Trace Fossils, Ichnofabrics and Problematic Sedimentary Structures at the Proterozoic-Cambrian Transition: Implications for the Early Evolution of Animals and their Habitats

元古代-寒武纪过渡时期的痕迹化石、遗迹构造和有问题的沉积结构：对动物及其栖息地早期进化的影响

• 批准号: 0074021
• 负责人: Mary Droser
• 金额: $ 14万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0074021&HistoricalAwards=false
• 关键词: Trace; Fossils; Ichnofabrics; Problematic; Sedimentary

Trace Fossils, Ichnofabrics, and Problematic Sedimentary Structures at theProterozoic-Cambrian Transition: Implications for the Early Evolution ofAnimals and Their HabitatsMary DroserEAR-0074021The Cambrian radiation was the most significant event in the history of complex animals. Critical to this understanding this event is the record of the burrows, tracks and trails made by soft-bodied animals and preserved in the fossil record; these are known as trace fossils. Additionally, animals mix or churn the sediment and produce a mottled fabric known as ichnofabric. The importance of the ichnological record is exemplified by the fact that the Precambrian-Cambrian boundary is defined on the basis of trace fossils (Narbonne et al., 1987). This research project will be the first detailed systematic field analysis of the correlation of changes in ichnofabrics, discrete trace fossils and mat-related sedimentary structures across the Precambrian-Cambrian boundary. For the proposed project PI has selected four sections located in Newfoundland, Namibia, South Australia and western United States. These sections provide a complete range ofshallow-water siliciclastic facies. Examination of terminal Proterozoic trace fossils has applications to questions of the appearance of bilaterian animals. In addition, the rise in bioturbation (sediment mixing) at the terminal Proterozoic-Cambrian boundary interval profoundly and irreversibly changed the benthic habitat. One consequence was the reduction in microbial binding of siliciclastic sediments, which seem to have occurred in fully marine settings. These microbial mats may have been responsible for the unusual style of preservation of the soft-bodied Ediacara-type faunas. It is also likely that unusual sedimentary structures owe their formation and preservation to these mats. To date there has been no detailed examination of the changes in ichnofabric and discrete trace fossils to constrain the notion of the disappearance of a 'taphonomic window'

元古代-寒武纪过渡时期的痕迹化石、地质构造和有问题的沉积结构：对动物及其栖息地早期进化的影响玛丽·德罗塞尔EAR-0074021寒武纪辐射是复杂动物历史上最重要的事件。对这一事件的理解至关重要的是软体动物留下的洞穴、足迹和小径的记录，这些记录保存在化石记录中；这些被称为痕迹化石。 此外，动物混合或搅拌沉积物并产生一种称为 ichnofabric 的斑驳织物。 前寒武纪-寒武纪边界是根据遗迹化石确定的（Narbonne et al., 1987），这一事实说明了地貌记录的重要性。该研究项目将是对跨前寒武纪-寒武纪边界的物质结构、离散痕迹化石和垫相关沉积结构变化相关性的首次详细系统现场分析。 对于拟议的项目，PI 选择了位于纽芬兰、纳米比亚、南澳大利亚和美国西部的四个部分。这些剖面提供了完整的浅水硅质碎屑相。对元古代末期遗迹化石的检查可应用于解决两侧对称动物的外观问题。 此外，元古界末期-寒武纪边界区间生物扰动（沉积物混合）的增加深刻且不可逆转地改变了底栖栖息地。结果之一是硅质碎屑沉积物的微生物结合减少，这似乎发生在完全海洋环境中。这些微生物垫可能是软体埃迪卡拉型动物群不同寻常的保存方式的原因。不寻常的沉积结构的形成和保存也很可能归功于这些垫子。迄今为止，还没有对物质结构和离散痕迹化石的变化进行详细检查来限制“埋藏学窗口”消失的概念