Abstract Despite the vast extent of the Arabian Nubian Shield (ANS) and its growth during the renowned Neoproterzoic dramatic climatic changes (Snowball Earth Events), only few records of snowball events are identified among its rocks. Here we present geological and geochemical evidence that the northern part of the Arabian Nubian Shield (Um Zariq Formation (UZF), southeast Sinai, Egypt) witnessed global snowball event(s). The UZF was deposited in a convergent plate margin during Cryogenian and comprises metapelitic schists and cap-carbonates on top. The whole succession underwent amphibolite facies metamorphism around 660 Ma ago. In the upper most part of the metapelitic schists, intercalations of conglomeritic, poorly sorted components and large pebbles show many features comparable to metamorphosed diamictites and dropstones. The arsenic (As) contents of metapelites are 1–3 orders of magnitude higher than average phyllites. The high As contents and the presence, cap carbonates, diamictites and dropstones at UZF point toward deposition under glacial -postglacial conditions apparently during the Sturtian (717-660 Ma) snowball event.

中文翻译：

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埃及西奈东南部的 Um Zariq 地层：阿拉伯努比亚地盾 Sturtian Snowball Earth 事件的新记录

摘要 尽管阿拉伯努比亚地盾 (ANS) 的范围很广，并且在著名的新元古代剧烈气候变化（雪球地球事件）期间不断增长，但在其岩石中发现的雪球事件记录很少。在这里，我们展示了阿拉伯努比亚地盾北部（Um Zariq 组（UZF），埃及西奈东南部）见证了全球雪球事件的地质和地球化学证据。UZF 沉积在 Cryogenian 的会聚板块边缘，包括变泥质片岩和顶部碳酸盐岩。整个序列在660 Ma前经历了角闪岩相变质作用。在变泥质片岩的最上部，砾岩、分选不良的成分和大卵石的夹层显示出许多与变质混叠岩和滴石相当的特征。变泥质岩的砷 (As) 含量比普通千枚岩高 1-3 个数量级。在 Sturtian (717-660 Ma) 雪球事件期间，UZF 的高 As 含量和帽状碳酸盐、混叠岩和滴石的存在表明冰期 - 冰后条件下的沉积。