POWRE: Biostratigraphy, Paleoceanography, and Community Dynamics of Silceous Microfossils From The Silurian of The Canadian Arctic

POWRE：加拿大北极地区志留纪硅质微化石的生物地层学、古海洋学和群落动态

• 批准号: 9870431
• 负责人: Paula Noble
• 金额: $ 1.5万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-10-01 至 1999-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9870431&HistoricalAwards=false
• 关键词: POWRE; Biostratigraphy; Paleoceanography; Community; Dynamics

9870431NobleThe Silurian is an interesting time in earth's history. Following the end-Ordovician crisis, benthic marine faunas underwent a period of community restructuring and diversification. Plankton likewise underwent faunal turnovers and diversification, yet there has been little work on the plankton community as a whole and their relationship to changes in the physical environment. One of the least understood groups of Silurian plankton are radiolarians. They are exclusively marine organisms whose highest abundance and diversity is usually associated with ocean settings and complex watermass structure. In cherts, they commonly are the bulk constituents in the rock, and in distal shelf settings, they can be found intermittently in great abundance. Radiolarians are a potentially valuable resource for understanding the paleoceanographic history of early Paleozoic marine basins providing their range and distribution can be closely constrained and calibrated with better studied fossil groups.This study proposes to examine radiolarians and siliceous sponge spicules from the Cape Phillips Fm., Canadian Arctic, and to integrate these data with graptolite biostratigraphy and geochemistry in order to get a better picture of the dynamics of Silurian plankton communities. This work may eventually feed into research proposed by Canadian colleagues on the organic-walled microfossils and conodonts. Three specific problems will be addressed:1. Biostratigraphic tool development - The investigator has been working towards developing a biostratigraphic scheme for the Ordovician-Silurian, but lacks independent age control on Late Silurian sections. The Cape Phillips Fm., has the best preserved Silurian radiolarians in the world, its age is well constrained by graptolites, and 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 diversification. Carbon isotope analysis of the non-carbonate fraction will be conducted across the extinctions 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.

志留纪是地球历史上一个有趣的时期。 在奥陶纪末期危机之后，底栖海洋动物群经历了一个群落重组和多样化的时期。 浮游生物同样经历了区系更替和多样化，但对浮游生物群落作为一个整体及其与物理环境变化的关系的研究很少。 志留纪浮游生物中最不为人所知的类群之一是放射虫。 它们完全是海洋生物，其最高丰度和多样性通常与海洋环境和复杂的水团结构有关。 在硅质岩中，它们通常是岩石中的主体成分，在远陆棚环境中，它们可以间歇性地大量存在。 放射虫是了解早古生代海盆古海洋学历史的一个潜在的有价值的资源，它们的范围和分布可以通过更好的研究化石群来密切限制和校准。加拿大北极地区，并将这些数据与笔石生物地层学和地球化学相结合，以便更好地了解志留纪浮游生物群落的动态。 这项工作最终可能会为加拿大同事提出的关于有机壁微化石和牙形刺的研究提供信息。 三个具体问题将被解决：1。生物地层工具开发-研究人员一直致力于开发奥陶纪-志留纪的生物地层方案，但缺乏对晚志留世剖面的独立年龄控制。 菲利普斯角地层，拥有世界上保存最完好的志留纪放射虫化石，其时代受到笔石的良好制约，最有可能提供所需的年龄控制.灭绝/多样化的事件-放射虫的反应将在两个中志留世笔石灭绝和随后的多样化。 将对各区块的非碳酸盐组分进行碳同位素分析，以寻找相关的地球化学特征。古生态学中的硅质骨针-在奥陶纪晚期的剖面中，已经观察到石骨针与六角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。