Upcoming Presentations

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• Sunstones: The Good, The Bad, & The Ugly (in other words, the complex petrogenesis of our state gemstone)

  • When
    24 Oct 2023
  •  
    5:30 PM
  • Location
    Online and in-person at Bridge 99 Brewery

  Emily Cahoon
  

  Oregon State University
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  5:30 pm social hour

  6:00 pm student poster session
  

  7:00 pm presentation

  
  

  Sunstones are copper-bearing and gem-quality plagioclase crystals found within basaltic lavas in eastern Oregon. Native copper is visible as macroscopic platelets within the crystals and evidence suggests it partitioned magmatically into the crystal structure during growth. Lava flows containing sunstones are situated within the spatial footprint of the Columbia River Basalt Group (CRBG), the worlds youngest continental flood basalt. This has led to the assumption that sunstones are petrogenetically linked to the CRBG, as nearby CRBG lavas often contain coarse plagioclase phenocrysts. This connection however is unconfirmed, and ages for sunstones and hosting basaltic groundmass indicate they were emplaced during two temporally discrete eruptive events. In this talk, we explore the eruptive timing, spatial distribution, and geochemical homogeneity of these copper-bearing plagioclase crystals -- giving insights on the magmatic plumbing systems and melt segregation processes within flood basalt provinces. Dr. Emily Cahoon will also highlight aspects of these ethically sourced gemstones and the copper inclusions that make them unique.

  
  

  Oregon State University student poster session at 6:00 pm:

  Join us before the talk for a student poster session from three OSU students working with Dr. Emily Cahoon on various aspects of sunstone research. Each of these students was a recipient of a 2023 COGS student research grant.
  

  Kyle Nunley: Argon geochronology on basalt and hosted sunstones in eastern Oregon

  Scott Toney: Sunstones: A gemstone formed by a magmatic or hydrothermal process?

  Cheyenne Yost: Copper and lithium diffusion analysis of eastern Oregon sunstones

  
  

    

  
    

  
  

  Please join us at Bridge 99 Brewery:

  63063 Layton Avenue, Bend

  5:30 pm social hour

  6:00 pm student poster session
  

  7:00 pm presentation

  COGS talk are free and open to the public -- all are welcome! Please join us for the social hour before the presentation.
  
  All presentations are also live-streamed through Zoom. There will be a registration link at the top of this page as we get closer to the date of this presentation.

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• Hydrology of High-Desert Springs in Eastern Oregon

  • When
    28 Nov 2023
  •  
    5:30 PM
  • Location
    Online and in-person at Bridge 99 Brewery

  Hank Johnson
  

  U.S. Geological Survey
  

  
  

  
  

  
  

  
  

  
  

  5:30 pm social hour

  7:00 pm presentation

  
  

  Throughout eastern Oregon, small springs often are the sole source of water for wildlife and livestock for many miles, yet their hydrology is poorly understood. Most springs are known only as points on decades-old maps or unattributed features in geospatial data sets. Predicting their continuing viability as water resources during the on-going and future droughts poses a challenge to land management agencies. This talk focuses on the work done since 2015 to better understand the distribution and behavior of springs across eastern Oregon, and to predict their hydrologic response to changing precipitation by combining repeat field observations, water chemistry, and Landsat imagery.

  
  

  Please join us at Bridge 99 Brewery:

  63063 Layton Avenue, Bend

  5:30 pm social hour

  7:00 pm presentation

  COGS talk are free and open to the public -- all are welcome! Please join us for the social hour before the presentation.
  
  All presentations are also live-streamed through Zoom. There will be a registration link at the top of this page as we get closer to the date of this presentation.

  Show details