Will Hutchison’s paper with his co-authors, which looks comprehensively at the modelling of sulfur isotopes, has just been published in Geochimica et Cosmochimica Acta. This work builds upon his successful publication in Nature Communications which put forwards a hypothesis that sulfur was cycled through the Earth’s mantle.
Here, Will explores how the partitioning of sulfur isotopes will occur between sulfide and sulfate minerals as a hydrothermal fluid associated with mineralisation cools. He showed that changes in pH, temperature and redox can be encoded in the partitioning of sulfur between different minerals. He applied the methods to real published S isotope data from porphyry and epithermal mineralising systems, before tackling the most complex systems associated with alkaline igneous rocks. Whereas other mineralising systems have relatively restricted ranges of pH, redox and T, alkaline igneous rocks are associated with fluids with a wide range of pH and redox states. As temperature falls, the fluids in these systems experience sudden changes in redox, slewing from very reducing conditions to relatively oxidising states.
Will’s work looked at particular analysis of the Ilimaussaq and Motzfeldt regions and involved fieldwork there in 2017 and 2018.
Will is presenting to the Geological Society of London conference on Sulfur in the Earth System in November about his most recent research.
Full reference: Hutchison W, Finch AA & Boyce AJ (2020) The sulfur isotope evolution of magmatic-hydrothermal fluids: insights into ore-forming processes. Geochimica et Cosmochimica Acta, 288, 176-198.
Data: Code and original data can be obtained directly from the authors.