Metals in Magmas and Applications in Igneous and Environmental Geology

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The Earth's surface is organized into a series of rigid moving plates, some of which converge into one another at subduction zones. These subduction zones are a key location in the earth system for the fluxes of mass (rock and water) between the deep solid earth (crust and mantle), and the oceans and atmosphere over geologic time (millions to billions of years). This research program focuses on three components of subduction zones that affect the mobility of certain elements or metals and ultimately their availability in the surface environment where they may form ore resources, or pollute and impact the biosphere. Over the next five years we examine: (1) the release of sulfur during the subduction of different rock types which make up the plates, (2) the mobility of metals (like Copper) deep in the mantle near subduction zones, and upward into the crust to make ore deposits, and (3) the degassing of toxic trace metals (like Lead or Arsenic) into the atmosphere by active volcanoes. To do this, we simulate the conditions of plate subduction at very high pressures (P) and temperatures (T) in the laboratory and examine how these parameters affect the behaviour of sulfur in certain rock types. In turn, the release of metals by the subducted plate, or their behaviour at depth in the mantle, is often intrinsically linked to the P, T and/or behaviour of sulfur, and helps us understand what kinds of metals are mobile and how they can be enriched upward in the crust by magmas to form certain ore resources above subduction zones. In addition, we can also simulate the release of toxic trace metals from magma in a volcano at high temperatures in the lab and condense those metals from the gas phase at cooler temperatures. These experiments inform us of what toxic metal species can emanate from volcanoes, how much can be lost to the atmosphere, and to what degree they can pollute the environment, and potentially impact the biosphere, both now and in the past.