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| 成矿侵入体的岩石学标志 | |
| 引用本文： | 罗照华,卢欣祥,许俊玉,刘翠,李德东.成矿侵入体的岩石学标志[J].岩石学报,2010,26(8):2247-2254. |
| 作者姓名： | 罗照华 卢欣祥 许俊玉 刘翠 李德东 |
| 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,郑州,450053 3. 国家地质实验测试中心,北京,100037 |
| 基金项目： | 中俄合作基金项目（40911120079，RFBR-GFEN08-05-92224）、国家科技支撑计划重点项目（2006BAB07B08）、中国地质调查局地质调查工作项目（1212010911028）和河南省地质矿产重大科技攻关计划项目(26417) |
| 摘 要： | 侵入体的含矿性是资源勘查领域最为关注的问题之一。确定含矿性的宏观标志并为其提供理论基础因而是科学研究的重要任务。但是,传统岩石学研究主要关注含少量水体系或干体系的形成与演化,内生金属成矿作用却主要与流体有关,所取得的岩石学认识常常不适应矿区的地质实际。本文基于透岩浆流体成矿理论分析了熔浆-流体相互作用的性质及其对成矿作用的可能影响,指出在大量流体参与的情况下,成岩过程将具有明显不同的特征,并留下显著的岩石学标志。流体的增减可以导致岩浆密度和黏度的巨大变化,也导致熔浆固相线温度和首晶区矿物相类型和共结成分的变化,因而侵入岩结构构造特征可反映流体参与成岩过程的程度,并指示侵入体的成矿潜力。熔浆与流体的分离导致岩浆黏度增加和快速固结,达到临界值后必然圈闭部分含矿流体于颗粒之间和内部,因而含有造矿矿物的共结结构和浸染状构造确定性地指示了含矿流体通道的位置。多晶体岩浆的流变学特征与多斑斑状结构在矿区的广泛出现是一对线性系统中不可调和的矛盾,可以用含矿流体的突然大规模注入来解释。据此,可以认为多斑斑状是大部分成矿金属仍保留在侵入体内的可靠标志。此外,文章还提供了另外几个辅助性标志,可用于综合分析侵入体的含矿潜力。最后,作者得出结论,大量流体参与的成岩过程是一种非线性过程,可以产生一系列特殊的结构构造,对成矿作用具有重要的指示意义。 |
| 关 键 词： | 岩石学 找矿标志 透岩浆流体 非线性过程 高位侵入体 |
| 收稿时间： | 4/1/2010 12:00:00 AM |
| 修稿时间： | 6/1/2010 12:00:00 AM |
Petrographic indicators of the ore-bearing intrusions |
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| LUO ZhaoHu,LU XinXiang,XU JunYu,LIU Cui and LI DeDong.Petrographic indicators of the ore-bearing intrusions[J].Acta Petrologica Sinica,2010,26(8):2247-2254. | |
| Authors: | LUO ZhaoHu LU XinXiang XU JunYu LIU Cui and LI DeDong |
| Institution: | State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;Scientific Academy of Land and Resources of Henan, Zhengzhou 450003, China;National Research Center for Geoanalysis, Beijing 100037, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China |
| Abstract: | One of the key questions attracted attention in the resource exploring field is the potential from an intrusion to produce metals. Hence determining the macroscopic indicators of ore-bearing intrusion and providing its theoretical interpretations are of the important responsibilities of scientific studies. However, due to the traditional petrology is mainly concerned with formation and evolution of the dry or H2O-unsaturated systems, but generation of the endogenic mineral deposits is mainly relative to the fluids, the obtained progresses in petrology often can not satisfy exploration geologists. This paper, based on the theory of metallogenesis by transmagmatic fluids, aims at analyzing the features of melt-fluid interaction and their potential effects on ore-forming processes. It is suggested that the rock-forming processes involving huge fluid are obviously different to the generally recognized magmatic processes, and they should leave distinct petrographic signals. Adding or reducing fluid induces density and viscosity of the magma to be changed obviously and modify the solidus temperature and liquidus phase relation and the eutectic composition. Therefore, the textures and structures of intrusive rocks reflect the degree of fluids involved in the rock-forming processes, and can be used as indicators for ore-forming potentials of an intrusion. Separation of the fluids from a melt increases the melt viscosity up to orders of magnitude and solidus temperature and induces to rapid consolidation. Subsequently, portions of the metal-bearing fluids must be trapped into and between the crystal grains, and eutectic and /or poikilitic texture and disseminated structure should be formed. These texture and structure, therefore, indicate which intrusion is the conduit for the ore-bearing fluids. The rheology of poly-crystal magma and the poly-phenocryst porphyritic texture, which broadly occur in many orthomagmatic ore deposits, are of irreconcilable contradicting features in terms of linear system. However, it can be attributed to the unexpected fluxing of the ore-bearing fluid flow into the barren magma. Accordingly, the poly-phenocryst porphyritic texture is a reliable indicator showing preservation of the most of ore-forming metals in the magma body without significant escape. In addition, several other supplementary indicators, which can be used to integratively evaluate the ore-producing potential of an intrusion, are suggested in this contribution. Finally, the authors have concluded that the ore-forming processes involving huge fluids are non-linear and produce series of specific fabrics with important signification for evaluation of mineralization. |
| Keywords: | Petrography Prospecting indicator Transmagmatic fluid Non-linear process High-level intrusion |
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