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d18O曲线的形成：古生代气候、磷酸盐d18O成岩作用和牙形刺古生物学密苏里大学Ken MacLeod和Raymond L.ethington EAR-0545799ABSTRACT对早古生代的现有温度估计存在较大误差和/或可能受到强烈的成岩偏向的影响。这种不确定性影响了利用早古生代的条件作为自然气候实验的努力，当控制变量(例如，二氧化碳、太阳光度、陆地植被、古地理)与显生界晚期到现代明显不同时。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刺样本的d18O值。由于磷酸盐氧，特别是在结晶度相对较高的物质中，如牙形刺元素的片状羟基氟磷灰石，在成岩作用上比碳酸盐氧更健壮，因此生物磷灰石的d18O测量在提高古生代温度方面具有巨大的潜力。在不影响准确度或精密度的情况下，分析技术的进步减少了所需的样本量，增加了样品量。此外，对于这项提案，采购经理可以访问数千个已经处理过的样本。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，可以有效地从代表不同地区、不同时间和不同保存状态的一系列分类群中进行d18O调查。分析的样本将主要来自密苏里大学的牙形刺标本，但也将包括俄亥俄州立大学收藏的跨越晚奥陶世的大量标本，以及密苏里州立大学收藏的跨越寒武纪-奥陶系界线的标本。通过这些样本，PI将1)以高于百万年平均分辨率的分辨率记录多个地点近1.6亿年来牙形刺d18O的时间模式，2)将d18O值与目测(阴极发光、颜色变化指数、反射光和扫描电子显微镜)和地球化学(ICP-MS)保存观察结果进行比较，以经验地测试牙形刺d18O值的健壮性，以及3)比较多个样本中不同牙形刺分类群的d18O值，以寻找一致的物种间差异。

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.