Spatial biases in oxygen-based Phanerozoic seawater temperature reconstructions

作者：Alexandre Pohl, Thomas W. Wong Hearing, Arnaud Brayard, Ethan L. Grossman, Michael M. Joachimski, Guillaume Le Hir, Thomas Letulle, Daniel J. Lunt, Mathieu MARTINEZ, Emmanuelle Pucéat, Guillaume Suan, Paul J. Valdes, Yannick Donnadieu · 发表于：Earth and Planetary Science Letters · 年份：2025 · DOI：10.1016/j.epsl.2025.119418 · 被引用次数：4 · 研究领域：Paleontology and Stratigraphy of Fossils、Hydrocarbon exploration and reservoir analysis、Methane Hydrates and Related Phenomena

Stable oxygen isotopes (δ 18 O) are routinely used to reconstruct sea-surface temperatures (SSTs) in the geological past, with mineral δ 18 O values reflecting a combination of the temperature and oxygen isotope composition of seawater (δ 18 O sw ). Temporal variation of mean-ocean δ 18 O sw is usually accounted for following estimates of land-ice volume. Spatial variations in δ 18 O sw , however, are often neglected or corrected using calibrations derived from the present-day or recent past. Geochemical methods for constraining δ 18 O sw and isotope-enabled general circulation model (GCM) simulations are still technically challenging. This lack of constraints on ancient δ 18 O sw is a substantial source of uncertainty for SST reconstructions. Here we use the co-variation of δ 18 O sw and seawater salinity, together with GCM simulations of ocean salinity, to propose estimations of spatial variability in δ 18 O sw over the Phanerozoic. Sensitivity tests of the δ 18 O sw -salinity relationship and climate model, and comparison with results of isotope-enabled GCMs, suggest that our calculations are robust at first order. We show that continental configuration exerts a primary control on δ 18 O sw spatial variability. Complex ocean basin geometries in periods younger than 66 Ma lead to strong inter-basinal contrasts in δ 18 O sw . Latitudinal SST gradients may be steeper than previously suggested during most of the Mesozoic and Cenozoic. This work has limitations, with δ 18 O sw ...