Abstract The Carajas Basin, Amazonian Craton, hosts extensive Neoarchean to Paleoproterozoic sedimentary archives, which are still poorly constrained regarding their depositional settings, ages, and type of basin in which they have been deposited. In this study, we performed detailed sedimentological investigations and U-Pb dating of detrital zircon in four drill cores intercepting the recently defined Serra Sul Formation. Our data show that this formation corresponds to various shallow to deep subaqueous environments. Shallow water environments are characterized by local occurrences of microbially-mediated structures, while deep water environments are characterized by polymictic conglomerates resulting from the mixing of materials of different origins during downslope debris flow. Both sedimentary facies and common occurrence of syn-sedimentary deformations attest for recurrent slope instabilities. Geochronological investigations allow to define a maximum depositional age of 2684 ± 10 Ma, that is several tens million years younger than other Neoarchean sedimentary units of the Carajas Basin. Major peaks in age distribution indicate that the Serra Sul Formation derives from local sources that constitute the basement of the Carajas Basin. The infilling of the Carajas Basin by local sources, together with sedimentary facies and depositional environments attesting for slope instabilities, suggest that the Serra Sul Formation was deposited during an active extensional tectonic phase. Such Neoarchean to early Paleoproterozoic tectonic setting compares with those documented in many other cratons worldwide and suggests that it could correspond to the break-up of one of the first documented supercontinent.

中文翻译：

---

Serra Sul 组（Carajás 盆地，亚马逊克拉通，巴西）的地层和地质年​​代限制

摘要 亚马逊克拉通卡拉哈斯盆地拥有广泛的新太古代至古元古代沉积档案，但其沉积环境、年龄和沉积盆地类型仍然缺乏限制。在这项研究中，我们对截获最近定义的 Serra Sul 地层的四个钻芯中的碎屑锆石进行了详细的沉积学调查和 U-Pb 测年。我们的数据表明，该地层对应于各种浅到深的水下环境。浅水环境的特点是局部出现微生物介导的结构，而深水环境的特点是在下坡碎屑流过程中混合不同来源的材料产生的复合砾岩。沉积相和同沉积变形的普遍发生都证明了斜坡的反复失稳。地质年代学研究可以确定最大沉积年龄为 2684 ± 10 Ma，比 Carajas 盆地的其他新太古代沉积单元年轻数千万年。年龄分布的主要峰值表明 Serra Sul 地层来自构成 Carajas 盆地基底的当地资源。Carajas 盆地的局部来源充填，连同证明斜坡不稳定性的沉积相和沉积环境，表明 Serra Sul 组是在活动的伸展构造阶段沉积的。