Burgess Shale-type deposits and the ichnology of fine-grained systems

伯吉斯页岩型（BS）矿床对重建显生宙初期生命的多样性和复杂性具有重要意义。缺氧的优势与BS沉积物有着内在的联系，这导致了一种有害的想法，即痕量化石不存在或太稀少，无法用于古生态重建或揭示宏观进化趋势。然而，在世界上大多数BS矿床中都记录了微量化石，他们的研究开始揭示寒武系生态和控制BS化石形成的古环境参数的重要信息lagerstätten。BS矿床的一个共同特征是氧胁迫；这种基本的生态控制作用体现在微量化石的大小范围、沉积物的渗透程度和分类组成上。然而，与这些矿床独特的地层学有关的其他控制因素似乎也发挥了重要作用，值得进一步探索。此外，人们越来越认识到，许多传统上被称为“未受生物扰动”的细粒地层实际上含有洞穴，这正在改变我们对细粒沉积系统的沉积动力学和生态学的理解。研究的目标是：(1)记录与BS矿床相关的虫群，并评估它们对提高我们对寒武系和早奥陶世生态学认识的潜力；(2)探索技术信息如何提供对环境参数和语音学叠印的见解；(3)探讨BS遗迹化石组合在宏观进化尺度上的意义；(4)细粒沉积体系框架下的BS区系。计划的活动包括：(1)在BS的各个地方进行实地考察；（二）修改收藏；(3)核心描述与解释；(4)建立全球BS矿床及相关细粒矿床的鱼类学数据库。这一调查的结果将允许：(1)在进化古生态背景下构建BS鱼动物群；(2)对选定的BS矿床进行微量化石、体化石、地层学和沉积学数据的整合；(3)比较世界范围内不同bs型鱼群，以更好地了解环境和进化控制因素；(4)通过地质年代对细粒系统的动物群进行校正，以适应早古生代泥质基质的非现实条件。这个项目将扩大我们对生态系统结构和功能的理解，通过增加一个技术层面的重建，完全基于对身体化石记录的分析。最后，最终目标是在全球和宏观进化的尺度上从BS lagerstätten中构建鱼群，以解决关于寒武纪大爆发的相互矛盾的观点，即可保存的人工制品或现代生活的大爆炸（即现代门）。

Burgess Shale-type (BS) deposits have been instrumental to reconstruct the diversity and complexity of life at the beginning of the Phanerozoic. The preponderancy of anoxia, as intrinsically related to BS deposits, has resulted in the detrimental idea that trace fossils were inexistent or too rare to be useful in paleoecologic reconstructions or to reveal macroevolutionary trends. However, trace fossils have been recorded in most BS deposits worldwide, and their study is starting to reveal crucial information about Cambrian ecology and paleoenvironmental parameters governing formation of BS fossil lagerstätten. A common feature of BS deposits is oxygen stress; this fundamental ecologic control is reflected in size range of trace fossils, penetration in the sediment, and taxonomic composition. However, other controls related to the unique taphonomy of these deposits seem to also have played a significant role and warrant further exploration. In addition, the growing realization that many fine-grained strata traditionally referred to as "unbioturbated" do in fact contain burrows is changing our understanding on the sedimentary dynamics and ecology of fine-grained depositional systems. The objectives are to: (1) document ichnofaunas associated with BS deposits, and evaluate their potential to improve our understanding of Cambrian and Early Ordovician ecology; (2) explore how ichnologic information provides insights into environmental parameters and taphonomic overprints; (3) address the significance of BS trace-fossil assemblages at a macroevolutionary scale; and (4) frame BS ichnofaunas within the context of fine-grained depositional systems. The activities planned include: (1) fieldwork in various BS localities; (2) revision of collections; (3) core description and interpretation; and (4) construction of a global database of ichnofaunas in BS deposits and related fine-grained deposits. The results of this investigation will allow: (1) framing BS ichnofaunas within an evolutionary paleoecology context; (2) integration of trace fossil, body fossil, taphonomic and sedimentologic data for the selected BS deposits; (3) comparison of different BS-type ichnofaunas worldwide to best understand environmental and evolutionary controls; and (4) calibration of ichnofaunas from fine-grained systems through geologic time to accommodate the anactualistic conditions of early Paleozoic muddy substrates. This project will expand our understanding of ecosystem structure and functioning by adding an ichnologic dimension to reconstructions based exclusively on the analysis of the body-fossil record. Finally, the ultimate goal is to frame ichnofaunas from BS lagerstätten at a global and macroevolutionary scale in order to address conflicting views of the Cambrian explosion, namely an artifact of preservability or the big bang of modern life (i.e. modern phyla).