The Cascadia subduction zone (CSZ) is an inherently complex three-dimensional system, where along strike variability in physical parameters likely exerts significant control over widespread deformation patterns. Evaluating fundamental characteristics of the CSZ and coupling with upper crustal deformation requires quantifying the effects of physical properties in the subducting and overriding plates. For example, subduction zone geometry, rheological properties, mantle flow boundary conditions, and continental scale structures have been shown to effect crustal deformation in Alaska (Jadamec et al., 2013). Similar along-strike variability exists within the Cascadia subduction zone system but remains relatively unexplored.
The goal of this Mendenhall Research Opportunity is to use state-of-the-art subduction zone modeling to better understand physical controls on the Cascadia subduction zone and how stresses are translated into forearc and backarc deformation and landscape evolution. Sophisticated high-resolution forward modeling of along-strike cross sections provides a potential means for reconciling north-south variations in geologic and geophysical observations of the Cascadia subduction zone and exploring fundamental controls on upper crustal deformation and landscape evolution. Objectives include exploring physical parameters that may control modern subduction dynamics and upper crustal deformation patterns in the U.S. Pacific Northwest.
Critical parameters to explore may include: (1) Structure of the downgoing slab and downgoing-overriding plate interface; (2) Overriding plate structure, including inherited lithospheric shear zones and variations in temperature and strength across distinct geologic terranes; (3) Lithospheric and upper mantle rheology, including viscous flow laws, brittle failure criterion, phase changes and fluid transport; (4) Geographic model size and the importance of boundary conditions on both regional and large-scale deformation patterns; (5) Coupling between lithospheric deformation and landscape evolution.
This project involves simulating highly non-linear systems and quantitative comparisons with geologic and instrumental observations, requiring familiarity with computational dynamics and understanding of geophysical datasets, tectonic systems, and structural geology. We encourage the post-doctoral researcher to develop innovative approaches to address outstanding questions in Cascadia subduction zone science.
Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.
References:
Jadamec et al., (2013). Three-dimensional numerical models of flat slab subduction and the Denali fault driving deformation in south-central Alaska. EPSL, 376, 29–42.
Proposed Duty Station: Portland, OR
Areas of PhD: Geology and geophysics or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).
Qualifications: Applicants must meet one of the following qualifications: Research Geologist, Research Geophysicist
(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)
Human Resources Office Contact: Audrey Tsujita, 916-278-9395, atsujita@usgs.gov
