ARC Centre of Excellence for Core to Crust Fluid Systems

Dr John Adam

Credentials

BSc (Hons) University of New England, Australia, 1984; PhD, University of Tasmania, 1989.

Research Interests

I use geochemistry and experimental techniques to investigate the origins of igneous rocks. My most recent work has focused on the partitioning of trace elements between igneous minerals and melts. This has included examinations of the way pressure, temperature, melt composition (including H2O content) and crystal structure can affect partitioning. The focus of my current studies are crystal/melt/fluid partitioning of elements, the influence of volatiles on magmatic and mantle processes, the origins of intraplate basaltic magmatism, and genesis of continental crust both now and in the earliest Archaean. Projects currently running with PhD and research staff within the group include similar work on volcanic arc magmas in the Philippines and southern New Zealand. I am also working with Tracy Rushmer to test theories of early crustal genesis by establishing phase relationships for the oldest mafic rock discovered on the planet (4.28 Ga; O’Neil & Francis, 2008).

Example:
This capsule contains the products of an experiment conducted on a  nepheline basanite (from Bow Hill in Tasmania) at 1050 °C and 2 GPa with 7.5 wt. % of dissolved H₂O. Laser ablation pits are visible in the large brown amphiboles. Work on this basanite was used to investigate controls on the way trace elements partitioning between crystals and melts. Factors included pressure, temperature, mineral composition and structure, and the radius and valance of cations and anions included in the crystal structure. Near-liquidus phase relationships for the Bow Hill basanite show that it is in equilibrium with a garnet lherzolite phase assemblage at 1200 °C and 2.6 GPa with 4.5 wt. % of H₂O and 2 wt. % of CO₂ dissolved in it. Mineral/melt partition coefficients for garnet, amphibole, mica, clinopyroxene, orthopyroxene and olivine obtained under similar conditions are consistent with a garnet lherzolite source for the basanite that was enriched in incompatible trace and minor elements relative to the bulk-silicate-earth.

Selected Publications

Adam, J., Oberti, R., Camara, F., 2007. An electron microprobe, LAM-ICP-MS and single-crystal X-ray structure refinement study of the effects of pressure, melt-H₂O concentration and fO₂ on experimentally produced basaltic amphiboles.  European Journal of Mineralogy, 19(5), 642-655.

Xiong, X.L., Adam, J., Green, T.H., 2006. Trace element characteristics of partial melts produced by melting of metabasalts at high pressures: Constraints on the formation condition of adakitic melts. Science in China Series D-Earth Sciences, 49(9), 915-925.

Adam, J., Green, T.H., 2006. Combined experimental and geochemical evidence for the origins of Tasmanian intraplate basalts. Geochimica et Cosmochimica Acta, 70 (18), A2-A2.

Adam, J; Green, T.H., 2006. Trace element partitioning between mica- and amphibole-bearing garnet lherzolite and hydrous basanitic melt: 1. Experimental results and the investigation of controls on partitioning behaviour. Contributions to Mineralogy and Petrology, 152(1), 1-17.

Xiong, XL; Adam, J; Green, T.H., 2005. Rutile stability and rutile/melt HFSE partitioning during partial melting of hydrous basalt: Implications for TTG genesis. Chemical Geology, 218(3-4), 339-359.

Green, T.H., Adam, J., 2004. Trace element partition coefficients for mica and a variety of mantle-derived melts and fluids. Geochimica et Cosmochimica Acta, 68(11), A577-A577.

Adam, J., Green, T.H., 2001. Experimentally determined partition coefficients for minor and trace elements in peridotite minerals and carbonatitic melt, and their relevance to natural carbonatites. European Journal of Mineralogy, 13, 815-827.

Green, T.H., Adam, J., 2003. Experimentally-determined trace element characteristics of aqueous fluid from partially dehydrated mafic oceanic crust at 3.0 GPa, 650-700 °C. European Journal of Mineralogy, 15(5), 815-830.

Green, T. H., Adam, Adam, J., 2002. Pressure effect on Ti- or P-rich accessory mineral saturation in evolved granitic melts with differing K?O/Na?O ratios. Lithos, 61(3-4), 271-282.

Adam, J., Green, T.H., 2001. Experimentally determined partition coefficients for minor and trace elements in peridotite minerals and carbonatitic melt, and their relevance to natural carbonatites. European Journal of Mineralogy, 13(5), 815-830.

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