This article reports the existence of subduction-related tholeiitic, normal mid-ocean ridge basalt (N-MORB)-type mafic intrusives emplaced within the Sapi-Shergol ophiolitic mélange of the Indus Suture Zone, western Ladakh. The Shergol mafic intrusives show Fe enrichment with basalt to basaltic-andesite composition. Based on their mineralogy and textures, these mafic rocks can be identified as fine- to medium-grained gabbros that have undergone greenschist-grade metamorphism. These rocks have N-MORB-type geochemical characteristics, exhibiting nearly flat to depleted light rare earth element patterns ((La/Sm)N=0.66–1.05). Petrogenetic modeling suggests <20% partial melting of a depleted MORB-type mantle source, within the spinel peridotite stability. The presence of slightly negative anomalies of high field strength elements like Nb, Zr, and Ti in multielement patterns reflect the influence of subduction zone magmatism. The presence of low-Ti clinopyroxene (En38–50Fe11–25Wo31–43; enstatite-ferrosilite-wollastonite), Ca-rich plagioclase (An2–36; andesine), and pargasitic amphibole also reflects their subduction-related depleted-mantle origin. The MORB–island arc tholeiite signature displayed by the Shergol gabbros intrusive in Shergol peridotites reflect their generation in a mantle wedge associated with the Early Cretaceous intraoceanic subduction within the Neo-Tethys Ocean. They are similar to Spongtang ophiolite gabbros intrusive in the Spongtang ophiolite mantle peridotites from south Ladakh, ophiolitic mélange gabbros from southern Tibet, and Muslim Bagh ophiolite gabbros from Pakistan. Based on this study, we offer a geodynamic model suggesting that the Sapi-Shergol ophiolitic slice was intruded by mafic intrusive rocks that represent the relict of the intraoceanic substratum of the Cretaceous Dras arc complex.

中文翻译：

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拉达克西部印度河缝合带 Sapi-Shergol 蛇绿混杂岩中镁铁质侵入岩的岩石学和地球化学：对岩石成因和构造环境的限制

本文报告了拉达克西部印度河缝合带 Sapi-Shergol 蛇绿岩混杂岩中存在的与俯冲相关的拉斑岩、正常洋中脊玄武岩 (N-MORB) 型基性侵入岩。Shergol 镁铁质侵入岩显示铁富集玄武岩至玄武岩-安山岩组成。根据它们的矿物学和质地，这些镁铁质岩石可以被确定为经历了绿片岩级变质作用的细粒至中粒辉长岩。这些岩石具有 N-MORB 型地球化学特征，表现出近乎平坦至贫化的轻稀土元素模式 ((La/Sm)N=0.66–1.05)。岩石成因模型表明，在尖晶石橄榄岩稳定性范围内，贫化 MORB 型地幔源的部分熔融 <20%。高场强元素如 Nb、Zr、多元素模式中的 Ti 和 Ti 反映了俯冲带岩浆作用的影响。低钛单斜辉石（En38-50Fe11-25Wo31-43；顽火石-铁硅石-硅灰石）、富含钙的斜长石（An2-36；中长石）和斜长闪石的存在也反映了它们与俯冲相关的贫化地幔起源。侵入 Shergol 橄榄岩的 Shergol 辉长岩所显示的 MORB 岛弧拉斑岩特征反映了它们在与新特提斯洋内的早白垩世洋内俯冲相关的地幔楔中的生成。它们与侵入拉达克南部Spongtang蛇绿岩地幔橄榄岩的Spongtang蛇绿辉长岩、藏南蛇绿混杂辉长岩和巴基斯坦Muslim Bagh蛇绿辉长岩相似。基于这项研究，