Stable isotope and trace element analysis of natural materials by SIMS

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Igneous Geochemistry and Volcanology. Microanalysis of sulphur isotopes in erupted materials will be applied to understanding the pre-eruptive accumulation of gaseous sulphur within convergent plate boundary volcanoes such as Nevado del Ruiz, Colombia. These volcanoes can release extremely large volumes of SO2 to the atmosphere - with consequences for volcanic hazard, acid rain and global climate change. Microanalysis of chlorine isotopes in submarine eruptive materials of the Lau and Marianas basins will be directed at improving our understanding of the chlorine isotope systematics during subduction of oceanic basalt - a fundamentally important, large volume process in the recycling of crustal and oceanic chlorine. Marine Biomineralization. Fine scale determination of Sr/Ca ratios and oxygen isotopes in marine biomineralization by SIMS can provide crucial information on the temperatures of both modern and ancient oceans. This study will examine temperature records preserved in deep water coral species. SIMS will also be applied to the environmental monitoring of modern coral reefs. For example, in areas compromised by mine tailings, ion imaging of trace elements can reveal the distribution of contaminant metals resident in entrained particles within the coral skeletons. Microanalyses of oxygen and carbon isotopes will be used to detect short term changes in reef coral skeletons due to environmental stress such as severe storms or large fires. Ore Deposit Geochemistry and Mineralogy. Magmatic assimilation of wallrock sulphur is fundamental to the formation of almost all commercially viable Cu-Ni deposits. Nevertheless, the exact mechanisms and sequences involved in this process remain uncertain. A study of the giant Voisey's Bay deposit will examine episodicity of magmatic inputs, and determine whether sequential aliquots of assimilated S (and Se) are reflected as ore zonations. If this proves true, then paired sulphur isotope and Se/S microanalysis could assist in delineation and extension of orebodies as mine development continues. Ion imaging studies of trace element distributions in the ores will also be applied to the environmental control of tailings and waste containments.