Abstract Records of Precambrian glaciation have been reported from southeastern Brazil for over a century. We present sedimentological, stratigraphic and isotopic (U-Pb and Lu-Hf on detrital zircons, C and O on carbonates) studies on diamictite-rich to diamictite-free successions of the Aracuai Orogen, the Brazilian counterpart of the Aracuai – West Congo Orogenic System (AWCO). From base to top, the Chapada Acaua Formation (Macaubas Group) includes a diamictite-rich unit, with lenses of graded sandstone and clast-supported conglomerate, that gradually passes to graded sandstone, pelite with sparse oversized clasts and rare carbonate lenses on top, representing mass flow and turbidity current deposits of submarine fan, followed by finer-grained turbiditic sedimentation with iceberg discharges along fan fringes, from glaciomarine to post-glacial scenarios. The Salinas Formation comprises a deep-sea sand-mud sequence composed of pelites and pelitic wackes. The Chapada Acaua Formation was deposited in-between 750 and 667 Ma. It shows wide spectra of zircon ages (typical of continental rift to passive margin settings) that start around 3.2 Ga and display main age peaks indicating sediment provenance from the Rhyacian-Orosirian basement (eHf(t) = +14.6 to −18.5) and Early Tonian anorogenic rocks (950–880 Ma; eHf(t) = −3.2 to −23.2) for the diamictite-rich lower unit and, for the upper unit, also in Early Cryogenian anorogenic rocks (ca. 715 Ma, eHf(t) = −9.6). In contrast, the Salinas Formation shows most ages in-between 676 and 620 Ma and a maximum sedimentation age around 551 Ma, with eHf(t) from +6.9 to −18.2, unravelling an important shifting of sediment provenance to sources located in magmatic arcs and collisional granites of the Aracuai and Ribeira orogens. The Early Cryogenian age and negative Hf signature for the glaciomarine Chapada Acaua Formation point to sediment sources in the 720–670 Ma anorogenic igneous rocks found in AWCO and adjacent Congo – Sao Francisco Craton, and suggest correlation with the Sturtian global glaciation.

中文翻译：

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叠加盆地中物源随时间的转变：从早低温纪冰川到晚埃迪卡拉造山沉积（Araçuaí Orogen，巴西东南部）

摘要 一个多世纪以来，巴西东南部已经报道了前寒武纪冰川的记录。我们介绍了 Aracuai 造山带的富硅藻土到无硅藻土系列的沉积学、地层学和同位素（碎屑锆石上的 U-Pb 和 Lu-Hf，碳酸盐上的 C 和 O）研究。系统 (AWCO)。从底部到顶部，Chapada Acaua 组（Macaubas Group）包括一个富含混叠岩的单元，具有级配砂岩和碎屑支撑的砾岩透镜体，逐渐过渡到级配砂岩、具有稀疏超大碎屑的泥质岩和顶部稀有的碳酸盐透镜体，代表海底扇的质量流和浊流沉积，随后是细粒浊流沉积，沿扇边缘有冰山排放，从冰川到冰后情景。Salinas 组包括由泥质岩和泥质泥岩组成的深海砂泥层序。Chapada Acaua 组沉积于 750 至 667 Ma。它显示了广泛的锆石年龄谱（典型的大陆裂谷到被动边缘环境），开始于 3.2 Ga 并显示主要年龄峰值，表明来自 Rhyacian-Orosirian 基底的沉积物来源（eHf(t) = +14.6 至 -18.5）和早期Tonian 无造山岩（950–880 Ma；eHf(t) = -3.2 至 -23.2）为富含混叠岩的下部单元，对于上部单元，也在早低温纪无造山岩中（约 715 Ma，eHf(t) = -9.6）。相比之下，Salinas 组显示大多数年龄在 676 至 620 Ma 之间，最大沉积年龄在 551 Ma 左右，eHf(t) 为 +6.9 至 -18.2，揭示沉积物来源向位于 Aracuai 和 Ribeira 造山带的岩浆弧和碰撞花岗岩中的源的重要转移。Glaciomarine Chapada Acaua 组的早低温纪时代和负 Hf 特征表明在 AWCO 和邻近的刚果 - 圣弗朗西斯科克拉通发现的 720-670 Ma 非造山火成岩中的沉积物来源，并表明与 Sturtian 全球冰川的相关性。