CANADIAN ARCTIC 





and appear to be of cratonic origin. These range from narrow, steep-flanked 

 anticlines to broad synclines and anticlines. Conglomerates and two uncon- 

 formities indicates that the Cornwallis folds had an initial, intermittent develop- 

 ment extending from Middle Silurian to the Middle Devonian. During short 

 times of stability in the Silurian many small reefs grew along the margins of 

 some anticlines. 



The east-west Parry Islands miogeosynclinal fold belt consists of long parallel 

 folds which decrease in amplitude eastward toward the Cornwallis folds. How- 

 ever, at several places the Cornwallis structures are relatively highly deformed 

 by the east-west folds. The Parry Islands belt was deformed in the latest 

 Devonian or during the Mississippian. 



The final phase of deformation occurred as persistent north-south postoro- 

 genic faults. In the southeastern part of Bathurst Island the faults controlled 

 the emplacement of small sills, dykes and plugs of olivine basalt. 



Sverdrup Basin 



The Sverdrup Basin includes a voluminous sequence of Pennsylvanian to 

 Tertiary beds which have been mainly deformed in Tertiary time. In the best 

 exposed and apparendy thicker part of the basin, the units of the sequence, 

 although varying in thickness, appear essentially conformable. At the periphery 

 of the basin there are unconformities, disconformities, oversteps and some 

 facies developments. 



In the southern and eastern peripheries of the basin, the Permo-Carboniferous 

 commonly includes units of limestone, units of sandstone with layers of con- 

 glomerates, and lesser units of shale. In the northern part of Axel Heiberg 

 Island, the Permo-Carboniferous includes volcanic measures. Nearby, Permian 

 limestone is at least 5,000 feet thick. Across the middle part of the island, the 

 basin contains the following units: Permian siltstone with lesser shale and silty 

 shale, 4,000 feet thick; Middle, Upper, and probable Lower Triassic shale 

 with siltstone and sandstone, 10,000 feet thick; Upper Triassic, marine, and 

 possibly Lower Jurassic, non-marine sandstone, shale, siltstone, with carbonace- 

 ous film in the upper part, up to 5,600 feet thick; Jurassic marine shale up 

 to 900 feet thick, non-marine sandstone and lesser marine shale up to 1,300 

 feet thick; Jurassic and Cretaceous shale as thick as 2,500 feet; Lower Cretace- 

 ous sandstone with a maximum thickness of 4,500 locally with a 200-foot 

 stratum of volcanic breccia, and shale in thicknesses reaching 3,000 feet; Lower 

 or Upper Cretaceous sandstone and shale, over 700 feet thick, locally overlain 

 by basalt flows up to 600 feet thick; Upper Cretaceous shale, as thick as 1200 

 feet and conformably overlain by Tertiary and possibly Cretaceous non-marine 

 siltstone, sandstone and silty shale with coal, over 8,000 feet thick. In the 

 Ringnes and Cornwallis Islands these or similar units down to the Upper 

 Triassic occur but in somewhat lesser thicknesses. Facies indicate an eastern 

 and southern source for most of the Mesozoic sediments. Gabbro sills and lesser 

 dykes are common in some units and are most numerous in the region of 

 Eureka Sound. They are as far widespread as from Melville Island to the region 



of Baumann Fiord, from Ellef Ringnes to the northeast coasl ot KHwtiimie 

 Island. There is no regional metamorphism and any alteration related to these 

 intrusions is limited to a few feet in the country rocks. 



The strata of the basin have been folded in Tertiary time. From the Ri] 

 Island eastward the deformation has been more marked, and the northwester!) 

 and northerly trending folds form the Eureka Sound Fold Belt. On the southern 

 part of Axel Heiberg Island many folds are of the "box" type. The regional 

 plunge of the folds is inward to the basin, that is towards the longitudinal axis 

 of the basin. This axis on the Ringnes and Axel Heiberg Islands is generally 

 the locus of the youngest formations. Coinciding with this axis Irom northern- 

 most Melville Island, across the Ringnes Island, middle Axel Heiberg Island. 

 the eastern part of this island along Eureka Sound to Nansen Sound and Elles- 

 mere Island is a zone of diapiric intrusions of gypsum of Pennsylvanian and or 

 Permian age. Most of these intrusions are in the crestal area ot the Tertian 

 folds. There is a rough parallelism between the longitudinal axis of the Sverdrup 

 Basin, the zone of diapiric intrusions, and the trend of the deformed lower 

 Paleozoic miogeosyncline. It would thus appear that the Paleozoic orogen) 

 had long range effects in that not only was it a factor in the formation of the 

 depression in which Permo-Carboniferous evaporites were eventually laid down, 

 but also it ultimately had some bearing on Tertian' tectonism (Fortier, 195 



See the summary by Tozer (1960). 



ARCTIC COASTAL PLAIN 



The Arctic Coastal Plain covers the western part of Banks Island, the west- 

 ern and northwestern parts of Prince Patrick Island and probably extends to 

 the northwestern parts of Brock, Borden, and Ellef Ringnes Islands. The rocks 

 include Cenozoic beds unconformably covering Mesozoic strata and. south of 

 the Sverdrup Basin, comprise Cretaceous and possibly Jurassic formations ap- 

 parently overlapping Devonian strata (Fortier. 1957). 



CORRELATION WITH ALASKA AND THE YUKON 



Reference to Fig. 39.13 will bring to one's attention the following 

 possible correlations of the geologic provinces of the Arctic Archipelago 

 and Alaska and the Yukon. The Pennsylvanian and Permian of the 

 Sverdrup basin would appear to have a tie with the Late Pennsylvanian 

 and Permian of the basins of northeastern Alaska and northern Yukon. 

 The closeness of the shelf margin to the present shore leaves little room, 

 however, to connect them into a continuous basin. The unconformitv 



