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首页> 外文学位 >Causes and consequences of marine carbon burial: Examples from the Cretaceous Niobrara Formation and the Permian Brushy Canyon Formation .
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Causes and consequences of marine carbon burial: Examples from the Cretaceous Niobrara Formation and the Permian Brushy Canyon Formation .

机译：海洋碳埋藏的成因和后果：以白垩纪的尼布拉拉组和二叠纪的毛刷峡谷组为例。

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摘要

The stratigraphic record of the Phanerozoic provides key evidence of temporal changes in the global carbon cycle over the past 560 myr of Earth history. Measurements of carbon concentrations in ancient marine sediment, in conjunction with a chronological framework, provide a means to reconstruct burial flux history and, thus, evaluate mass exchange between surface reservoirs of the carbon cycle. The goal of this study is to evaluate the controls on carbon enrichment in ancient marine sediment and to constrain burial fluxes of the two major carbon-bearing components in marine depositional systems, organic and inorganic carbon.; The research is conducted through a series of case studies. The first addresses longterm oscillations in carbonate mineralogy through the Phanerozoic and modeling results suggest that on these timescales alkalinity changes, potentially derived from variations in riverine runoff, may have been an important aspect to the saturation state of carbonate minerals in seawater. The second study evaluates hypotheses of Milankovitch cyclicity in limestone-shale rhythms of the Upper Cretaceous. Application of spectral techniques to depositional rhythms demonstrates Milankovitch cyclicity and provides an orbital timescale for calculation of high-resolution accumulation rates. The third study evaluates chalk and marl facies changes and the potential linkage to sea level change in the Upper Cretaceous. The results suggest the need for revising reconstructions of sea level history based on hemipelagic facies. The fourth study attempts to discriminate between paleoceanographic hypotheses responsible for orbital-scale depositional rhythmicity in the Late Cretaceous. Stratigraphic, geochemical, and modeling evidence indicate oscillations in siliciclastic flux to offshore settings. The fifth study incorporates a geochemical model to evaluate the potential effect of widespread chalk deposition on the global carbon isotopic composition of marine waters in the Late Cretaceous. Changes in the global proportion of carbonate production may have significantly influenced the carbon isotopic signature of dissolved inorganic carbon and dampened positive carbon isotopic excursions associated with times of elevated organic carbon flux in the Upper Cretaceous. The final study examines the role of siliciclastic flux on organic carbon enrichment in the Late Permian. Organic enrichment is interpreted to reflect depositional condensation.
机译：火山生代的地层记录提供了过去560 myr地球历史上全球碳循环时间变化的关键证据。结合时间框架对古代海洋沉积物中碳浓度的测量提供了一种手段来重建埋藏通量历史，从而评估碳循环地表储层之间的质量交换。这项研究的目的是评估对古代海洋沉积物中碳富集的控制，并限制海洋沉积系统中有机和无机碳这两个主要含碳成分的埋藏通量。该研究是通过一系列案例研究进行的。第一部分通过发古生代论证了碳酸盐矿物学的长期振荡，模拟结果表明，在这些时间尺度上，可能源自河流径流变化的碱度变化可能已经成为海水中碳酸盐矿物饱和状态的重要方面。第二项研究评估了上白垩统石灰岩-页岩节律中Milankovitch周期性的假设。频谱技术在沉积节律中的应用证明了米兰科维奇的周期性，并为计算高分辨率累积速率提供了一个轨道时标。第三项研究评估了上白垩统的粉笔和泥灰岩相变化以及与海平面变化的潜在联系。结果表明需要修改基于半海相的海平面历史重建。第四项研究试图区分造成白垩纪晚期轨道尺度沉积节律的古海洋学假说。地层，地球化学和模型证据表明，硅碎屑流向海上环境的振荡。第五项研究纳入了地球化学模型，以评估白垩纪后期广泛的白垩沉积对全球海水碳同位素组成的潜在影响。全球碳酸盐产量比例的变化可能显着影响了溶解的无机碳的碳同位素特征以及与上白垩统有机碳通量升高时间相关的正碳同位素偏移。最终研究检验了硅质碎屑流对二叠纪晚期有机碳富集的作用。有机富集被解释为反映沉积的冷凝。

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  • 作者

    Locklair, Robert Eric.;

  • 作者单位

    Northwestern University.;

  • 授予单位 Northwestern University.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 515 p.
  • 总页数 515
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

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