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STRUCTURAL GEOLOGY OF NORTH AMERICA 



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Fig. 12.6. Section across the St. Lawrence at Quebec City. Reproduced from Alcock, 1947. 



smooth curve easterly to the tip of Gaspe, passing between Anticosti 

 Island and the peninsula. Where information is available, the faults in 

 the great arcuate zone of deformation south of the St. Lawrence are 

 known to be overthrusts from the southeast. The rocks of this belt, 

 particularly those of Gaspe, can be divided into four main assemblages 

 according to the number of orogenies by which they have been affected. 

 The metamorphic rocks of the Macquereau group were deformed by a 

 late Proterozoic to early Cambrian orogeny; the Upper Cambrian and 

 Ordovician rocks were deformed by the Taconic orogeny; the Silurian 



and Devonian rocks were affected by the Acadian orogeny; the Car- 

 boniferous is comparatively little disturbed (Alcock, 1935). Figure 12.5 

 illustrates the structures in a small way. 



Ry reference to the Geologic Map of Canada, it will be seen that the 

 lower and outer part of Nova Scotia is made up of Precambrian rock, as 

 well as a belt through St. John, New Rrunswick. These were not immune 

 to Paleozoic orogeny, however, because overlying and marginal Paleozoic 

 strata are much deformed and the Precambrian rocks are intruded by 

 many plutons of Paleozoic age. 



