USGS-GD-Scientific Capabilities - STABLE ISOTOPE OXYGEN 18 Technique




  • Element:
Oxygen delta18O (SMOW - PDB)
  • Material:
    • carbonate minerals
    • organic compounds (organic oxygen)
    • gases (CO2, CO, molecular O2, H2O vapor)
    • oxides and silicates
    • water oxygen
    • trace atmospheric gases- ozone, NOx
    • aerosols- atmospheric SO4
    • sulfate minerals oxygen (anhydrite, gypsum, barite, celestite)
    • soluble sulfates/evaporites in mine drainage
    • aqueous nitrate oxygen
    • phosphate oxygen (phosphate minerals, teeth, bones, etc.)
  • Form:
extract and process to carbon dioxide, analyze as CO2 on mass spectrometer (molecular O2 into mass spectrometer to analyze 17O directly)
  • Precision:
Typically ± 0.04 to 0.1 per mil
  • Applications:
Temperature, kinetics, sources and tracers, reaction pathways
  • Instruments:
Finnigan 252, Finnigan 251, VG Optima
  • Speciality Peripherals:
Kiel devise, Multiprep, extraction lines, CO2 and Nd:YAG laser microbeam sampling, auto trapping/gas separation, fluorination line using F2 and BrF5 reagents to liberate oxygen
  • Automation:
Yes - Kiel (46/day), Trapping box cleaning (24/day), Multiprep (60/day)
  • Sample Size:
    • minimum: 1 nanomole as CO2 extracted from sample
    • typical: 20-60 micromole as CO2


 | Capabilities |
| Geochronology, Geochemistry, and Tracer Studies  |
| Geochemistry, and Tracer Studies  |