Collaborative Research: New Constraints on the Geodynamics of the Lake Bonneville Basin

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The significance of this project is based, in part, on the rarity of this type of opportunity in geodynamic research. Lake Bonneville was one of the largest pluvial lakes on the planet during the late Pleistocene, has one of the best known lake-level histories, possesses multiple shorelines of known ages, and is now covered by the best topographic data set for any pluvial lake basin of comparable size. The convergence of these factors, as well as advances in modeling and analysis, will facilitate greater understanding of the processes and rates of isostatic rebound and accompanying crustal deformation. This study will provide a template for what is possible for geodynamic studies in lacustrine basins located in other regions and on other continents. In addition to developing new insights on the geodynamics of the Bonneville basin that will be used by geophysicists and others to better constrain viscosity models and understand the earthquake cycle, the results of this research have implications for other disciplines such as geochronology. Results from this work may also assist in geothermal energy exploration by better constraining the dimensions of high heat flow anomalies, which may be expressed by regions of super-elevated shorelines not consistent with their loading history. This project will also result in the interdisciplinary training of graduate students and be highlighted and disseminated to a broad audience through the Great Basin Paleoenvironmental Database website (www.dri.edu/gbped). In addition to adding to this database with new publications resulting from the research, the project will develop an online educational module highlighting the Bonneville basin's well documented environmental and geodynamic history. This module will be part of a larger effort to educate interested viewers on various aspects of the Quaternary history of the Great Basin.The Lake Bonneville basin has become one of the premier examples of geodynamic research since the isostasy model of an elastic plate overlying a visco-elastic substrate was introduced in 1890. Since that time, the basin has been the subject of numerous studies elaborating on the timing, magnitude, and processes of isostatic rebound and the response of the crust and upper mantle to the enormous loads imposed by Lake Bonneville. The goal of this project is to employ much higher density shoreline elevation measurements, a more refined loading history, geographic information system spatial analysis of the rebound signal, and a fully three-dimensional finite-element model for simulating the isostatic response of the Earth. Since the last major publication on the rebound of the basin, significant improvements have been made to the lake-level chronology (loading history), modeling sophistication, three-dimensional analysis, topographic data, and the ability to define the geometry of rebound recorded by multiple, discrete shorelines. The combination of these improvements will lead to a much better constrained three-dimensional Earth model documenting lateral variations in lithospheric strength and viscosity structure. Geochronology results from the work may provide constraints on rates of shoreline development and also may lead to revision of calibrated production rates for cosmogenic surface exposure dating.