ARC Centre of Excellence for Core to Crust Fluid SystemsDr Bruce Schaefer
BSc Adel, BSc(Hons 1st) Adel, PhD Adel
Senior Lecturer, Isotope Geochemistry
Contact DetailsOffice : E7A 506 |
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Profile
Bruce Schaefer is a lecturer within the department of Earth and Planetary Sciences and is currently appointed in a research intensive CoRE position. He co-ordinates the 3rd year geochemistry unit (GEOS343) and is involved in the third year field mapping trip (GEOS307). Bruce came to Macquarie in late 2008, having completed a 4 year postdoc at the Open University, UK, followed by almost 7 years as a lecturer at Monash University.
Research
Interests
• Geochemistry and Cosmochemistry
• Planetary Chemical Geodynamics
• Precambrian Tectonic Processes
• Hydrosphere-Lithosphere Interactions
My research interests have been driven by the application of isotopes to solving a wide range of geological problems. My motivations have generally been through identifying a particular problem, and subsequently applying, or occasionally, developing, and appropriate isotopic tracer to investigate the key issues. Therefore my interests are primarily curiosity driven, but generally have a wide range applications.
Current research programs include:
Extraterrestrial materials
In conjunction with Dr Andy Tomkins at Monash University, we have been developing a program of meteorite collection and characterisation from the South Australian Nullarbor and the western NSW. This interest has been largely prompted by the discovery of the meteorite Eldee 2 whilst on a third year mapping trip, which preserved a snapshot of planetesimal differentiation and core formation in a brecciated heterogeneous parent body. A program combining physical modelling, melting experiments (with Dr Tracy Rushmer, Macquarie University) in addition to isotopic characterisation of extraterrestrial materials is currently underway
Other “extraterrestrial” work involves investigation of the Lawn Hill Impact crater in Queensland, through a Monash PhD student (Jess Salisbury), jointly supervised with Andy Tomkins.
Mantle plumes, convection within the Earth, and planetary differentiation
Ocean Island basalts preserve isotopic signatures of the source regions melting within the convecting earth to produce the magmas. Increasing sophisticated isotopic techniques, including Os, Li and B isotopes, point to ancient recycled components in many mantle plumes, such as the Azores. Current work involves extending the fragmentary geochemical and isotopic datasets of particularly low buoyancy flux plumes, such as the Azores (PhD student Felix Genske) and comparing them with larger systems, such as the Ontong Java Plateau and North Atlantic Igneous Province (collaborative with Dr Ian Parkinson, Open University, UK).
Other aspects of planetary magmatism and differentiation focus more on the transfer and interaction between the convecting earth, the lithospheric mantle (primarily sub-continental) and the crust. Small volume partial melts in regions of overthickened continental crust, such as shoshonites provide insights into the thermal state of the lithosphere before, during and after crustal thickening, and allow an assessment of the relative roles of heat and mass transfer to the lithosphere during geothermal rebound (PhD student Matt Pankhurst). The nature and degree of (re-)fertilisation in the source regions of small volume partial melts in different geodynamic settings (eg continental collisional such as the Himalaya and the Betics cf subduction in the Andean Altiplano) are likely to inform the nature of metasomatism and modification of the SCLM.
Another exciting project, joint with Prof John Foden (Adelaide University, supported by an ARC Discovery grant) involves the Os isotope record of boninite magmatism. An initial investigation of Palaeozoic boninites has revealed significant insights into the nature of depletion and subsequent refertilisation of the mantle wedge in subduction settings, and further investigations of young systems are underway.
Precambrian Geodynamics
The Precambrian, notably the Proterozoic, preserves a record of phenomena that cannot be easily reconciled with a straightforward plate tectonic paradigm. Foremost amongst these is the combination of elevated heat flow in many Proterozoic terrains and the corresponding magmatism, notable A-type granites within Australia. Piecing together the relationship between magmatism, deformation and metamorphism (collaborative with Dr Peter Betts, Monash University) is critical to understanding the processes of crustal growth and continental amalgamation and breakup during this time. Specifically, investigations into the Gawler Craton, SA (PhD student Robin Armit, Monash University) supported by an ARC Linkage project and PIRSA aim to integrate the Nd and Hf isotopes of different marginal terrains in order to constrain when and how different portions of the craton grew and amalgamated. Other aspects relating to IOCG mineralisation and magmatism on the Gawler Craton have been supported by Oz Minerals around the Prominent Hill Mine through a series of honours projects over the last three years.
