High-resolution UK'37 sea surface temperature reconstruction in the southwestern Atlantic Ocean during the Holocene

Modern sea surface temperatures (SST) were assessed using the alkenone calibration index (U-37(K '); SST-U-37(K ')) values from twenty-one core-top sediment samples collected along the Southwestern Atlantic Ocean and validated by comparison with satellite-derived SSTs. The SST-U-37(K ') values revealed an annual signal between 28 and 30 degrees S and a winter signal (83% of the region samples) between 30 and 34 degrees S, with deviations falling within the U-37(K ') calibration error range. The paleotemperature (SST-U-37(K ')) reconstruction through the Holocene was performed using two high-resolution marine sediment cores from 33 to 34 degrees S latitude band. Millennial-scale variations dominate most of the SST-U-37(K ') results with changes up to similar to 6 degrees C. Considering the modern ocean circulation dynamics, the SST-U-37(K') in our records likely stems from the combined influence of the Subtropical Shelf Front (STSF) position and the interaction between the warm, salty, and nutrient-poor Subtropical Shelf Water (STSW) and the cold, fresh, and nutrient-rich Subantarctic Shelf Water (SASW). Our SST-U-37(K') results also suggest that the northernmost position limit of the STSF reached around 33 degrees S during the mid-to-late Holocene, while after similar to 5500 cal yr BP the Plata Plume Water became the dominant influence on the regional SST-U-37(K') signal. Spectral analyses revealed statistically significant oscillations of similar to 8600 and similar to 2250 years in record MDBT 557, and similar to 5300 and similar to 2600 years in record MDBT 561 which suggests the influence of Southern Westerly Winds (SWW) on the SST-U-37(K'), and therefore, on the STSF dynamic through the Holocene.