CANADIAN ARCTIC 



641 



of the same age extends across the northern margin of the great island. 

 The East Greenland fold belt developed during three phases (Koch, 

 1961): 



1. Orogeny of Silurian (?) age affected the entire east coast, with 

 thrusting toward the west and extensive granitization. 



2. Deformation south of 76° N. Lat, in places closely related to in- 

 trusive granite bodies, occurred in Devonian time. 



3. Subsiding basins were filled with thick deposits of molasses-type sedi- 

 ments in the Middle and Late Devonian, in the Carboniferous and in the 

 Early Permian. They attest times of nearby crustal unrest and elevation, 

 but the Devonian detritus was mildly deformed itself in two episodes, 

 one in Early Carboniferous and one in Early Permian. The entire east 

 coastal area was strongly affected by faulting, especially during the 

 Carboniferous. 



Mesozoic and Tertiary 



A marine transgression in Late Permian time covered large areas along 

 the coast, and this was followed by several Mesozoic transgressions. 

 Many of the old faults were reactivated in the Tertiary. 



A large basalt field of Late Cretaceous and early Tertiary age occurs 

 in the east-central part of Greenland ( Fig. 40.5 ) and of this region Wager 

 (1947) writes: 



Subsequent to the forging of the metamorphic complex which probably took 

 place in Pre-Cambrian times, the area was for long dominantly subjected to 

 upward movement with concomitant erosion. Towards the end of the Mesozoic 

 era, when next there is definite information, the area seems to have been of sub- 

 dued relief and near sea level. In the Kangerdlugssuaq area a local marine 

 transgression of approximately Senonian age produced thin sediments resting 

 on the metamorphic complex, and a similar and perhaps contemporaneous 

 marine transgression took place further south on what is now Kap Gustav Holm. 

 Within a short time of the maximum development of the Cretaceous trans- 

 gression volcanic activity broke out in the Kangerdlugssuaq region giving the 

 Lower Lavas and Tuffs. 



The Lower Lavas and Tuffs of latest Cretaceous or very early Eocene age, 

 mark the beginning of intensive igneous activity in East Greenland, extending 

 in a N.N.E. direction over a distance of 1,200 km., from 66° to 75° N. South- 

 wards, the coast line has the same N.N.E. direction and there are many basic 

 dikes, which almost certainly form part of the same igneous episode. 



The eruption of vast quantities of basalt to give the Plateau Basalt Series, 



Fig. 40.5. Upper map, very generalized distribution of seas and lands of the Arctic during 

 Triassic and Jurassic times. The seas at any one time were not as extensive as the total dis- 

 tribution shown. Lower map, early Tertiary deposits of the Arctic. The dotted lines are isoflors 

 after Chaney, 1940, and the crosses denote Chaney's Eocene and Oligocene localities, plus a 

 few other localities where "Arctic Miocene" coal beds are known. The ruled area denotes 

 the Greenland-lceland-Scotland basalt field of early Tertiary time. 



attaining in places a thickness of certainly O.'-i km. and probably a good dial 

 more, is the greatest igneous event in the region judging by the quantity of 

 magma involved. The time taken for the accumulation of the Plateau Basalt 

 Series can be estimated from the fossils found immediately below and above the 

 series as approximately equal to the duration oi the Lower Eocene, and this 



