NOAA/WDS Paleoclimatology - Dominican Republic Late Miocene Fossil Coral Stable Isotope Data

Reconstructions of Pliocene sea-surface temperature (SST) gradients and thermocline depths suggest that the zonal temperature gradient of the tropical Pacific was distinct from the modern. However, the nature of any El Nino-Southern Oscillation (ENSO) variability superimposed on this mean state is difficult to determine. We developed monthly resolved multidecadal stable isotopic time series from an extremely well preserved central Caribbean coral dating to the Miocene-Pliocene transition, prior to closure of the Central American Seaway (CAS). Paleoceanographic modeling suggests that the flow of water associated with El Nino and La Nina events through the CAS allowed Caribbean corals to record the ENSO-related SST anomalies. Spectral analysis of coral oxygen isotope ratios reveals periodicities similar to modern ENSO signatures, suggesting that ENSO-like variability characterized the Miocene-Pliocene transition.

上新世（Pliocene）海表温度（sea-surface temperature, SST）梯度与温跃层深度的重建结果表明，热带太平洋的纬向温度梯度与现代存在显著差异。然而，叠加于该平均状态之上的任何厄尔尼诺-南方涛动（El Niño-Southern Oscillation, ENSO）变率的本质，仍难以确定。本研究从保存极为完好的、形成于中美洲海道（Central American Seaway, CAS）关闭前的中新世-上新世过渡期的加勒比海中部珊瑚中，构建了月分辨率的多年代际稳定同位素时间序列。古海洋学模拟结果显示，厄尔尼诺与拉尼娜事件相关的水体流经中美洲海道（CAS），使得加勒比海珊瑚能够记录与ENSO相关的海表温度异常。对珊瑚氧同位素比值的频谱分析显示，其周期特征与现代ENSO信号特征相似，表明类ENSO变率是中新世-上新世过渡期的典型特征。