RUI -- COLLABORATIVE RESEARCH: Integrated Stratigraphic Study of Cambrian-Ordovician Inner Shelf Facies of the Western United States

9973082Ripperdan晚寒武世劳伦斯台地无脊椎动物的周期性灭绝被归因于海平面变化和其他古海洋事件。这些假设是可验证的，但需要比目前可用的更精确和完整的生物地层学、沉积学和化学地层学数据集。对美国西部上寒武统和下奥陶统内陆架序列的彻底层序地层学分析将提供这样的数据集。亚米级的三叶虫、牙形刺和碳同位素采样将提供一个高度精细的年代地层框架，在其中测试动物群变化与海平面上升或下降和/或海洋翻转时间的假设一致性。此外，对西部(怀俄明州和蒙大拿州)和东部(美国西南部)古陆架构造的相对海平面曲线进行比较，将检验为晚寒武世和奥陶纪早期提出的众多海平面事件的有效性。

9973082RipperdanPeriodic extinctions of Laurentian platform invertebrates in the Late Cambrian have been attributed to changes in sea level and other paleoceanographic events. Such hypotheses are testable but require a more precise and complete biostratigraphic, sedimentologic, andchemostratigraphic data set than is currently available. A thorough sequence-stratigraphic analysis of Upper Cambrian and Lower Ordovician inner shelf successions in the western United States will provide such a data set. Sub-meter scale sampling for trilobites, conodonts, and Carbon isotopes will provide a highly-refined chronostratigraphic framework in which to test the posited coincidence of faunal change with times of sea level rise or fall and/or oceanic overturn. Additionally, comparison of relative sea level curves constructed for the western (Wyoming and Montana) and eastern (southwestern US) paleoshelves will test the validity of numerous eustatic events that have been proposed for the Late Cambrian and earliest Ordovician.