158 ENOGGERA GRANITE AND ALLIED INTRUSIVES. 



directions making an angle of thirty degrees, so that the 

 latest folding of the schists also antedated the appearance 

 of the granites. 



Unfortunateh^ the age of the Brisbane schists them- 

 selves is still in the region of doubt, but there seems 

 little reason to doubt that they are early Palaeozoic sedi- 

 ments, and that the folding referred to took place in late 

 Palaeozoic — probably Permo-Carboniferous — times. 



Although the granites lie in such close proximity to 

 the Ipswich beds, neither they, nor any of the ailied, but 

 somewhat later, intrusives intrude these strata. Since 

 the Brisbane representatives are the basal members of the 

 Ipswich series, and since this is the lowest division of 

 the Trias-Jura, the granites are probably pre Trias-Jura. 

 These facts, though .slight, point to the probability that 

 the granites are late Permo-Carboniferous in age. 



If we now resort to less direct methods and consider 

 the evidence gained by a correlation of these granites with 

 those of other areas, a practically indentical result is arrived 

 at. From a study of the works of Andrews, Carne, and 

 Cotton on the New England granites, the writer has come 

 to the conclusion that in spite of superficial differences the 

 Enoggera granites resemble very closely, and are probably 

 related to in point of time, the granites which Andrews 

 considers under his " Later Granite Types " or '" Acid "' 

 granites which are indentical with the Stanthorpe granites. 

 The chief grounds for this conclusion are, the general 

 mineralogical similarity,' the marked variability of the 

 rocks of both areas — Andrew's description^ might be applied 

 word for word to the Enoggera granite — the absolutely sharp 

 lines of demarcation between the granites and the invaded 

 rocks, ^ the association of each of the granites with some- 

 what later finer-grained aplitic types, lacking in ferro- 

 magnesian constituents and containing black tourmaline 

 and molybdenite^ and the further association of the granites 

 with rhyolitic intrusions, quartz por})hyries, and porphyries.^ 



1. Card Mineral Resources of X.8.W. Records, Vol. \'ITI., p. 23. 



2. Op. cit. p. 113. 



3. Andrews, Op. cit. p. 232. 



4. Andrews, Op. cit. p. 232. 



5. Andrews, Op. cit. p]). 117. 128^ 



