青岛大珠山高分异花岗岩地球化学特征与含矿性分析
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本文为山东省重大科技创新工程项目“山东东部海域日青威盆地油气赋存条件研究(编号:2017CXGC1608)”、中石化科技部项目“北黄海—渤海湾盆地低勘探程度区勘探潜力评价(编号:P20028)”、中石化石勘院开放基金“深水混合沉积过程及其对页岩储层发育的控制作用——以日青威盆地莱阳组为例(编号:HX20220005)”的成果


Geochemical characteristics and mineralization analysis of Dazhushan highly differentiated granite
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    摘要:

    青岛大珠山位于莱州湾南西,小珠山南西侧,属于中生代晚燕山期酸性侵入花岗岩体,岩性以中粗粒钾长花岗岩和花岗斑岩为主。前人对小珠山地球化学特征已有研究,但大珠山花岗岩地球化学研究尚处空白阶段。对所取的十件样品进行岩相学、全岩主微量及稀土元素、Li同位素、锆石UPb测年、斜长石电子探针原位分析。结果显示:岩相学表明研究区花岗岩含有锂辉石,有明显伟晶岩脉,岩石类型为I—S型花岗岩;样品为高硅花岗岩(SiO2=66. 97%~74. 97%);全碱含量高(Na2O+K2O=8. 70%~10. 73%),属于过铝质高钾钙碱性系列;Eu负异常明显(δEu=0. 25~0. 56)。计算高分异花岗岩常见指数:铝饱和指数(A/CNK=0. 91~1. 01);分异指数(DI)为87. 07~96. 65;锆饱和温度为836. 3~862. 6℃;锆石Ti温度计反映岩浆结晶温度为698. 5~738. 9℃。年代学表明样品年龄为113. 1±0. 36 Ma,为早白垩世崂山期花岗岩。研究区花岗岩具有明显稀土元素四分组效应(TE1, 3=1. 04~1. 15)和较高氧逸度,表明研究区花岗伟晶岩具有锂矿的成矿潜力。花岗岩分异过程经历斜长石、锆石、磷灰石等矿物的分离结晶。岩浆沿岛弧和大陆碰撞俯冲带裂缝上涌,形成具有成矿潜力的高分异花岗岩。

    Abstract:

    Dazhushan is located southwest of Xiaozhushan and belongs to Mesozoic's Late Yanshanian acidic intrusive granite. The lithology is mainly potassium feldspar granite and granite porphyry. Previous studies on the geochemical characteristics of Xiaozhushan have been conducted, while the geochemical study of Dazhushan granite remains blank. Methodologies: The ten samples were analyzed by petrography, main trace and rare earth elements of the whole rock, Lithium isotope, zircon U- Pb dating, and plagioclase electron probe. Results: The results indicate that, through the petrography analysis, the granite in the study area contains spodumene, pegmatite veins obvious, and rock type belonging to I—S granite. The samples are high silica granite (SiO2=66. 97%~74. 97%), high total alkali content (Na2O+K2O=8. 70%~10. 73%), belonging to peraluminous high potassium calc- alkaline series; Eu negative anomaly is obvious (δEu=0. 25~0. 56). Calculating the highly differentiated granities index: aluminium saturation index is (A/CNK=0. 91~1. 01); differentiation index (DI) is 87. 07~96. 65; zircon saturation temperature is 836. 26~862. 16°C; zircon Ti thermometers reflect magma crystallization temperatures range from 698. 52~738. 91°C。Geochronology shows that the sample age is 113. 1±0. 36 Ma, which is Early Cretaceous Laoshan granite. Conclusions: The granite in the study area has the tetrad effect of rare earth elements (TE1, 3=1. 04~1. 15) and a high oxygen fugacity, indicating that the granite pegmatite in the study area has the metallogenic potential of lithium deposit. The differentiation process of granite experienced the separation and crystallization of plagioclase, zircon, apatite and other minerals. Magma upwelling along the fractures of the island arc and continental collision subduction zone, forming highly differentiated granites with metallogenic potential.

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刘瑞杨,周瑶琪,周腾飞,陈彤彤,刘汉青,白冰洋,李孙义.2023.青岛大珠山高分异花岗岩地球化学特征与含矿性分析[J].地质论评,69(1):179-198,[DOI].
LIU Ruiyang, ZHOU Yaoqi, ZHOU Tengfei, CHEN Tongtong, LIU Hanqing, BAI Bingyang, LI Sunyi.2023. Geochemical characteristics and mineralization analysis of Dazhushan highly differentiated granite[J]. Geological Review,69(1):179-198.

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  • 收稿日期:2022-07-04
  • 最后修改日期:2022-10-11
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  • 在线发布日期: 2023-01-20
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