Collaborative Research: Stratigraphic, geochemical, and paleobiological tests of the co-evolution of multicellular life and environment in the late Ediacaran Period

美国马里兰大学的Alan J. Kaufman、弗吉尼亚理工学院的Shuhai Xiao和俄罗斯国立大学的Dima Grazhdankin将对西伯利亚北部偏远地区以碳酸盐岩为主的Khatyspyt组进行一项全盆地的地层学、地球化学和古生物学研究。这个单位的埃迪卡拉纪化石在细粒碳酸盐中得到了显著的保存，这为地球上最早的动物提供了解剖学和古生态学的视角。鉴于埃迪卡拉纪生物群可能需要大量的游离氧来维持代谢活动，我们假设它们的分布可能与环境条件有关，并提出了通过对整个哈蒂斯特沉积盆地多个等价剖面的碳和硫同位素的高分辨率时间序列分析以及氧化还原条件的其他生物、元素和同位素指标来验证这种联系的方法。Khatyspyt组包含了一系列独特的以碳酸盐为寄主的埃迪卡拉纪生物，以及碳质大化石、小贝壳化石、微量化石和浮游微化石，这些生物都分布在奥列内克河、霍博苏卡河和勒拿河沿岸，厚度达450米。该研究结果将为软组织保存现象提供新的见解，增加埃迪卡拉-寒武纪过渡的生态分辨率，并为地球最早的后生动物及其起源、多样化和最终灭绝的海洋的历史提供重要的约束。本研究的主要目的是测试埃迪卡拉纪在复杂多细胞生命中的短暂地质实验是否受到浅海环境氧化状态的控制。拟议中的研究将与俄罗斯的同事建立新的国际合作关系，并需要在西伯利亚北部的北极圈以上进行为期两个月的实地考察。来自两所美国院校的研究生将陪同pi实地考察，为他们提供加强学习的机会，促进科学和文化交流。

Stratigraphic, Geochemical, and Paleobiological Tests of the Co-Evolution of Multicellular Life and Environment in the Late Ediacaran Period Alan J. Kaufman, University of Maryland Shuhai Xiao, Virginia Polytechnic Institute and State University Dima Grazhdankin, Russian Academy of Sciences The PIs will undertake a basin-wide stratigraphic, geochemical, and paleobiological study of the carbonate-dominated Khatyspyt Formation in remote northern Siberia. Ediacaran fossils in this unit are remarkably preserved in fine-grained carbonates, promising a much enhanced anatomical and paleoecological view of Earths earliest animals. Insofar as the Ediacaran biota may have required abundant free oxygen to sustain metabolic activities, we hypothesize that their distribution may track environmental conditions, and propose tests of this linkage through high resolution time-series analyses of carbon and sulfur isotopes in multiple equivalent sections across the Khatyspyt depositional basin as well as other biological, elemental and isotopic indicators of redox conditions. The Khatyspyt Formation contains a wide range of unique carbonate-hosted Ediacaran organisms, as well as carbonaceous macrofossils, small shelly fossils, trace fossils and planktonic microfossils all in a single, 450-m-thick continuous succession cropping out along the Olenek, Khorbosuonka and Lena rivers. Results of the study should provide insights to the phenomenon of soft tissue preservation, increase the ecological resolution of the Ediacaran-Cambrian transition, and provide important constraints on the history of Earths earliest metazoans and the oceans in which they originated, diversified, and ultimately perished. The primary aim of this field and laboratory based proposal is to test whether the geologically brief Ediacaran experiment in complex multicellular life was controlled by the oxidation state of shallow marine environments. The proposed research will establish a new international collaboration with colleagues in Russia, and require two month-long field seasons above the Arctic Circle in northern Siberia. Graduate students from both U.S. institutions will accompany the PIs in the field, providing them with an enhanced learning experience that will promote both scientific and cultural exchange.