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| 透岩浆流体成矿作用——理论分析与野外证据 | |
| 引用本文： | 罗照华,莫宣学,卢欣祥,陈必河,柯珊,侯增谦,江万.透岩浆流体成矿作用——理论分析与野外证据[J].地学前缘,2007,14(3):165-183. |
| 作者姓名： | 罗照华 莫宣学 卢欣祥 陈必河 柯珊 侯增谦 江万 |
| 作者单位： | 1. 中国地质大学,地质过程与矿产资源国家重点实验室,北京,100083 2. 河南省国土资源科学研究院,河南,郑州,450053 3. 中国地质科学院,地质研究所,北京,100037 4. 中国地质科学院,地质力学研究所,北京,100081 |
| 基金项目： | 国家重点基础研究发展计划(973计划) , 河南省地质矿产重大科技攻关计划项目 |
| 摘 要： | 文中介绍并发展了科尔任斯基等有关透岩浆流体成矿作用的基本概念,结合当今地质学领域的一些基本事实,以及混沌边界成矿理论和小岩体成大矿的原因分析,力图完整地阐述透岩浆流体成矿理论,并从地球动力学的视角来讨论成矿作用的基本问题。大多数矿区的岩石遭受过强烈蚀变,暗示成矿作用伴随着大规模流体活动。然而,地质观察和实验研究表明岩浆中流体的含量有限、小岩体常常与大型矿床有关、围岩中的流体由于高温岩浆的热压力而不能进入岩浆体中,表明成矿流体主要来自深部的独立流体系统。前人的实验还表明,流体中成矿元素的溶解度随压力快速增加。因此,成矿作用的前提条件是:(1)存在大量的深部流体和流体中高的金属浓度;(2)岩浆系统和成矿流体系统是两个独立的地质系统,它们具有类似的起源;(3)巨量金属堆积有赖于深部含矿流体的快速上升,岩浆体是含矿流体上升的有利通道,流体是岩浆快速上升侵位的驱动力之一。因此,岩浆系统和成矿流体系统往往具有同时活动的特点,这两个地质系统常常叠合在一起,形成我们现在观察到的火成岩及与其密切相关的成矿现象。根据这个理论,成矿作用的规模和位置取决于:(1)岩浆系统与流体系统的体积比,(2)含矿流体的上升速度,(3)金属堆积的边界条件,(4)岩浆系统与流体系统分离的程度。因此,快速上升侵位的岩浆有利于形成斑岩型矿床,较慢速侵位的岩浆可以形成夕卡岩型甚至远程低温热液型矿床,多数情况下是这三类矿床的复杂组合。冈底斯带曲水岩体中含铜暗色微粒包体的野外观察有助于理解成矿物质的来源、迁移和集聚成矿,是透岩浆流体成矿作用的一个缩影。将暗色微粒包体展现的成矿现象与藏东玉龙等斑岩铜矿相比,发现二者具有很好的类比性。可见,透岩浆流体成矿作用理论是一种非常重要的成矿理论,可以解释许多内生成矿作用之谜。 |
| 关 键 词： | 透岩浆流体 成矿作用 火成岩 溶解度 物理化学边界层 |
| 文章编号： | 1005-2321（2007）03-0165-19 |
| 收稿时间： | 2007-01-20 |
| 修稿时间： | 2007-01-202007-02-04 |
Metallogeny by trans-magmatic fluids——theoretical analysis and field evidence |
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| Luo Zhaohua,Mo Xuanxue,Lu Xinxiang,Chen Bihe,Ke Shan,Hou Zengqian,Jiang Wan.Metallogeny by trans-magmatic fluids——theoretical analysis and field evidence[J].Earth Science Frontiers,2007,14(3):165-183. | |
| Authors: | Luo Zhaohua Mo Xuanxue Lu Xinxiang Chen Bihe Ke Shan Hou Zengqian Jiang Wan |
| Institution: | 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China ;2. Scientific Academy of Land and Resources of Henan , Zhengzhou 450003, China ;3. Institute of Mineral Resources, CAGS, Beijing 100037, China; 4. Institute of Geomechanics , Chinese Academy of Geological Sciences, Beijing 100081, China |
| Abstract: | This paper is aimed at introducing and developing the principle of Metallogenic Theory through Trans-magmatic Fluids (MTTF) proposed by the Russian Kozhinskii's school. Some fundamental problems of metallogeny are discussed on geodynamic bases. In this theory, the trans-magmatic fluid is interpreted as a moving fluid passing through magma which is not yet consolidated. The intensive wallrock alteration of most of hydrothermal ore systems suggests that large scale fluid flow accompanies metallogenesis. However, geological observations and experiments imply a very limited solubility of fluids in magmas. In addition, the close relationship between small igneous bodies and large ore systems together with the difficulty of fluids that from the wallrocks might enter a magmatic body, which is under high pressure and temperature, need also to be considered. Those ore-bearing fluids that originate from a deep fluid system, are independent of magmas. Experiments show rapid increases of the solubility of ore-forming elements or their compounds in hydrothermal fluids. Therefore, the essential prerequisites for mineralization are (1) large volumes of deep ore-bearing fluids with high concentration of metals, and (2) the large amounts of metal accumulation depend on the rapid ascent of the deep ore-bearing fluid. Magmas are the favorable medium for the ascending fluids, because these magmas provide conditions that prevent re-equilibrium between the fluid and the wallrocks at different deep levels. The fluids in turn, may provide the driving force for the rapid ascent of magmas. Therefore, the two systems act together to account for the close relationship between magmatism and metallogeny. According to this theory, the scale and location of an ore-forming process are decided by (1) the volumetric ratio of the magma and the fluid systems, (2) the ascending rate of the ore-bearing fluid, (3) the boundary conditions for metal accumulation and (4) the segregation of the fluid from the magma. The field investigations of copper-bearing Melanocratic Macrogranular Enclaves (MME) in the Qushui massif, Gangdise belt are very helpful for understanding of source, transport and precipitation of ore-forming materials. In this example, it can be seen that fluid-rich MMEs is the source of the ore-forming element copper. Copper is transported out from MMEs by the fluid, following dispersal in the granitic magma. The copper-bearing fluid is then transferred through the magma and induced to deposit mineralization elsewhere. These processes have been noted when comparing the metallogenic features in both MME in the Qushui massif and the porphyry copper deposits in Yulong, eastern Tibet,. It is obvious that MTTF is a very important theory for metallogeny of endogenic deposits. Using this theory, many paradoxes in metallogenesis can be interpreted in easier manner. |
| Keywords: | transmagmatic fluid metallogeny igneous rock solubility physico-chemical boundary layer |
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