The Middle Eocene Climatic Optimum (MECO) was a ~400,000-year-long global warming event which occurred ~40 million years ago and interrupted the Eocene's long-term cooling trend. We investigated silicate weathering dynamics during the MECO by measuring lithium isotope ratios and elemental ratios (Li/Ca, Al/Ca, Mn/Ca, Sr/Ca, Rb/Ca) from a suite of open-ocean carbonate-rich sediments.

This dataset contains d7Li, 187Os/188Os, Li/Ca, Al/Ca, Mn/Ca, Sr/Ca, Rb/Ca data from bulk carbonates from two ODP sites (1263 - South Atlantic and U1333 - Equatorial Pacific); and d7Li, 187Os/188Os data from bulk carbonates from ODP site 959 (Equatorial Atlantic). Data from sites 1263 and U1333 include ages tied to the 2020 Geologic Time Scale. Trace element ratios were determined by quadrupole ICP-MS, and δ7Li were obtained using a Nu Plasma 3 MC-ICP-MS, at the LOGIC laboratories at UCL. 187Os/188Os were previously published in van der Ploeg et al. (2018) Middle Eocene greenhouse warming facilitated by diminished weathering feedback, Nature Communications, 9, 1-10 (https://doi.org/10.1038/s41467-018-05104-9).