Sea surface temperature estimation for sediment core MD95-2037

Sea surface temperatures (SST) and input of continental materials have been reconstructed from the study of the long-chain alkenones and n-alkanes, respectively, in a core located in the western side of the Mid-Atlantic Ridge (MD952037, 37°05'N 32°02'W, 2630 m depth). Both the long- and short-term variability recorded by the temperatures and the planktonic d18O are basically the same over the last 280 kyr, showing a clear glacial/interglacial evolution. Comparison with core SU90/08, located only 6° north and directly influenced by the cold polar waters associated with the polar front during glacial times, revealed different climatic conditions during glacial periods at both locations. Whereas core MD952037 recorded similar SST values during the last two glacial periods (ca. 14-15°C), the northern core displayed colder conditions during isotopic stage 2 (8-10°C) than in stage 6 (13-15°C). These results indicate the existence of a well-developed steep north-south gradient between 37 and 43°N during the last glacial period but not during stage 6, which suggests a southern expansion of the polar front during the last glacial maximum.本研究通过对大西洋中脊西侧一处岩芯（MD952037，北纬37°05'、西经32°02'，水深2630米）中的长链烯酮与正构烷烃分别开展分析，重建了海表温度（Sea Surface Temperature, SST）与陆源物质输入记录。过去28万年以来，海表温度与浮游氧同位素（planktonic d¹⁸O）所记录的长、短尺度气候变率基本一致，均呈现出清晰的冰期-间冰期演化特征。将本岩芯与仅位于其以北6°的SU90/08岩芯进行对比后发现，两者在冰期阶段的气候条件存在显著差异：该北部岩芯在冰期直接受极锋相关的寒冷极地水团影响。MD952037岩芯在末次两个冰期的海表温度值约为14~15℃，且二者较为接近；而北部的SU90/08岩芯在同位素阶段2（8~10℃）的温度较同位素阶段6（13~15℃）更低。上述结果表明，在末次冰期期间，北纬37°至43°之间存在显著的南北向温度梯度，而在同位素阶段6则无此现象，这暗示末次冰盛期时极锋发生了南向扩张。