The iron speciation paleoredox proxy uses iron content and species in shales to determine past water column oxygenation. The proxy operates by removing several chemically defined pools of iron, but studies have indicated that some clay minerals can affect these extractions. My analyses show that the presence of certain clay minerals does significantly affect iron speciation results.
I set out to use the iron speciation proxy to constrain redox conditions during the development of an archaeocyathan reef from the Harkless Formation in Nevada. However, abundant glauconite and chamosite clays in the shale seemed to produce redox results that did not agree with other metal proxies. I set up an experiment where I subjected samples to the iron speciation extraction sequence, but stopped after each extraction to measure mineral content using XRD. I was able to track what minerals were removed during each extraction, illustrating that glauconite and chamosite were not adequately extracted.
Check out our paper to learn more: https://doi.org/10.1016%2Fj.chemgeo.2024.122453
I set out to use the iron speciation proxy to constrain redox conditions during the development of an archaeocyathan reef from the Harkless Formation in Nevada. However, abundant glauconite and chamosite clays in the shale seemed to produce redox results that did not agree with other metal proxies. I set up an experiment where I subjected samples to the iron speciation extraction sequence, but stopped after each extraction to measure mineral content using XRD. I was able to track what minerals were removed during each extraction, illustrating that glauconite and chamosite were not adequately extracted.
Check out our paper to learn more: https://doi.org/10.1016%2Fj.chemgeo.2024.122453