Abstract
We have developed a diode laser (25 W 808 nm) system for He extraction from minerals for (U-Th)/He chronometry. The laser beam is delivered via a 600 μm fiber cable and focused using a binocular microscope. Temperatures necessary for He release from apatite (500-600°C) and zircon (1100-1300°C) encapsulated in Pt-foil tubes are attained by heating to 0.5 W for 30 s and 1.25-2.5 W for 20 min, respectively, using a defocused beam. Heating at these powers does not result in measurable U and/or Th loss from apatite, as noted by the preservation of the distinct Th/U in multiple splits of two different Durango apatite crystals. Analyses of Durango and the California Institute of Technology internal standard apatite 97MR22 yield (U-Th)/He ages of 32.8 ± 1.8 Ma (1
| Original language | English |
|---|---|
| Article number | Q04015 |
| Journal | Geochemistry, Geophysics, Geosystems |
| Volume | 7 |
| Issue number | 4 |
| Publication status | Published - Apr 2006 |
Keywords
- (U-Th)/He dating
- Apatite
- Helium
- Laser methods
- Low-temperature thermochronology
- Zircon