Placing the deep Baltic Sea sediment stratigraphy in a precise chronological framework: Improved paleoenvironmental studies and 14C reservoir age calibration

将波罗的海深部沉积物地层置于精确的年代框架中：改进的古环境研究和 14C 储层年龄校准

• 批准号: 502442046
• 负责人: Dr. Markus Czymzik
• 金额: --
• 依托单位: Leibniz-Institut für Ostseeforschung Warnemünde (IOW)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/502442046?language=en
• 关键词: Placing; deep; Baltic; Sea; sediment

Varying climate and human activity altered the Baltic Sea ecosystem and left their footprint in the physical, biological and chemical properties of its sediments. Particularly, the partly fine-laminated sediments from the deep basins are valuable archives of these changes, because of their sub-decadal resolution. Understanding the processes behind the recorded environmental changes requires (i) knowledge about their temporal progression, i.e. the exact timing of the succession of changes within an event and the time-span from event to event, and (ii) to put them in a regional to hemispheric context. This knowledge is for Baltic Sea sediments presently hampered due to centennial-scale chronological uncertainties. Therefore, utilizing the down to sub-decadal environmental information in deep Baltic Sea sediments necessitates their placement in an improved chronological framework. Globally common production rate variations of the cosmogenic radionuclides 10Be and 14C can provide a novel tool for constructing such a framework. A pilot 10Be time-series covering the Mid-Holocene enabled the synchronization of Baltic Sea sediments from the Western Gotland Basin to the absolute dated 14C production record from the IntCal20 calibration curve. This alignment reduced the existing centennial chronological uncertainties to ± 10-15 years. Within this proposal, we aim at the establishment of a continuous decadal-scale 10Be record from sediments of the Western Gotland Basin, as well as its alignment to the atmospheric 14C record for the complete brackish Littorina Stage of the Baltic Sea, i.e. the last 8000 years. In addition, the project will apply the common cosmogenic radionuclide production rate variations to synchronize the new 10Be record to existing cosmogenic radionuclide time-series from sediment and ice core archives in the Circum-Baltic region and across the Northern Hemisphere. Based on the improved chronological constraints, we will determine the progression of physical, chemical and biological proxy responses in Baltic Sea sediments associated with major environmental transitions at sub-decadal precision and place them into a regional to hemispheric context. Such investigations provide significantly improved constraints about possible temporal ranges and amplitudes of Baltic ecosystem responses to contrasting environmental forcing and allow us to better anticipate the effects of the anthropogenic climate change. In addition, comparing the new 10Be-based chronology with systematic offsets in existing 14C dates can enable us the construction of a 14C reservoir age calibration curve and reduce the presently centennial-scale uncertainties of radiocarbon dating in this archive to a few decades.

不同的气候和人类活动改变了波罗的海的生态系统，并在其沉积物的物理、生物和化学性质上留下了足迹。特别是，来自深盆地的部分细层状沉积物是这些变化的宝贵档案，因为它们具有亚十年的分辨率。要理解记录的环境变化背后的过程，需要(I)了解其时间进程，即一个事件内连续变化的确切时间和事件之间的时间跨度，以及(Ii)将它们放在区域到半球的背景下。这一知识适用于波罗的海沉积物，目前由于百年尺度的年代学不确定性而受阻。因此，利用波罗的海深海沉积物中向下到亚十年的环境信息，必须将其置于改进的年代学框架中。宇宙成因放射性核素10Be和14C的全球共同产生率变化可为构建这样一个框架提供新的工具。覆盖中全新世的Pilot 10Be时间序列使来自西部哥特兰盆地的波罗的海沉积物与IntCal20校准曲线的绝对日期14C生产记录同步。这一调整将现有的百年时间不确定度减少到±10-15年。在这项建议中，我们的目标是从西部哥特兰盆地的沉积物中建立连续的十年尺度10Be记录，并使其与波罗的海完整的微咸水Littorina阶段的大气14C记录保持一致，即过去8000年。此外，该项目将应用共同的宇宙成因放射性核素产生率变化，使新的10Be记录与来自环-波罗的海区域和整个北半球沉积物和冰芯档案的现有宇宙成因放射性核素时间序列同步。基于改进的年代学约束，我们将确定波罗的海沉积物中与重大环境转变相关的物理、化学和生物替代反应的进展，并将其置于区域至半球的背景下。这类调查大大改善了对波罗的海生态系统对不同环境强迫的反应可能的时间范围和幅度的限制，并使我们能够更好地预测人为气候变化的影响。此外，将新的基于10Be的年代学与现有14C年代学中的系统偏移量进行比较，可以构建14C储集层年龄校准曲线，并将该档案中目前百年尺度的放射性碳测年不确定度减少到几十年。