Date of Award
12-1-2024
Degree Name
Master of Science
Department
Geology
First Advisor
Hummer, Daniel
Abstract
There is an implication that minerals have been evolving for the entirety of Earth’s history. Iron silicate minerals are very abundant in Earth’s crust, form in a wide range of pressure, temperature, Eh, pH conditions, and are more resistant to weathering than other iron mineral groups, therefore are expected to be representative of the overall changes that occur through geologic time. Iron is a redox sensitive element, and the valence state of iron in iron silicate minerals can be used to track large-scale geologic events, such as supercontinent formation periods and the Great Oxidation Event. Comparing the average oxidation state of iron through geologic time with atmospheric oxygen abundance reconstructions we can observe a 200-million-year time lag between the increase in average iron oxidation and the increase in O2 in the atmosphere. This time lag is interpreted as iron acting as a sink for molecular oxygen. Iron was being oxidized from Fe2+ to Fe3+ and being deposited in large quantities as the Banded Iron Formations.
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