Abstract Detrital zircon U–Pb geochronology and heavy mineral data from four main rivers in coastal southern Tanzania - the Rufiji, Matandu, Mbwemkuru and Ruvuma rivers - are compared with the bedrock geology of their catchment and with data from the Mesozoic strata of the Mandawa Basin, also in coastal Tanzania. The objective is to evaluate the source-to-sink pattern of sedimentation through time, between the Mesozoic and present day. The recent river sediments display variations in both heavy mineral assemblages and U–Pb zircon populations, reflecting their different catchment areas. The Matandu and Mbwemkuru rivers transport sediments characterised by amphibole-dominated heavy mineral assemblages, whereas the great Rufiji and Ruvuma rivers are characterised by more stable heavy mineral assemblages. The detrital zircon populations show age peaks at c. 2900–2500, 2000–1800, 1000, 800 and 700–500 Ma, the common denominators are the Late Mesoproterozoic (c. 1000 Ma) and Late Neoproterozoic (700–500 Ma) age fractions. The Rufiji River and the Matandu River display similar zircon age distributions, both containing abundant Palaeoproterozoic zircons, interpreted as recycled from Karoo successions in a part of the Selous Basin which is drained by both rivers. The Mbwemkuru and Ruvuma rivers contain mainly Late Mesoproterozoic and Late Neoproterozoic aged zircons that were supplied from the Unango and Marrupa complexes and the Cabo Delgado Nappe Complex/Eastern Granulites. The more diverse zircon population in the Rufiji and Matandu river is likely reflects recycling of older sedimentary successions in addition to sediments supplied from basement lithologies.

中文翻译：

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坦桑尼亚南部河流沉积物物源研究：重矿物特征和 U-Pb 锆石年龄

摘要 将坦桑尼亚南部沿海四条主要河流——鲁菲吉河、马坦杜河、姆布韦姆库鲁河和鲁武马河——的碎屑锆石 U-Pb 年代学和重矿物数据与其集水区的基岩地质和曼达瓦盆地中生代地层的数据进行了比较，也在坦桑尼亚沿海。目的是评估中生代和现代之间随时间推移的沉积源-汇模式。最近的河流沉积物显示出重矿物组合和 U-Pb 锆石种群的变化，反映了它们不同的集水区。Matandu 和 Mbwemkuru 河运输的沉积物以角闪石为主的重矿物组合为特征，而 Rufiji 和 Ruvuma 河流的特征为更稳定的重矿物组合。碎屑锆石群在 c 处显示年龄峰值。2900–2500、2000–1800、1000、800 和 700–500 Ma，共同点是晚中元古代 (c. 1000 Ma) 和晚新元古代 (700–500 Ma) 年龄分数。Rufiji 河和 Matandu 河显示出相似的锆石年龄分布，均含有丰富的古元古代锆石，被解释为从被两条河流排出的塞卢斯盆地一部分的 Karoo 层序中回收。Mbwemkuru 和 Ruvuma 河主要包含晚中元古代和晚新元古代的年龄锆石，这些锆石来自 Unango 和 Marrupa 杂岩以及 Cabo Delgado 推覆杂岩/Eastern Granulites。