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构造—流体—成矿体系的复杂性及其动力学研究

The Study of the Complexity of Tectonic-Fluid-Mineralization System and Its Dynamic Mechanism

【作者】 谢焱石

【导师】 谭凯旋; 陈广浩;

【作者基本信息】 中国科学院研究生院(广州地球化学研究所) , 构造地质学, 2004, 博士

【副题名】以水口山铅锌金银多金属矿田为例

【摘要】 成矿系统是地球物质系统的重要组成部分,成矿作用是多组成和多重地质作用耦合的复杂动力学体系与复杂动力学过程,并以构造和流体作用为主导,构成构造、流体、成矿相互耦合的统一动力学体系——构造-流体-成矿体系。本文通过对水口山铅锌金银多金属矿田矿床断裂构造的分形和多重分形特征、成矿元素空间分布的分形与混沌特征的分析及非线性成矿动力学模拟研究,分析和探讨了构造-流体-成矿体系的复杂性及其动力学机理。 水口山铅锌金银多金属矿田内的矿床为浅成热液矿床,成矿作用与构造活动、流体作用密切相关。地质地球化学分析表明,成矿物质主要来源于上地壳,部分来自深源岩浆,成矿流体主要沿断裂带向上迁移并沉淀成矿。矿田区域断裂构造为多重分形分布。不论是由全部断层、不明性质断层到逆冲断层,还是由全部断层、有矿区断层到无矿区断层,多重分维谱f(α)的最大值、标度指数τ(q)的变化范围的大小、奇异指数α(q)的变化范围的大小、多重分维谱f(α)与X轴的左交点均呈递减的趋势,说明其复杂性亦呈递减的趋勢。 马王塘和新盟山地区金的地表化探数据服从分形和多重分形分布,其二维化探曲面面积具有双分形(bifractal)关系,显示新盟山地区金的分布要比马王塘地区的分布更复杂,两地区的成矿元素富集程度较高且存在地球化学场的局部富集叠加。矿田区域地层和花岗岩体的元素含量分布的分形关系表明地层和花岗岩体只显示了元素的原生分布规律,而断裂带内的元素分布有两个地质过程控制,即经受了后期改造叠加作用,并可能使一些活动性较强的元素富集程度增高,掩盖了元素的原生分布规律。此外,较小的分维值可以指示成矿作用的发生,F5、F16断裂带也有较好的找矿前景。康家湾矿区钻孔和坑探资料中各元素品位变化序列的混沌分析表明各元素品位变化为混沌序列,成矿流体的演化及成矿元素的沉淀富集成矿过程为复杂的混沌动力学过程,且垂直方向的复杂性要大于水平方向的复杂性,从而成矿流体以垂直方向演化为主,描述或控制本矿区成矿元素品位变化的独立变量至少需要6~8个。 数值模拟研究表明,在相对自由的空间内,矿物是分形集聚生长的,分形维数在一定的条件下随着表面粘附几率Pg的增大而减小,随着粒子间的引力场强度的增大而增大。构造对成矿作用控制最重要方面就是显著增高岩石的渗透率,在最佳的构造-岩石组合条件下,形成高的并能较长时间保持的断裂渗透串区域,促进流体流动,构造应力还可以促进矿物的溶解、元素的活化迁移与富集,从而形成大规模的矿床。 总之,成矿物质的沉淀过程是一个复杂的非线性动力学过程,矿物在热液体系中通过构造应力、流体流动、流体-岩石反应等之间的复杂非线性反馈作用,最终在合适部位沉淀下来,形成了各种具分形与混沌特征的矿床。

【Abstract】 Ore-forming system is an important part of the material system of the Earth. Ore-forming is a complex dynamic system and a complex dynamic process coupled multicomponents and multi- processes. The dominant processes are tectonics and fluid, and the coupling of structural deformation, fluid flow and mineralization construct an unitive dynamic system-tectonic-fluid-mineralization system. Using fractal and chaotic theory, the paper researches the fractal and multifractal character of fractures, fractal and chaotic character of spatial distribution ore-forming element of Shuikoushan Pb-Zn-Au polymetallic ore field, Hunan, China. And what’s more, along with the nonlinearity ore-forming dynamics numerical simulation, the complex of tectonic-fluid-mineralization system and its dynamic mechanism are analysed and discussed in this paper.The deposits in the Shuikoushan Pb-Zn-Au polymetallic ore field are epithermal deposit and their mineralizations have closed correlation with tectonic deformation and fluid processs. The geological and geochemical data indicate that ore-forming material major come from upper crust and a part of them come from anatectic magma and the ore-forming fluid major transfer along fractures from down to up and deposit at the appropriate site. The fractures in this ore field are multifractal distribution. Not only from all faults, uncertain property faults to reverse thrust faults, but also from all faults, ore bearing area faults to barren area faults, all of the maximum of f(a), the size of x(q) variation range, the size of a(q) variation range, the left point of intersection of f(a) and X axis show a decrease successively tendency and indicate their complex have the same change tendency.The geochemical exploration data of Mawangtang area and Xinmengshan area show fractal and multifractal distribution and the 2 D geochemical exploration curved surfaces have bifractal relation. The fractal values indicate that the Au distribution of Xinmengshanarea more complex than Mawangtang area and ore-forming elements of both two area have a high grade of concentration, and what’s more, the geochemical field show a local enrichment superposition.The fractal analyses of element content of ore field stratum, granite body and fractute zone indicate stratum and granite body can only show the original element distribution but fractute zone show two geological processes control the element distribution. The deuteric superposition processes increse the enrichment of some high activity elements. Furthermore, the little fractal value can show mineralization and F5 and F16 fracture zones show a good ore prospecting forefround.Numerical simulating studies indicate that minerals grow in a relatively free space is a fractal aggregate process and the fractal dimension values will decrease increase along with the increase of sticking probability to the flat surface Pg and increase with the increase of gravitation field intension between ions. The fracture structure is an important role for controlling on hydrothermal mineralization. One of the most important sides is to increase remarkably rock permeability through all kinds of coupling and feedback processs among the tectonic-fluid dynamic system, furthermore, with the best structure-rock combination, to form a long time persistence high fracture permeability zone and therefore lead large scale deposition.In conclusion, the deposition of ore-forming material is a complex nonlinearity dynamics processs. Through all kinds of coupling and feedback processs among the tectonic stress, fluid flow, fluid-rock reaction, minerals deposition at the appropriate site in fault structures al last and then form epithermal deposits with fractal and chaotic character.

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