Late Cretaceous to Early Tertiary granitic plutons associated with W skarn or Sn greisen-skarn occur interspersed in a belt 70 × 200-km-long just northeast of Fairbanks, Alaska. All plutons intrude the late Precambrian–early Paleozoic Yukon-Tanana terrane and are similar in major-element compositions (dominantly granodiorite to monzogranite), initial Sr isotopic ratios (0.710 to 0.719), and Pb isotopic signatures (²⁰⁶Pb/²⁰⁴Pb = 19.17 to 19.37). Biotite compositions and opaque mineral abundances indicate both types of plutons crystallized along a buffered path intermediate between nickel–nickel oxide and quartz-magnetite-fayalite. Both suites contain multiple igneous units, with younger, usually equigranular, units spatially...