DEVELOPING AND UTILIZING PALEOREDOX PROXIES TO CONSTRAIN MARINE OXYGEN LEVELS
Recent work shows a steady loss of oxygen in modern oceans related to climatic change, with the degree of effect that this deoxygenation will have on marine life still not fully constrained. Using multiple instances of extinction throughout Earth’s history as examples of modern climate is one means to better understand these processes. Thus, better constraining the redox conditions of the ancient oceans during such events is vital to better understanding these extinction intervals and how they may relate to modern ocean conditions. One means to do this is through the development and improvement of novel and useful redox proxies, such as thallium (Tl) isotopes. However, minor additional constraints for this proxy are still necessary, which has been partially rectified with recent work. Nevertheless, this proxy can be applied to the end-Permian mass extinction, indicating extensive anoxia around this interval as well as rapid changes in marine oxygen across this event in particular that contributed to the extinction. In addition, the following Early Triassic recovery, which is longer lasting than most extinction recovery intervals, maintains continuous anoxic conditions with potential rapid fluctuations in oxygen that hamper recovery from the mass extinction. These studies show that not only is anoxia a major concern for the biodiversity of life in the oceans, but also that rapid changes in anoxia such as seen in modern oceans may represent a greater likelihood of extinction.
Additional information: Dr. Sean NEWBY, snewby@hku.hk