Rhenium-osmium abundance and isotope data synopsis obtained for the Nakatengu Creek and Soashibetsu-gawa OAE1a (oceanic anoxic event 1a) Sections, Hokkaido, Japan, and the Sauzeries OAE1a Section, France. Sample collection August 2021 principally funded by NSF-NERC award. For the Nakatengu Creek and Soashibetsu-gawa sections approximately 2000 m stratigraphically thick Cretaceous section mainly comprises organic bearing siltstone, siliceous mudstone, sandstone and interbedded tuff horizons. The Re-Os data is published in Youjuan Li et al. ,Radioisotopic chronology of Ocean Anoxic Event 1a: Framework for analysis of driving mechanisms.Sci. Adv.10,eadn8365(2024).DOI:10.1126/sciadv.adn8365 For the Sauzeries OAE1a section, a 20 m interval comprises interbedded marl-dominated, marl-limestone and fine grained clays. This data is currently not published