EAR-9505217 Lithgow-Bertelloni The Fellow proposes to calculate the global intraplate stress field for the last 65 My of EarthOs history based on simple models of mantle flow and detailed plate tectonic reconstructions. The approach is to test first the hypothesis that global scale mantle circulation can explain relatively large-scale (>500 km) intraplate variations in stress regimes and geology, by carefully comparing a large variety of existing geological and geophysical data sets (e.g., intraplate stress data, paleostress indicators, seismic, gravity, and heat flow profiles, etc.). The results will serve as a baseline for assessing the importance of smaller scale dynamic features, such as localized upwellings, and of regional scale crustal heterogeneities. A regional study using detailed seismic tomography models will be carried out for Western North America, to understand the influence of global dynamic processes on the development of the three types of stress regimes represented by the Rocky Mountains compressional region, the Basin and Range extension and the strike-slip deformation in California. This work has the potential to reach far beyond parochial applications in deciphering the mechanics of enigmatic intraplate tectonic features; evolution of the stress field is one missing key to understanding mantle convection.
