U/PB AGES OF ISOLATED BUTTES IN SPOKANE, WASHINGTON AREA TO HELP PROJECT DEFORMATION IN THE SUBSURFACE

The Cambrian to Mesoproterozoic isolated buttes in the Spokane, Washington area provide great insight into Cretaceous fold and thrust deformation as well as Eocene uplift. Multiple different cross sections were made prior to using U/Pb age determination to explore possible variations of the deformation in eastern Washington, which now may be revisited after age determination. Of the 10 samples which were analyzed, three buttes contained detrital zircon (DZ) signatures similar to Cambrian units from northeast Washington found to be Cambrian, three samples had similar DZ signatures to Neoproterozoic Deer Trail Group, and four samples had a similar DZ distribution to Mesoproterozoic Belt Supergroup rocks. Mapping of sample locations coupled with cross sectional analysis will provide useful information about the understudied basement rock in the Spokane region.