Generation of a Late Cambrian-Early Carboniferous conodont-based ?18O curve: Paleozoic climates, phosphate ?18O diagenesis, and conodont paleobiology

晚寒武世-早石炭世基于牙形刺的 ?18O 曲线的生成：古生代气候、磷酸盐 ?18O 成岩作用和牙形刺古生物学

• 批准号: 0545799
• 负责人: Kenneth MacLeod
• 金额: $ 12.5万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0545799&HistoricalAwards=false
• 关键词: Generation; Late; Cambrian; Early; Carboniferous

Generation of a late Cambrian-Early Carboniferous conodont-based d18O curve: Paleozoic climates, phosphate d18O diagenesis, and conodont paleobiologyKen MacLeod and Raymond L. EthingtonUniversity of MissouriEAR-0545799ABSTRACTExisting temperature estimates for the early Paleozoic have large errors and/or are likely affected by strong diagenetic biases. This uncertainty compromises efforts to use conditions of the early Paleozoic as a natural climate experiment for times when controlling variables (e.g., pCO2, solar luminosity, terrestrial vegetation, paleogeography) differed markedly from the later portions of the Phanerozoic up to the modern. To begin to address this problem, PIs will measure d18O values of up to 1000 early to mid-Paleozoic conodont samples. Because phosphate oxygen, especially in material with relatively high crystallinity like the lamellar hydroxyfluorapatite of conodont elements, is diagenetically more robust than carbonate oxygen, d18O measurements of bioapatite has great potential to advance knowledge of Paleozoic temperatures. Analytical advances have reduced the required sample size and increased sample throughput without compromising accuracy or precision. In addition, for this proposal PIs have access to thousands of samples that are already processed. Coupled with our analytical capabilities, this sample base provides an unparalleled opportunity to efficiently conduct a d18O survey from a range of taxa representing different regions, different times, and different states of preservation. Samples analyzed will come primarily from the University of Missouri conodont collection but will also include specimens from the large collections spanning the Late Ordovician housed at Ohio State University and from those spanning the Cambrian-Ordovician boundary housed at Missouri State University. With these samples PIs will 1) document temporal patterns in conodont d18O across ~160 million years at multiple sites with better than million-year average resolution, 2) compare d18O values with visual (cathodoluminescence, color alteration index, reflected light, and SEM) and geochemical (ICP-MS) observations of preservation to test empirically how robust conodont d18O values are, and 3) compare d18O values of various conodont taxa within multiple samples to search for consistent interspecies differences.

晚寒武世-早石炭世牙形刺d18O曲线的生成：古生代气候、磷矿d18O成岩作用和牙形刺古生物学【摘要】现有的早古生代温度估计存在较大误差和/或可能受到强烈成岩偏差的影响。当控制变量（如二氧化碳分压、太阳光度、陆生植被、古地理）与显生宙晚期到现代显著不同时，这种不确定性影响了利用早古生代条件作为自然气候实验的努力。为了开始解决这个问题，pi将测量多达1000个早到中古生代牙形石样品的d18O值。由于磷酸盐氧，特别是在具有相对高结晶度的材料中，如牙形石元素的层状羟基氟磷灰石，在成岩作用上比碳酸盐氧更坚固，生物磷灰石的d18O测量具有很大的潜力，可以推进对古生代温度的认识。分析的进步减少了所需的样本量，增加了样品吞吐量，而不影响准确性或精度。此外，对于该提案，pi可以访问已经处理过的数千个样品。再加上我们的分析能力，这个样本库提供了一个无与伦比的机会，可以有效地对代表不同地区、不同时间和不同保存状态的一系列分类群进行d18O调查。分析的样本将主要来自密苏里大学的牙形石收集，但也将包括来自俄亥俄州立大学收藏的晚奥陶世和密苏里州立大学收藏的寒武纪-奥陶纪边界的大型收藏的标本。利用这些样品，pi将1)在多个地点以优于百万年平均分辨率记录约1.6亿年牙形石d18O的时间模式，2)将d18O值与视觉（阴极发光、色变指数、反射光和SEM）和地球化学（ICP-MS）保存观测结果进行比较，以经验检验牙形石d18O值的可靠性。3)比较多个样本中不同牙形石分类群的d18O值，寻找一致的种间差异。