MSA Distinguished Lectures Lecture Tour: Matthew Steele-MacInnis, University of Alberta
Title: The iron-oxide-apatite problem, and the carbonate-sulfate solution
Dr. Matthew Steele-MacInnis
Department of Earth and Atmospheric Sciences
University of Alberta
Abstract: The origins of iron-oxide apatite deposits (or IOAs) are extremely contentious. Even very basic questions, like whether these ores crystallized from magma or were precipitated from hot water, are still fiercely debated. Fundamentally, the problem is that we have been missing a known geologic fluid capable of mobilizing and depositing massive amounts of ferric iron and phosphate, especially without simultaneously depositing voluminous quartz. Here, I will describe my group’s recent progress in characterizing IOA ore-forming fluids by analyzing fluid inclusions in minerals. Our results reveal some surprises: Especially, that the main liquids involved are neither hot water nor Fe-oxide-phosphate melts. Instead, hitherto unexpected liquids dominated by carbonate and sulfate components prevail. These liquids—the carbonate-sulfate solution—paint a very different picture of what these deposits represent, and help explain many of the previously puzzling characteristics of these ores. Besides, these liquids are probably excellent agents for concentrating a variety of critical metals that are otherwise hard to mobilize.
Bio: Matthew Steele-MacInnis is an Associate Professor of Geology at the University of Alberta, whose research focuses mainly on geologic processes involving fluids, especially formation of mineral deposits. Originally from Newfoundland, he did his BSc in Earth Science at Memorial University (2008) and his PhD in Geoscience at Virginia Tech (2013). He then held a Marie Curie postdoctoral fellowship at ETH Zurich (2013-2015), and was an Assistant Professor of Geology at the University of Arizona (2015-2017) before taking up his current position at University of Alberta. Steele-MacInnis has been a recipient of the Hisashi Kuno award from the American Geophysical Union (2017); the Young Scientist Award from the Mineralogical Association of Canada (2018) and the SGA Young Scientist Award from Society for Geology Applied to Mineral Deposits (2022).
Milligan Room, 8th Floor Biology-Earth Sciences Wing, Life Sciences Centre, Dalhousie University