Isotopic Studies of Late Paleozoic Cyclical Sedimentary Deposits

研究目标是制定一个详细的， 晚古生代的半连续同位素记录， 2）同位素的应用 从地层学到古环境分析 确定晚古生代旋回成因的目标 沉积矿床 这两个目标是不可分割的， 了解沉积环境对于 解读同位素记录 该研究采用了严格的 避免对成岩蚀变材料取样的措施。 腕足动物的外壳从页岩基质中分离出来，嵌入在 环氧树脂和薄片。 这些薄片的照片 在阴极发光和平面光下拍摄，并用作 从薄片中提取不发光方解石样本的地图 用一把牙签 电子探针元素分析 选择外壳用于确认阴极射线发光的使用 来识别被改变的外壳 该研究将集中在一个 有限的腕足动物种类，从而最大限度地减少或 消除了生物对同位素组成的影响。 沉积学和古生物学数据也将被 为古环境提供了独立的证据 变化 PI将分析宾夕法尼亚晚期的腕足动物 新墨西哥州、俄克拉荷马州、堪萨斯和密苏里州的矿床进行检查 同位素组成的横向变化1）测试 利用~（13）C对比地层的可能性; 2）确定 海洋古温度的横向和时间梯度， 化学. PI还将扩展同位素地层学的范围， 晚古生代在得克萨斯州研究古环境变化， 得克萨斯州的陆缘海，并提供一个详细的， 精确的同位素地层学可作为标准 晚古生代化石中稳定同位素的其他研究。 项目将采用创新技术分析全球 地球历史时期的环境变化 今天的。 这次气候变化的全球变化分析 变化可能会揭示有关原因，比率和 气候变化的后果。

Research objectives are the development of a detailed and semi-continuous isotopic record for the late Paleozoic Era and the testing of its accuracy, and 2) the application of isotope stratigraphy to paleoenvironmental analysis with the specific goal of determining the origin of late Paleozoic cyclical sedimentary deposits. These two objectives are inseparable since understanding the depositional environment is vital for interpreting the isotopic record. The study employs stringent measures to avoid sampling diagenetically altered material. Brachiopod shells are separated from shale matrix, embedded in epoxy, and thin-sectioned. Photographs of these thin sections are taken under cathodoluminescence and plane light, and used as a map to sample non-luminescent calcite from the thin section with a dental pick. Electron microprobe elemental analysis of select shells is used to confirm the use of cathodoluminescence to identify altered shell. The study will concentrate on a limited number of brachiopod species, thereby minimizing or eliminating biological effects on isotopic composition. Sedimentological and paleontological data will also been collected, providing independent evidence for paleoenvironmental change. PIs will analyze brachiopods from late Pennsylvanian deposits in New Mexico, Oklahoma, Kansas and Missouri to examine lateral variations in isotopic composition 1) to test the possibility of using 13C to correlate strata and 2) to define lateral and temporal gradients in ocean paleotemperature and chemistry. PIs will also extend the isotope stratigraphy of the late Paleozoic in Texas to examine paleoenvironmental changes in the epicontinental seas of Texas and to provide a detailed and accurate isotope stratigraphy which can be used as the standard for other studies of stable isotopes in late Paleozoic fossils. Project will apply innovative techniques to analysis of global environmental change in a period of earth history much like today's. Analyses of global change in this time of climatic change may reveal information about the causes, rates and consequences of climate change.