The evolution and extinction of life are tied intimately to the oxygen state of the ocean, and
particularly to the presence of anoxic and H2S-containing (euxinic) water on a global scale.
Anoxia and euxinia were more common in the past, relative to today's< 0.5% euxinic
seafloor. We are able to constrain the distributions of these conditions through a
combination of indirect numerical modeling methods and more direct geochemical proxies,
with particular emphasis on Fe-S-Mo analysis of fine-grained siliciclastic rocks for the latter …