Biostratigraphy, Paleoceanography, and Community Dynamics of Siliceous Microfossils from the Silurian of the Canadian Arctic

9972845Noble本研究将资助志留系Cape Phillips Fm的地球化学和微古生物样本的收集。加拿大北极地区。这是美国和加拿大工作人员协同努力的一部分，目的是从重要的和偏远的剖面中提取最大数量的数据，这些数据以后可以综合起来，产生一个从晚奥陶世到早泥盆世的陆架边缘历史的全面故事。本项目的数据收集将解决三个具体问题：1。生物地层工具开发：研究者一直致力于开发奥陶系-志留系放射虫的生物地层方案，但缺乏对晚志留系剖面的独立年龄控制。菲利普斯角Fm。它拥有世界上保存最完好的志留纪放射虫，它的年龄很好地受到笔石的限制，它最有可能提供所需的年龄控制。2. 灭绝/多样化事件-放射虫的反应将在两次志留纪中期笔石灭绝和随后的多样化中进行研究。2、对灭绝期全岩无机碳和有机碳进行碳同位素分析，对非碳酸盐部分进行元素分析，寻找相关的地球化学特征。古生态中的硅质针状体——早前在晚奥陶世剖面中观察到，岩石质与硅质针状体的比例随海平面上升而变化。将结合物理地层学对针状体进行检查，以测试它们对当地海平面波动的敏感性。这些数据将与观察到的浮游生物群落和盆地历史的变化联系起来。

9972845Noble This study will fund the collection of geochemical and micropaleontological samples from the Silurian Cape Phillips Fm., Canadian Arctic. It is part of a coordinated effort between U. S. and Canadian workers to extract the maximum amount of data from important and remote sections that can later be synthesized to produce a comprehensive story of the shelf margin history from Later Ordovician-early Devonian time. The data collection in this project will address three specific problems:1. Biostratigraphic tool development-The investigator has been working towards developing a biostratigraphic scheme for Ordovician-Silurian radiolarians, but lacks independent age control on Late Silurian sections. The Cape Phillips Fm. has the best preserved Silurian radiolarians in the world, it is age is well constrained by graptolites, and it has the best possibility of providing the age control needed. 2. Extinction/diversification events- Radiolarian response will be examined across two mid Silurian graptolite extinctions and subsequent diversifications. Total organic Carbon, carbon isotope analysis of whole-rock inorganic and organic carbon, and elemental analysis of the non-carbonate fraction will be conducted across the extinction's to look for related geochemical signatures.3. Siliceous spicules in paleoecology-The percentage of lithistid to hexactinellid spicules has previously been observed to vary with sea level rise in Late Ordovician sections. Spicules will be examined in conjunction with the physical stratigraphy in order to test their sensitivity to local sea-level fluctuation. These data will be tied into changes observed in the plankton community and the basin history.