Sustained Warmth in Low Latitudes during the Late Miocene-Pliocene: A High-Resolution Record from the Northern South China Sea

Abstract:

The late Miocene-Pliocene period represents a warmer climate state prior to the northern hemisphere glaciations that occurred 2-3 Ma. A few existing sea surface temperature (SST) records from the Western Pacific warm pool and South China Sea, at a low resolution, suggest warmer SSTs during this epoch. However, the magnitude of the warmth, as compared to modern conditions, as well as the temperature fluctuations within this period, remains largely elusive. In this study, we reconstruct biomarker-based high-resolution SST records during the late Miocene-Pliocene period from a sediment core retrieved from the Qiongzhou Strait, northern South China Sea. The records reveal the details of the SST variability over this period. Within the late Miocene-Pliocene, a few notable relatively cooling periods at 4.3 Ma, 5.5 Ma, could be identified, which appear to correspond to global benthic d18O changes. Overall, our results suggest that SSTs was indeed warmer than today and that the SST fluctuations within this period was probably modulated by orbital changes.