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22-16. Characterizing the neotectonic evolution of the Cascade Range

We seek a Mendenhall Fellow to examine the neotectonic evolution of the Cascade Range (CA, OR, WA), a dynamic, high-elevation landscape controlled by recent glaciation, magmatism, and faulting. We invite proposals to conduct interdisciplinary research to characterize the interactions and spatiotemporal patterns of climate, magmatism, tectonics, and natural hazards within the Cascade Range.

Description of the Research Opportunity

The Cascade Range (WA, OR, northern CA) is one of the largest US mountain ranges with a complex history of glacial episodes, crustal deformation, volcanism, vertical uplift, and mountain building related to the Cascadia subduction zone. The recent discovery of active normal and strike-slip faults near the crest of the range in northern California and Oregon suggests that the volcanic arc is a fundamental tectonic element in the broader Cascadia subduction zone plate boundary. This contrasts with active fault systems farther north, which cut obliquely across the range in Washington. Recent acquisition of lidar topographic data along much of the Cascade Range provides unprecedented insight into the geomorphic expression of glacial, volcanic, and tectonic processes. However, detailed geologic mapping and chronologic histories of glacial and volcanic deposits are lacking and prevent the complete characterization of these active fault systems. Analysis of faults and their deformation history will require a detailed understanding of glacial and volcanic history to determine rates and magnitudes of deformation and to better understand the Cascade Range in the regional tectonic framework. Fundamental to understanding these histories is detailed geologic mapping of both bedrock and surficial deposits, complemented by geoscience techniques, such as geochemistry, geochronology, terrestrial and/or lacustrine paleoseismology, geophysics, and geodesy.  

The successful research fellow will use geologic mapping coupled with other techniques to make progress towards an interdisciplinary understanding of the neotectonic history of the Cascade Range. Research approaches might focus on the glacial response to, and spatial extent of, late Quaternary glacio-climatic cycles, the style, tempo, and composition of Cascade volcanism, the rates, linkages, and kinematics of active fault systems, or the interplay of these and other processes. Samples for geochemical analysis, Ar/Ar geochronology, cosmogenic exposure dating, and low-temperature thermochronology may be collected to provide compositional, temporal, and/or thermal constraints on these processes. Regional bedrock geologic units (e.g., Columbia River Basalt Group) provide laterally extensive horizons to characterize longer-term deformation. Structural field measurements, such as offset strain markers or fault kinematic data, might compliment geologic mapping and the construction of cross sections and 3D geologic maps. The project might incorporate the analysis and interpretation of recently collected airborne aeromagnetic data along the Cascade Range in southern WA and northern OR. These aeromagnetic data could be integrated with existing and/or newly collected gravity data and/or new higher-resolution magnetic data to provide a comprehensive 3D characterization of subsurface geology that relates to Cascade Range neotectonics. 

Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas. 

Proposed Duty Station(s)

Portland, Oregon 


Areas of PhD

Geology, tectonics, structural geology, glaciology, volcanology, paleoseismology, geochronology, geochemistry 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). 



Applicants must meet one of the following qualifications: Research Geologist 

(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.)