【作者】 胡宝群； 吕古贤； 王方正； 孙占学； 李满根；

【Author】 HU Bao-qun~1,LU Gu-xian~2,WANG Fang-zhang~3,SUN Zhan-xue~1,LI Man-gen~1 (1.Key Laboratory of Fundamental Science for National Defense on Radioactive Geology and Exploration Technology, East China Institute of Technology,Fuzhou of Jiangxi Prov.344000,China; 2.Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China; 3.Faculty of Earth Sciences,China University of Geosciences,Wuhan of Hubei Prov.430074,China)

【机构】 东华理工大学放射性地质与勘探技术国防重点学科实验室； 中国地质科学院地质力学研究所； 中国地质大学地球科学学院；

【摘要】 在热液成矿作用中,流体主要组分是水。在研究热液矿床时,除了要重视不同介质之间的化学反应、地质背景及演化等因素外,水的相变也是了解热液成矿作用过程的窗口。以等压热容为例,应用NIST提供的计算平台,研究了地壳中随着温度和压力的改变,水的热容变化规律,发现一、二级相变可以造成水的物理化学参数急剧变化;特别是在临界点处还会出现奇异性变化、导致热容等参数趋于无穷大,这与非相变区物理化学性质小幅度的渐变区别明显;只有当温度和压力同时趋于临界值时,临界奇异性才出现,而随着温压对临界值的偏离,临界奇异性以负指数形式迅速减弱。相变引起水物理化学性质的突变,极大地影响着矿质是迁移和沉淀,是热液成矿作用的必要条件。据水的相图和地温线可知,当温度低于临界温度时,正常地温线均处于水的液相,且明显偏离水的气-液相变线,即在正常地温条件下封闭的地壳中不会发生水的气-液间相变,只有发生断裂降压时才能出现一级相变。按正常地温梯度和地压梯度计算,在地温梯度变化正常的、相对封闭的岩石圈中,不可能存在一个区域能使温压同时达到水的临界常数,也就是不会出现热容、溶解度等物理化学参数的奇异性变化,即成矿可能性也不大;只有在局部降压、局部升温、或两者同时出现等一些特殊的情况下,才能在岩石圈中某一区域能同时达到水的临界温度和压力,出现临界奇异性变化。因此,通过水的相变研究,揭示出热液成矿作用中水的相变和断裂(或断裂+岩浆活动)之间的内在耦合关系,由此,通过水的相变可建立成矿期次与断裂期次之间的对应关系。水的相变是连接微观和宏观控矿因素的纽带,是热液矿床形成的重要控制因素之一。更多还原

【Abstract】 Water is the main composition of the geo-fluid in the hydrothermal mineralization.The phase transition of water is also the key factor to understand the processes of hydrothermal mineralization,as well as the reactions among various substances and the geological evolutions.The paper,takes the iso-pressure heat capacity(C_p) for example of physicochemical properties,has studies the changing regularity of C_p according to temperature and pressure in the crust with the method from National Institute of Standards and Technology(NIST) and showed that the phase transition of water can cause the sharp variations of the physicochemical properties of water and is one of the essential factors to hydrothermal mineralization.From the study the paper has also revealed the interior coupling relations between the phase transitions of water and fracture or magma activities.Furthermore,the article suggests that the corresponding relations between fracture epoch and metallogenic epoch can be created by the aid of the water phase transitions and concludes the phase transition of water is the important factor to control the hydrothermal mineralization.更多还原