337 
The Shere. oF of differentiation can be summarized in the 
appended chart 
Residual Magma=——Albite Pegmatites. 
(dominantly sodic). 
us Microcline Albite Aplites 
Chonolitic (differentiation may cease 
. a re). 
Differentiation 
in 
situ. : 
Residual Magma 
(dominantly potassic). 
Granite [Adamellite]. 
.. Salic 
differentiate 
from 
: a wr 
batholitic Granitic Magma. 
Magma. 
this relation be preserved at doy it follows that the com- 
Position of the residual magma lies very close to that of the 
potassic-a aplites. 
In this connection the writer would point out that the 
differentiation of the residual magma may be controlled by a 
ctor. W 
forced into fissures and caused to rapidly cool, further 
differentiation may be inhibited and the magma solidify as a 
e aggregate of quartz, microcline, and subordinate 
a 
. , On the other hand, the filtering of the residual magma 
into a subsidiary pool without rapid change of temperature 
and its slow crystallization undisturbed, then fractional 
eration may take Jae with the production of a small 
ount of residual liquid, enriched in mineralizers and of 
composition markedly different. from that of the original 
residual m magma. 
Movement at this stage would result in the straining off 
of the small amount of yours liquid, giving rise 
sions Td es em E 
e potassic-aplites so derived would 
difor 1 but sl t slightly ia that representing the composition of 
the residual magma. 
