Ichnofossils as Environmental Proxies

化石作为环境指标

• 批准号: RGPIN-2020-05138
• 负责人: Gingras, Murray
• 金额: $ 4.44万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=717152
• 关键词: Ichnofossils; Environmental; Proxies

An ichnofossil also referred to as trace fossil is fossil evidence, such as fossil-burrows or -tracks, of an animal's living behaviours. Ichnofossils are used to understand animal (vertebrate and invertebrate) distributions in the rock record and for sedimentary rocks to better understand environments of sediment deposition. This proposal outlines research that will establish relationships between ichnofossil characteristics (e.g. size, diversity and distributions of trace fossils) and sedimentary environment parameters. We will seek to provide semiquantitative and quantitative proxies for sedimentary parameters including salinity, oxygenation and sedimentation rate. Salinity Stress: Brackish water represents a continuum between fresh and normal marine water. Trace fossil assemblages associated with sediments deposited in brackish water are characterized by specific characteristics: (1) low diversity of trace fossil forms; (2) preponderance of morphologically simple burrow structures; (3) diminutive trace fossils; and, (4) some ichnospecies present in high densities. The use of these criteria has been repeatedly demonstrated and confirmed in modern studies, but only a few of these have attempted to associate absolute salinity with ichnological characteristics. Additional research is essential to refine our understanding of the influence of salinity on infaunal communities. Oxygen Stress: Oxygen deficiency is most characteristic in deep, and/or sheltered environments. Normally, oxygen stress is accompanied by the slow accumulation of fine-grained sediments. Some modern and many rock-record studies have shown that low dissolved-oxygen concentrations in depositional waters induce a noticeable reduction in the size of the burrows observed and the diversity of ichnogenera decreases markedly. Sedimentation Stress: Conditions related to the stresses induced by high sedimentation rates include high current velocities (limiting filter feeding) and episodic sedimentation. In modern settings, these sedimentary challenges limit bioturbation to motile worm-generated structures and, more rarely, anenomes, crustaceans and robust bivalves dominate energetic settings. Turbid conditions, which may accompany high sedimentation rates, also exert a significant environmental stress on filter-feeding animals. Providing quantified ichnological proxies for the above three physico-chemical parameters is the basis of my Discovery Grant. The research projects used to address the proposed research span geological time using datasets from the Cambrian through to modern and laboratory-based studies. Multiple methods are proposed, including visualization techniques (X-ray, CT, hyperspectral imaging), compositional assessments (XRF, XRD, ICPMS, petrography), and field techniques (outcrop analysis, modern sedimentary environments).

一种被称为痕量化石的鱼类化石是化石证据，例如化石或轨道，表明了动物的生活行为。鱼类化石用于理解岩石记录中的动物（脊椎动物和无脊椎动物）分布，并用于沉积岩石，以更好地了解沉积物沉积的环境。该提案概述了将建立Ichnoposs特征（例如，痕量化石的多样性和分布）与沉积环境参数之间建立关系的研究。我们将寻求为沉积参数提供半定量和定量代理，包括盐度，氧合和沉降率。 盐度胁迫：咸水代表新鲜和正常海水之间的连续体。与沉积在咸水中的沉积物相关的痕量化石组合的特征是特定特征：（1）痕量化石形式的低多样性； （2）形态上简单的洞穴结构的优势； （3）小型化石； （4）一些高密度的疫苗。这些标准的使用已在现代研究中反复证明和证实，但其中只有少数试图将绝对盐度与流行特征相关联。进一步的研究对于完善我们对盐度对臭殖社区的影响的理解至关重要。 氧气应激：缺氧缺乏在深处和/或庇护所环境中最有特征。通常，氧应激伴随着细粒沉积物的缓慢积累。一些现代和许多岩石记录的研究表明，沉积水中的低溶解氧浓度可引起观察到的洞穴大小的明显减少，而孔氏菌的多样性显着降低。 沉积应力：与高沉积速率引起的应力有关的条件包括高电流速度（限制过滤器进食）和情节沉积。在现代环境中，这些沉积物挑战将生物扰动限制在动力虫生成的结构上，更少的是厌食症，甲壳类动物和强大的双壳类动物主导了充满活力的环境。可能伴随高沉积速率的浑浊条件也对喂食动物施加了明显的环境压力。 为上述三个物理化学参数提供量化的量化替代方案是我发现赠款的基础。用于解决拟议研究的研究项目涵盖了从寒武纪到现代和基于实验室的研究的数据集。提出了多种方法，包括可视化技术（X射线，CT，高光谱成像），组成评估（XRF，XRD，ICPMS，岩石学）和现场技术（露头分析，现代沉积环境）。