Late Pleistocene variations of the diatom productivity in the high-latitude Atlantic: convergence shifts, nutrient availability, and rapid climate variability

该项目将研究亚北极大西洋(U1304站点)硅质古生产力的变异性及其与过去450KYR期间发生的气候、生物地球化学和水文事件的关系。U1304站点(约53？N，33？W)代表了高纬度大西洋晚上新世和更新世环境条件的高沉积记录。通过探索硅藻群落在晚更新世发生的长期和快速的变化(&lt；103年)，我们将研究与北大西洋气候历史有关的硅藻产量的变化以及硅质生物和钙质生物的生产转变。蛋白石、主量元素和痕量元素将有助于描述生产力的变化和亚北极辐合的纬向迁移。对U1304站点富含硅藻的层状沉积物的长序列的研究将提供关于亚极地大西洋气候和水文变异性的超高分辨率信息。所提出的多参数方法将有助于理解高纬度北大西洋大气和海洋变化的相对阶段性，这对于我们理解全球气候变化在轨道到千年时间尺度上的机制至关重要。

This project will address the variability of the siliceous paleoproductivity in the Subarctic Atlantic (Site U1304) and its relation to climatic, biogeochemical and hydrographic events occurred during the last 450 kyr. Site U1304 (ca. 53ºN, 33ºW) represents a high-sedimentation record of late Pliocene and Pleistocene environmental conditions in the high-latitude Atlantic. By exploring the long-term and the rapid variations (<103 yr) in the diatom community occurred during the late Pleistocene, we will address the variations of diatom production related with North Atlantic climate history and the shift between production of siliceous and calcareous organisms. Opal, and major and trace elements will help to characterize variations of productivity and latitudinal migration of the Subarctic Convergence. The study of long sequences of diatom-rich laminated sediments at Site U1304 will deliver ultra-high resolution information on climate and hydrography variability of the subpolar Atlantic. The proposed multi-parameter approach will contribute to the comprehension of the relative phasing of atmospheric and oceanic changes in the high-latitude North Atlantic that are central to our understanding of the mechanisms of global climate change on orbital to millennial timescales.