GEMOC ARC National Key Centre

Technology development program

research facilities

background

The Key Centre's Research, Training and Industry Interaction programs require a high level of geochemical analytical technology, which is provided by the state-of-the-art facilities available to the Key Centre. Further development of both technology and innovative analytical and microanalytical approaches are required to meet the research aims. GEMOC is developing new analytical strategies for determining the chemical and isotopic compositions of geological materials (both solid and fluid). Special emphasis is being placed on the development of advanced in-situ microbeam methods. These developments are transmitted to industry via open and collaborative research, through technology exchange visits and workshops, and as an integral part of the training program.

research facilities

The Key Centre brings together the analytical instrumentation and support facilities of the Macquarie University Geochemical Analysis Unit (GAU) and the geochemical facilities at the ANU Dept. of Geology and CSIRO Exploration and Mining. Macquarie University is a partner (with management responsibility) in the Centre for Isotope Studies housed at the CSIRO, North Ryde.

• The GAU contains:
  
  • a Cameca SX-50 electron microprobe
  • a Perkin-Elmer ELAN 5100 ICPMS
  • a Perkin-Elmer ELAN 6000 ICPMS (industry collaboration)
  • a custom-built laser microprobe attached to the ICPMS
  • an automated Siemens XRF
  • a LECO H2O-CO2 analyser.
  • Newly installed clean labs and sampling facilities to provide the infrastructure required for ICPMS and isotopic analyses of small and/or low-level samples.
  • a new multi-collector ICPMS under construction by NU Instruments for 1998 installation in refurbished laboratories.
• Experimental petrology laboratories in GEMOC include piston-cylinder (9, 15 and 40 kb), hydrothermal apparatus, and controlled atmosphere furnaces; each node is well-equipped.
• The Centre for Isotope Studies provides access to state-of-the-art thermal ionisation mass spectrometers for analysis of the Rb-Sr, Sm-Nd and U-Th-Pb systems, and extraction lines and gas-source mass-spectrometers for stable-isotope analysis of fluids and minerals.
• The ANU INAX facility includes:
  • a new Spectro energy dispersive XRF
  • an automated Philips XRF
  • Australia's only non-commercial Neutron Activation Laboratory
  • atomic absorption spectrophotometry
  • sample preparation facilities for mass spectrometric analysis
  • access to a Cameca Camebax microprobe, ICPMS and thermal ionisation mass spectrometer facilities through the Institute of Advanced Studies.

action 1997

the GEMOC Facility for Integrated Microanalysis (FIM)
and
Micro GIS development

GEMOC is developing a unique, world-class geochemical facility, based on in-situ imaging and microanalysis of trace elements and isotopic ratios in minerals and rocks. By the end of 1998, the Facility for Integrated Microanalysis will consist of four different analytical instruments; all will be linked by a single sample positioning and referencing system to combine spot analysis with images of spatial variations in composition ("micro-GIS").

The Facility will provide:

• The capability to image both major- and trace-element distribution in a sample, as an interpretive tool and the basis for higher precision spot analysis of trace element concentrations and isotopic ratios.
• Co-registration of images and spot data from different instruments, and use of digitized images to locate spots with a precision of better than 5 microns.
• Analytical capability for most elements of the periodic table at ppm to ppb levels.
• In-situ isotopic-ratio measurement for a range of elements, at the precision required for geologically useful results.
• New approaches to data interpretation through application of micro-GIS principles.

Micro-GIS system: A key aspect of the Facility is the co-registration of images and point analyses collected on all instruments. All data for a sample, from any of the instruments or from a bench microscope, are in the same coordinate system and can be overlaid in the computer to enhance interpretation. Images from one instrument can be read into the computer of another instrument and used to guide the analysis. Major-element maps from EMP, or trace-element maps from the nuclear microprobe, can be linked directly to images from eg petrographic or cathodoluminescence microscopes, BSE or SEM, or to spot analyses.

Electron Microprobe, for imaging and point analysis of major and minor elements.

Scanning Nuclear Microprobe, for imaging and point analysis of trace elements at ppm levels.

Laser-ablation ICPMS Microprobe, for point analysis of a wide range of trace elements at low ppb levels.

Multi-collector Sector ICPMS with laser microprobe, for high-precision in-situ analysis of isotopic ratios.

Current status:

Electron microprobe (EMP): The existing GEMOC EMP is a

CAMECA SX50, installed in 1993; it routinely produces high-precision analyses of major and minor elements with a spatial resolution of one micron, as well as high-quality images of major-element (>0.1 wt%) distribution over areas up to 45 x 45 mm, by stage-scanning with five fixed wavelength-dispersive spectrometers. The EMP is being upgraded with an energy-dispersive X-ray detector to allow rapid and simultaneous mapping of all major elements.

