Sprague Creek map area is underlain by multiply deformed Upper Proterozoic to mid-Paleozoic metasedimentary rocks and undeformed Cretaceous felsic intrusions. The oldest and structurally deepest rocks underlie most of the southern two-thirds of the map area. Three phases of regional deformation and a younger suite of faults and fractures are represented in Sprague Creek map area.
Mineral occurrences in the area comprise veins, breccias, and skarns spatially and probably genetically related to Cretaceous intrusions, and gossanous breccias along NNW-trending lineaments.
