Modern sea surface productivity and temperature estimations off Chile as detected by coccolith accumulation rates

• Modern regional gradients of SST and productivity offshore Chile were detected.
• The present-day SST reconstruction is based on coccolith accumulation rates (CARs).
• There are five key coccolithophore species which record SST information.
• CARs reflect the regional upwelling conditions along the Chilean continental margin.

Recent coccoliths from 74 surface sediment samples recovered from the southeastern Pacific off Chile were examined quantitatively to investigate modern regional gradients of sea surface productivity and temperature. All findings are based on coccolith accumulation rates. Therefore an approach was designed to estimate recent sedimentation rates based on 210Pb and bulk chemistry analyses of the same set of surface samples. Highest total coccolith accumulation rates were found off north-central Chile, where seasonal upwelling takes place. Based on a multiple linear regression between calculated coccolith accumulation rates and World Ocean Atlas derived sea surface temperatures, a calibration model to reconstruct annual average temperatures of the uppermost 75 m of the water column is provided. The model was cross-validated and the SST estimates were compared with SST observed and SST estimates based on diatoms and planktonic foraminifera, showing a good correlation.