U-series isotopes in mineralised systems
U isotope disequilibria offer the potential to track the passage of U through aquifers and place time constraints on U mobility in mineralised systems. Further, potential links to changes in climate (eg, aridification) and hence U mobility can be investigated through groundwater studies. An ARC linkage grant with Heathgate Resources to investigate the behaviour of U-series isotopes around the Beverley Mine in South Australia is being conducted, largely through the efforts of PhD student Mel Murphy (co-supervised with Prof Simon Turner, Macquarie University, Dr Tony Dossetto, Wollongong University), with further work regarding the record of evolution of the Australian landscape being conducted within the context of this project by Dr Heather Handley (Macquarie University).
Previously I have been involved in U-series investigations into the weathering of Icelandic basalts as recorded in river waters and the REE budget of fractured controlled aquifers in Victoria. I am currently collaborating with colleagues at Bristol and Oxford University regarding the behaviour of Li and Si isotopes in the Great Artesian Basin.
The Snowball Earth
Collaboration with Dr Ian Parkinson and PhD student Pierre Bonand (The Open University, UK) investigating the “Snowball Earth” Neoproterozoic sedimentary sequences through Cr isotopes is ongoing. Linking the redox sensitive properties with Cr to seawater chemistry throughout geological time also displays some promise for tracking the redox state of the oceans globally.
Technique development
One of my primary motivations in research has been developing new tools, or improving existing tools to tackle scientifically interesting problems. Much of this work is blue sky in nature, and hence not generally funded by granting bodies, however at Macquarie we have been succesfully pursuing development of routine 186Os/188Os. Further protocol refinements, such as routine single dissolution Re-Os isotope+PGE abundance analysis is now in place at Macquarie. Applications for Os isotopes in organic materials are also under investigation.
My previous experience in Cr isotope chemistry, coupled with work in refining N-TIMS analytical techniques and development of new in situ protocols (eg Nd isotopes in titanite) highlights an ongoing focus on new and innovative isotopic techniques. The Geochemical Analytical Unit (GAU) has a number of programs, co-ordinated through Dr Norm Pearson for new techniques, including the development of non-traditional stable isotope techniques.
RESEARCH OPPORTUNITIES
Opportunities exist in any of the above or related fields for honours and PhD projects. Macquarie has excellent cotutelle and internal PhD scholarship schemes for supporting international students in addition to conventional nationally competitive scholarships for postgraduate research.
Applications for potential postdoctoral research utilising isotopic techniques are welcomed.
Publications
22. Pankhurst, M.J., Schaefer, B.F., Betts, P.G., Phillips, N. and Hand, M. 2010. A Mesoproterozoic continental flood rhyolite province: The end member of the the Large Igneous Province clan. Solid Earth Discussion. 2, 251-274.
21 Pankhurst, M.J., Schaefer, B.F., and Betts, P.G. In Review. Geodynamics of rapid voluminous felsic magmatism through time. Lithos, doi:10.1016/j.lithos.2010.11.014
20. Schaefer, B.F., Pearson, D.G., Rogers, N.W. and Barnicoat, A.C., 2010, Re-Os isotope and PGE constraints on the timing and origin of gold mineralization in the Witwatersrand Basin. Chemical Geology, 276, 88-94
19. Stewart, J.R., Betts, P.G., Collins, A.S. and Schaefer, B.F. 2009. Multi-scale analysis of Proterozoic shear zones: An integrated structural and geophysical study. Journal of Structural Geology 31, (10) 1238-1254 doi:10.1016/j.jsg.2009.07.002
18. Betts, P.G., Giles, D., Foden, J. Schaefer, B.F., Mark, G., Pankhurst, M.J., Forbes, C.J., Williams, H.A., Chalmers, N.C. and Hills, Q. 2009. Mesoproterozoic plume-modified orogenesis in eastern Precambrian Australia. Tectonics, 28, TC3006, doi:10.1029/2008TC002325.
17. Aitken, A.R.A, Betts, P.G., Schaefer, B.F. and Rye, S.E. 2008 Assessing uncertainty in the integration of aeromagnetic data and structural observations in the Deering Hills region of the Musgrave Province. Australian Journal of Earth Sciences 55, (8) 1127-1138
16. Gregory, M.J., Schaefer, B.F., Keays, R.R. and Wilde, A.R. 2008. Re-Os systematics of the Mt Isa copper ore body and the Eastern Creek Volcanics, Queensland, Australia. Mineralium Deposita 43, 553-573
15. Salisbury, J., Tomkins, A.G., & Schaefer, B.F., 2008. New Data on the Timing and Size of the Lawn Hill Impact Crater, northwest Queensland. Australian Journal of Earth Sciences 55, 587-603.
