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首页> 外文期刊>Journal of geodynamics >The tectonic evolution of the Dras arc complex along the Indus Suture Zone, western Himalaya: Implications for the Neo-Tethys Ocean geodynamics
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The tectonic evolution of the Dras arc complex along the Indus Suture Zone, western Himalaya: Implications for the Neo-Tethys Ocean geodynamics

机译：喜马拉雅西部印度河缝线带Dras弧复合体的构造演化：对新特提斯海洋地球动力学的启示

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摘要

In this study we present new whole-rock geochemical data on the Dras arc complex exposed along the Dras-Kargil National Highway, western Ladakh. This complex forms a part of the Indus Suture Zone, which is a major tectonic unit extending along the Himalaya from the Pakistan in the west to the Tibet in the east. The Dras arc complex is dominated by mafic volcanics, with subordinate gabbros at the base exposed near Kargil. The Dras volcanics have augite and plagioclase phenocrysts embedded in a groundmass of plagioclase and pyroxene with porphyritic, intergranular and ophitic textural relationships. Also chlorite and epidote are present as secondary mineral assemblage in these volcanics. Plagioclase and pyroxene are the dominant mineral assemblage in the Kargil gabbro, with minor amounts of oxides and relict olivine. These rock types are characterized by ophitic textures and are devoid of any secondary mineral assemblage when compared to the mafic volcanics, which have suffered greenschist metamorphism. Geochemically, the Dras volcanics and the Kargil gabbros are classified as sub-alkaline tholeiites and show a compositional variation from basalt to basaltic andesite. On a Nb/Yb vs. Th/ Yb diagram, they fall within the compositional field of arc-related rocks. NMORB-normalized multi-element patterns shows enrichment in large ion lithophile elements (e.g., Rb, Ba, Th, U, K and Pb) and light rare earth elements (LREE), but a depletion in high field strength elements (e.g., Nb, P, Zr and Ti), which supports a subduction-related origin. Lower Ba/La and La/Yb ratios indicate contribution from fluid fluxing, rather than slab melts to the mantle wedge. The Dras volcanics show similar geochemical trends to volcanic arc rocks from the Nidar and the Spongtang ophiolite complex of the Ladakh Himalaya as well as the Hasanbag and Kata Rush arc rocks from the Iraqi Zagros Suture, having similar age relationships in the context of the Neo-Tethys Ocean.
机译：在这项研究中，我们介绍了拉达克西部Dras-Kargil国家公路沿线Dras弧复合体的新全岩石地球化学数据。该建筑群构成印度河缝合带的一部分，印度河缝合带是喜马拉雅山脉的主要构造单元，从西部的巴基斯坦一直延伸到东部的西藏。 Dras弧复合体以镁铁质火山为主，底部的辉长岩暴露在Kargil附近。德拉斯火山的火山岩和斜长石斑晶嵌在斜长石和辉石的地基中，具有斑状，粒间和片状质地关系。在这些火山中，亚氯酸盐和附子还作为次生矿物组合存在。斜长石和辉石是卡吉尔辉长岩中的主要矿物组合，具有少量的氧化物和残留的橄榄石。这些岩石类型的特征是辉光岩质地，与遭受绿片岩变质作用的镁铁质火山岩相比，不含任何次生矿物组合。在地球化学上，Dras火山岩和Kargil gabbros被归类为亚碱性辉长岩，并显示出从玄武岩到玄武安山岩的组成变化。在Nb / Yb与Th / Yb图上，它们落入与弧有关的岩石的成分范围内。 NMORB归一化的多元素图样显示了大型离子亲石元素（例如，Rb，Ba，Th，U，K和Pb）和轻稀土元素（LREE）的富集，但高场强元素（例如，Nb）的耗尽，P，Zr和Ti），它支持与俯冲有关的起源。较低的Ba / La和La / Yb比表明流体通量的贡献，而不是平板熔体到达地幔楔。 Dras火山岩的地球化学趋势与Ladakh喜马拉雅山的Nidar和Spongtang蛇绿岩复合体的火山弧岩以及伊拉克Zagros缝合线的Hasanbag和Kata Rush弧岩相似，在新时代背景下具有相似的年龄关系。特提斯海洋。

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