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首页> 外文期刊>Paleoceanography >North Atlantic Evidence for a Unipolar Icehouse Climate State at the Eocene-Oligocene Transition
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North Atlantic Evidence for a Unipolar Icehouse Climate State at the Eocene-Oligocene Transition

机译：北大西洋证据在苗族 - 寡世人转型的单极冰水屋气氛

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摘要

Earth's climate transitioned from a warm unglaciated state to a colder glaciated “icehouse” state during the Cenozoic. Extensive ice sheets were first sustained on Antarctica at the Eocene-Oligocene Transition (EOT, ~34 Ma), but there is intense debate over whether Northern Hemisphere ice sheets developed simultaneously at this time or tens of millions of years later. Here we report on EOT-age sediments that contain detrital sand from Integrated Ocean Drilling Program Sites U1406 and U1411 on the Newfoundland margin. These sites are ideally located to test competing hypotheses of the extent of Arctic glaciation, being situated in the North Atlantic's “iceberg alley” where icebergs, calved from both the Greenland Ice Sheet today, and the Laurentide Ice Sheet during the Pleistocene, are concentrated by the Labrador Current and deposit continentally derived detritus. Here we show that detrital sand grains present in these EOT-aged sediments from the Newfoundland margin, initially interpreted to represent ice rafting, were sourced from the midlatitudes of North America. We find that these grains were transported to the western North Atlantic by fluvial and downslope processes, not icebergs, and were subsequently reworked and deposited by deep-water contour currents on the Newfoundland margin. Our findings are inconsistent with the presence of extensive ice sheets on southern and western Greenland and the northeastern Canadian Arctic. This contradicts extensive bipolar glaciation at the EOT. The unipolar icehouse arose because of contrasting latitudinal continental configurations at the poles, requiring more intense Cenozoic climatic deterioration to trigger extensive Northern Hemisphere glaciation.
机译：在新生代，地球的气候从温暖的无冰川状态转变为寒冷的冰川“冰库”状态。在始新世-渐新世过渡期（EOT，~34 Ma），南极洲首次形成了广泛的冰盖，但关于北半球冰盖是在此时还是在数千万年后同时形成的，存在着激烈的争论。在这里，我们报告了纽芬兰边缘U1406和U1411综合海洋钻井项目现场的EOT年龄沉积物，其中含有碎屑砂。这些地点位于北大西洋的“冰山小巷”中，是检验北极冰川化程度的相互矛盾的假设的理想地点。在这里，今天从格陵兰冰盖和更新世期间从劳伦斯蒂德冰盖上崩解下来的冰山被拉布拉多海流集中，并沉积了来自大陆的碎屑。在这里，我们表明，纽芬兰边缘的EOT年龄沉积物中存在的碎屑砂粒，最初被解释为代表冰漂流，来自北美中纬度地区。我们发现，这些颗粒通过河流和下坡过程而不是冰山被输送到北大西洋西部，随后在纽芬兰边缘被深水等高线流改造和沉积。我们的发现与格陵兰岛南部和西部以及加拿大北极东北部广泛冰盖的存在不一致。这与EOT广泛的两极冰川作用相矛盾。单极冰库的形成是因为两极的纬度大陆结构形成对比，需要更强烈的新生代气候恶化来触发广泛的北半球冰川作用。

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  • 来源
    《Paleoceanography》 |2019年第7期|共15页
  • 作者

    James F. Spray; Steven M. Bohaty; Andrew Davies; Ian Bailey; Brian W. Romans; Matthew J. Cooper; James A. Milton; Paul A. Wilson;

  • 作者单位

    National Oceanography Centre Southampton University of Southampton Waterfront Campus Southampton UK;

    National Oceanography Centre Southampton University of Southampton Waterfront Campus Southampton UK;

    Halliburton Abingdon UK;

    Camborne School of Mines and Environment and Sustainability Institute College of Engineering Mathematics and Physical Sciences University of Exeter Penryn Campus Penryn UK;

    Department of Geosciences Virginia Tech Blacksburg VA USA;

    National Oceanography Centre Southampton University of Southampton Waterfront Campus Southampton UK;

    National Oceanography Centre Southampton University of Southampton Waterfront Campus Southampton UK;

    National Oceanography Centre Southampton University of Southampton Waterfront Campus Southampton UK;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 海洋学;
  • 关键词

    North Atlantic; Evidence for; Unipolar Icehouse;

    机译：北大西洋;非糖冰屋的证据;

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