[dresser] serpentine SERIES OF QUEBEC 13 



Summary 



In a review of the granitic rocks of the serpentine series two forms 

 of occurrence are distinguished, viz.: dykes and irregular masses. 

 These are only selected as types since there are all gradations in shape 

 between them. 



The dykes and dyke-like forms are small and irregular; they do not 

 intersect one another and are limited to the peridotite-serpentine area. 

 They are believed to be local fillings of contraction cracks, or other 

 spaces, in the cooling peridotite by part of the more acid and still 

 liquid magmatic residues. 



The irregular masses are now known to be isolated from one 

 another in numerous cases that could be observed and may be so 

 isolated in many more, perhaps in a great majority of the occurrences. 

 Along the margin of larger masses there is a tendency to develop 

 pegmatitic phases rather than fused or transitional contacts, between 

 them and the adjacent rocks. Reactions such as might be expected to 

 take place between thermal acid waters and ultra basic rocks is 

 evidenced in places by the development of lime silicates. On the 

 whole there is strong ground for the belief that these granites, aplites, 

 etc., are residual segregations from the rnagma of the peridotite and 

 that they have been formed by differentiation in situ. 



