Thermal Ionization Mass Spectrometry Facility

The Thermal Ionisation Mass Spectrometry (TIMS) Facility provides highly accurate and precise measurements of the isotopic composition of elements using a Thermo Scientific Triton™ TIMS instrument. The TIMS Facility includes two clean laboratories for sample preparation in clean, contamination-free environments. The history of TIMS-based research at Curtin can be traced back to the 1960s, when the isotope study group carried out atomic weight measurements, extraterrestrial and Rb-Sr chronological studies. The TIMS Facility at Curtin University has contributed to accurately measuring the concentrations of various elements in international reference materials. The currently accepted atomic weights of Cd, Te and Sn are based on measurements made at Curtin.

We specialise in the generation of high-precision geochronology and isotope data for application to a wide range of isotope geochemistry and geochronology, geological and environmental research applications.

Techniques/Capabilities

Although the Curtin TIMS and clean facilities can be applied to isotopic analysis of most heavy elements on the periodic table, the current focus is on:

• Re-Os isotope determination: for model ages of molybdenite, isochron geochronology of sulphides, hydrocarbons, or black shales, for igneous source tracer studies, and isotope fingerprinting for the minerals and energy sector.
• Sm-Nd isotope determination: isochron geochronology and for igneous source tracer studies.
• Pb-Pb isotope determination: model ages of galena/sulphides, K-feldspar and native gold, isochron geochronology of whole rock and mineral separates, and for source tracer studies. Note that source tracer studies are often integrated with SHRIMP U-Pb age and Laser-ICPMS geochemical fingerprints, also analysed at Curtin.

Infrastructure – Instrumentation

Thermo Scientific Triton™ TIMS

Our ThermoFisher Triton™ TIMS instrument, installed in 2010, features a multi-collector system consisting of nine 10¹¹ Ohm resistance Faraday cups. The multi-collector array consists of eight computer controlled movable Faraday collectors arranged as four high mass and four low mass Faraday collectors with one fixed channel Faraday cup. The motor driven detector array ensures flexibility and versatility for measurements of many different isotopic systems. In addition to the Faraday collectors, our instruments ion counting systems include: a secondary electron multiplier (SEM), Retarding Potential Quadrupole Lenses (RPQ) for improved abundance sensitivity, and an additional multiple ion counting setup. The TIMS represents the gold standard for isotopic analysis, reaching a precision of 0.001% on isotopic ratios.

The Triton™ TIMS instrument is housed in a newly remodelled, High Efficiency Particulate Air (HEPA) filtered, positively pressured laboratory thereby minimising the interference of ultra-trace samples from contaminated outside air. Within the TIMS laboratory, there is a vacuum outgassing unit and a non-exhaust horizontal laminar flow hood for loading samples. For welding filaments, the laboratory has two dedicated benchtops in separate locations and welding stations to keep the Os material (Pt filaments) set apart from the other isotope system analytical material (e.g. Re and Ni filaments).

Infrastructure – Clean Laboratories

Acid Digest Laboratory

Sample preparation and chemical separation of elements is carried out in a purpose-build Acid Digest Laboratory with clean air environment designed for low-blank processing of geological samples for isotopic measurements. The Acid Digest Laboratory is a positively pressurized clean room equipped with ULPA-Filtered air to reduce particle levels, an ANALAB hotplate with no exposed metal, a ducted ULPA-filtered fume cupboard (class 10/ISO 4 vertical laminar flow workspace) and deionized distilled ultra-pure water.

Trace Research Advanced Clean Environment Facility (TRACE)

For ultra-trace sample material, the TRACE Facility is a 434 m², pressurised, class 100 (ISO 5) clean air space housing five class 10 (ISO 4) ultra-trace laboratory modules, of which the TIMS Facility clean laboratory is located in Module 2. The extremely low ultimate particle counts are achieved with successive ‘spaces within spaces’ and HEPA filtration at each stage.

The class 10 (ISO4) Module 2 laboratory within the TRACE Facility contains a ducted ULPA-filtered fume cupboard (class 10/ISO 4 vertical laminar flow workspace) equipped with a scrubber for hydrofluoric acid use, an ANALAB hotplate with no exposed metal, and a laminar flow workbench within the centre of the module for an extremely low particle count workbench for the handling of sample solutions and chromatography.

Most acids used within both the Acid Digest Laboratory and the TRACE Module 2 Laboratory are distilled in-house within the TRACE Module 2 Laboratory via two sets of Savillex DST-1000 acid purification systems (a dedicated set each to double distil HCl and HNO₃) and sub-boiling Teflon elbow stills (CCl₄ and HBr).

Applications

The TIMS Facility specialises in the implementation of the isotope dilution method. Pairing the TIMS instrumentation with the isotope dilution methodology can determine elemental concentrations to an ultra-trace level (i.e. sub pg g^-1). This technique is considered the ‘definitive’ method of analysis for producing the highest achievable accuracy and precision of isotopic ratio information being widely used for the calibration of isotopic standards, the calculation of isotopic abundances and atomic weights.

The present applications utilised within the TIMS Facility are mainly in the broad field of geochronology and isotopic tracing studies involving Re-Os, Pb-Pb and Sm-Nd isotope systems as well as in isotope fingerprinting (Pb and Nd isotope systems and Highly Siderophile Elements determined via isotope dilution) in the study of ore- and petroleum formation processes.

Exploration for Potential of Economic Deposits

• Fundamental and applied studies to better understand the genesis, evolution, geodynamic setting with a goal to better predict the location of mineral deposits for exploration.
• Using isotope geochemistry integrated with U-Pb geochronology to discern the sources and age of volcanic and plutonic rocks from ‘brownfield’ mineralised regions and underexplored Western Australian ‘greenfields’ regions specifically targeting mineral exploration.
• Nationally coordinated regional-scale isotopic mapping of igneous rocks to better understand the crustal structure and to help identifying fertile, primitive geological terranes most likely to host giant ore deposits.

Understanding Mantle and Crustal Processes

• Fundamental isotope geochemistry studies into the creation of the crust and the evolution of the mantle through local terrane specific research to national scale mapping projects.
• Isotopic tracing of the sources of volcanic rocks and using multiple geochronological techniques to constrain the petrogenesis and evolution of these igneous systems (which often produce or are involved in the genesis of mineralising systems).

Direct Dating and Fingerprinting of Petroleum Systems

• Applying the Re-Os mass spectrometry technique to fingerprint oil, pyrobitumen and shales and determine provenance, timing of hydrocarbon expulsion and depositional age of source rocks.