30. Linking Cenozoic Uplift and Basin Development to the Formation of Mineral, Energy, and Water Resources in the Northern Great Basin

The Basin and Range province offers exceptional need and opportunities for quantitative tectonic analysis to advance the understanding of the Nation's mineral, energy, and water resources. As the Nation's premier mining region, the northern Great Basin contains world-class gold, silver, base-metal, and diatomite deposits, as well as petroleum, geothermal, and water resources. Cenozoic magmatic, tectonic, thermal, and sedimentary activity formed or defined many of these resources, overprinting earlier events. In addition, parts of the region are seismically active, such that determining long-term strain rates from uplift histories, would augment GPS-based research on present-day strain rates, and will improve the understanding of seismic hazards and recurrence intervals of tectonic movements.

Current understanding of the geologic framework in which these natural resources occur is challenged by uncertainties in the history and processes of uplift and denudation of the structural mountain ranges and the development of associated sedimentary basins. These ranges and basins resulted from late Cenozoic extensional faulting superposed on earlier Cenozoic extensional structures and multiple generations of Paleozoic and Mesozoic contractional tectonics. Comprehensive understanding of the Cenozoic tectonic history is needed to unravel the structural geometry and to understand linkages between extensional tectonic processes, sedimentation, and magmatism, mineralization, geothermal and hydrothermal systems, and structural disruption of mineral deposits from their roots.

We seek a postdoctoral researcher to study fundamental aspects of uplift and basin timing and formation processes in the northern Great Basin. Anticipated results will have important application to diverse USGS projects and programs. Research will focus on select geographic areas that would best provide important information for multiple purposes. The USGS Great Basin Metallogeny project utilizes multidisciplinary research to develop 3-dimensional reconstructions at key time intervals, including the metallogenically important middle Miocene and late Eocene, in order to better understand the genesis and modifications of the major ore deposits. These time-specific reconstructions will be combined to produce a 4-dimensional model for the evolution of the northern Great Basin and its associated mineral deposits, including quantitative modeling of regional-scale fluid flow. Syn-metallogenic uplift of the ranges and development of the basins would have affected structural patterns and regional fluid flow. Subsequent uplift and landscape changes likely modified the metalliferous deposits, including burying them or exposing and weathering them with release of metals into the environment. Thus, an important ingredient needed for both the 3- and 4-dimensional time-space reconstructions and for fluid-flow modeling is a quantitative understanding of the timing of basin development and uplift of ranges.

Ongoing USGS and industry studies of world-class Miocene diatomite deposits show that they formed in sedimentary basins in response to regional time-space variations in tectonic activity, climate, and nutrient inflow. Understanding of the timing and amount of uplift and the effects on basin formation are critical to producing a regional model for the formation of the diatomite deposits. Current USGS studies indicate that some basin-bounding ranges record a late Eocene uplift, whereas others initially formed in the Miocene. Distinguishing between the two uplift events would provide information needed to understand evolving sedimentation patterns and nutrient inflow. Complex sedimentary basins serve as the primary groundwater reservoirs for domestic and agricultural water resources in the northern Great Basin, and for geothermal resources. Ongoing cooperative research within the USGS and with the proposed Great Basin Geothermal project require quantitative knowledge of the histories of basin formation, uplift-related faulting, and the resulting structural-lithologic characteristics of the aquifers in order to adequately evaluate the quantity and quality of groundwater resources. These basins also serve both as source and reservoir rocks for many of Nevada's petroleum reserves. Defining the structural and thermal histories of these basins and their effects on hydrocarbon deposition, maturation, and migration would contribute directly to the USGS national petroleum resource assessments.

The successful postdoctoral research applicant will integrate field geology skills with U-Th/He, cosmogenic, and fission-track or other dating methods to develop models of Cenozoic uplift and basin development for key study areas. The researcher will integrate these models into ongoing USGS structural reconstructions of middle Miocene and late Eocene time. The incumbent is expected to have a strong background in field geology and extensional tectonics and be able to combine a variety of research techniques to develop quantitative models for uplift history and processes.

Potential additional USGS collaborators for this opportunity are: Gary Landis, Constance Nutt, and Al Hofstra.

Proposed Duty Station: Menlo Park, CA or Reno, NV

Areas of Ph.D.: Geology, geophysics, geochemistry, with a strong background in structural geology, tectonics, and geochronology (fission-track, (U-Th)/He, Ar-Ar)

Qualifications: Applicants must meet one of the following qualifications: Research Geologist, Research Geophysicist, 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 Personnel specialist.)

Research Advisor(s): David John, (650) 329-5424, djohn@usgs.gov; Keith Howard, (650) 329-4923, khoward@usgs.gov; Alan Wallace (775) 784-5789, alan@usgs.gov; Tom Moore, (650) 329-5713, tmoore@usgs.gov

Personnel Office contact: Marie Guillory, (650) 329-4112, guillory@usgs.gov

Summary of Opportunities