. 



NEWFOUNDLAND APPALACHIANS 



209 



lith. These two phases are generally gradational, but sharp contacts and local 

 cross-cutting relationships have been observed. 



Basic and intermediate rocks are completely absent, although early phases of 

 the differentiation series may be represented by the nearby Bay du Nord batho- 

 lith. 



The Bay du Nord and Ackley batholiths are in turn cut by the Belle- 

 orum granite, which is known to intrude the Great Bay de l'Eau con- 

 glomerate of Devonian age (D. A. Bradley, personal communication). 

 The three plutons are regarded by Bradley as closely related genetically. 



Composite batholiths have been noted in the St. Lawrence area of the 

 Burin peninsula where the Lawn (?) metagabbro, possibly of Taconic 

 age, is succeeded by the St. Lawrence granite of Acadian age (Van Al- 

 stine, 1948); in the Trinity Bay area where the Powder Horn diorite is 

 intruded by the Northern Bight granite (Hayes and Bose, 1948); and in 

 j the Notre Dame Bay area where a pink granite batholith with satellites in 

 the Hodges Hills vicinity intrudes a gray hornblende diorite. The latter 

 diorite has gabbro facies and exhibits all the characters of xenolithic 

 assimilation (John J. Hayes, personal communication). 



MAJOR STRUCTURAL DIVISIONS AND THEIR CHARACTERISTICS 



Tectonic Map 



The tectonic map of Fig. 13.6 is an attempt to classify the major struc- 

 tural divisions of Newfoundland, and to show some of the important fold 

 axes and faults of the large island. It is based chiefly on Snelgrove's Geo- 

 logic Map of Newfoundland (1938) and on additions that he has made 

 on a copy loaned to the writer. The faults and folds of the Notre Dame 

 Bay area were taken from a work map of John J. Hayes. 



Considerable field work has been done that is not yet in print; much 

 of the central plateau has never been seen by geologists; and areas of 

 crystalline rock are now being considered more as Acadian orogenic com- 

 plex rather than Precambrian. These factors lead to an almost hopeless 

 task of bringing the geologic map up to date and making it tolerably 

 correct, even if generalized. As a substitute, a generalized tectonic map 

 was constructed (Fig. 13.6) that divides Newfoundland into four major 



Fig. 13.5. Geologic map of Recontre Bay area. Reproduced from White, 1940. 



geologic zones, each with distinguishing characteristics. In addition, the 

 Carboniferous basins, basic plutons, principal fold axes and faults, and 

 Cambrian outcrops, as far as known, are shown. Each zone will be de- 

 scribed separately. 



Principal Structural Directions 



Overall, the fold axes, the faults, and the foliation take a north-north- 

 easterly direction; but upon closer observation, some structures trend 

 more easterly, especially in the Notre Dame Bay area. The stratigraphic 

 and structural composition is much like that of the Maritime Provinces 

 and New England, and undoubtedly Newfoundland is part of the great 

 Appalachian Mountain systems. 



Relation to Physiographic Provinces 



The Long Bange highland of the physiographic map, Fig. 13.1, is 

 coincident with the crystalline Precambrian (?) rocks of zone 1 of the 

 tectonic map, Fig. 13.6; the serpentine plutons are generally strong relief 



