The Condrey Mountain Schist (CMS) of the Klamath Mountains (northern California and southern Oregon) represent low grade oceanic and terrigenous sediments thrust beneath higher grade ophiolitic rocks of the Rattlesnake Creek Terrane (RCT). This study presents new U-Pb detrital zircon dates from the CMS, and from the possibly correlative basin rocks of the Galice Formation and accretionary rocks of the South Fork Mountain Schist. The Galice Formation yields a maximum depositional age of ca. 152 Ma with prominent date distributions of ca. 150-200 Ma (39% of analyzed grains), 200-600 Ma (1%), 600 - 1000 Ma (2%), and 1000-3200 Ma (58%). The South Fork Mountain Schist yields a detrital zircon age spectrum with a maximum depositional age of ca. 135 Ma, and prominent age distributions of ca. 120-200 Ma (28.5% of analyzed grains), 200-600 Ma (24%), 600-1000 (8.5%), and 1000-2850 (39%). An interior unit of the CMS has a maximum depositional age of ca. 136 Ma and contains detrital zircon age distributions within 136 to 200 Ma (24% of analyzed grains), 200 to 600 Ma (27.5%), 600 to 1000 Ma (10%), 1000 to 2300 Ma (38.5%). Structural, petrographic, and detrital zircon geochronologic similarities between the CMS and SFMS suggest a common provenance. Kinematic indicators within the Condrey Mountain shear zone, a shallowly dipping ductile structure separating the CMS from the RCT, suggest that the CMS was transported eastward during prograde metamorphism and exhumed during top-to-the-east normal faulting. A tonalitic intrusion from the exterior unit of the CMS yields an inferred igneous emplacement age of ca. 172 Ma. These relations indicate that the exterior CMS was tectonically emplaced at least 37 Myr prior to deposition of the interior CMS --Abstract, page iii
