should be 
(Abso) to have separated from the parent 
magma at that degree of crystallization. The 
same objection applies in lesser degree to 
