This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Tectonic deformation, magmatism, and associated changes in erosion rates and paleodrainage systems directly affect sedimentary basin evolution in active tectonic settings. Thus, a detailed and robust evaluation of convergent margin sedimentary basins may provide the most complete record of tectonic and magmatic events in ancient convergent margin systems. The North American Cordillera provides an ideal setting for developing this robust provenance technique because extensive geochronologic, geochemical, and isotopic studies throughout the orogen establish an explicit basis for comparing sediment sources against the provenance data to be collected. Because no clear consensus has been reached on the Mesozoic and younger paleogeographic evolution of the western Cordillera, provenance results will address longstanding questions of terrane translation and rotation. The scientific merit of the proposed study lies in the development of an integrated sedimentary provenance technique that will be generally applicable to basin evolution studies in convergent systems worldwide.
The proposed basin provenance analysis integrates sedimentary petrography with detrital zircon analysis, whole-rock major and trace-element geochemistry, and neodymium isotopic analysis to develop a detailed approach to studying convergent margin basins that should be transferable to similar systems around the world. The robust geochemical and geochronologic dataset resulting from a combination of multiple provenance tools includes information from all grain sizes and compositions within a basin?s stratigraphy. Integrated provenance analysis that includes the more homogenized fine-grained component of basin strata will permit better correlation within and between basins. Cretaceous basins whose sedimentary provenance may provide crucial links to source regions include the Methow basin in southern British Columbia and northern Washington State, the Ochoco basin in eastern Oregon, the Hornbrook Formation in southern Oregon and northern California, and the Great Valley Group in California. With the exception of the Great Valley Group, the provenance of these Cretaceous Cordilleran basins has been studied largely at a reconnaissance level, and none of these basins have been studied through integration of all proposed provenance tools. Together, these various provenance methods permit documentation of the evolution of sediment sources through time and space within a single basin, improved stratigraphic age control, and better correlation within a single basin and between basins.
