Evolution of the Terminal Ediacaran–earliest Cambrian ecosystems in the southern Nama Basin (GRIND-ECT drilling project): When, why, and how? – A multidisciplinary approach

纳马盆地序列为研究地球上最早的多细胞生命形式的生存条件、快速灭绝和由形态上不同的动物取代提供了独特的可能性。该项目提案涉及在这些后生动物的起落过程中重建变化的环境，这一过程伴随着Adamastor海洋的关闭和沉积条件的变化。了解地球生命演化中这些关键事件的机制和时间对于确定生命本身发展的驱动因素至关重要。据我们所知，本项目是第一个详细描述新元古代晚期至寒武纪早期那玛盆地动力学的综合方法，它将使用盆地分析中公认的方法组合的新方法，提供关于盆地演化的全面图景。我们试图回答以下工作假设：(1)那马盆地序列包含了大量的大小规模的沉积事件。(2)库伊比斯亚群沉积以被动边缘沉积为特征。(3)施瓦茨朗亚群沉积物受阿达马斯托大洋闭合和构造体制变化的影响，具有较高的火山弧影响。(4)埃迪卡拉纪后生动物对那马盆地的殖民史是由盆地构造环境决定的。(5)第一后生动物宿主生态系统的演化受海平面变化的影响。(6)前寒武纪-寒武纪过渡期间可能的动物群交换驱动因素是由构造环境引起的，对这些假说的分析将得到前寒武纪那玛盆地全面的、高时间的风化方案，并可能为理解海水中的大地构造影响和破译埃迪卡拉纪晚期首次出现多细胞生命的驱动力提供独特的机会。我们将通过现代和创新的方法(碳酸盐的U-Pb测年、灰烬的U-Pb高精度锆石测年、碎屑锆石的最大沉积年龄、基于尖晶石的生物地层学)来实现更好的年龄控制。这决定了影响这些生态系统的因素和事件何时发生，为什么被触发，以及它们是如何导致生物群更替的。

The Nama Basin successions offer a unique possibility for studying the living conditions, rapid extinction and replacement by morphologically distinct animals of the first multi-cellular lifeforms on earth. This project proposal deals with reconstructing changing environments during the rise and fall of these metazoans which was accompanied by the closure of the Adamastor Ocean and changing sedimentary conditions. Understanding the mechanism and timing of these key events in evolution of life on earth is crucial for determining drivers of development of life itself. To the best of our knowledge the present project represents the first integrated approach describing the Nama Basin dynamics in such a detail during the Late Neoproterozoic to the earliest Cambrian that it will provide a comprehensive picture concerning the basin evolution using a novel approach of a combination of well-established methods in basin analysis. We try to answer the following work hypotheses: (1) The Nama Basin successions incorporate a great number of small and big scale sedimentary events. (2) The Kuibis Subgroup sediments are characterized by passive margin sedimentation. (3) The Schwarzrand Subgroup sediments show high volcanic arc influence induced by the closure of the Adamastor Ocean and a changing tectonic regime. (4) The colonisation history of the Nama Basin by the Ediacaran metazoans was determined by the basinal tectonic setting. (5) The evolution of first metazoan hosting ecosystems is influenced by sea level changes. (6) Possible driving factors of faunal exchange during the Precambrian-Cambrian transition are induced by tectonic environments.Answering these hypotheses will result in a comprehensive, high temporal weathering scheme of the Precambrian Nama Basin and may offer a unique opportunity understanding the geotectonic impact in seawater and to decipher driving forces for the late Ediacaran of-a-kind appearances of the first multicellular life. We will do so with the help of a much more improved age control by modern and innovative methods (U-Pb dating of carbonates, U-Pb high precision zircon dating of ashes, maximum deposition ages derived from detrital zircon, biostratigraphy based on acritarchs). This determines WHEN factors and events influencing these ecosystems happened, WHY they were trigged, and HOW they led to a biota replacement.