School of Earth and Environmental Sciences

Argon Geochronology Laboratory

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Image of researcher using the noble gas mass-spectrometer
The Mass Analyser 215-50 noble gas mass-spectrometer room is one of four spaces.

We are world leaders in the determination of geological ages using the argon-argon (40Ar-39Ar) and uranium-thorium/helium (U-Th/He) dating method. Our Argon Geochronology Laboratory is equipped with two mass spectrometers and other suitable equipment for that purpose.

The laboratory supports research projects in the fields of:

  • weathering
  • regolith development
  • paleoclimate reconstruction
  • geochemical models for mineral exploration
  • effects of weathering in the formation and supergene enrichment of ore deposits
  • environmental management.

The facility consists of four main spaces in the Richards Building (Building 5):

  • the sample encapsulation room
  • the radioactive sample manipulation/loading and storage room
  • the Mass Analyser Products 215-50 noble gas mass-spectrometer room
  • the Thermo Fisher Helix SFT mass-spectrometer room.

For more details about specific facilities and instruments, see the table below.

Availability

Honours students, PhD students and post-doctoral researchers can use the Argon Geochronology Laboratory.

We can also perform analyses for external clients.

To discuss your analytical requirements and sample preparation, email the SEES Tech Team.

Custom parts

By combining the resources at our Argon Geochronology Laboratory with those housed in the Faculty of Science Workshops, we also make and sell custom parts for Mass Analyser Products 215-50 noble gas mass-spectrometers that are no longer available from the manufacturer (such as source and MAP emission regulators).

We also make irradiation disks and sample holders for CO2 and diode lasers.

For further information, email the SEES Tech Team.

Facilities and instruments

Equipment in the sample encapsulation roomSample encapsulation room

  • For the careful transfer of powdered samples and fine-grained material (clay minerals) to a glass capillary capsule under vacuum. This allows for better irradiation of the sample prior to dating.

Sample disksThe radioactive sample manipulation and storage room

  • For storage of irradiated samples that have returned from the Oregon State TRIGA Reactor in the US. You can then load irradiated grains individually on to a sample disk behind a lead-liner before transferring them to the sample chamber for analysis.
  • Several geometries for the sample disks are available, depending on the size and number of samples you want to analyse: the most commonly used disks are 145-pit and 221-pit copper disks.

The Mass Analyser Products 215-50 noble gas mass-spectrometer Mass Analyser Products 215-50 noble gas mass-spectrometer (MS) and ultra-high vacuum extraction line

  • The mass spectrometer is an extended geometry 90° sector ESA equipped with a Nier-type source and a dual collector system (a Faraday detector and a Balzers™, 217 electron multiplier).
  • The signal from the electron multiplier is further amplified through a Keithley™, 6512 Electrometer, which increases the dynamic range of signals analysed.
  • The system is fully automated.
  • The ultra-high vacuum extraction line is equipped with two independent heating sources, a Coherent 10W continuous Ar-ion laser and a custom-built, Berkeley-type, resistance furnace.
  • The laser extraction line is further equipped with Newport™, stepper- motors and an MM3000 motion controller, which allows for the pre-programming of step-heating analyses of up to 221 samples. A Sony™, CCD camera continuously monitors the sample chamber.
  • Laser-heating experiments are ideally suited to the analyses of very small or very young samples. The high spatial resolution of this heating technique results in intrinsically low blanks. Laser-heating is also very fast and is ideal for geochronological applications where heating temperatures do not need to be known.
  • If precise temperature measurements are necessary, you can heat the sample in a double-vacuum 600A-5V resistance furnace that is equipped with a molybdenum crucible, a niobium heating element, and a custom-designed automated loading device capable of handling up to 20 samples.
  • The laser, resistance furnace and extraction line gas flow is fully automated through Mass Spec, a Macintosh-based software developed by Al Deino, from the Berkeley Geochronology Center in Berkeley, California.

Thermo Fisher HELIX SFT split flight tube noble gas mass-spectrometerThermo Fisher HELIX SFT split flight tube noble gas mass-spectrometer (MS)

  • Our newest instrument is ideally suited for the analysis of both He and Ar isotopes.
  • It is located in a refurbished room that was purpose built to ensure a clean and continuous supply of electricity, air and water.
  • The HELIX SFT system is an extended geometry 35cm radius 120° magnetic sector analyzer with a flange mounted 'Nier' type ion source and a dual collector system that consists of a Balzers SEV217 ion counting multiplier detector (for the low mass range) and voltage suppressed deep Faraday bucket (for the high mass range). For extreme abundance analysis, a 50mm electrostatic analyser further amplifies the signal from the ion counter.
  • You can achieve ultra-high vacuum pumping by using a rotary pump, an ion pump designed specifically for pumping the noble gases, a turbo molecular pump backed by a two-stage diaphragm pump and getter pump.
  • The system also has a CO2 and diode laser. The CO2 laser emits in the 10,550-10,650nm wavelength and allows for fusion of a wide range of materials. The diode laser emits in the 970nm wavelength with an integrated optical pyrometer for temperature-controlled experiments. Together with a Heine resistance furnace, this set-up allows you to carry out incremental heating (or step-heating) analysis of single or multiple grains from samples with a thermally complex history.