| 小秦岭西段驾鹿金矿田成矿流体特征、物理化学条件及演化 |
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| 引用本文： | 高珍权,刘继顺,陈德兴.小秦岭西段驾鹿金矿田成矿流体特征、物理化学条件及演化[J].地球化学,2001,30(3):257-263. |
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| 作者姓名： | 高珍权 刘继顺 陈德兴 |
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| 作者单位： | 1. 中南大学地质研究所,
2. 中国地质大学武汉地球化学研究所， |
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| 摘 要： | 以成矿系列理论为指导，在对比性研究了小秦岭西段驾鹿金矿田的葫芦沟、莲子沟和王排三个金矿床的赋矿地层、控矿构造、矿化蚀变类型及分带性、成矿期、成矿阶段划分和矿床类型等地质特征的基础上，运用包裹体测温学、流体成分分析及计算方法，研究了三个矿床不同成矿阶段的包裹体特征、成矿的物理化学条件和成矿溶液的组分特征及演化，认为：（1）虽然它们的矿床类型不同，主要地质特征差异明显，但所经历的成矿期、成矿阶段和相同阶段的矿物共生组合十分相似。在空间位置上，从下到上矿床类型由蚀变岩型过渡到石英脉型，因而隶属于同一成矿系列。（2）从蚀变岩型到石英脉型金矿床，成矿的物理化学条件和成矿溶液具有与之相对应的变化特征:①各成矿阶段的平均均一温度降低；②成矿的压力和深度减少；③成矿溶液的盐度相当或有所增加；（3）在金的成矿作用过程中，从I→Ⅳ阶段各矿床的物理化学条件的演化具有下述类型的特征：①成矿的温度、压力逐渐降低；②成矿溶液的酸碱度具有从弱碱性（中性）→弱酸性→酸性→弱碱性的演化规律；③氧化还原电位表现为相对氧化→相对还原→相对氧化的变化趋势。
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| 关 键 词： | 成矿流体 包裹体 物理化学条件 小秦岭 成矿系列 金矿田 金矿床 控矿构造 成矿作用 |
| 文章编号： | 0379－1726(2001)03－0257－07 |
| 修稿时间： | 2000年6月19日 |
Characteristics of mineralizing fluid, physicochemical conditions and their evolution of Jialu gold orefield, West Xiao Qinling |
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| GAO Zhen-quan,LIU Ji-shun,CHEN De-xing.Characteristics of mineralizing fluid, physicochemical conditions and their evolution of Jialu gold orefield, West Xiao Qinling[J].Geochimica,2001,30(3):257-263. |
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| Authors: | GAO Zhen-quan LIU Ji-shun CHEN De-xing |
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| Abstract: | Jialu gold ore field, whose geotectonic position is in the south side of the west part of Taihua uplift at the southern margin of the North China platform, is located in the south flank of Dayueping Jingluoban anticlinorium. It is one of important parts of Xiao Qinling gold district. There are three gold deposits in it: Hulugou altered rock type gold deposit is located in Qingcanggou Formation of Taihua Group, Lianzigou alliterated rock type gold deposit in Gaoshanhe Formation of Jixian System and Wangpai gold bearing quartz vein type deposit in Sanguanmiao Formation of Taihua Group. Guided from the theory of metallogenic series, and on the basis of the comparative study of geological characteristics, such as ore bearing strata, ore controlling structures, types and zoning of mineralizations and alterations, types of metallogeny, classification of mineralized epochs and periods of these three gold deposits in Jialu gold ore field of West Xiao Qinling, and with the principles and methods of petrography and microthermometry, composition analyses and calculation of the fluid composition, it is focused on characteristics of fluid inclusion in different stages of three gold deposits, as well as on physicochemical conditions, such as temperature, pressure, density, salinity, pH, Eh values, of ore forming fluid and the features of their component and their evolution. The results are as follows. (1) Three gold deposits belong to the same metallogenic series because of their similarities in geological characteristics such as mineralized epochs and periods, mineral association in the same epoch, and also because of their relation in space in which types of gold deposits gradually change from altered rock to gold bearing quartz vein while the depth of which changes from deep to shallow, though the differences of main geological characteristics are obvious, such as the character and occurrence of ore controlling structures, ore bearing strata, types of wall rocks, occurrence of ore bodies and types of ore between them. (2) The results of inclusion thermometry show that main features of inclusions in quartz of main ore forming stages in these three gold deposits are similar in abundance, and size. The distribution of inclusions is commonly irregular asteroid and directional array locally. Fluid inclusions exhibit at room temperature several kinds of phrase combinations: mainly single phase aqueous, minor two phase (liquid gas). The differences of the fluid inclusion characteristics among stages are notable. There are more abundant, bigger volume, higher gas/liquid ratio and variety in the stage Ⅱ and stage Ⅲ than those in the rest stages. There exist multiphase (CO2 rich) fluid inclusion and boiling fluid inclusion usually in stage Ⅲ . (3) Ore forming physicochemical conditions and fluid features from altered rock type to gold bearing quartz vein type are characterized by reduction of average homogenization temperature of the same stage, decrease of ore forming pressure and depth, and equivalent or increase of fluid salinity. (4) The evolution of physicochemical conditions in different types of gold deposits from stage Ⅰ to stage Ⅳ during gold mineralizing process has similar features as follows. Homogenization temperature and pressure reduce gradually. Alkalinity acidity of ore forming fluid changes from slight alkalinity (neutrality) to slight acidity and to acidity, at last to slight alkalinity. The change of the redox potential is from relative oxidation to relative reduction and to relative oxidation. |
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