Norman Pearson, and postgraduate students, Eloise Beyer and Shixin Yao, at the electron microprobe.

Scanning nuclear microprobe (SNMP): This instrument is being built by C. Ryan as a separate beam line on the HIAF particle accelerator at CSIRO, North Ryde. It will incorporate several complementary types of detector, a new high-resolution probe-forming system and an innovative optical system, and is designed to provide both images of trace-element distribution and spot analyses, with a lateral resolution of 1-3 microns. The capabilities will include:
(a) micro-PIXE : Proton Induced X-ray Emission (PIXE) using focused MeV proton beams provides non-destructive, simultaneous, quantitative microanalysis of trace elements with concentrations down to the ppm level.
(b) micro-PIGE : Proton Induced Gamma-ray Emission (PIGE) spectra can be collected simultaneously with PIXE analysis. The gamma-rays provide non-destructive analysis of light elements (e.g. Li, Be, B, F, Na) with detection limits of 10-200 ppm. PIGE also provides analysis of anions (H, C, O, S, Cl) which are difficult to analyse by ICPMS and EMP.
(c) CCM: In Channelling-Contrast Microscopy (CCM), MeV energy beams of alpha particles or protons are channelled into the crystal planes and axes of minerals. CCM can be used to yield images of lattice location information or to distinguish elements sited in inclusions from those in solid solution. This capability can be applied to the trace levels detected using ion backscattering, micro-PIXE and micro-PIGE.
(d) Quantitative True Elemental Imaging: The SNMP will provide trace-element imaging of areas up to 2.5 mm across; these images will be digitised so that any pixel or larger area can be retrieved, and analysed separately for its element concentrations. The Dynamic Analysis (DA) method developed by C. Ryan enables live-time assembly of true elemental images that discriminate against pile-up, inter-element overlap, background and detector artefacts such as escape peaks and tailing.

Laser Ablation ICPMS microprobe (LAM): The existing GEMOC LAM was installed in December 1994, using a Perkin-Elmer ELAN 5100 ICPMS, attached to a UV laser ablation microprobe built for GEMOC by Memorial University, Newfoundland. The instrument now routinely provides quantitative analyses of >30 elements at sub-ppm levels in minerals, glasses and metals. Spatial resolution varies with the application, but typically is on the order of 30-40 microns. The LAM is fitted with a computer-driven sample stage to provide co-registration of X-Y coordinates with the other instruments.

Backscattered electron image of zircon from the Dundee Rhyodacite, New England, Australia. Internal zoning reflects a complex growth history. Two holes in the grain are craters from the laser ablation ICPMS analyses.

Multi-collector LA-ICPMS microprobe (MC-LAM-ICPMS): A fully-equipped MC-ICPMS is an integral part of the Facility. This instrument combines a laser ablation microsampler, an Ar-plasma ionisation source, and a multi-collector magnetic-sector mass spectrometer, to provide high-precision in-situ analysis of isotope ratios in geological materials. The MC-ICPMS also can be used in solution mode, to supplement the capabilities of the conventional mass spectrometers at the Centre for Isotope Studies.

Planned applications include:

Laser Analysis (in-situ point analysis)

• U-Pb dating of zircon, monazite, apatite
• Hf isotope analysis in zircon for crustal generation studies
• Sm-Nd dating, Nd isotopes in apatites, REE minerals
• Sr isotope analysis of carbonates, feldspars, apatites, pyroxenes
• Pb isotopes in sulfides
• Stable isotope ratios of Zn, Cu and other cations in hydrothermal systems

Solution Analysis

• Re-Os -- mapping of mantle depletion ages in whole rocks and chromites
• Lu-Hf -- crustal genesis, mantle metasomatism; Lu-Hf dating of garnet peridotites, eclogites, granulites
• Sm-Nd, U-Pb -- faster and simpler than TIMS; simplified chemistry, no time-dependent mass fractionation, hence greater precision

progress in 1997

1. Facility for Integrated Microanalysis a. MC-ICPMS: Following factory and laboratory visits and extensive testing and evaluation, an order was placed for a multi-collector magnetic sector ICPMS for in-situ (laser-ablation) and solution analysis of isotopic ratios. The instrument chosen is the Nu Plasma, designed and manufactured by Nu Instruments of Wrexham, UK. Key factors in the choice were the instrument's innovative design, low potential maintenance costs and flexibility of application, combined with high sensitivity and stability. The Nu Plasma combines a double-focussing mass spectrometer with a unique fixed collector array interspersing Faraday cups and high-precision ion counters, combined with a zoom lens that allows the dispersion length of the instrument to be varied electronically for analysis of all relevant isotopic systems in dynamic or static mode. The Faraday cups are a new robust ceramic design, allowing easy and inexpensive replacement, and the electronics are designed for multiple redundancy and low maintenance costs. Installation is scheduled for April 1998.

