AGE CONSTRAINTS ON THE CONNOR CREEK FAULT AND CONTRACTIONAL DEFORMATION IN THE BLUE MOUNTAINS PROVINCE, EASTERN OREGON

The Connor Creek thrust fault is the apparent terrane boundary between the Baker accretionary complex and the eastern continental-fringing Olds Ferry volcanic arc terrane of the Blue Mountains Province. In its southern exposures, the fault juxtaposes mélange sediments, greenstones, and mafic plutonic rocks of the Baker terrane with marine flysch of the Izee basin sedimentary onlap sequence. The fault is crosscut by a series of granodiorite intrusions. This study systematically applies U-Pb zircon geochronology to volcanic and intrusive units in the vicinity of the Connor Creek fault to constrain its movement history with respect to the depositional history of the Izee basin. New geochronology will be presented for faulted gabbros of the Baker terrane, tuffaceous horizons in the adjacent Weatherby Formation of the Izee basin, and the fault stitching granodiorite of Big Lookout Mountain. These data will be complemented by detrital zircon provenance and maximum age constraints for sediments of the Weatherby Formation to further constrain the timing of contractional deformation along the Baker-Izee-Olds Ferry terrane boundary. The results will be compared with analogous timing relationships for the Baker-Wallowa and Baker subterrane boundaries, and used as constraints on the accretionary history of the Blue Mountains terranes to the North American margin.