CRYSTALLINE BASEMENT 45 
aplite dikes, especially the crosscutting ones are getting more 
, scarce, and in some schist-zones red granite is completely lacking. 
But in some other parts there are, however, not dikes, but 
_ whole zones of red granite. Also real bodies of granite of this 
. appear, giving an abyssal character to the locality. Such 
Strongly sranitized areas to the west are: Cerro Cordobés, Cerro 
la Pampa (northern part of the Cerro Potrero Viejo) and the 
western slope of the Cerro Cacho, down to the tertiary fault line 
. the Cordilleran border. In the last; named area there are also 
_ porphyric varieties, but the dominant rock is a red granite. 
= The structures of all these granite bodies are not described here, 
because they are almost crushed by later movements, and these 
phenomena will be treated of later on (pag. 50 and foll.). 
- ©) AN EARLY PALAEOZOIC REGIONAL METAMORPHISM, 
SUBSEQUENT TO THE FAMATINA INTRUSION. 
- In the Umango area there are signs of orogenetic disturbances 
, accompanied by an intrusion of a white granite-pegmatite and syenite 
of apparently younger date, than the Famatina intrusion. The above 
“mentioned white eruptives cut across the red granite in marked 
dikes, although the most common appearance of the former is a 
parallel banding in the schists to the west, apart from the Famatina 
batholith with its network of apophyses. Simultaneously with this 
younger intrusion a lateral pressure (stress) occurred, causing folds 
in the limestone banks and also a marked banding over broader 
‘zones between amphibolite and other schists and concordant dikes 
of white granite (syenite). This injection has as a whole a less 
d markedly abyssal character than the Famatina plutonic phase and 
belongs probably to a somewhat higher crustal horizon, than the 
- last mentioned. It is evident that the white granite-syenite intrusion 
occurred in prepermian („pre-Gondwana“) time, because of the fact, 
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