Global Controls on the Carbon Isotopic Composition of Carbonate Platforms: Unrelated to the Glocal Carbon Cycle

对碳酸盐台地碳同位素组成的全球控制：与全球本地碳循环无关

• 批准号: 0825577
• 负责人: Peter Swart
• 金额: $ 30.79万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-15 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0825577&HistoricalAwards=false
• 关键词: Global; Controls; Carbon; Isotopic; Composition

The PI will test the hypothesis that over the past 25 yrs the variations in the carbon isotopic composition of marginal platform carbonates are not related to changes in the global carbon cycle as widely believed, but are instead related to the variations in global sea-level fluctuations and reflect the relative input of isotopically enriched carbonate produced in shallow water on the adjacent platforms. This hypothesis will be tested by analyzing the ä13C in bulk carbonate material sampled from DSDP and ODP sites cored adjacent to modern carbonate platforms. PI?s preliminary data has shown that (i) the ä13C of bulk carbonate sediments retrieved from such sequences cored at a number of sites adjacent to carbonate platforms such as the Bahamas can be correlated with each other, but that these variations are unrelated to changes in the global carbon cycle, and (ii) similar change can be recognized at locations in the Maldives and Australia over the past 10myrs. The PI will further investigate this phenomenon, by (i) extending the study to additional sites, (ii) extending the time range of samples back to 25 Ma, (iii) investigating the phenomenon over high amplitude glacio-eustatic changes in sea level, (iv) adding variations in the ä13C of organic material as a proxy of production from shallow-water carbonate platforms, and (v) developing a model combining the notion that input from shallow marine carbonate platforms alters the ä13C with changes in calcite-aragonite seas, and the varying burial of organic material. Broader Impacts: Recognition that other factors than the carbon cycle can control the ä13C of carbonates will improve the understanding of the history of the burial of organic carbon, but also lead to understanding of how such records relate to the present anthropogenic experiment of increasing the pCO2 of the atmosphere and transferring carbon from the organic to inorganic reservoirs. The project will support a Ph.D. thesis as well as the interaction of undergraduates, high-school students, and high-school teachers in the geochemical laboratories at RSMAS.

PI将检验这样一个假设，即在过去25年中，边缘台地碳酸盐的碳同位素组成的变化并不像人们普遍认为的那样与全球碳循环的变化有关，而是与全球海平面波动的变化有关，并反映了邻近台地浅水中产生的同位素富集碳酸盐的相对输入。这一假设将通过分析从现代碳酸盐台地附近取芯的DSDP和ODP现场取样的散装碳酸盐材料中的Δ 13 C进行检验。派？的初步数据表明，（i）从邻近碳酸盐台地（如巴哈马）的一些地点取心的此类层序中提取的大量碳酸盐沉积物的Δ 13 C可以相互关联，但这些变化与全球碳循环的变化无关，（ii）在马尔代夫和澳大利亚的位置可以识别出过去1000万年的类似变化。PI将进一步调查这一现象，通过（i）将研究扩展到其他地点，（ii）将样本的时间范围扩展到25 Ma，（iii）调查海平面高幅度冰川-海平面变化的现象，（iv）增加有机物质的Δ 13 C变化，作为浅水碳酸盐台地生产的代理，以及（v）开发一个模型，结合以下概念：来自浅海碳酸盐台地的输入改变了Δ 13 C，方解石-文石海的变化以及有机物质埋藏的变化。更广泛的影响：认识到碳循环以外的其他因素可以控制碳酸盐的Δ 13 C，将提高对有机碳埋藏历史的理解，但也有助于理解这些记录与目前人为实验的关系，即增加大气中的pCO 2，并将碳从有机库转移到无机库。该项目将支持一个博士学位。论文以及本科生，高中生和高中教师在RSMAS地球化学实验室的互动。