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Regional Geology and Mineral Exploration

Topics of Research:

New Sensor Characterization
Field Based and Airborne Data Integration
Regional Structural Analysis

New Sensor Characterization (SEBASS, HyperSPECTIR)

New Sensor Characterization
Collaborators: Jim Taranik and Wendy Calvin, UNR, Mark Landers, CEO SpecTIR, Tom Cudahy, CSIRO, John Hackwell, Aerospace Corp.

Summary of Research: As part of our on-going commitment to development of new technologies we regularly collaborate on validation and analysis of new sensor systems. Two systems we have recently worked with are the SEBASS hyperspectral thermal instrument, developed by Aerospace Corporation and the HyperSpecTIR, AVIRIS class instrument developed by SpecTIR Corp of Santa Barbara. These studies involve field measurements at the time of overflight, analysis of sensor quality and mineral mapping abilities. We typically confirm remote identifications with subsequent laboratory and field analyses using spectral field instruments from Analytical Spectral Devices (0.4 to 2.5 um) and from Designs and Prototypes (7 to 15 um).

Field based and airborne data integration

Extensional and Strike-Slip Faulting Interactions In the Northern Sierran – Great Basin Transition Zone Inferred from New Integrated Gravity Data
Collaborators: Oppliger, Gary L., Geological Sciences, Univ of Nevada Reno, Mackay School of Mines, Widmer, Michael, Water Resources, Washoe County, Faulds, James E., and Henry, Christopher D., (both of Nevada Bureau of Mines and Geology, University of Nevada, Reno).

Summary of Research: Basin geometries visualized from recently integrated gravity data suggest interactions between extensional and strike-slip fault systems in the northwestern Great Basin. These interacting fault systems may have accommodated late Cenozoic westerly to northwesterly relative displacement of the Sierran Block. More than 1100 new stations near Reno, over 1000 previously unincorporated stations from published surveys, and 3900 stations from the National Geodetic Survey's gravity database were combined to form a new compilation that elucidates structural features in the transition zone between Carson Valley and Honey Lake. Gravity defined basin geometries in the transition zone show a discontinuous but well defined series of north-trending, 500 to 1500 meter deep grabens. This zone consists of several subparallel basins over a width of 20 to 40 km in the Great Basin and a prominent end-member - the Lake Tahoe basin - within the Sierran block. The north-trending pattern of basins terminates abruptly northward against the inferred trace of the Walker Lane zone between Pyramid and Honey Lakes signifying a possible kinematic relation between northwest-striking dextral faults in the Walker Lane and the northerly striking normal faults. The relatively deep Honey Lake basin appears to have developed between two northwest-striking strands of the Walker Lane, with faults on the southwest and northeast basin margins accommodating a significant component of normal offset. Ongoing studies are integrating these observations with geologic field relations. (For more information on this research, see Dr. Oppliger's research page.)

Structural and Lithologic Constraints to Metalogenesis In the Bodie Hills, Nevada and California, Interpreted with Geophysical and Geostatistical Methods
Collaborators: Smailbegovic, Amer, Arthur Brant Laboratory for Exploration Geophysics, Universitiy of Nevada, Reno, Oppliger, Gary, Arthur Brant Laboratory for Exploration Geophysics, Universitiy of Nevada, Reno, Mihalasky, Mark, Richard Stockton College of New Jersey, Taranik, James. V., Geological Sciences, Mackay School of Mines, University of Nevada, Reno.

Summary of Research: Using a multifaceted geophysical and geostatistical approach to investigate the geology and metalogenesis is a novel approach towards understanding factors influencing regional- and local-scale metalogenesis. The Aurora and Bodie mining districts are located in the Miocene volcanics of the Bodie Hills, north of Mono Lake, on the opposite sides of the Nevada-California state line. From the standpoint of economic geology, both deposits are structurally controlled, low-sulfidation, quartz-adularia-sericite precious metal vein deposits with an extensive alteration halo. Using detailed field mapping and a combined array of geophysical data in conjunction with traditional field mapping and GIS-based Weights of Evidence (WofE) modeling was utilized to attain better understanding of the districts in the local and regional framework. The gravity data suggests a NE-trending, positive anomaly, resulting from a density contrast between the presumably uplifted pre-Tertiary basement and Miocene volcanic assemblage in the Bodie Hills. The aeromagnetic data are dominated by the strong signature of the Miocene volcanism (vents, flows, etc.) and suggests that the volcanic activity is concentrated along the northeasterly corridor of basement uplift. Multispectral, spaceborne imagery (Landsat ETM, ASTER) shows the regional structural setting, which is dominated by NNE and NE-trending lineaments and major alteration trends in the Bodie Hills. Individual segments of the regional-to-local geophysical survey are field checked and spatially integrated using WofE. The interpretation and WofE modeling of the geophysical data and detailed geologic field mapping reveal a close relationship between the basement uplift (source for metals), NE-trending structures (conduits), volcanic activity (energy), hydrothermal activity (genesis) and mineralization in Aurora and Bodie. This study confirms that the deposits in the Bodie Hills represent low-sulfidation systems hosted in a strike-slip influenced vein systems, which may be genetically associated with the initial phase of Miocene extension and stress accommodation in Western Great Basin during 15 – 8 Ma. (For more information on this research, see Dr. Oppliger's research page.)

Regional Structural Analysis

Targeting of potential geothermal resources in the Great Basin from regional relationships between geodetic strain and geological structures
Collaborators: Geoff Blewitt and Mark F. Coolbaugh: funded by DOE.

Summary of Research: The ability of GPS-based measurements of geodetic strain to identify zones of crustal extension, and the role those zones of extension play in controlling geothermal activity, is being investigated. The Quaternary structural fabric of Nevada is being used to help constrain the mode and location of strain.