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首页> 外文学位 >Arctic lake sediments as records of climate change using rock magnetic properties and paleomagnetic data.
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Arctic lake sediments as records of climate change using rock magnetic properties and paleomagnetic data.

机译：北极湖的沉积物利用岩石的磁性和古磁性数据作为气候变化的记录。

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摘要

Two lakes were studied in detail for rock magnetic properties: Lake El'gygytgyn, a crater lake formed 3.6Ma in the Far Eastern Russian Arctic, and Heimerdalsvatnet, a Holocene coastal lake located in the Lofotens off the coast of northern Norway. These two lakes have vastly different environmental histories, the former a terrestrial lake formed from a meteor impact and never covered by continental ice sheets whereas the latter went from a coastal marine setting to a completely lacustrine environment due to isostatic rebound and sea level fluctuations. Their differences are considerable, however they provide the opportunity to compare Arctic lake systems to discern similarities and differences in their magnetic properties for application to future climatic investigations.;Paleomagnetic measurements and down-core magnetic susceptibility were performed at the GFZ German Research Centre for Geosciences in Potsdam for Lake El'gygytgyn and at the Laboratoire de paleomagnetisme sedimentaire at ISMER for Heimerdalsvatnet. Rock magnetic properties were measured at the University of Massachusetts Amherst, Institute of Rock Magnetism, and/or Trinity College. These measurements included: magnetic susceptibility, hysteresis parameters, Curie temperatures, and low-temperature magnetic behavior. Imaging of magnetite grains was also performed.;Magnetic susceptibility measurements in Lake El'gygytgyn suggested a correlation between glacials (interglacials) and low (high) susceptibility. The large range in susceptibility indicated there could be magnetite dissolution. The first study supported this hypothesis with evidence at low temperatures (10-35K) of minerals such as siderite, rhodochrosite, and/or vivianite which could form from iron released during dissolution. Marine Isotope Stage 31 was investigated for rock magnetic properties that could continue to support or oppose findings from the first study. It was determined the presence of siderite only occurred in interglacial periods whereas its absence (and probably presence of vivianite) related to glacial periods, indicating more reduced environments during glacials versus interglacials.;Heimerdalsvatnet paleomagnetic data from the marine environment (lower part of the core) revealed scattered directions whereas data from the upper part of the core (lacustrine environment) showed better consistency. Rock magnetic measurements showed some variation downcore, however the measurements are not dependable since the amount of paramagnetic material was overwhelming compared to any ferromagnetic mineral present.
机译：对两个湖泊的岩石磁学性质进行了详细研究：El'gygytgyn湖，一个在远东俄罗斯北极形成3.6Ma的火山口湖，和Heimerdalsvatnet，一个位于挪威北部沿海Lofotens的全新世沿海湖。这两个湖的环境历史迥然不同，前者是流星撞击形成的陆地湖，从未被大陆冰盖覆盖，而后者由于等静回弹和海平面波动而从沿海海洋环境变成了完全湖相环境。它们之间的差异很大，但是它们提供了比较北极湖系统的机会，以辨别其磁特性的相似性和差异，以应用于未来的气候研究。；古磁测量和下层磁化率是在GFZ德国地球科学研究中心进行的在波兹坦的El'gygytgyn湖和在ISMER的Healerdalsvatnet的Lapotomagnetisme沉积工场。岩石磁性能是在麻省大学阿默斯特分校，岩石磁学研究所和/或三一学院测量的。这些测量包括：磁化率，磁滞参数，居里温度和低温磁性能。还对磁铁矿颗粒进行了成像。； El'gygytgyn湖的磁化率测量表明，冰川（间冰期）与低（高）磁化率之间存在相关性。磁化率的大范围表明可能存在磁铁矿溶解。第一项研究提供了在低温（10-35K）下由溶解过程中释放出的铁形成的菱铁矿，菱锰矿和/或堇青石等矿物的证据。对海洋同位素第31期进行了研究，研究其岩石磁性能可以继续支持或反对第一项研究的发现。已确定菱铁矿的存在仅在冰期之间发生，而铁菱铁矿的缺失（可能存在白云母）与冰川期有关，表明冰期与冰期之间的环境减少程度更大;;来自海洋环境的Heimerdalsvatnet古地磁数据（岩心下部） ）揭示了散布的方向，而来自岩心上部（湖泊环境）的数据显示出更好的一致性。岩石磁性测量结果显示出一些向下变化，但是测量结果并不可靠，因为与存在的任何铁磁性矿物相比，顺磁性材料的数量非常庞大。

著录项

  • 作者

    Murdock, Kathryn J.;

  • 作者单位

    University of Massachusetts Amherst.;

  • 授予单位 University of Massachusetts Amherst.;
  • 学科 Geology.;Geophysics.;Paleoclimate science.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 129 p.
  • 总页数 129
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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