This data set contains authigenic uranium concentrations from ODP Site 198-1208 that span ~2 to 330 thousand years ago. These data give insight into glacial-interglacial changes in sedimentary redox chemistry at the drill site.

Methods:Sample depths, ages, and Th concentrations have been previously published for the both the late Quaternary (Abell et al., 2023; Kinsley et al., 2022) and Pliocene-early Pleistocene (Abell et al., 2021). Because the late Quaternary data are based on measurements of distinct isotopes of U/Th (238U and 232Th) and not bulk concentrations of these elements, the lithogenic correction for these samples is made using activity ratios. Here we assume an activity ratio of 0.5. While the (U/Th)lith activity ratio for Pacific sediments is typically assumed to be higher at 0.7 (Henderson & Anderson, 2003), use of this value would produce negative Uauth concentrations. A ratio of 0.5 does not lead to negative Uauth concentrations, and is consistent with estimates for other ocean basin (Henderson & Anderson, 2003).In order to make consistent comparison within a site across time, we convert this (U/Th)lith activity ratio to a concentration ratio (0.16125) for calculating Uauth concentrations within the 2.5–4.5 Ma window. This value is only slightly lower than if we adopted the U concentration of upper continental crust (2.8 ppm; Taylor & McLennan, 1995) and the Th concentration of fine-grained dust (14 ppm; McGee et al., 2016).We note that any value higher than this would also produce negative Uauth concentrations in this interval, lending confidence in our selected lithogenic (U/Th) ratio.