Abstract In this contribution we outline the outstanding attributes and inferred depositional controls for dark mudstones of the Alicia Formation (∼570 Ma) in order to reveal the intrinsic characteristics of unknown Ediacaran marine depositional conditions of the basin. The Alicia Formation represents a continuous and undeformed ∼150 m thick sequence in which nine siliciclastic lithofacies were accumulated controlled by the Clymene sea conditions. Sedimentary facies analysis of their fine-grained rocks reveals a deposition across two depositional sequences. The basal portion is described as formed in an upper offshore while the upper portion represents a lower shoreface environment. This study combines the stratigraphic characterization with detailed facies descriptions, petrographic, XRD, SEM and geochemistry analyses. This succession was deposited under relatively constant marine environmental conditions with relative sea level variations manifested between the fair-weather and storm wave bases. Bottom-water conditions during its sedimentation show fluctuations in the geochemical indicators as redox-sensitives (U, Mo, V), terrigenous supply (Si, Al, Zr, Th), carbonate productivity (CaO) and organic productivity (Cu, Ni, P/Al). This research represents an exceptional example of preserved fine-grained Ediacaran tidal shelf deposits in the Tandilia Basin. The data provide evidence for the middle Ediacaran anoxia, which post-dates a previous oceanic oxygenation event (EOO, 580 Ma) and pre-dates the white sea assemblage radiation (560 Ma) probably developed in a well oxygenated sea. Within the SW Gondwana scenario, our findings may support a link between the depositional setting during most severe redox changes.

中文翻译：

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克莱门洋埃迪卡拉纪缺氧期间，坦迪利亚盆地艾丽西亚组细粒硅质碎屑潮汐棚沉积物内部的暴露

摘要 在这篇文章中，我们概述了 Alicia 组（~570 Ma）暗色泥岩的突出属性和推断的沉积控制，以揭示盆地未知埃迪卡拉纪海相沉积条件的内在特征。Alicia 组代表一个连续的、未变形的约 150 m 厚的层序，其中 9 个硅质碎屑岩相在 Clymene 海条件控制下堆积。对其细粒岩石的沉积相分析揭示了跨越两个沉积序列的沉积。基底部分被描述为形成于上部近海中，而上部代表下部岸面环境。这项研究将地层特征与详细的相描述、岩相学、XRD、SEM 和地球化学分析相结合。这个序列是在相对恒定的海洋环境条件下沉积的，在晴朗天气和风暴波基地之间表现出相对海平面变化。沉积过程中的底水条件显示出地球化学指标的波动，如氧化还原敏感性（U、Mo、V）、陆源供应（Si、Al、Zr、Th）、碳酸盐生产力（CaO）和有机生产力（Cu、Ni、朋友）。这项研究代表了坦迪利亚盆地保存完好的埃迪卡拉纪潮汐陆架沉积物的一个特殊例子。这些数据为埃迪卡拉纪中期缺氧提供了证据，它发生在先前的海洋氧化事件 (EOO, 580 Ma) 之后，并且在白海组合辐射 (560 Ma) 之前可能在一个充氧良好的海洋中形成。在 SW Gondwana 情景中，