NSF Award
1450840
The goal of this project is to investigate the role that crustal fluids have played in deformational processes that created the classic Wyoming salient of the Cordilleran fold and thrust belt of the western United States. The Cordilleran orogenic belt is a major tectonic feature consisting of folds and faults that resulted from convergent margin tectonic activity due to subduction of the Farallon plate beneath the North American plate about 140 to 50 million years ago during the Sevier Orogeny. The Wyoming salient is considered to be an ideal place for this study given that it has been extensively studied and is of the best characterized fold and thrust belts in the world. The results of the project will provide insights into how fluids contribute to large-scale deformation associated with mountain building events, fault zone processes, and the results will have implications for a variety of disciplines that have societal relevance, including mineral exploration, hydrocarbon exploration, hydrology. In addition to the research goals of the project, the project will contribute to training of graduate and undergraduate students in a STEM discipline; collaboration between three universities; contributions to research infrastructure at at Ph.D. granting and primary undergraduate institutions; incorporation of research results into classroom curricula; and dissemination of research results via peer-reviewed publications, presentations at professional geoscience meetings, and by web accessible digital data sets. <br/><br/>This project will innovatively integrate detailed structural, fluid inclusion, stable isotope, and geochronologic studies along transects across the curved Wyoming salient into the foreland and along traverses of key large-scale folds and major fault zones, providing extensive new regional data sets that relate fluid flow with progressive deformation. Although previous laboratory studies have provided insights into deformation micromechanisms and previous field and modeling studies of thrust belts have revealed the importance of fault zones and evolving topography on fluid flow systems, quantitative interrelations between regional to local fluid flow and progressive deformation within propagating fold-thrust wedges remains poorly understood. This project will build on previous structural studies in the Wyoming salient, with results synthesized to improve our understanding of feedbacks between fluid flow and thrust wedge mechanics. The project will test models of fluid-flow systems within curved fold-thrust belts, including nature of micro-, meso-, and megascopic fluid pathways; changing contributions of meteoric-, formation-, and metamorphic-waters during progressive wedge propagation and development of topography; evolving stratigraphic and structural compartmentalization of fluid flow as deformation changes style from distributed layer-parallel shortening to concentrated thrust slip; and propagation of detachment faults and early layer-parallel shortening in front of the fold-thrust wedge related to enhanced fluid flow and burial. This project will build on previous structural studies in the Wyoming salient, with results synthesized to improve our understanding of feedbacks between fluid flow and wedge mechanics. The project will combine a variety of methodologies, including mesoscopic structural analysis and sampling of veins/fracture sets, cleavage, and minor faults that provided fluid pathways,
