210 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



THRUST FAULT 



SAW TEETH ON SIDE 

 OF UPPER PLATE 



s 1 MAJOR ANTICLINE OR 

 r ANTICLINORIUM 



/K MINOR FOLD AXIS 



w' HIGH ANGLE FAULTS 



^^r SERPENT I NIZEO 

 I NTRUSIONS 



GABBRO OR PERIOOTITE 



>'>'' CARBONIFEROUS 3ASI N 



Fig. 13.6. Tectonic map of Newfoundland, taken mostly from Snelgrove's Geo/ogic Map of New- 

 foundland, Newfoundland Geological Survey. Interpretations assisted by J. J. Hayes, D. Bradley, 

 and Joe Kerr. Zone I consists of schists, gneisses, and intrusives, believed to be chiefly Pre- 

 cambrian, which in part may be metamorphosed volcanics. It was actively deformed during 

 Taconic and Acadian orogenies. Zone II is the Paleozoic orogenic belt of Ordovician, Silurian, 

 and Devonian metasediments, metavolcanics, and batholiths. It may contain both older and 

 younger rocks, but in exposure they are of minor importance. Zone III is a Paleozoic orogenic 

 belt, but in addition to the rocks of zone II it contains major Precambrian linear elements. Zone 



features; and the Carboniferous areas are for the most part lowlands; 

 but the uplands and lowlands east of these do not clearly indicate in- 

 dividualized geologic provinces, as far as known. 



Characteristics of Tectonic Zones 



Zone One. Zone one is the Long Range highland, and it consists chiefly 

 of schists and gneisses similar to those of the nearby Canadian Shield of 

 Labrador. At the south and between La Poile Ray and Cape Ray, how- 

 ever, part of the rocks may be metamorphosed Paleozoic. George Phair 

 has mapped the coast from La Poile Ray westward, according to Joe Kerr 

 (personal communication), and finds at the bay a fossiliferous Lower 

 Devonian formation with the argillaceous members slaty and sharply 

 folded. As the upturned succession is traversed westward, it becomes phyl- 

 litic and finally schistose. No contacts could be found between the 

 Devonian slates and the phyllites, and the schists, previously called Pre- 

 cambrian. Phair visualizes the southern end of the Long Range as an anti- 

 clinorium of isoclinal folds, pitching north-northeastward, and with 

 increasing metamorphism toward the core; perhaps Precambrian rock is 

 exposed in the core, but contact relations are not evident to prove it. 



At the north end of the range and along its flanks at intervals — Ray of 

 Islands area on the west and White Ray on the east — Cambrian beds rest 

 on the schists and gneisses, and hence demonstrate the Precambrian age 

 there of the foliate rocks. 



Zone Two. Zone two east of Long Range appears to be basically the 

 Acadian orogenic complex. It is made up principally of the great Ordo- 

 vician and Silurian volcanic sequences and numerous great batholiths, 

 presumably of Caledonian or Acadian age. The stratified sequences are 

 much folded and generally subject to low-grade metamorphism. Some 

 Precambrian rocks may exist, but this possibility seems less as work 



IV consists principally of Precambrian sediments and volcanics with small infolded or faulted 

 basins of Cambrian and Ordovician strata. The zone is generally much less deformed than the 

 others. Carboniferous basins are stippled and postdate the major orogeny, but were affected by 

 Appalachian faulting. Black areas with smooth borders are serpentinized intrusions, and black 

 areas with hachured edges are gabbros and peridotites. Numbers 1 to 1 1 are lines of cross 

 sections. 



