Geology, Stevenson Ridge (northwest part), Yukon

The northwestern Stevenson Ridge map sheet (parts of NTS 115-J and K) is underlain by Paleozoic to Paleogene rocks that locally host Au mineralization. The backbone of the Dawson Range is underlain by the mid-Cretaceous Whitehorse plutonic suite. Late Devonian metamorphosed volcanic, plutonic and sedimentary rocks of the White River assemblage and the Late Triassic Snag Creek suite gabbro occur southwest of the Dawson Range. These rocks are structurally overlain by a thrust sheet of the Early Permian Harzburgite Peak complex. The north side of the Dawson Range is characterized by Paleozoic rocks typical of the Yukon-Tanana terrane, including Permian Klondike schist, Permian Sulphur Creek plutonic suite and pre-Devonian Snowcap assemblage. The White River assemblage and the Yukon-Tanana terrane are juxtaposed along the post-Triassic Moose Creek thrust, which is partly demarcated by lozenges of peridotite. Late Cretaceous and younger faults occur throughout the area but have only modest offsets.