The proposed research will investigate the origin of igneous rocks in the Klamath Mountain province that are the remnants of two extensive arc systems. Although the systems, the western Hayfork/Ironside Mountain complex and the Rogue/Chetco complex, represent the most voluminous accretionary arcs in the province, they have received little detailed petrologic study. Their origin will be investigated with the use of detailed mapping and sampling, U-Pb (zircon) geochronology, mineral analysis, bulk-rock elemental analysis, and isotopic analysis of bulk samples and mineral separates. These data will be used to estimate the composition of the source rocks, to model the effects of fractional crystallization and crustal contamination, and to provide a means of comparing the arc-related rocks with adjacent, well-studied, remnant arc and back-arc magmatic systems. The results will be interpreted in the context of local and regional tectonic activity and metamorphism, and will be used to compare Mesozoic arc magmatism in the Klamath Mountain province with that elsewhere in the North American Cordillera.
