User:Guisasola13/Innuitian orogeny

The Innuitian orogeny, also called the Ellesmere orogeny was a major mountain building episode responsible for the formation of a series of mountain ranges in the Canadian arctic and Northernmost Greenland. The episode is believed to have started with late Middle Proterozoic rifting event that shows an overall southwesterly to westly trend [[1].

==Pre-Cambrian Geologic History==

Orogenesis of the geology composing the Innuitian orogeny began in the Precambrian and formed the northern part of the Canadian Shield, which includes Greenland. This formed by a number of relatively small continental plates from the Archean age that welded together into a single supercontinent [1].

In the Late Middle Proterozoic a rifting event occurred. Evidence for this is found from the mafic volcanic and intrusive rocks and associated course clastic sediments. Radiometric dating associated these intrusions with the Mackenzie dyke swarm in the eastern Cordillera that was dated at about 1.2 Ga [1].

A rifting event in the Late Proterozoic initiated the Franklinian mobile belt. The early history of the Franklinian mobile belt is not well known [1].

Further rifting events created a series of basin and ranges along the orogeny. In Northeastern Ellesmere Island volcanism and intrusions are present but less abundant than in other sections of the islands. This is likely due to it be adjacent to the Lomonosov Ridge, which is interpreted as a continental fragment caused by tertiary seafloor spreading [1].

==Paleozoic Geologic History==

The deep water basin is divisible intoa southeast and northwest subprovinces. The southeastern subprovidence is dominated by sedimentary rocks. It is exposed from Northwestern Melivlle Island to North Eastern Greenland. It is dominated by five major units[1]:• Early Cambrian resedimented carbonates

• Early Cambrian craton-derived turbidites

• Highly diachronous and lithologically variable layers of resedimented carbonates, mudrock and chert with an age range from Early Cambrian to Middle Devonian

• Diachronous turbidites with an age range from late Ordovician/early Silurian to eifelian

• Middle Devonian mudrock deposited in transitional slope to the outer shelf environment

The northwest subprovidence is composed of sedimentary and volcanic rocks. The area around the northern Ellesmere and Axel Heiberg islands is arc-type volcanics and volcanic sediments alongside strata similar to units 2, 3, and 4 in the sedimentary subprovidence.The sedimentary and volcanic subprovidence  has been dividedinto the Clements Markham and Northern Heiberg fold belts[1].

A series of deformational pulses affected this area from the Late Silurian to early carboniferous. This deformational event can be summaraized in five major events[1].• The Pearya Terrane was transported by sinistral strike slip faulting and has been affected by horizontal flexuring. This is tentatively dated to late Silurian to Early Devonian

• A section of deformation in northern Axel Heiberg Island is characterized by southwest to northeast compression due to wouthwestward motion of ellesmere island or due to the stress field that caused deformation to the Boothia Uplift. This is dated to Late Silurian to early Devonian.

• The Boothia Uplift was most likely formed by thrust faulting from an east-west compressional regime. This was dated to Late Silurian to early Devonian.

• A givetian-Frasnian uplift of the northwestern section of the Hazen fold belt was most likely caused by sinistral motion along the faulted boundary of the two belts. This could be tied to the second compressional deformation of northern Axel Heiberg island that happened around early Devonian to early carboniferous.

• The Ellesmerian Orogeny affected the entire mobile belt, from North Greenland to Prince Patrick Island. This area is a highly sinuous assemblage of fold belts and is more than 375 km wide. This was dated to be late Devonian to early Carboniferous.

==References==

1.      H.P. Trettin (ed.), Geology of the Innuitian Orogen and Arctic Platform of Canada and Greenland. 1991, p. 46