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Garrett S. Vice James Faulds Mark Coolbaugh Bill Ehni

Structural Controls of a Blind Geothermal System in the Northern Pyramid Lake area, Northwestern Nevada. Garrett S. Vice James Faulds Mark Coolbaugh Bill Ehni. Overview. Purpose of Study Regional Geology Geothermal Stratigraphy Structure Drilling Results. Location. Reno.

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Garrett S. Vice James Faulds Mark Coolbaugh Bill Ehni

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  1. Structural Controls of a Blind Geothermal System in the Northern Pyramid Lake area, Northwestern Nevada Garrett S. Vice James Faulds Mark Coolbaugh Bill Ehni

  2. Overview • Purpose of Study • Regional Geology • Geothermal • Stratigraphy • Structure • Drilling • Results

  3. Location Reno

  4. Location Continued

  5. Purpose of Study • Understand how structure controls blind geothermal systems • Evaluate geothermal resource for the Pyramid Lake Paiute Tribe • Elucidate the structural history of the Terraced Hills in context of Walker Lane

  6. What is a Blind Geothermal System? • No Usual Surface Expressions • Hot Springs • Geysers • Example of developed blind systems – Desert Peak, Nevada; Newcastle, Utah • Blind systems probably bulk of resource in this arid region

  7. Regional Geology Stratigraphy Mesozoic - Tertiary • Basement • Volcanics • Lacustrine Structure Northern Walker Lane

  8. Walker Lane • Northern Walker Lane • Mohawk Valley • Honey Lake • Warm Springs Valley • Pyramid Lake • Total offset NWL = 30-40 km

  9. Pyramid Lake Fault • Dextral strike-slip • Offset 5-10km • Quaternary scarps • ~2.6mm/yr • Termination?

  10. Geothermal Exploration • Pyramid Lake • Intersection of Black Rock & Walker Lane belts • Culturally sensitive areas • Needle Rocks – 117°C • Pyramid Rock - 97°C

  11. Methods • Geologic Mapping • Structural Analysis • Shallow Temperature Survey • Geophysical Analyses • Drilling • Trenching • Remote Sensing

  12. Stratigraphy • Pyramid Sequence • Miocene ~16 - 13 Ma • Basaltic Andesite • Dacite • Tuff of Mullen Pass – 13.8 Ma • Rhyolite Plugs – 15.3 Ma • Lake Lahontan Deposits • Shorelines • Tehpra – Wono ~ 27- 37 Ka Shorelines WonoAsh

  13. Structure • Looking for fault: • Intersections • Overlaps • Terminations • Steps • Two Domains • Northeast • Northwest

  14. Northeast Domain Fault Trace • Fault Scarp • Trench • Bathymetry • Seismic Data Fault Seismic Line

  15. Offset Rhyolite Northwest Domain • Linear tufa towers • Offset rhyolite dome • Kinematic data

  16. Northwest Domain Fault Zone

  17. N Drilling • Drilled dilational quadrant • ~ 550 m (1800 ft) • Temperatures ~ 90° C Drill Site Drill Site

  18. Results ‘ Tufa Tower 87°C 94°C 79°C A’ 550 m 90°C A 82°C 93°C 104°C 116°C

  19. Conclusions • Terraced Hills – low discontinuous hills • Multiple intersecting faults • Region of strain transfer = enhanced dilation • Can use structure to help predict blind geothermal • systems in regions of known activity • Region records the termination of the Pyramid Lake Fault • Displacement split between normal and strike-slip faults

  20. Continued Research • Paleomagnetic Investigation • Trenching • New Drilling • Dating • Paleontology Bone

  21. Acknowledgements • Pyramid Lake Paiute Tribe • Great Basin Center for Geothermal Energy • Department of Energy • Nevada Petroleum Society • Shane Thompson, Laura Hubner, Joanna Redwine, Danny Lazzereschi, John Bell, Rick Zehner, Jill Pocock, Lisa Shevenell, and Gary Oppliger.

  22. Questions?

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