Yukon–Tanana terrane

The YTT consists of polymetamorphosed and polydeformed metasedimentary, metavolcanic, and metaplutonic rocks of Upper Paleozoic and older ages that were deposited or emplaced near the edge of the North American continental margin.

[5][6] The right-lateral strike slip Tintina Fault occurs along the suture zone between the YTT (on the south and west) and ancestral North America to the east; it forms a significant boundary between North America cratonic rocks and rocks of the YTT and associated terranes, although displaced continental rocks are found south of the Tintina Fault and pieces of the YTT occur north of the Tintina Fault.

In most of the Alaskan part of the YTT the Denali Fault forms the modern day southern boundary of the terrane.

In Alaska (Delta district) and Yukon (Finlayson Lake belt) the YTT contains a number of Devonian volcanogenic massive sulfide ore deposits with significant copper, zinc, lead, silver and gold mineralization.

Sulfide minerals include massive to disseminated pyrite and pyrrhotite with lesser amounts of chalcopyrite, galena, sphalerite and arsenopyrite.

The Yukon–Tanana terrane (yellow) stretches across Alaska, Yukon, and British Columbia. Kaltag–Tintina fault (north of YTT) and Denali-Fairweather Fault (south of YTT) in white.