The Importance of Diagenesis upon the C, S, and B Isotopic Composition of Carbonates: Implication for Reading the Rock Record

成岩作用对碳酸盐 C、S 和 B 同位素组成的重要性：对解读岩石记录的启示

• 批准号: 1537727
• 负责人: Peter Swart
• 金额: $ 49.69万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1537727&HistoricalAwards=false
• 关键词: Importance; Diagenesis; upon; Isotopic; Composition

The study of diagenesis in carbonates uses classic tools of C and O isotopes and trace elements and now there are a number of additional geochemical proxies and methods that are potentially available. The PI proposes to examine the influence of diagenetic process upon the isotopic systematics of two of these proxies, sulfur and boron, as well as take a new look at factors controlling the carbon isotopes of organic material and inorganic carbonates. This work will be carried out mainly in Plio-Pleistocene sediments using material collected by shallow water and land drilling as well as the ODP. Material will include unaltered samples as well as those affected by diagenesis involving freshwater and marine fluids. In addition to the more Modern samples, the PI will also study B within older, Neoproterozoic, sections which have been proposed by some to have both retained their original geochemistry and by others to have been influenced by diagenesis. The PI will test one of the most established criteria for determining that the carbon isotopic signals are original, rather than diagenetic, mainly the presence of a correlation between the carbon isotopes of organic and inorganic material, which has recently been questioned. The work has implications for paleoclimatic and paleoceanographic studies. Other broader impacts include graduate and undergraduate training, outreach to high school students and collaboration with the Miami-based Creative Learning and Engagement Opportunities program.The PI suggests that the study of diagenesis in carbonate rocks using geochemistry is at an exciting point. Not only have the classic tools of C and O isotopes and trace elements continued to improve in terms of their accuracy, sensitivity and microsampling ability, but there are a number of additional geochemical proxies and methods of applying these proxies potentially available. Some of these proxies need to be refined while others wait to be discovered and developed. The PI will examine the influence of diagenetic process upon the isotopic systematics of two of these, sulfur and boron, as well as take a new look at factors controlling the carbon isotopes of organic material and inorganic carbonates. This work will be carried out mainly in young carbonate sediments (Plio-Pleistocene) deposited on the flanks and surface of carbonate platforms using material collected by shallow water and land drilling as well as the ODP. Material will include supposedly unaltered samples as well as materials which have been unequivocally affected by diagenesis involving freshwater and marine fluids. The rationale for this proposal is that the isotopes of C, B, and S have already been used over a wide ranges of geological time scales to interpret changes in the Earth?s geochemical systems. Such work is being undertaken without some of the fundamental understanding of the processes which may alter these proxies. In addition to the more Modern samples, the PI will also study B within Neoproterozoic sections which have been proposed by some to have both retained their original geochemistry and by others to have been influenced by diagenesis. Finally, one of the most established criteria for determining that the carbon isotopic signals are original, rather than diagenetic, mainly the presence of a correlation between the carbon isotopes of organic and inorganic material, has recently been questioned. Hence there is a need to establish to what extent such correlations indicate that the signals are original or whether in fact the presence of a correlation indicates that diagenesis has actually occurred. The work has implications for paleoclimatic and paleoceanographic studies. Other broader impacts include graduate and undergraduate training, outreach to high school students and collaboration with the Miami-based Creative Learning and Engagement Opportunities program.

碳酸盐成岩作用的研究使用 C 和 O 同位素和微量元素的经典工具，现在还有许多其他潜在可用的地球化学代理和方法。该项目负责人建议研究成岩过程对其中两种替代物（硫和硼）同位素系统的影响，并重新审视控制有机物质和无机碳酸盐碳同位素的因素。这项工作将主要在上更新世沉积物中进行，使用浅水和陆地钻探以及 ODP 收集的材料。材料将包括未改变的样品以及受涉及淡水和海洋流体的成岩作用影响的样品。除了更现代的样本外，PI 还将研究更古老的新元古代剖面中的 B，一些人提出这些剖面保留了其原始地球化学性质，另一些人则提出受到成岩作用的影响。 PI 将测试最确定的标准之一，以确定碳同位素信号是原始的，而不是成岩的，主要是有机和无机材料的碳同位素之间是否存在相关性，这一点最近受到质疑。这项工作对古气候和古海洋学研究具有重要意义。其他更广泛的影响包括研究生和本科生培训、对高中生的推广以及与迈阿密创意学习和参与机会计划的合作。PI 表明，利用地球化学对碳酸盐岩成岩作用的研究正处于一个令人兴奋的时刻。不仅 C 和 O 同位素和微量元素的经典工具在准确性、灵敏度和微量采样能力方面不断提高，而且还有许多其他地球化学代理和应用这些代理的方法可能可用。其中一些代理需要完善，而另一些则等待被发现和开发。该项目负责人将研究成岩过程对其中两种物质（硫和硼）同位素系统的影响，并重新审视控制有机物质和无机碳酸盐碳同位素的因素。这项工作将主要在碳酸盐台地侧面和表面沉积的年轻碳酸盐沉积物（上更新世）中进行，使用浅水和陆地钻探以及 ODP 收集的材料。材料将包括据称未改变的样品以及明确受到涉及淡水和海洋流体的成岩作用影响的材料。该提议的基本原理是，C、B 和 S 的同位素已在广泛的地质时间尺度上用于解释地球地球化学系统的变化。此类工作的开展缺乏对可能改变这些代理的流程的一些基本了解。除了更现代的样本外，PI 还将研究新元古代剖面中的 B，一些人提出这些剖面保留了其原始地球化学性质，另一些人则提出受到了成岩作用的影响。最后，确定碳同位素信号是原始信号而不是成岩信号的最确立的标准之一，主要是有机和无机材料的碳同位素之间存在相关性，最近受到质疑。因此，需要确定这种相关性在多大程度上表明信号是原始的，或者事实上相关性的存在是否表明成岩作用已经实际发生。这项工作对古气候和古海洋学研究具有重要意义。其他更广泛的影响包括研究生和本科生培训、对高中生的推广以及与迈阿密创意学习和参与机会计划的合作。