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首页> 外文学位 >Late Paleozoic glaciation and ice sheet collapse over western and eastern Gondwana: Sedimentology and stratigraphy of glacial to post-glacial strata in western Argentina and Tasmania, Australia.
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Late Paleozoic glaciation and ice sheet collapse over western and eastern Gondwana: Sedimentology and stratigraphy of glacial to post-glacial strata in western Argentina and Tasmania, Australia.

机译：冈瓦纳西部和东部晚古生代冰川作用和冰盖塌陷：阿根廷西部和澳大利亚塔斯马尼亚岛的冰期至冰期后地层的沉积学和地层学。

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摘要

The late Paleozoic ice age (LPIA; 345-280 million years ago) provides the last complete record of a major deglaciation on a vegetated Earth, and therefore can serve as a proxy for Earth's inevitable transition out of its present glaciated state. This project analyzes climate change during and following the LPIA using two different approaches:;1) Detailed sedimentology analyses of five glacially-influenced formations in Argentina and Australia in order to determine the size and thermal regime of glaciers during the LPIA.;2) An investigation of massive volcanism along the Panthalassan margin of Gondwana as a source of CO2 that may have contributed to the end of the LPIA and to two ensuing extinction events.;During the LPIA, glaciation occurred over the supercontinent Gondwana, and resulting glacial deposits are found in South America, Africa, Antarctica, India, and Australia. This project focuses on glacial and post-glacial outcrops in western Argentina and Tasmania, Australia that were deposited in western and eastern Gondwana, respectively. A study of outcrops from these two regions enables characterization and comparison of the early stages of the LPIA (when Argentina was glaciated) and when glaciation was at its peak (when Tasmania was glaciated). Glacial and post-glacial deposits are analyzed using sedimentologic field techniques to interpret depositional events, thin section analysis to determine the micromorphology of the deposits, and mineralogical (x-ray diffraction, or XRD) and elemental (x-ray fluorescence, or XRF) analysis to differentiate sediment sources and determine the oxygenation of the environments.;Atmospheric CO2 fluctuations have been linked to ice volume fluctuations during the LPIA, and CO2 input from massive volcanism is considered a major driver of the Middle and Late Permian extinctions (261 and 250 million years ago, respectively). Although these events were previously considered as unrelated, volcanism along the subducting Panthalassan margin of Gondwana occurred throughout both the deglaciation of the LPIA and the Permian extinctions. Therefore, this study will also explore the hypothesis that Panthalassan margin volcanism influenced both deglaciation and the Permian extinctions. Ultimately this dissertation will improve the understanding of climate change during and following the LPIA and inform predictions for when and how Earth will experience deglaciation in the future.
机译：古生代末期的冰河时代（LPIA； 345-2.8亿年前）提供了植被地球上主要冰消作用的最新完整记录，因此可以作为地球不可避免地从当前冰川状态过渡的代表。该项目使用两种不同的方法分析了LPIA期间和之后的气候变化：; 1）对阿根廷和澳大利亚的五个受冰川影响的地层进行了详细的沉积学分析，以确定LPIA期间冰川的大小和热状况。; 2）调查冈瓦纳州Panthalassan边缘的大规模火山活动，可能是导致LPIA终结和随后发生的两次灭绝事件的CO2来源;在LPIA期间，超大陆冈瓦纳大陆发生了冰川沉积，并发现了冰川沉积物在南美，非洲，南极洲，印度和澳大利亚。该项目的重点是分别位于冈多纳西部和东部的阿根廷西部和澳大利亚塔斯马尼亚州的冰川和冰川后露头。对这两个地区露头的研究可以表征和比较LPIA的早期阶段（阿根廷被冰川化时）以及冰川达到顶峰时（塔斯马尼亚州被冰川化）。使用沉积学现场技术分析冰川和冰川后沉积物，以解释沉积事件，进行薄片分析以确定沉积物的微观形态，以及矿物学（X射线衍射或XRD）和元素学（X射线荧光或XRF）分析，以区分沉积物来源并确定环境的含氧量。LPIA期间大气中的CO2波动与冰量波动有关，大规模火山活动的CO2输入被认为是中，二叠纪灭绝的主要驱动力（261和250）一百万年前）。尽管这些事件以前被认为是无关的，但在LPIA的冰消作用和二叠纪的灭绝过程中，冈瓦纳俯冲的Panthalassan边缘都发生了火山活动。因此，本研究还将探讨Panthalassan边缘火山作用影响冰消作用和二叠纪灭绝的假说。最终，本文将增进对LPIA期间和之后对气候变化的了解，并为未来地球何时以及如何经历冰消的预测提供依据。

著录项

  • 作者

    Henry, Lindsey C.;

  • 作者单位

    The University of Wisconsin - Milwaukee.;

  • 授予单位 The University of Wisconsin - Milwaukee.;
  • 学科 Geology.;Sedimentary Geology.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 312 p.
  • 总页数 312
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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