How oxygen levels in Earth's atmosphere and oceans evolved has always been a central question in Earth System Science. Researchers have developed numerous trace

Paleosols formed in direct contact with the Earth's atmosphere, so they can record the composition of the atmosphere through weathering processes and products.

Ce anomalies track changes in oxygen availability due to the anomalous redox-sensitivity of Ce compared with the other rare earth elements. The proxy systematic

The attraction of selenium isotopes as a paleoenvironmental tracer lies in the high redox potential of selenium oxyanions (SeIV and SeVI), the dominant species

Vanadium isotope ratios (51V/50V) have potential to provide information about changes in past ocean oxygen contents. In particular, V isotopes may find utility