We report detrital zircon U–Pb ages, radiogenic Sm–Nd isotopic compositions, major and trace element compositions of the intra-plate extensional rhomb-shaped Neoproterozoic Malagarasi Supergroup of north-western Tanzania in order to elucidate the paleo-tectonic setting, source rocks chemistry and paleo-oxygenation in the basin. Assuming that provenance trace element proxy ratios, including the rare earth elements (REE) contents, behave as closed systems during sedimentation and diagenesis, we suggest that the detritus for the Malagarasi Supergroup originated from more felsic rocks than those for upper crustal composites (i.e. Post-Archean Australian Shale; PAAS, Proterozoic Shale; PS). This observation is also supported by enriched chondrite-normalized light REE (La/Sm_CN = 2.36–7.84; mean = 3.85), overall negative Eu anomalies (Eu/Eu* = 0.56–0.93; mean = 0.69) and flat heavy REE patterns (Gd/Yb_CN = 1.01–2.04; mean = 1.47). Paleo-weathering proxies using the Chemical Index of Alteration (CIA ~59–78%) protocol indicate an overall moderate weathering intensity in the basin. V/Cr ratios (mean = 1.18; range = 0.48–1.69) coupled with intra-sample Ce anomalies reveal an overall oxidizing state during deposition. Mantle extraction ages (T_DM = 1594–2394 Ma) suggest a diverse mixing of protolith terranes including Archean (Tanzania craton), Eburnian (Ubendian Belt) and possibly the nearby Mesoproterozoic Kibaran Belt. Radiogenic laser ablation detrital zircon U–Pb ages of between 1826 and 2656 Ma may preclude contribution from the Kibaran. Given that Nd systematics in sedimentary rocks provide mixing ages of different hinterland source rocks (1594–2394 Ma; in our study), we suggest relatively juvenile sources such as the local post-orogenic effusive bodies farther south of the basin in the realm of Rodinia Supercontinent. Thus, a northerly flow direction of the of the proto/paleo river system in the region is inferred.

我们报告了坦桑尼亚西北部的板内伸展菱形新元古代马拉加拉西超群的碎屑锆石 U-Pb 年龄、放射成因 Sm-Nd同位素组成、主要和微量元素组成，以阐明古构造环境、烃源岩盆地中的化学和古氧化作用。假设包括稀土元素(REE) 含量在内的物源微量元素替代比率在沉积和成岩过程中表现为封闭系统，我们建议马拉加拉西超群的碎屑来源于更多的长英质岩石比那些上地壳复合材料（即后太古代澳大利亚页岩；PAAS，元古代页岩；PS）。富集球粒陨石归一化轻稀土元素（La/Sm _CN = 2.36–7.84；平均值 = 3.85）、整体负 Eu 异常（Eu/Eu* = 0.56–0.93；平均值 = 0.69）和平坦的重稀土元素模式也支持这一观察结果（Gd/Yb_CN = 1.01–2.04；平均值 = 1.47）。使用化学变化指数 (CIA ~59–78%) 协议的古风化代理表明盆地整体风化强度中等。V/Cr 比率（平均值 = 1.18；范围 = 0.48-1.69）加上样品内 Ce 异常显示沉积过程中的整体氧化状态。地幔提取年龄（T_DM = 1594-2394 Ma）表明原岩地体的多样化混合包括太古代（坦桑尼亚克拉通）、埃本纪（乌本底带）和附近的中元古代基巴兰带。1826 至 2656 Ma 的放射性激光烧蚀碎屑锆石 U-Pb 年龄可能排除 Kibaran 的贡献。鉴于沉积岩中的 Nd 系统学提供了不同腹地烃源岩的混合年龄（1594-2394 Ma；在我们的研究中），我们建议相对年轻的来源，例如位于罗迪尼亚地区盆地以南的当地后造山喷流体超大陆。因此，推断出该地区原始/古河流系统的北流方向。