Figure 3. Schemata of a multi-proxy approach to interpreting hypoxia categories, including severe hypoxia ([O₂]<0.5 ml L^-1), intermediate hypoxia ([O₂]>0.5–1.5 ml L^-1) and mild hypoxia to oxic conditions ([O₂]>1.5 ml L^-1).

These hypoxia categories are detailed in Table 1, and follow Hofmann et al., [24]. Hypoxia proxies include [Re], [Mn], [U], [Cd], [Mo], δ¹⁵N, foraminiferan communities, and sedimentary laminations. Units for each proxy reflect the cited literature, which constrains the proxy to a specific oxygenation category.