USGS-GD-Scientific Capabilities - GAS GEOCHEMISTRY Technique




  Quadrapole mass spectrometry provides a rapid and highly accurate means of obtaining a mass spectrum finger print of a gas or gas mixtures derived from virtually any source. The facility consist of three high resolution fully computerized quadrapole mass spectrometers, both a CO2 and a Nd:YAG (IR and Green) laser microbeam system, a fully remote operated laser microbeam sampling system in a cold room for ice core and clathrate gas analysis, GC capillary flow injection and jet separator for gas mixtures and for isotopic analysis of selected elutant gas species, micro- and bulk-furnaces for fluid inclusion decrepitation, and a vacuum crushing devise for extracting gas from samples. Instruments are controlled via a ArcNet fiber optic network at .2.5 MB/sec. Typically 20-100 mg of fluid inclusion (or clay mineral) containing polished plates are selected for gas analysis. Individual fluid inclusions can be targeted for opening and analysis with the laser microbeam equipment. A fully versatile sampling manifold enables instrument calibration with reference gas mixtures and extraction of head-space gases or other sampling procedure. Any gas yielding mass fragments in the range of 1-341 AMU can be identified, with detection limits of . 8x10-15 at 2x background.

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