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

9973082里珀丹晚寒武世劳伦阶平台无脊椎动物的周期性灭绝被归因于海平面的变化和其他古海洋事件。 这些假设是可以检验的，但需要比目前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层序进行彻底的层序地层分析，将提供这样一个数据集。 三叶虫，牙形刺和碳同位素的亚米尺度采样将提供一个高度精炼的年代地层框架，以测试假设的一致性动物群的变化与海平面上升或下降和/或海洋翻转的时间。 此外，西部（怀俄明州和蒙大拿州）和东部（美国西南部）的古大陆架构建的相对海平面曲线的比较将测试的有效性，已提出的许多海平面升降事件的晚寒武世和最早的奥陶纪。

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.