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21-4. Field, laboratory, remote sensing and prospectivity analysis of deeply weathered mineral deposits

 

Closing Date: November 1, 2022

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.

Please communicate with individual Research Advisor(s) on the right to discuss project ideas and answer specific questions about the Research Opportunity.

How to Apply

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Deeply weathered regolith deposits host globally important resources of several critical mineral commodities, including aluminum and gallium in bauxite, nickel and cobalt in laterites, and rare earth elements in ion-absorption clays. Exploration of mineral deposits in deeply weathered (i.e., tropical) environments can be challenging due to limited exposures of bedrock outcrops, extensive vegetation cover, and limited opportunities to obtain cloud-free remote sensing imagery. Also, for some deposit types, the hydrothermal alteration mineralogy of the ore, gangue, and host rock can become indistinguishable from mineral assemblages resulting from chemical weathering processes (e.g., Cox and Singer, 1986). Despite these challenges, natural and anthropogenic changes to the landscape (e.g., slash and burn agriculture, deforestation, post-hurricane landslides, etc.) occur frequently in these areas, and can enhance exposure of weathered host rock, soils, and mineral deposits over time. Although such exposures are often spatially discontinuous, new geospatial methods can facilitate mineral prospectivity modeling (MPM) of lateral variation across such boundaries and gaps when combined with other evidence data layers.

We are therefore seeking a post-doctoral candidate who can address various challenges in using remote sensing data to map mineral deposits in tropical or deeply weathered temperate climates. Focus areas of study could include, but are not limited to: 1) mineral deposits primarily of chemical weathering origin such as bauxites and Ni-Co laterites; 2) rare earth elements (REEs) in residual deposits derived from chemical and physical weathering 3) mineral deposits whose hydrothermal alteration mineralogy has been changed by deep chemical weathering such as porphyry and VMS (massive sulfides) deposits in tropical areas; 4) temporal analysis of the life cycle and land-use patterns associated with mining in tropical areas; 5) strategies for accurate calibration of hyperspectral and/or multispectral imagery with cloud-cover; 6) field-based and laboratory spectral studies of the mineralogy of analogous mineral deposit types in modern and paleo-weathering environments in the United States, with emphasis on distinguishing chemical weathering from hydrothermal alteration; and 7) combining any of the above field, lab and remote sensing data products into prospectivity models and maps showing the distribution of various mineral deposits across permissive tracts and host geologic units.

Ideal candidates should have some experience in working with either hyperspectral or multispectral imagery, though expert processing of such data is not required. More importantly is a background in fundamental geological principles, demonstrated experience using remote sensing and geographic information systems analysis software, and the use of multivariate statistics for geospatial modeling.

Because we will provide additional training in remote sensing and mineral prospectivity mapping methods, we will consider and welcome candidates with other relevant research experiences. For example, experience in working with satellite imagery, high resolution elevation data such as lidar, or airborne geophysical datasets such as gravity, magnetic, radiometric and/or electromagnetic resistivity/conductivity data. Also of interest are applicants working on 1) studies of soil and regolith materials, and especially soil mineralogy and geochemistry using methods such as XRD and XRF; 2) studies of planetary surfaces and remote sensing datasets used to characterize them, and especially utilizing terrestrial analogs and earth-based geologic mapping; 3) studies of land-use/land-cover change applied to soil erosion, environmental degradation and effects of anthropogenic disturbances such as mining, construction and agriculture, including multi-temporal analysis using Landsat and/or Sentinel imagery. Geographic location of proposed study areas is broadly open, but proposals focusing on study areas within the United States and its territories will be more competitive.

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

References:

Cox, D.P. and Singer, D.A., 1986, Mineral Deposit Models: U.S. Geological Survey Bulletin 1693, 379 p.

Proposed Duty Station(s): Reston, Virginia

Areas of PhD: Geology, geography, mineralogy, petrology, geophysics, soil science, geochemistry, geophysics, economic geology, remote sensing, planetary geology, geologic mapping, GIS 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 Geographer, or 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