IODP expedition 347: Baltic Sea basin paleoenvironment and biosphere
IODP expedition 347: Baltic Sea basin paleoenvironment and biosphere
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DOI：
10.5194/sd-20-1-2015
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发表时间：
2015-12-01
影响因子：
1.2
通讯作者：
Green, S.
中科院分区：
文献类型：
--
作者：
Andren, T.;Jorgensen, B. Barker;Green, S.
综合海洋钻探计划 (IODP) 考察了来自波罗的海不同环境的 347 个岩心沉积物，涵盖了最后一个冰期-间冰期周期。主要目的是研究波罗的海的地质发展与该地区极端气候变化的关系，包括冰盖变化以及温度、盐度和生物群落的重大变化。我们利用 Greatship Manisha 作为欧洲海洋研究钻探联盟 (ECORD) 的特定任务平台，从 9 个地点回收了 1.6 公里长的岩心，其中 4 个地点还额外进行了微生物学取心。这些地点覆盖了北海和大西洋的门户、波罗的海南部的几个次盆地、波罗的海中部的深海盆地以及北部的河口。斯堪的纳维亚冰盖的盛衰深刻地影响了波罗的海沉积物。在威克瑟利期，冰川的进展重塑了海底景观，并取代了第四纪早期的沉积物。当冰川退缩时，留下了由耕地、沙子和湖相粘土组成的复杂图案，盆地中的这些区域后来被厚厚的全新世富含有机质粘土沉积物覆盖。由于咸水波罗的海的分层水柱和经常出现的广泛缺氧，较深的盆地蕴藏着层状沉积物，这为高分辨率年代学研究提供了独特的机会。波罗的海是一个富营养化的内陆海，受到陆地径流和营养通量的强烈影响。今天记录的全新世沉积物深达 50m，并且受到有机质降解驱动的成岩蚀变的地球化学影响。许多岩心层序的甲烷含量高度过饱和，这导致岩心回收时发生强烈脱气。保守海水离子的深度分布仍然反映了末次冰期末期淡水粘土向全新世微咸泥的转变。间隙水化学的高分辨率采样和分析揭示了主要生物地球化学过程的密集矿化和分区。对沉积物中微生物细胞的定量分析得出了科学钻探记录以来最高的细胞密度。
The Integrated Ocean Drilling Program (IODP) expedition 347 cored sediments from different settings of the Baltic Sea covering the last glacial-interglacial cycle. The main aim was to study the geological development of the Baltic Sea in relation to the extreme climate variability of the region with changing ice cover and major shifts in temperature, salinity, and biological communities. Using the Greatship Manisha as a European Consortium for Ocean Research Drilling (ECORD) mission-specific platform, we recovered 1.6 km of core from nine sites of which four were additionally cored for microbiology. The sites covered the gateway to the North Sea and Atlantic Ocean, several sub-basins in the southern Baltic Sea, a deep basin in the central Baltic Sea, and a river estuary in the north.The waxing and waning of the Scandinavian ice sheet has profoundly affected the Baltic Sea sediments. During the Weichselian, progressing glaciers reshaped the submarine landscape and displaced sedimentary deposits from earlier Quaternary time. As the glaciers retreated they left a complex pattern of till, sand, and lacustrine clay, which in the basins has since been covered by a thick deposit of Holocene, organic-rich clay. Due to the stratified water column of the brackish Baltic Sea and the recurrent and widespread anoxia, the deeper basins harbor laminated sediments that provide a unique opportunity for high-resolution chronological studies.The Baltic Sea is a eutrophic intra-continental sea that is strongly impacted by terrestrial runoff and nutrient fluxes. The Holocene deposits are recorded today to be up to 50m deep and geochemically affected by diagenetic alterations driven by organic matter degradation. Many of the cored sequences were highly supersaturated with respect to methane, which caused strong degassing upon core recovery. The depth distributions of conservative sea water ions still reflected the transition at the end of the last glaciation from fresh-water clays to Holocene brackish mud. High-resolution sampling and analyses of interstitial water chemistry revealed the intensive mineralization and zonation of the predominant biogeochemical processes. Quantification of microbial cells in the sediments yielded some of the highest cell densities yet recorded by scientific drilling.