William Griffin, Simon Jackson and Ashwini Sharma discussing results from the Laser Ablation Microprobe ICPMS.

b. Scanning Nuclear Microprobe: Design was completed, most of the components have been purchased, and completion tests on the lenses (being constructed at Melbourne University Dept. of Physics) are expected in March. Beam tests are scheduled for mid-year, with full operation in the latter half of 1998.
c. Laser-ablation ICPMS microprobe: The laser microprobe was moved to the new ELAN 6000 ICPMS provided by Perkin Elmer Australia, resulting in improved sensitivity and a more flexible software environment, and freeing the existing Elan 5100 ICPMS for solution analysis. Several modifications to improve sensitivity on the ELAN 6000 will be carried out during 1998. The laboratory produced large volumes of data for five PhD thesis projects, several projects carried out by international visitors, and in-house research projects. It also routinely provides data for projects related to mineral exploration (diamonds, base metals, Au), as a consulting service to the industry. The UV laser ablation microprobe in the GAU will be reconfigured in 1998 to allow increased flexibility (e.g., viewing of the sample in reflected light during ablation) and enhanced performance (shorter wavelength capability). The short wavelength option will be achieved by addition of a 5th harmonic generator, giving a new operating wavelength of 213 nm. This wavelength will provide significantly improved ablation characteristics, signal stability, ablation times and sensitivity for many minerals.
d. Software: Esmé van Achterbergh and Chris Ryan developed the off-line version of the GLITTER (GEMOC Laser ICPMS Total Trace Element Reduction) software, a new interactive program featuring linked graphics and analysis tables (see graphics on back cover of this report). In 1998 the on-line version will be completed and installed on the ELAN 6000. This will provide the first real-time interactive data reduction for LAM-ICPMS analysis, allowing inspection and evaluation of each result before the next analysis spot is chosen.
e. Micro-GIS: The software and hardware for digitisation of analysis points became fully operational, providing the basis for co-registration of images and analysis points between the EMP, SNMP, LAM-ICPMS and MC-ICPMS.

2. Energy Dispersive XRF

The new Spectro was installed at ANU during November 1996 and is fully operational. By using the polarised nature of scattered X-rays, backgrounds are reduced very substantially, and sensitivities enhanced. The instrument analyses 16 samples/day for all elements heavier than Co (ca 30) with abundances greater than ca 0.3 ppm. For elements near Z=50, such as Ag, Cd and Sn the detection limits are below 100 ppb. A large body of granite samples from SE Australia is being reanalysed specifically for Ge, Ag, Cd, Cs, Tl and Bi which were not previously measured, and to improve the data for As, Mo and Sn. The behaviour of those elements within granite suites of diverse composition is important, and precise measurement of the abundances of the heavy metals such as Mo, Ag, Cd, Sn, Sb, Hg and Bi is potentially of great interest in relating mineralisation of specific associations to various types of granites.

3. Laser development

GEMOC will benefit from a new 2-year (renewable) industry partnership with Merchantek EO, a US manufacturer of laser ablation systems, which has agreed to make Macquarie its Alpha-Test Site. Merchantek will maintain their latest model UV laser ablation sampling system, a fully programmable frequency quadrupled Nd:YAG-based system, at GEMOC and will involve us in any new technology developments into shorter wavelength ablation systems. The Merchantek system, scheduled for delivery in February/March, will be coupled to the Nu Plasma MC-ICPMS allowing high precision isotope ratio determinations to be performed on minerals in situ.

4. Centre for Isotope Studies (CIS)

R. Flood (Manager of CIS) and the Deputy Vice-Chancellor (Research) at Macquarie, negotiated the funding of two technical positions for CIS through guaranteed annual contributions from member Universities to enable laboratory procedures to run smoothly and efficiently for University users.

Dr Anita Andrew (CSIRO) developed a technique for C-isotopic analysis of diamonds using very small sample sizes (0.1mg), allowing analysis of microdiamonds or multiple fragments of different zones of small stones. This is an essential addition to GEMOC capabilities and over 100 analyses were carried out in 1997 on diamonds from Canada, eastern Australia, Thailand, Siberia and China.

