| 福建沿海中生代变质带中花岗质岩石的地球化学 |
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| 引用本文： | 周旋,于津海.福建沿海中生代变质带中花岗质岩石的地球化学[J].地球化学,2001,30(3):282-292. |
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| 作者姓名： | 周旋 于津海 |
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| 作者单位： | 南京大学地球科学系金属矿床成矿机制研究国家重点实验室, |
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| 基金项目： | 国家自然科学基金49632080，49773191 |
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| 摘 要： | 福建东南沿海中生代变质带的花岗质岩石分布于东山、晋江和莆田等广大地区。花岗岩中常包含黑云母、石榴子石或白云母。但地球化学研究表明，这些花岗岩属于钙碱性或高钾钙碱性，以低Rb、Zr、Hf、Nb、Y、Ga含量和Rb/Sr比值，以及高Ba、Sr丰度为特征，属于典型的Ⅰ型花岗岩。它们的稀土总量普遍较低，具有轻稀土富集、铕中等亏损的稀土分布模式。本带三个地区花岗岩的微量元素组成存在一定差异，但具有相似的Sr、Nd同位素组成，以高εNd(t)(-4.49～-3.15)和低ISr(0.7055-0.7074)、tDM(1.19-1.29Ga)为特征。地球化学研究显示本带花岗岩形成于相同的构造背景－大型边缘火山弧环境。其母岩浆是由类似于麻源群的古老火成变质岩部分熔融产生的熔融体与同期的幔源玄武质岩浆发生一定程度混合而成。不同地区或同一地区花岗岩地球化学组成上的差异是不同程度的部分熔融和结晶分异的结果。
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| 关 键 词： | 花岗质岩石 地球化学 岩石成因论 平潭－东山变质带 福建 中生代 |
| 文章编号： | 0379－1726(2001)03－0282－11 |
| 修稿时间： | 2000年8月1日 |
Geochemistry of the granitoids in Mesozoic metamorphic belt of coastal Fujian Province |
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| Zhou Xuan,YU Jin-hai.Geochemistry of the granitoids in Mesozoic metamorphic belt of coastal Fujian Province[J].Geochimica,2001,30(3):282-292. |
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| Authors: | Zhou Xuan YU Jin-hai |
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| Abstract: | The granitoids of Mesozoic metamorphic belt, along southeastern coast of Fujian Province often contain biotite, garnet or muscovite. However, the geochemical data indicate that these granitoids are of calc alkaline or high potassium calc alkaline, and are characterized by low Rb, Zr, Hf, Nb, Y, Ga contents and Rb/Sr ratios and high Ba, Sr contents, which are the typical I type granite. They have low REE concentration with LREE enrichment and mediate Eu depletion. The granites from three different regions in this metamorphic belt have similar Sr and Nd isotopic compositions, with high ε Nd(t)（ － 4.49～ － 3.15） and low ISr（ 0.705 5～ 0.707 4） and tDM（ 1.18～ 1.29 Ga） , although there are trace element composition variations among them. Geochemical features show that these granites were generated in same tectonic setting, volcanic arc of continental margin, which are consistent with the geological observations. The parental magma of the granitoids were created by the partial melting of ancient metamorphic rocks, similar to Mayuan Group, and added by young mantle derived materials; or from magma mingling of the melt produced by partial melting of ancient metamorphic rocks and the coeval basaltic liquids. The chemical variations of the granites in three regions are interpreted to result probably from the varied melting extent and consequent fractional crystallization. |
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| Keywords: | granitoids geochemistry petrogenesis Pintan Dongshan metamorphic belt coastal Fujian Province |
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