The geology of Yukon includes sections of ancient Precambrian Proterozoic rock from the western edge of the proto-North American continent Laurentia, with several different island arc terranes added through the Paleozoic, Mesozoic and Cenozoic, driving volcanism, pluton formation and sedimentation.
The Mackenzie Mountains Supergroup in the east and the Fifteenmile Group in the west were deposited with carbonates, sandstone, siltstone, and shale around one billion years ago.
Regional folding, which produced the Corn Creek orogeny took place around 900 million years ago, leaving behind interlaced transcurrent faults in the vicinity of the current day Snake River.
The Yukon was part of the supercontinent Rodinia until it began to break up 850 million years ago, separating the proto-North American continent of Laurentia.
[2] In the early Paleozoic, the Mackenzie Platform accumulated material, including deep water sediments in the Cambrian in the vicinity of Mayo and Dawson.
Regional crustal extension formed the Redstone Arch (now present in the Mackenzie Mountains) as well as embayments found along the provincial line with Northwest Territories and British Columbia.
The Tintina Fault shifted the Cassiar Terrane—a 60-kilometer-wide section of carbonates on continental crust north up to 490 kilometers, where it now forms a part of the Pelly Mountains in the center of the territory.
Into the Devonian, the Road River Group chert, siltstone and mudstone built up in the basin, supplied with high temperature brines from seafloor vents which created zinc-lead deposits in Howards Pass and Anvil Ridge.
In the Middle Devonian, 390 million years ago, eastern Yukon was blanketed in sandstone, black shale and siltstone during a major marine advance.
However, the Selwyn Basin was uplifted, leading to erosion of a chert-pebble conglomerate in the Earne Group which may have been carried along submarine canyons to the Macmillan Pass.
In the southeast and in the Ogilvie Mountains, the Keno Hill Quartzite and sandstone-mudstone Mattson Formation accumulated from Carboniferous river deltas carrying eroded material from a landmass to the north.
The thickening of the crust during the orogeny caused melting and granite intrusions visible at Hoidahl Mountain, Old Crow Range and Mount Sedgwick.
The Cache Creek terrane is near the center and is the remains of oceanic crust, in the form of basalt, argillite, chert, gabbro, various ultramafic rocks and limestone dating from the Pennsylvanian to the Jurassic.
Southwest Yukon built up with addition of exotic terranes in the Mesozoic, uplifting the platform and resulting in erosion of older sedimentary units.
As the Stikinia, Cache Creek and Quesnellia terranes converged in the Middle Jurassic the Whitehorse Trough developed as a basin, filling with three kilometers of Laberge Group sandstone, conglomerate, shale, coal, deep-water turbidite and Nordienskiold Formation pyroclastic flows.
Nickel, copper and platinum group elements formed in ultramafic intrusions within the Nikolai Formation, deposited as gabbro, pyroxenite and dunite as the Kluane mafic-ultramafic complex.
The most inland Cretaceous plutons are the Mayo, Tungsten and Tombstone suites northeast of the Tintina faults, intruding older rocks deposited in the Selwyn Basin.
[8] From the Paleocene into the Oligocene, the conglomerate, coal seams and sandstone of the Amphitheatre Formation deposited atop the Alexander and Wrangellia terranes in a basin that developed along the Denali Fault.