| 强烈亏损重稀土元素的中酸性火成岩(或埃达克质岩)与Cu、Au成矿作用 |
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| 引用本文： | 王强,许继峰,赵振华.强烈亏损重稀土元素的中酸性火成岩(或埃达克质岩)与Cu、Au成矿作用[J].地学前缘,2003,10(4):561-572. |
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| 作者姓名： | 王强 许继峰 赵振华 |
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| 作者单位： | 中国科学院,广州地球化学研究所,广东,广州,510640 |
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| 基金项目： | 国家重点基础研究发展规划项目(2001CB409803,2002CB412601)，国家自然科学基金(40273019,40172028)，中国科学院知识创新工程项目(KZCX3-SW-122,KZCX2-102和KZCX2-SW-117) |
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| 摘 要： | 文中概述了强烈亏损重稀土元素的中酸性火成岩(或埃达克质岩)的研究历史、现状和意义,列出了扬子地块东部、青藏高原以及新疆北部与铜金成矿有关的同类岩石的一些特征,重点分析了当前强烈亏损重稀土元素的中酸性火成岩(或埃达克质岩)的研究中所存在的问题,并提出了一些初步的设想。强烈亏损重稀土元素的中酸性火成岩(或埃达克质岩)不仅具有重要的地球动力学意义(可能与俯冲、拆沉、底侵、板片窗或地幔交代等深部过程有关),而且具有极其重要的Cu、Au成矿意义。俯冲洋壳熔融形成的埃达克岩及其成矿作用已有相当深入的研究,但是来自大陆内部的强烈亏损重稀土元素的中酸性火成岩的成因、岩石组合及其成矿作用是否类似于俯冲洋壳熔融形成的埃达克岩,还需要深入的研究。一些强烈亏损重稀土元素的中酸性火成岩(或埃达克质岩)的所表现出的高钾特征很可能与高压(>1 GPa)条件下的熔融或源岩的高钾有关。文中提出了一个有别于俯冲洋壳熔融+埃达克岩+Cu、Au成矿的新工作模型——拆沉洋壳或下地壳熔融+强烈亏损重稀土元素的中酸性火成岩(或埃达克质岩)+Cu、Au成矿。拆沉洋壳或下地壳熔融形成熔体的Fe_2O_3对地幔的交代(氧化)作用可能是Cu、Au从地幔迁出并最终成矿的一个重要原因,但是增厚下地壳环境中流体的作用也不?
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| 关 键 词： | 埃达克岩 Cu、Au成矿 拆沉 底侵 地幔交代(氧化)作用 高钾 扬子地块 青藏高原 新疆 |
| 文章编号： | 1005-2321(2003)04-0561-12 |
| 修稿时间： | 2003年4月23日 |
INTERMEDIATE-ACID IGNEOUS ROCKS STRONGLY DEPLETED IN HEAVY RARE EARTH ELEMENTS(OR ADAKITIC ROCKS) AND COPPER-GOLD METALLOGENESIS |
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| WANG Qiang,XU Ji-feng,ZHAO Zhen-hua Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou ,China.INTERMEDIATE-ACID IGNEOUS ROCKS STRONGLY DEPLETED IN HEAVY RARE EARTH ELEMENTS(OR ADAKITIC ROCKS) AND COPPER-GOLD METALLOGENESIS[J].Earth Science Frontiers,2003,10(4):561-572. |
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| Authors: | WANG Qiang XU Ji-feng ZHAO Zhen-hua Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China |
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| Institution: | WANG Qiang,XU Ji-feng,ZHAO Zhen-hua Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China |
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| Abstract: | The research history, status quo and significance of intermediate-acid igneous rocks strongly depleted in heavy rare earth elements (or adakitic rocks) are summarized in this paper. Some geochemi-cal characteristics of the same kind of rocks related to Cu-Au mineralizations are listed here, and these rocks are from the east Yangtze Block, the Tibet Plateau and the north Xinjiang. In this paper, some questions are emphasized, for instance, petrogenesis mechanism, K2O contents, rocks association, and metallogenesis of the intermediate-acid igneous rocks strongly depleted in heavy rare earth elements (or adakitic rocks). The high K2O contents of some intermediate-acid igneous rocks strongly depleted in heavy rare earth elements (or adakitic rocks) are possibly related to partial melting under high pressure (>1. 0 GPa) or high K2O contents of the source rocks. Some elementary conceives on these questions are also proposed. The intermediate-acid igneous rocks strongly depleted in heavy rare earth elements (or adakitic rocks) have not only important geodynamic significances (related to deep processes, such as subduction, delamination, underplating, slab windows or mantle metasomatism), but also very important significances of Cu and Au metallogenesis. Adakite related to partial melting of subducting oceanic crust and its metallogenesis have been studied in detail, but how are the petrogenesis, rocks association and metallogenesis of intermediate-acid igneous rocks strongly depleted in heavy rare earth elements from inner continent? Are they similar to that of adakite derived from partial melting of subducting oceanic crust? These questions need to be further studied. A new work model different from partial melting of subducting oceanic crust + adakite + Cu and Au metallogenesis is proposed in this paper: partial melting of delaminated oceanic crust or of lower crust + intermediate-acid igneous rocks strongly depleted in heavy rare earth elements (or adakitic rocks) + Cu and Au metallogenesis. The processes that the Fe2O3 from the magmas derived from partial melting of delaminated oceanic crust or of lower crust metasomate (or oxidize) the mantle likely make Cu and Au emigrate from the mantle and produce Cu-Au mineralization at last. But the fluid roles in the setting of thickened lower crust are impossibly ignored. |
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| Keywords: | adakite Cu and Au metallogenesis delamination underplating mantle metasomatism (or oxidation) high-potassium Yangtze Block Tibet Plateau Xinjiang |
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