| 海南岛中元古代花岗岩地球化学及成因研究 |
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| 引用本文： | 许德如,梁新权,陈广浩,黄智龙,胡惠东.海南岛中元古代花岗岩地球化学及成因研究[J].大地构造与成矿学,2001,25(4):420-433. |
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| 作者姓名： | 许德如 梁新权 陈广浩 黄智龙 胡惠东 |
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| 作者单位： | 1. 中国科学院长沙大地构造研究所,
2. 中国科学院地球化学研究所, |
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| 基金项目： | 中国科学院知识创新工程项目，KZCX1-Y 003， |
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| 摘 要： | 海南岛中元古代花岗岩岩体主要由二长花岗岩、花岗冈长岩等岩石组成，构成一个明显的 自花岗岩向花岗闪长岩和英云闪长岩的岩浆演化系列及钙碱性演化趋势。该岩体为一套板块碰撞 后隆起期原地一半原地过铝质花岗岩。是板块碰撞引起的地壳增厚升温和随之的玄武岩浆底侵加 热联合作用下，主要由抱板群变质沉积岩及斜长角闪片麻岩部分融熔、并在幔源物质的参与下形 成的，所形成的花岗质岩浆在“走滑扩容泵吸”机制驱动下沿戈枕剪切带上升、固结就位，因而具壳 幔二元混合成因特点。化学成分以高 ＳｉＯ２、Ｋ２Ｏ、Ｒｂ、Ｂａ、Ｔａ、Ｃｅ和贫Ｐ、Ｔｉ、Ｚｒ、Ｓｒ、Ｆｅ２Ｏ３＋ＦｅＯ、 ＭｇＯ、ＣａＯ为特征；元素比值Ｚｒ／Ｎｂ、Ｌａ／Ｎｂ、Ｂａ／Ｎｂ、Ｒｂ／Ｎｂ、Ｋ／Ｎｂ、Ｂａ／Ｌａ及Ｃｒ、Ｃｏ、Ｎｉ、Ｖ均接近 大陆中下地壳成分，Ｒｂ、Ｓｒ、Ｂａ、Ｔａ、Ｚｒ及比值Ｋ／Ｓｒ、Ｒｂ／Ｓｒ石ｒ／Ｂａ变化范围小，反映岩浆源区成分 或熔融方式上的一致性；轻重稀土较强分馏，负铕异常明显，稀土配分模式总体相似，呈左高右低 型，和抱板群变质沉积岩稀上元素组成基本一致；εＮｄ（ｔ）值普遍高于抱板群地层，（８７Ｓｒ／８６Ｓｒ）ｉ值变化 大，暗示幔源参与信息。结合抱板群变基性火山岩的
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| 关 键 词： | 地球化学和成因 原地-半原地过铝质 二元混合 中元古代花岗岩 海南岛 |
| 文章编号： | 1001-1552(2001)04-420-14 |
| 修稿时间： | 2001年3月10日 |
RESEARCH ON THE GEOCHEMISTRY AND GENESIS OF MESOPROTEROZOIC GRANITES ON HAINAN ISLAND |
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| Abstract: | Mesoproterozoic granites on Hainan island are composed of granite, granodiorite with the same origination, and show an evolution series evidently from granite to granodiorite and quartz-diorite with the evolution trend to calc-alkalic. The suits are in situ-semisitu prealuminous granites during the upheaval after collision of plate, have the genesis characteristics of mantle-crust two-component mixing, and are the result of situ-remelting of mid-lower crust bia-basic material(metasedimentary rocks and plao-amphibole-geniss within Baoban Group) and participating of mantle material by heating caused by crust thickinning and following underplating of tholeiitic magma because of the collision of plate, at last, the melting magma ascends, concretes and posits along the Gezhen ductile shear zone because of the mechanism of strike-slip dilatancy pumping. The granites are characterized of high SiO2, K2O, Rb, Ba, Ta, Ce and low P, Ti, Zr, Sr, Fe2O3+FeO, MgO, CaO contents, the specific value of elements of Zr/Nb, La/Nb, Ba/Nb, Rb/Nb, K/Nb, Ba/La and Cr, Go, Ni, V are closed to that in mid-lower crust, the content of Rb, Sr, Ba, Ta, Zr and ratio of K/Sr, Rb/Sr, Sr/Ba have relatively less variable boundary, show consistence of the composition of originative rocks or melting mode. The granites have strong contrasts between LREE and HREE, an important negative Eu abnormality, and consistency REF models with right-inclining type, are identical to that of metasedimentary rocks within the Baoban Group. The higher value of positive εNd than that of rocks within Baoban Group and the variant of(87Sr/86~ Sr), suggest the formative information of mantel-crust mixing. Considering the feature of space distribution of metabasic volcanic rocks, We think that the transformation of tectonic system during Mesoproterozoic era might go through the whole course from feeble subduction, collision to underplating. |
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| Keywords: | Geochemistry and the genesis situ-semisitu prealuminous granites two-composonent mixing Mesoproterozoic granites Hainan island |
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