14. Betts, P.G., Giles, D. and Schaefer, B.F. 2008. Comparing 1800-1600 Ma Accretionary and basin processes in Australia and North America; possible geographic connections in Columbia. Precambrian Research 166 81-92.
13. Betts, P.G., Giles, D., Schaefer, B.F. and Mark, G. 2007. 1600-1500 Ma hotspot track in Eastern Australia: implications for continental reconstruction. Terra Nova, 19, 496-501.
12. Turner, S.P., Tonarini, S., Bindeman, I., Leeman, W. and Schaefer, B.F. 2007. Boron and oxygen isotope evidence for recycling of subducted components over the past 2.5Gyr. Nature, 447, 702-705.
11. Heyworth, Z., Turner, S.P., Schaefer, B.F., George, R., Berlo, K., Cunningham, H., Price, R. and Gamble, J. 2007. 238U-230Th-226Ra-210Pb constraints on the time scales of high Mg andesite evolution at White Island, New Zealand. Chemical Geology, 243, 105-201.
10. Tweed, S.O., Weaver, T.R., Cartwright, I. and Schaefer, B.F. 2006 Behaviour of rare earth elements in groundwater during flow and mixing in fractured rock aquifers: An example from the Dandenong Ranges, southeast Australia. Chemical Geology, 234, 291-307
9. Vigier, N., Burton, K.W., Gislason, S.R., Rogers, N.W., Duchene, S., Thomas, L., Hodge E. and Schaefer B.F. 2006 The relationship between riverine U-series disequilibria and erosion rates in a basaltic terrain. Earth and Planetary Science Letters, 249, 3-4, 258-273.
8. Schaefer, B.F. 2005 When do rocks become oil? Science, 308, (5726): 1267-1268
7. Schaefer, B.F. and Burgess, J. M. 2003 Re-Os isotopic constraints on deposition in the Centralian Superbasin: Implications for the "Snowball Earth". Journal of the Geological Society of London 160 825-828.
6. Schaefer, B.F., Turner, S.P, Parkinson, I.J., Rogers, N.W., and Hawkesworth, C.J. 2002 Recycled oceanic mantle lithosphere in the Azores plume. Nature, 420, 324-326.
5. Burgess J.M., Johnstone, A.L., Schaefer, B.F., Brescianini R.F. and Tingate, P. 2002 New perspectives of the Amadeus Basin, Northern Territory. Petroleum Exploration Society of Australia Journal. 29, p. 14-23
4. Elburg, M.A., Bons, P.D., Dougherty-Page, J.D., Janka, C.E., Neumann, N. and Schaefer, B.F. 2001 Age and metasomatic alteration of the Mount Neill Granite Porphyry at Nooldoonooldoona Waterhole, Mount Painter Inlier, South Australia. Australian Journal of Earth Sciences. 48, p. 721-730.
3. Schaefer, B.F., Turner, S.P., Rogers, N.W., Hawkesworth, C.J., Williams, H.M., Pearson, D.G. and Nowell, G.M. 2000 Re-Os isotope characteristics of post-orogenic lavas: implications for the nature of young lithospheric mantle and its contribution to basaltic magmas. Geology, 28, no. 6, p. 563-566.
2. Schaefer, B.F., Parkinson, I. and Hawkesworth, C. 2000 Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites. Earth and Planetary Science Letters, 175, 1/2 p. 105-118.
1. Hoek, J.D. and Schaefer, B.F. 1998. The Palaeoproterozoic Kimban mobile belt, Eyre Peninsula: Timing and significance of felsic and mafic magmatism and deformation. Australian Journal of Earth Sciences. 45, p. 305-313.
RESEARCH STUDENTS (current):
PhD:
Macquarie:
Felix Genske (commenced 2009)
Mel Murphy (commenced 2009)
Matt Pankhurst (commenced 2009)
Monash:
Robin Armit (commenced 2008)
Jess Salisbury (commenced 2008)
RESEARCH STUDENTS (completed):
PhD:
Monash:
Patti Durance-Sie (completed 2008)
Lucy Porritt (completed 2008)
Alan Aitken (completed 2009)
Ben Hagedorn (completed 2009)
John Stewart (completed 2010)
MSc:
Monash:
Russell Smits (completed 2004)
Neil Chalmers (completed 2009)
George Ross (completed 2011)