Closing Date: November 1, 2023
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.
Description of the Research Opportunity
Topaz-bearing rhyolites, such as those associated with volcanogenic Be deposits, are of resource significance for a wide range of additional rare-metal commodities in a variety of deposit types. Their established economic importance includes (1) volcanogenic deposits of Be, U, Sn, and fluorite, (2) fluorite- and silver-rich base metal ores, and (3) topaz-rich porphyry molybdenum ± tungsten deposits of the Climax and Henderson type. Fluorine-rich rhyolites that host volcanogenic Be deposits can also be associated with elevated and potentially economic concentrations of thorium, niobium, and rare earth elements (REEs). Deposit types found in close spatial association with the world-class Be-(U-F-REE-Li) volcanogenic deposits near Spor Mountain, Juab County, Utah, include (1) widely disseminated breccia pipe fluorite deposits, (2) classic volcanogenic uranium deposits/occurrences, and (3) pegmatitic and fumarolic beryl deposits. The Spor Mountain Be-(U-F-REE-Li) deposit provides a keystone because of recently determined geochronology and exploration strategies research that can be used for further mineral exploration in the region.
The world-class Spor Mountain Be deposit occurs in an area of extensive alkalic rhyolitic ash flow tuffs and Oligocene and Eocene calderas underlain by Paleozoic and older limestone, dolomite, shale, and quartzite. Spor Mountain is part of the Deep Creek-Tintic mineral belt. In addition to beryllium and fluorite at Spor Mountain, the belt contains other beryllium occurrences as well as deposits or occurrences of copper, base metals, gold, lithium, and uranium. These are distributed between the Deep Creek Mountains on the west and the East Tintic Mountains to the east. Older geophysical studies identified pronounced aeromagnetic anomalies, in part reflecting igneous stocks and thick accumulations of volcanic rocks in calderas, accompanying the mineral belt. The apparent geological uniqueness of the Spor Mountain deposit has been a source of controversy due, in part, to the lack of a modern comprehensive geologic framework and ore genesis models for the region. Recent USGS studies of the deposit and host volcanics of the Spor Mountain Formation (SMF) have established a more comprehensive geologic framework and ore genesis model for the deposit based on U/Pb zircon crystallization ages and the metallogeny of the upper topaz rhyolite and underlying stratified tuff that make up the SMF. Ongoing studies are addressing fundamental questions regarding ages and chemical evolution of the regionally extensive package of volcanic rocks that includes the SMF, and their regional metallogenic evolution. These studies have significantly advanced our understanding of the age, chemistry, and metallogeny of the regional volcanic rock sequence that includes the SMF.
We seek a Mendenhall Postdoctoral Fellow to further advance our understanding of crustal evolution and the regional economic potential for additional minerals on the U.S. Critical Minerals List that occur in greater West-Central Utah, with a focus on the Deep Creek-Tintic belt. The temporal, structural, and evolutionary relationships shared by the world-class Be deposit at Spor Mountain and other regionally distributed deposits and occurrences remain enigmatic. The region has economic mineral potential for Be from beryl, F from fluorite, Li from clays, and REEs from secondary sources or waste. Mines, prospects, and occurrences having these other critical minerals include: (1) Deposits of uraniferous fluorite in breccia pipes, veins, and disseminations along the east side of Spor Mountain, throughout the Thomas Range, and regionally in the Fish Springs Range, Honeycomb Hills, and the Dugway Range. (2) Lithium mineralization hosted in clay or claystone volcanic tuff units identified recently in Fish Springs Flats, an area between Spor Mountain and the Fish Springs Range. (3) Fluorine and U-mineralized volcanic rocks of the Topaz Mountain Formation located east of U deposits previously mined in The Dell area in stratified bentonite overlying circa 33 Ma (new, as-yet unpublished age) tuffaceous sandstone previously linked with the SMF. (4) Prospects and occurrences distributed throughout the region that have been identified as favorable for by-product REEs. (5) Pegmatitic beryl mined from deposits in the Wah-Wah Mountains and prospects occurring at Sheeprock Mountain. (6) Iron deposits and prospects having associated alunite, F, and Th-U minerals; for example, those associated with rhyolite domes and faults in underlying Neoproterozoic strata in southern Millard and Beaver counties.
Potential topics to address include, but are not limited to, the timing of regional fluid flow, dynamics of mineral precipitation, and the interplay among magmatic-hydrothermal-meteoric-water processes. Proposals combining field and laboratory studies done in conjunction with Earth Mapping Resources Initiative (Earth MRI) geophysical surveys are especially welcome. The Fellow’s project emphasis may cover various aspects of the full scope of a particular study. For example, a proposal could include a significant component of the Earth MRI geophysical surveys that are underway and in planning for the greater region. This affords a remarkable opportunity to evaluate ground-based economic geological studies to better understand the regional critical mineral potential in the context of newly available high-resolution geophysics. Alternatively, a fellow may propose a focus on the application of novel techniques for age determinations of formerly undatable minerals by adaptation of existing techniques and work with collaborators to provide valuable geochronological and isotopic information on Be-U-F-Li-REE mineralizing systems where other datable minerals are not readily available.
The Geology, Energy & Minerals Science Center (GEMSC) is equipped with an extensive inventory of laboratory facilities that are available for the Research Opportunity. For example, instrumentation and laboratories that make up the Radiogenic Isotope Laboratory include a Spectromat™ TIMS, Metrohm Ion Chromatograph, Thermo Element2 HR-ICPMS, ESL 193 Excimer Laser Ablation system, and an ESL MicroMill2 mineral sampling device for direct analysis of high-resolution milling of a sample. Sample preparation equipment is available for physical and chemical separations and dissolutions and ion chromatography. There are Ultra-clean labs (Class 100 and class 1000) for low-level studies and ancillary lab space for handling high-metal materials. The Fellow will also have access to other National Center labs including the Reston Electron Microbeam Laboratory (Hitachi SU 5000 FE-SEM with SE, BSE, and CL, and the JEOL 8900 EMPA), powder x-ray diffraction (XRD), clay mineral laboratories, and microscopy equipment (Nikon ECLIPSE E600W POL microscope with NIS-Elements D computer system). Utilization of Utah Earth MRI geophysical data will be coordinated through the Research Advisor (RA) in charge at the USGS Geology, Minerals, Energy, and Geophysics Science Center (GMEG SC), Western United States. Other USGS and external laboratory facilities (for example, USGS-Stanford SHRIMP, Synchrotron X-ray microscopy and spectroscopy, etc.) can be made available to meet the needs of a particular Fellowship.
Interested applicants are strongly encouraged to contact the Research Advisors early in the application process to discuss project ideas.
References: A summary of literature used in the preparation of the Research Opportunity is available upon request from the RAs.
Proposed Duty Station(s)
Reston, Virginia
Areas of PhD
Geology, geochemistry, 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, Research Physical Scientist, 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.)
