Exploring the potential of clumped isotope thermometry on coccolith‐rich sediments as a sea surface temperature proxy

Understanding past changes in sea surface temperatures (SSTs) is crucial; however, existing proxies for reconstructing past SSTs are hindered by unknown ancient seawater composition (foraminiferal Mg/Ca and δ18O) or reflect subsurface temperatures (TEX86) or have a limited applicable temperature range ( ). We examine clumped isotope (Δ47) thermometry to fossil coccolith‐rich material as an SST proxy, as clumped isotopes are independent of original seawater composition and applicable to a wide temperature range and coccolithophores are widespread and dissolution resistant. The Δ47‐derived temperatures from <63, <20, <10, and 2–5 μm size fractions of two equatorial Pacific late Miocene‐early Pliocene sediment samples (c1; c2) range between ∼18 and 29°C, with c1 temperatures consistently above c2. Removing the >63 μm fraction removes most nonmixed layer components; however, the Δ47 …