Age determination and paleotemperatures of western Mediterranean Sea sediments@en

Sea surface temperature (SST) profiles over the last 25 kyr derived from alkenone measurements are studied in four cores from a W-E latitudinal transect encompassing the Gulf of Cadiz (Atlantic Ocean), the Alboran Sea, and the southern Tyrrhenian Sea (western Mediterranean). The results document the sensitivity of the Mediterranean region to the short climatic changes of the North Atlantic Ocean, particularly those involving the latitudinal position of the polar front. The amplitude of the SST oscillations increases toward the Tyrrhenian Sea, indicating an amplification effect of the Atlantic signal by the climatic regime of the Mediterranean region. All studied cores show a shorter cooling phase (700 years) for the Younger Dryas (YD) than that observed in the North Atlantic region (1200 years). This time diachroneity is related to an intra-YD climatic change documented in the European continent. Minor oscillations in the southward displacement of the North Atlantic polar front may also have driven this early warming in the studied area. During the Holocene a regional diachroneity propagating west to east is observed for the SST maxima, 11.5-10.2 kyr B.P. in the Gulf of Cadiz, 10-9 kyr B.P. in the Alboran Sea, and 8.9-8.4 kyr B.P. in the Thyrrenian Sea. A general cooling trend from these SST maxima to present day is observed during this stage, which is marked by short cooling oscillations with a periodicity of 730±40 years and its harmonics.本研究对横跨加的斯湾（大西洋）、阿尔沃兰海与第勒尼安海南部（西地中海）的东西向纬度断面上的4个岩芯展开分析，解析了基于长链烯酮（alkenone）测定得到的过去25千年海表温度（SST）剖面。研究结果表明，地中海区域对北大西洋的短期气候变化，尤其是与极锋纬度位置变化相关的事件，展现出显著的敏感性。海表温度振荡的振幅向第勒尼安海方向逐渐增强，表明大西洋气候信号在地中海区域气候体系的作用下得到了放大。所有供研究岩芯均显示，新仙女木事件（Younger Dryas, YD）的降温持续时长（700年）短于北大西洋地区观测到的1200年。该时间穿时性与欧洲大陆记录到的新仙女木事件内部的气候变化存在关联。北大西洋极锋向南迁移过程中的小幅振荡，或同样驱动了研究区域的此次早期升温。全新世（Holocene）期间，海表温度峰值出现的时间存在自西向东传递的区域穿时性：加的斯湾为11.5~10.2 kyr B.P.，阿尔沃兰海为10~9 kyr B.P.，第勒尼安海则为8.9~8.4 kyr B.P.。该阶段内，从上述海表温度峰值至现代整体呈现降温趋势，且伴随有周期为730±40年及其谐波的短期降温振荡。