Geology, Stevenson Ridge (northeast part), Yukon

The northeastern Stevenson Ridge map sheet (parts of NTS 115-J, I, P and O) is underlain by Paleozoic to Paleogene rocks that locally host Cu-Au porphyry and Au mineralization. The southwestern part of the area is dominated by the mid-Cretaceous Whitehorse plutonic suite which forms the backbone of the Dawson Range Mountains. The north side of the Dawson Range comprises rocks typical of the Yukon-Tanana terrane, including a belt of Permian Klondike schist (metavolcanic rocks), Permian Sulphur Creek plutonic suite and pre-Devonian Snowcap assemblage metasedimentary rocks. The northeast side of the area is dominated by the Mississippian Simpson Range plutonic suite that is intruded by the Triassic Pyroxene Mountain suite and early Jurassic Aishihik suite. The Mississippian to Jurassic rocks are thrust over the Snowcap assemblage along the post-Triassic Yukon River thrust. Late Cretaceous and younger faults occur throughout the area but have only modest offsets.