Reconstructing Holocene temperature and salinity variations in the western Baltic Sea region : A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)
Reconstructing Holocene temperature and salinity variations in the western Baltic Sea region : A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)
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DOI：
10.5194/bg-14-5607-2017
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发表时间：
2017-12
期刊：
影响因子：
4.9
通讯作者：
U. Kotthoff;J. Groeneveld;J. Ash;A. Fanget;N. Q. Krupinski;O. Peyron;A. Stepanova;J. Warnock;N. V. Helmond;B. Passey;O. Clausen;O. Bennike;E. Andrén;W. Granoszewski;T. Andrén;H. Filipsson;M. Seidenkrantz;C. Slomp;T. Bauersachs
中科院分区：
文献类型：
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作者：
U. Kotthoff;J. Groeneveld;J. Ash;A. Fanget;N. Q. Krupinski;O. Peyron;A. Stepanova;J. Warnock;N. V. Helmond;B. Passey;O. Clausen;O. Bennike;E. Andrén;W. Granoszewski;T. Andrén;H. Filipsson;M. Seidenkrantz;C. Slomp;T. Bauersachs
摘要。在综合海洋钻探计划远征347期间从波罗的海恢复的沉积物记录为研究中欧和北欧的古环境和气候变化提供了一个独特的机会。这些研究有助于更好地了解大陆架海和封闭盆地的环境参数是如何变化的。在这里，我们提出了一个基于多个代理的重建古温度（海洋和陆地），古盐度和古生态系统的变化从小带（站点M0059）在过去~ 8000年，并评估了无机和有机为基础的代用物在这一特定背景下的适用性。所有盐度指标（硅藻、水生生物、介形虫、二醇指数）表明，直到~ 7400 calyr BP，小带的湖泊环境才发生。因此可以排除当时与卡特加特海峡的联系，但与波罗的海地区的直接联系可能已经存在。过渡到咸海阶段的半咸水海洋条件（更咸和更温暖）发生在~ 200年内，与卡特加特的联系在~ 7400 cal - yr BP之后建立起来。这里使用的不同盐度代用指标在盐度的相对变化方面通常显示出相似的趋势，但往往不能对盐度进行定量估计。水温的重建与特别大的不确定性和绝对值的变化有关，在底层水域可达8°C，在地表水可达16°C。关于利用有孔虫Mg / Ca比值重建温度，在较深的间隔中，自生涂层的污染可能导致温度的高估。基于脂质古温度计（长链二醇指数和TEXL86）的结果差异可以部分地解释为现代代理校准在沉积环境中经历了重大变化的间隔中的应用：在我们的研究中，从淡水到海洋条件的变化。我们的研究表明，在沿海环境和边缘海域应用和解释代用物时，必须特别小心，因为在这些地方，水团条件可能比在开阔的海洋环境中经历更快、更大的变化。因此，使用大量独立代理的方法可以进行更可靠的古环境评估。
Abstract. Sediment records recovered from the Baltic Sea during Integrated Ocean Drilling Program Expedition 347 provide a unique opportunity to study paleoenvironmental and climate change in central and northern Europe. Such studies contribute to a better understanding of how environmental parameters change in continental shelf seas and enclosed basins. Here we present a multi-proxy-based reconstruction of paleotemperature (both marine and terrestrial), paleosalinity, and paleoecosystem changes from the Little Belt (Site M0059) over the past ∼ 8000 years and evaluate the applicability of inorganic- and organic-based proxies in this particular setting. All salinity proxies (diatoms, aquatic palynomorphs, ostracods, diol index) show that lacustrine conditions occurred in the Little Belt until ∼ 7400 cal yr BP. A connection to the Kattegat at this time can thus be excluded, but a direct connection to the Baltic Proper may have existed. The transition to the brackish–marine conditions of the Littorina Sea stage (more saline and warmer) occurred within ∼ 200 years when the connection to the Kattegat became established after ∼ 7400 cal yr BP. The different salinity proxies used here generally show similar trends in relative changes in salinity, but often do not allow quantitative estimates of salinity. The reconstruction of water temperatures is associated with particularly large uncertainties and variations in absolute values by up to 8 °C for bottom waters and up to 16 °C for surface waters. Concerning the reconstruction of temperature using foraminiferal Mg / Ca ratios, contamination by authigenic coatings in the deeper intervals may have led to an overestimation of temperatures. Differences in results based on the lipid paleothermometers (long chain diol index and TEXL86) can partly be explained by the application of modern-day proxy calibrations to intervals that experienced significant changes in depositional settings: in the case of our study, the change from freshwater to marine conditions. Our study shows that particular caution has to be taken when applying and interpreting proxies in coastal environments and marginal seas, where water mass conditions can experience more rapid and larger changes than in open ocean settings. Approaches using a multitude of independent proxies may thus allow a more robust paleoenvironmental assessment.