Many recent studies have concluded that subduction components exist in the mantle source of the Manus back‐arc basin lavas; however, the origin of these components remains an ongoing controversy. The East Rift at the eastern end of the Manus Basin is ideal for investigating the subduction components because of its unique geographic location. In this study, 10 samples from the East Rift were selected for geochemical and isotopic analysis. The results show that these samples can be compositionally divided into basaltic andesite and dacite belonging to the medium‐K calc‐alkaline series. Furthermore, the parental magma experienced fractional crystallization. The analyses also indicate that the subduction components came from the Solomon Plate and consist of altered oceanic crust (AOC) and sediments. The AOC materials entered the mantle source through fluids, while the sedimentary materials were transferred as melts. Assuming 5% partial melting of the sediments and 1% fluid production from the AOC in a modal melting process of an eclogitic source, the results of endmember modelling of Pb isotopic data reveal that the subduction components beneath the East Rift area consist of approximately 60–65% AOC fluids and 35–40% sediment melts and that the source contains approximately 1–5% subduction components.

中文翻译：

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玛努斯盆地东裂谷熔岩的地球化学和同位素组成：对俯冲成分成因的启示

最近的许多研究得出结论，在马努斯后弧盆地熔岩的地幔源中存在俯冲成分。但是，这些组件的起源仍然存在争议。马努斯盆地东端的东纵谷具有独特的地理位置，是研究俯冲分量的理想选择。在这项研究中，从东纵谷选出10个样品进行地球化学和同位素分析。结果表明，这些样品在成分上可以分为玄武质安山岩和辉绿岩，属于中等K钙碱性系列。此外，母岩浆经历了部分结晶。分析还表明，俯冲成分来自所罗门板块，由蚀变的洋壳和沉积物组成。AOC材料通过流体进入地幔源，而沉积材料则以熔体形式转移。假设在渐次流源的模态熔融过程中沉积物的5％沉积部分熔融和AOC产生1％的流体，Pb同位素数据的最终成员模拟结果表明，东纵谷地区下方的俯冲分量包括大约60– 65％的AOC流体和35–40％的沉积物融化，并且该源包含大约1–5％的俯冲成分。