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S45. Applying radiogenic isotope geochemistry to enhance geologic framework models

By Mendenhall Research Fellowship Program

 

Closing Date: November 15, 2019

This Research Opportunity will be filled depending on the availability of funds. All application materials must be submitted through USAJobs by 11:59 pm, US Eastern Standard Time, on the closing date.

CLOSED

The National Cooperative Geologic Mapping Program (NCGMP) of the USGS has the primary goal of producing detailed geologic framework models for the Nation.  This mandate includes creation of appropriate geologic maps and other datasets needed to address national issues of land-use management, natural resources assessment/utilization/conservation, groundwater management, hazard assessment, and environmental protection using an unbiased, science-informed approach.  Reliable geologic framework models require characterization of the map units involved as well as an understanding of their petrogenic origins and evolution through time. This requires collection and integration of data that better define the spatial and temporal distributions of sedimentary, igneous, and metamorphic lithologies and the processes that created the surface and subsurface geology of the Nation.  Geochronology and isotope geochemistry provide invaluable information for geologic framework development by placing absolute ages on mappable rock and sediment units, tracing fluid flow paths, and identifying processes of tectonics, volcanism, paleoenvironmental change, and economically-important mineralization, among others.

To further the goals of NCGMP, we seek an individual to conduct research focused on the development and application of radiogenic-isotope geochemistry by thermal-ionization mass spectrometry (TIMS) to a broad range of geologic problems and project goals.  Specifically, we seek research proposals focused on the collection and application of TIMS data for radiogenic isotope geochronology (e.g. U-Pb or U-Th disequilibrium), development of laboratory methods using existing instrumentation (Triton™ and Phoenix™ multi-collectors with ion-counting capabilities), and use of tracer geochemistry (e.g. Pb, Sm, Nd, Sr, U or other radiogenic isotope systems) for petrogenetic studies.  Candidates who can demonstrate an intimate knowledge of laboratory operations will be favored.  The successful candidate will be expected to collaborate with USGS geoscientists that encompass a wide spectrum of geological expertise.

Interested applicants are encouraged to contact USGS research advisors early in the application process to develop proposals compatible with existing project goals and laboratory facilities. The Geosciences and Environmental Change Science Center (GECSC)1, located in Lakewood (Denver), Colorado, maintains an NCGMP-funded TIMS radiogenic isotope laboratory with state-of-the-art clean lab facilities and instrumentation2 intended for use by a successful applicant(s).  The lab is collocated with other USGS isotope facilities including 40Ar/39Ar, noble gas, stable isotope, and LA-MC-ICPMS laboratories3.  The collaborative use of those facilities in combination with GECSC TIMS capabilities is possible and encouraged.  Potential research topics include, but are not limited to, the following areas:

  • Understanding paleo-climate, -hydrologic, and/or tectonic drivers of landscape evolution in the Intermountain West region.  Utilizing radiogenic isotope geochronology/geochemistry to produce records of coupled paleoenvironmental and geomorphic change.
  • Geochronology and isotope evolution of magmatic provinces in the western U.S. to better elucidate the timing and origins of caldera and volcanic-field evolution.
  • Development of U-Pb dating methods applied to older carbonate materials in both marine and freshwater records.
  • Application of radiogenic isotopes to rock and mineral records that allow tracing of fluid migration and evolution within the crust, including magmas, metamorphic fluids, and hydrogenic solutions.
  • Development of U-Pb geochronologic methods on authigenic components such as mineral overgrowths that would allow assessment of post-depositional diagenetic or metamorphic events.

References:

1  https://www.usgs.gov/centers/gecsc/science

2  https://www.usgs.gov/centers/gecsc/science/denver-radiogenic-isotope-lab?qt-science_center_objects=0#qt-science_center_objects

3  https://www.usgs.gov/centers/gggsc/science/isotope-and-aqueous-geochemistry

Proposed Duty Station: Lakewood, Colorado

Areas of PhD: Isotope geology, geochemistry, petrology, mass spectrometry (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 Chemist

(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