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| 胶北地块与金成矿有关的郭家岭岩体和上庄岩体年代学及地球化学研究 | |
| 引用本文： | 罗贤冬,杨晓勇,段留安,孙卫东.胶北地块与金成矿有关的郭家岭岩体和上庄岩体年代学及地球化学研究[J].地质学报,2014,88(10):1874-1888. |
| 作者姓名： | 罗贤冬 杨晓勇 段留安 孙卫东 |
| 作者单位： | 1. 中国科学技术大学地球和空间科学学院,合肥,230026;安徽省勘查技术院,合肥,230031 2. 中国科学技术大学地球和空间科学学院,合肥,230026 3. 中国科学院广州地球化学研究所矿物与成矿重点实验室,同位素年代学和地球化学重点实验室,广州,510640 |
| 基金项目： | 国家自然科学基金项目（面上项目，重点项目，重大项目） |
| 摘 要： | 胶东半岛是我国最主要的原生金矿矿集区,金矿的主要控矿围岩是郭家岭花岗岩,通过研究郭家岭花岗岩的地球化学特征对研究金矿的成因和物质来源具有指示性意义。本文研究的两个花岗岩岩体为上庄岩体和郭家岭岩体,两岩体同属郭家岭型花岗岩。通过对两岩体的花岗岩样进行岩相学矿相学观察、全岩主、微量元素和U-Pb同位素分析,获得胶东半岛中生代岩浆岩的成因机制与源区性质及自然金的产出形式等科学信息。LAICP MS锆石U-Pb年龄得出郭家岭岩体年龄125.4±2.2 Ma,上庄岩体U-Pb年龄128.8±2.0 Ma,都为中生代早白垩世,两岩体年龄相差3Ma,在年龄误差范围来看可以把两岩体作为同一期岩体,也在年龄角度证实两岩体都同属郭家岭花岗岩。两岩体的锆石组成都含有太古宙和晚侏罗纪的继承锆石,指示两岩体的成岩物质来源具相似性,都包含太古宙岩石成分和晚侏罗世花岗岩成分。两岩体具有相似的稀土元素和微量元素分配模式,表现出明显的LREE富集和HREE极度亏损,没有明显的铕负异常。郭家岭岩体和上庄岩体花岗岩都具有类似埃达克岩的特征,都具有高的Sr含量(913×10-6~1325×10-6),低的Y含量(2.2×10-6~8.4×10-6)和Yb含量(0.21×10-6~0.68×10-6),较高的(Dy/Yb)N比值1.62~2.28,暗示花岗岩岩浆形成时石榴石是一个重要的残留相,而没有斜长石作为残留相。两岩体具有较低的MgO、Cr、Ni含量和Mg#,反映郭家岭型花岗岩岩浆的形成可能是岛弧环境榴辉岩相压力条件下洋壳玄武质岩石的部分熔融。 |
| 关 键 词： | 胶北地块 郭家岭岩体 LA-ICP MS 埃达克岩 岛弧 |
| 收稿时间： | 9/9/2012 12:00:00 AM |
| 修稿时间： | 7/9/2014 12:00:00 AM |
Geochemical and Geochronological Study of the Gold Related Guojialing Pluton and Shangzhuang Pluton in Jiaobei Block |
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| YANG XIAOYONG.Geochemical and Geochronological Study of the Gold Related Guojialing Pluton and Shangzhuang Pluton in Jiaobei Block[J].Acta Geologica Sinica,2014,88(10):1874-1888. | |
| Authors: | YANG XIAOYONG |
| Institution: | School of Earth and Spce Sciences, University of Science and Techonology of China |
| Abstract: | The Jiaodong Peninsula is the most important pool of native gold ore deposits in China, which is mostly controlled by Granite. In this paper, we discuss the genesis and material source of gold deposit by study the geochemistry and geochronology characteristics of Guojialing Granite. Two granite plutons of Guojialing Granite are studyed in this paper, which are Shangzhuang pluton and Guojialing Pluton. This dissertation presents a combined study of petrography and mineralogy, whole-rock major, trace elements and U-Pb isotopes for granite of these two plutons, to obtain some recognition of the genesis, material source and presence of natural gold for Mesozoic magmatic rocks in Jiaodong Peninsula. LA-ICPMS zircon U-Pb dating yields Early Cretaceous age of 125.4±2.2Ma for Gguojialing pluton, and also Early Cretaceous age of 128.8±2.0Ma for Shangzhuang pluton, with an age difference of 3Ma. From the perspective of age, these two plutons all belong to Guojialing granite with the same intruding period. Granite of the two plutons contain inherited zircons with Archean and Late Jurassic ages, indicating similar material sources containing components of both Archean rocks and Late Jurassic granite composition. Guojialing and Shangzhuang plutons have similar distribution patterns of REE and trace elements, with LREE and LILE enrichement but HREE and HFSE depletio, slightly negligible Eu anomalies. Both of them have high Sr, low Yb and Y contents as well as high (La/Yb)N and Sr/Y ratios, which are similar to common adakites. This indicates the presence of garnet with none Plagioclase as residual phases during partial melting.They Both have relatively low MgO, Cr, Ni contents and thus low Mg#. All these results indicate that Guojialing Granite is formed by partial melting of basaltic rocks of oceanic crust with the presence of granet as residual phase in the island arc environment. |
| Keywords: | Jiaobei Block Guojialing Pluton La-ICPMS Adakites Island Arc |
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