北淮阳地区与斑岩型钼矿床相关岩浆岩的地质地球化学特征及成因

发布时间：2018-07-08 21:01

本文选题：岩浆岩 + 地球化学特征　；参考：《地学前缘》2016年04期

【摘要】：位于秦岭—大别造山带东段的北淮阳地区分布有众多的斑岩型钼矿床,其成矿与岩浆作用紧密相关。对该区与斑岩型钼矿床密切相关的岩浆岩进行了系统的岩石化学、微量元素和同位素地球化学研究,深入探讨了其成因。研究认为,成矿岩体规模较小,岩性为花岗(斑)岩类,受北东向与北西向区域性断裂的次级构造控制。岩石化学成分以高硅、高钾、富碱为特征,为高钾钙碱性-钾玄岩系列、准铝-过铝质岩石。岩石微量、稀土元素特征相似并显示壳源特征。岩石Sr-Nd-Pb-Hf同位素地球化学特征显示这些花岗质岩浆与整个大别地区白垩纪花岗岩的成岩物质来源一致,源于新元古界北大别片麻岩和扬子克拉通北缘TTG型岩浆,并混入一些古元古代扬子克拉通古老地壳物质(如崆岭杂岩)。在白垩纪发生的下地壳拆沉、软流圈上涌及大规模地壳伸展等机制下,扬子克拉通北缘的地壳熔融并提供了主要的成岩物质,幔源岩浆的上涌可能提供了热源,其物质的加入是次要的。该区与斑岩型钼矿床相关岩浆岩与东秦岭地区类似,属深源浅成型花岗岩类。
[Abstract]:There are many porphyry molybdenum deposits in the northern Huaiyang area located in the eastern section of Qinling-Dabie orogenic belt and their mineralization is closely related to magmatism. The petrochemistry, trace elements and isotopic geochemistry of magmatic rocks closely related to porphyry molybdenum deposits in this area are systematically studied, and their genesis is discussed in depth. It is considered that the ore-forming rock mass is small in scale, and its lithology is of granitic (porphyry) type, which is controlled by the secondary structures of NE and NW regional faults. The chemical composition of the rocks is characterized by high silicon, high potassium and alkali-rich, and belongs to the high potassium calc alkaline-potash rock series, quasi-aluminum-peraluminous rocks. Rock trace, REE characteristics are similar and show crust characteristics. The isotopic geochemical characteristics of the rocks Sr-Nd-Pb-Hf indicate that these granitic magmas are consistent with the source of diagenetic material of the Cretaceous granites in the whole Dabie area and originated from the Neoproterozoic Beidabie gneiss and the northern Yangtze craton TTG magma. And mixed with some Gu Yuan ancient Yangtze craton ancient crustal materials (such as the Kongling complex). Under the Cretaceous mechanisms of lower crust desubsidence, upwelling of the asthenosphere and large-scale crustal extension, the crust of the northern margin of the Yangtze craton melted and provided the main diagenetic material, and the upwelling of the mantle magma may provide the heat source. The addition of its substance is secondary. The magmatic rocks associated with porphyry molybdenum deposits are similar to those of the East Qinling area and belong to deep source shallow-formed granites.
【作者单位】：安徽省地质矿产勘查局313地质队;合肥工业大学资源与环境工程学院;
【基金】：国家自然科学基金项目(41172085) 2011年度安徽省国土资源科技项目(2011-K-1)
【分类号】：P618.65

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