CRYSTALLINE BASEMENT 43 
some apparently downfaulted schist-zones, where granite is lacking. 
These zones belong probably to a higher crustal horizon. 
The degree of metamorphism in the Umango area never reaches 
_the intensity of the abyssal phenomena as in the above described zone 
on the very border of the batholith, although smaller assimilations 
also occur here and there. 
i In the following pages only the products of the Famatina injec- 
tion will be treated of, while all the cases of alterations caused by 
a younger granite-syenite will be described afterwards. 
| The Famatina granite appears in the Umango schist body prin- 
_ cipally as crosscutting or concordant dikes of red granite aplite or 
pegmatite without differentiation. In some parts we find also broader 
zones of aplitic granite between the schists, showing at its borders 
EEE 
small assimilation phenomena. 
The eastern mountain slopes of the Mo area form a zone 
of some different character, compared with the zone to the east, at 
the foot of the Nevado. The schists are in the above named slopes 
4 not yet dissolved from their mutual connection, and the strike is 
in detail but slightly disturbed. Melting phenomena are of quite a 
limited extent. The granite appears here as crosscutting dikes, 
eva or 
=... 
oe? FA 
4 running in several directions. Only to a smaller extent a parallel 
injection may be observed. The dikes are of two petrographical 
_ kinds: red, evengrained aplite and red pegmatite, the later of an 
eutectic structure. These are more important and mightier than the 
_ aplite apophyses. 
_ The pegmatites are of a crom red colour and show no complete 
_ differentiation in the quartz- feldspar components. The fact that these 
_ pegmatites are „graphically“ developed, indicates some different 
conditions of consolidation than those in the zone nearest to 
the batholith, where katalytic gases and a slower cooling formed 
favourable conditions to the development of a zonar arrangement 
rae NN 
_ of the components. 
_ The feldspar in the graphic pegmatite is of backstone red colour 
ae ee 
ast © 5 
