W. G. Foye — Nephelite Syenites of Ontario. 413 



Art. XXX. — Nephelite Syenites of Halliburton County, 

 Ontario; by Wilbtjk G. Foye. 



Part I. Two differentiated Laccoliths of Nephelite Syenite in Glamor- 

 gan and Monmouth Townships. 

 Introduction. 



A. Gooderham Laccolith. 



General Geology. 

 Petrography: 



1. Ked syenite. 



2. Schistose canadite. 



3. Nephelite pegmatite. 



4. Kaolinized contact rock. 



B. Crescentic Laccolith near Tory Hill. 



General Geology. 

 Petrography: 



1. Garnet-pyroxene contact rock. 



2. Hornblende-nephelite rock. 



3. Monmouthite. 



4. Biotite-nephelite rock. 



5. Pegmatitic nephelite syenite. 



Part II. Suggestion concerning the Origin of the Nephelite Syenites. 

 Smyth's Theory. 

 Confirmatory Evidence. 



Pneumatolytic Metamorphism of the Limestone to Amphibolite. 

 Nature of the Solutions Introduced into the Limestones. 

 Quantitative Importance of this Alteration. 

 Origin of the Fluids Producing the Amphibolites. 



a. Segregation by juvenile gases. 



b. Interaction of the granite magma and limestone. 

 Emplacement of the Laurentian Granite and Origin of Lit-par-lit 



Structure. 

 Genetic Eelations of Amphibolite and Nephelite Syenite. 

 Field Facts Showing Desilication of the Granite and Origin of 



Soda-rich minerals. 

 Conclusions. 



PAET I. 



Introduction. 



The laccoliths of nephelite syenite, described in this paper, 

 are located in Haliburton County, Central Ontario. They 

 are reached by way of the Central Ontario Railroad from 

 Trenton and the Irondale, Bancroft and Ottawa Railroad, 

 which connects with the Central Ontario Railroad at Bancroft. 

 One of the laccoliths lies southeast of the village of Gooder- 

 ham ; the other lies southwest of Tory Hill. Messrs. F. D. 

 Adams and A. E. Barlow have described the general geology 

 of this area in their memoir, "The Geology of the Halibur- 

 ton-Bancroft Area, Ontario."* 



*F. D. Adams and A. E. Barlow, "The Geology of the Haliburton-Ban- 

 croft Area, Ontario," Memoir No. 6, Canada Geol. Surv., 1910. 



