In this study, we present new field geology, whole-rock geochemical and S–Pb isotope data for the Chambishi deposit in the Zambia Copperbelt (ZCB), in order to constrain the mineralization process and ore sulphur and metal source. The Lower Roan Subgroup clastic rocks are compositionally similar to the Post-Archean Australian Shale and have low Chemical Index of Alteration, indicating a felsic and slightly weathered source, which we proposed to be the felsic Lufubu Metamorphic Complex (LMC). The Th, Ti, and Zr elemental features suggest that the Lower Roan Subgroup was deposited in a rift basin of passive margin. The ³⁴S values of early-stage diagenetic Cu-Co sulphide (−6.2 to +6.6‰, Vienna Canyon Diablo Troilite [V-CDT]) from the nodular and layered ores are lower than those of the late-stage vein-type hydrothermal Cu–Co sulphides and disseminated molybdenites (3.9–11.9‰, V-CDT), indicating different sulphur precipitation mechanism in the two mineralization stages. Integrated with previous fluid inclusion studies, we suggest that the sulphur for the diagenetic sulphides was from bacterial reduction of sedimentary anhydrite and seawater sulphates, whereas that for the orogenic-stage sulphides was from both diagenetic sulphide remobilization and from thermochemical sulphate reduction. The mean ²³⁸U/²⁰⁴Pb ratios of the diagenetic- and orogenic-stage sulphides are 10.21 and 10.44, respectively, overlapping with those of the average Lufubu schist (10.38) and the Mufulira granodiorite (10.21), and suggest the LMC as the main ore metal source.

中文翻译：

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赞比亚铜带沉积层状铜钴矿床的成因：来自谦比希矿床的地球化学和 S-Pb 同位素约束

在这项研究中，我们为赞比亚铜带 (ZCB) 的谦比希矿床提供了新的野外地质、全岩地球化学和 S-Pb 同位素数据，以限制成矿过程和矿石硫和金属来源。下罗恩亚群碎屑岩在成分上与澳大利亚后太古代页岩相似，化学蚀变指数低，表明是长英质和轻微风化的源，我们建议它是长英质 Lufubu 变质杂岩 (LMC)。Th、Ti和Zr元素特征表明下罗恩亚群沉积在被动边缘的裂谷盆地中。在³⁴来自球状和层状矿石的早期成岩Cu-Co硫化物（-6.2至+6.6‰，Vienna Canyon Diablo Troilite [V-CDT]）的S值低于晚期脉状热液Cu– Co 硫化物和浸染辉钼矿 (3.9–11.9‰, V-CDT)，表明两个矿化阶段不同的硫沉淀机制。结合先前的流体包裹体研究，我们认为成岩硫化物的硫来自沉积硬石膏和海水硫酸盐的细菌还原，而造山期硫化物的硫来自成岩硫化物再动员和热化学硫酸盐还原。平均²³⁸ U/ ²⁰⁴成岩期和造山期硫化物的铅比分别为 10.21 和 10.44，与平均 Lufubu 片岩 (10.38) 和 Mufulira 花岗闪长岩 (10.21) 重叠，表明 LMC 是主要的金属矿源。