A STUDY OF 4-D CONTINENTAL DEFORMATION IN THE WESTERN US FACILITATED BY GEON

The diffuse continental deformation in the western US is an important issue with significant societal implications. Understanding the interplay between the crustal deformation and its complex spatial and temporal patterns, the heterogeneous thermomechanical and rheological structure, and the various driving forces in the western US requires integration and analysis of multidisciplinary data, which have been fast-growing in the past few decades and their growth will be greatly accelerated by the EarthScope initiative. Thus GEON (GEOscience Network, see www.geongrid.org), a NSF/ITR research project to build a national geosciences information cyberinfrastructure that will seamlessly integrate the geoscience data and analytic tools, will provide an unprecedented opportunity to address some of the fundamental questions concerning continental tectonics in western US.

We will present a case study focusing on some first-order questions of continental deformation in the western US in the past ~80 Myr: 1) What caused the Laramide deformation? Was it flat subduction or gravitational spreading of a high-standing Sevier plateau in the western Cordillera? 2) What caused the Tertiary extension in the Cordillera? Did metamorphic core-complex formation lead to Basin and Range extension? 3) What controls the present crustal deformation in the western US? How would the driving forces and deformation pattern changed over the past ~80 Myr? We will illustrate how the multidisciplinary data sets from the GEON project can be combined with advanced three-dimensional geodynamic modeling to explore answers to these questions.