NERC Argon Isotope Facility

NERC Argon Isotope Facility

Infrastructure and Service

The NERC AIF is hosted by the Scottish Universities Environmental Research Centre (SUERC), which with the NERC Radiocarbon Laboratory, ICSF, CIAF and the Accelerator Mass Spectrometer (Recognised Facility) form a unique cluster of analytical facilities for Earth and environmental sciences.

A defining feature of the cluster is its position as a dating centre of excellence, with radiometric, geochemical (bomb-test, Sellafield, Chernobyl fallout; stable lead isotopes etc), and physical (luminescence) dating methods useful on timescales ranging from several years to billions of years. 

The Scottish Universities noble gas isotope laboratory is adjacent to the AIF laboratory. It houses similar analytical equipment (MAP 215-50) and similar gas extraction and clean-up systems, as well as a quadrupole mass spectrometer-based system for (U-Th)/He dating. This creates a suitable intellectual ambience for the AIF and its visitors, but also opportunities for cross-calibration of dating techniques that are unrivalled.

At least 68% of the analytical capacity of the 40Ar/39Ar geochronology laboratory at SUERC is available to approved users of the AIF. In practice this has exceeded 85% over the past 5 years.

Analytical Infrastructure

  • 3 low-blank rare gas mass spectrometers for argon isotopic analysis (MAP215-50, upgraded with adjustable slit and electrostatic analyser, ARGUS-5 multi-collector mass spectrometer, Thermo Scientific HELIX-SFT).
  • Each mass spectrometer is attached to a low volume, all-metal gas clean-up system.
  • Low-blank resistance furnaces and mid-infrared (10.6 µm 25W CO2, run either CW or pulsed) lasers are integrated to all clean-up systems.
  • 1 ultra-violet (213 nm) laser for high spatial-resolution gas extraction.
  • 1 near-infrared (808 nm) fibre diode laser and integral thermocouple system for high-temperature-precision step-heating of encapsulated minerals.
  • Specialist sample and mineral separation facilities. This includes crushing, acid leaching, magnetic separation, overflow-centrifuge heavy liquid, and geochemical analytical equipment (such as binocular and petrographic microscopes, and SEM).
  • Dedicated radioactive handling and storage area.

Analytical Capabilities

Judicious use of the analytical systems allows the AIF to offer a comprehensive range of 40Ar/39Ar geochronological techniques designed to meet all current and anticipated needs:

  • Laser single-crystal fusion: For instance, for volcanic minerals where xenocryst contamination may be a problem (Harford  et al. 2002) or sediment provenance studies where a range of detrital mineral ages are expected  (Najman et al. 2003).
  • Laser or resistance furnace step-heating: For instance for screening for potential age heterogeneity resulting from alteration or deformation in igneous and metamorphic minerals (Koppers et al. 2003).
  • In situ UV laser probe dating: For instance, for dating authigenic feldspar overgrowths on detrital minerals to determine the timing of fluid flow (Mark et al. 2008).
  • Resistance furnace or laser step-heating of large samples:   Ideal for volcanic rocks with ages as young as Pleistocene (Sparks et al. 2008).
  • Conventional K-Ar analysis. Faster and cheaper than 40Ar/39Ar and more accurate for glasses and clay minerals (Rice et al. 2005).