地学前缘 ›› 2011, Vol. 18 ›› Issue (5): 78-89.

• 论文 • 上一篇    下一篇

浅成岩体引发的流体超压与岩石破裂及其对成矿的制约

刘亮明   

  1. 中南大学 计算地球科学研究中心， 湖南 长沙 410083
  • 收稿日期:2011-06-20 修回日期:2011-08-09 出版日期:2011-09-18 发布日期:2011-09-18
  • 作者简介:刘亮明（1964—），男，教授，博士生导师，主要从事矿床地质和构造地质专业的教学和研究。E-mail: liangming.liu@126.com
  • 基金资助:

    国家自然科学基金项目（40772195）

Fluid overpressure and rock fracturing caused by shallow intrusion and their constraints on hydrothermal mineralization.

  1. Liu Liangming. Fluid overpressure and rock fracturing caused by shallow intrusion and their constraints on hydrothermal mineralization. Earth Science Frontiers， 2011， 18(5): 078089
  • Received:2011-06-20 Revised:2011-08-09 Online:2011-09-18 Published:2011-09-18

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摘要：

浅成岩体成矿系统是一类非常重要的复杂动力学系统。在这类系统中，由浅成岩体引发的流体超压以及因此而促发的岩石破裂是制约成矿的关键动力过程。文章在综合前人有关研究成果的基础上，结合对铜陵—安庆地区夕卡岩矿床的研究，从理论上对浅成岩体成矿过程中流体超压的重要性、形成机制及其对成矿作用的制约进行了系统论述。夕卡岩矿床与角砾岩间的密切关系以及这种角砾岩本身的特征证明由流体超压引发的岩石破裂在成矿中具有重要作用。这种引起成矿的流体超压具有复杂的形成机制，除了源自岩浆的出溶和脱气外，还可以是岩浆加热圈闭在围岩中的流体以及岩浆与碳酸盐岩围岩间的变质反应所引起。超压流体对成矿的贡献是通过引起岩石的破裂及其促发的一系列动力学事件而实现，最主要的是由流体的泄压引起的相分离和不同来源流体的汇流和混合反应。流体超压—岩石破裂和流体泄压—破裂愈合两个相反的过程通过岩石孔隙度和渗透率的改变而耦合，在岩浆动力和构造动力条件配合下自组织地向高有序状态演化——成矿。由于岩石的破裂是构造应力和流体压力共同作用的结果，而岩石破裂又是成矿的关键动力过程，所以流体压力和构造应力相互配合不仅决定了岩石破裂的方式和机制，也同样制约了成矿的类型。

关键词: 流体超压, 流体泄压, 液压致裂, 浅成岩体, 成矿, 动力学

Abstract:

 The metallogenic systems related to shallow magmatic intrusions are the very important and complicated dynamic systems. In such a system, fluid overpressure caused by the shallow intrusion and consequent rock fracturing are critical dynamic processes for mineralization. This paper presents systemic analysis on the importance of fluid overpressure for mineralization related to shallow intrusions, the mechanisms for generating overpressure and the constraints of overpressured fluids on mineralization, with examples of skarntype mineralization from the TonglingAnqing district. The close association of skarn ore deposits with breccias and the characteristics of such orerelated breccias indicate the important role played by hydraulic fracturing in mineralization. The mechanisms for generating fluid overpressure associated with ore formation are very complex, including magma exsolution and degassing, expansion of pore fluids sealed in the country rocks due to heating by magma, and metamorphic reactions of the carbonate rocks with the magma. The contribution of the overpressured fluid to mineralization is realized through hydraulic fracturing followed by a series of dynamic events, mainly including the decompression of the fluids and consequent phase separation as well as mixing and reactions of fluids from different sources. The fluid overpressuringhydraulic fracturing and  the fluid decompressioncrack sealing, the two opposite processes, are coupled with fluid flow through changing the porosity and permeability of the rocks. These processes, governed by the magmatic dynamic input and tectonic stress field, selforganized the system towards a higher order state, leading to mineralization. Because rock fracturing is caused both by fluid pressure and tectonic stress, and is critical for ore formation, the combination of fluid pressure and stress field control not only the patterns and mechanisms of fracturing, but also the styles of ore formation.

Key words:  fluid overpressure, fluid decompression, hydraulic fracturing, shallow intrusion, ore formation, dynamics

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