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

9972845诺贝尔这项研究将资助从志留纪菲利普斯角组收集地球化学和微体古生物样本，加拿大北极。 这是联合国和美国政府协调努力的一部分。S.和加拿大的工作人员从重要和偏远的部分提取最大量的数据，以后可以合成产生一个全面的故事，从晚奥陶世早期泥盆纪的陆架边缘的历史。 本项目的数据收集将解决三个具体问题：1。生物地层学工具开发-研究者一直致力于开发奥陶纪-志留纪放射虫的生物地层学方案，但缺乏对晚志留世剖面的独立年龄控制。 菲利普斯角组拥有世界上保存最完好的志留纪放射虫，其年龄受到笔石的很好限制，并且最有可能提供所需的年龄控制。 2.灭绝/多样化的事件-放射虫的反应将在两个中志留世笔石沉积和随后的多样化。 总有机碳、全岩无机碳和有机碳的碳同位素分析以及非碳酸盐部分的元素分析将在整个灭绝过程中进行，以寻找相关的地球化学特征。古生态学中的硅质骨针--在晚奥陶世剖面中，已观察到石针与六角针骨针的百分比随海平面上升而变化。 将结合物理地层学对针状体进行研究，以测试其对当地海平面波动的敏感性。 这些数据将与浮游生物群落和流域历史中观察到的变化联系起来。

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.