5. New Equipment at the ANU

In 1997, the Department of Geology led a successful bid to the RIEF Program of the ARC, for two ICP-MS instruments. Funding support was also obtained from the School of Resource Management and Environmental Science, Department of Zoology, Faculty of Science, and Major Equipment Committee of the ANU, and the University of Canberra. One of these instruments will be dedicated to solution analysis and installed at the University of Canberra. The other will be equipped with a ultra-violet wavelength laser and installed at the Department of Geology. Assessment of rival equipment bidders is on-going with purchase and installations planned for 1998.

industry/end-user interaction

industry interaction, technology transfer and
commercialisation program

GEMOC relies on a vigorous interaction with the mineral exploration industry at both the research and the teaching/training levels. The research results of the Centre's work are transferred to the industry and to the scientific community by:

• Interaction through collaborative industry-supported Honours, MSc and PhD projects
• Short courses relevant to the industry and government sector users, designed to communicate and transfer new technologies, new techniques and new knowledge in the discipline areas covered by the Key Centre
• AMIRA- sponsored collaborative research projects
• One-on-one research collaborations and shorter-term consultancies on industry problems involving national and international partners
• Provision of high quality geochemical analysis and interpretations to industry and government organisations, extending our industry interface
• Use of Macquarie Research Limited (eg DIATREEM) and INAX (ANU) consultancies, which employ and disseminate the technological developments carried out by the Centre

support sources

GEMOC industry support includes:

• direct funding of research programs
• "in kind" funding including field support (Australia and overseas), access to proprietary databases, sample collections, digital datasets
• collaborative research programs (eg AMIRA, APA Industry and PhD program funding)
• two SPIRT applications are in preparation for 1998 submission
• assistance in the implementation of GIS technology in postgraduate programs
• participation of industry colleagues as guest lecturers in senior courses (eg Bachelor of Technology)

Progress in 1997

• The mineral exploration industry funded four postgraduate student projects in 1997. In each case, the companies have also provided invaluable in-kind support, and have been closely involved in shaping the research project.
• A new collaborative research project was started within the Lithosphere Mapping strand, (following the success of a separate project in 1996), with Kennecott Canada Inc. 1997 visits of GEMOC staff to Kennecott operations in Vancouver and Thunder Bay, and visits of Kennecott staff to Macquarie have been essential to the high-profile outcomes, many of which will be presented at the 7th International Kimberlite Conference in Cape Town in April (see Appendix 4 for abstract titles).
• A collaborative project using gravity data of the Siberian lithosphere to interpret effective elastic thickness and integrate this with tectonic analysis and geochemical data, was negotiated with Western Mining and VSEGEI, St Petersburg. Planning and workshop sessions at Macquarie with participants from Western Mining, VSEGEI and GEMOC are key activities.
• Anglo American Research Laboratories (Johannesburg) provided capital contributory funding for the new MC-ICP-MS and have a schedule of regular visits to Macquarie to participate in aspects of the development of LAM-ICPMS and MC-ICPMS techniques and applications
• BHP is sponsoring a strand of technology development on the LAM-ICPMS and Dr Steve Walters spends research periods at Macquarie to participate in this in collaboration
• Many companies have provided high levels of in-kind support in the form of samples: these include access to over 1000 diamonds through Rio Tinto and Diamond Ventures Ltd, field logisitic support by Ashton mining for PhD students to sample the Merlin and Coanjula (NT) kimberlites, volcanics and xenoliths.
• AMIRA project negotiated (Blevin and Chappell) on granite-related mineralisation
• The 4th Australasian Symposium on Applied ICP-Mass Spectrometry and associated LA-ICPMS Workshop held by Macquarie in May 1997 attracted many industry representatives from both manufacturing and exploration companies and was a successful vehicle for transfer of technology
• The Industry and Training Workshop on "Tectonic Evolution of East and Southeast Asia: A Framework for Reconstruction and Resources" held at Macquarie as a joint UNE-GEMOC venture, attracted 25 end-user representatives both national and international. The 4 volumes of notes and the interactive CD-ROM have been used for in-house training in several companies and at AGSO. An opinion survey of participants revealed a very high approval rating and constructive suggestions.
• Mr Bruce Wyatt, Director of Research and Technical Services at Stockdale Prospecting Ltd has a formal research collaboration and spends regular research time at Macquarie
• Numerous industry visitors spent varying short periods at GEMOC in 1997 to discuss our research and technology development (see visitor list, Appendix 3)
• DIATREEM continued to provide LAM-ICPMS analyses of garnets and chromites to the diamond-exploration industry on a routine basis, in cooperation with CSIRO-EM
• The Workshop on Silicate Analysis attracted end-user support and participation
• GEMOC publications available on request for industry libraries