摘要
剪切带构造成矿系统动力学模拟可以定量，并能展示成矿系统时空结构与发展，从而揭示其本质。可从质量平衡、输运反应耦合、转换界面成矿和动力分形弥散等四个方面对剪切带构造成矿系统动力学进行理论分析与数值模拟。质量平衡分析指出：（１）剪切蚀变作用过程中，各种物质组分发生了不同程度的迁移；（２）体积应变为增加型，金矿床定位于剪切带的扩容带中；（３）存在较大的流体与岩石比值，金矿体定位于流体流量最大部位。耦合成矿动力学模拟表明：（１）金属硫化物成矿作用发生于剪压构造变形岩相向剪张构造变形岩相转换的时空界面；（２）其决定因素是成矿元素的地球化学特性及成矿流体的特征和性状；（３）岩浆侵入后，形成以岩体为中心的温度梯度带，是热液成矿作用的主要动力之一；（４）成矿流体的流速可以促进混合热液的生长，剪切破碎带是强烈输运反应耦合成矿的有利场所。动力弥散作用过程理论分析与计算机模拟指出：（１）点源淀积弥散机制，Ｃ＝Ａρｖ２ｄｘｄｙｄｔｅ－ｋｒ／［２π（ｈ２－ｖ２ｔ）ｄｌ］；（２）分形弥散度，αｍ＝ｘｓ２Ｄ－１σ２（εｃ１－Ｄ）／２；（３）剪切带构造成矿系统是自相似的变形变质系统，在动力系统作用下，矿源系统与输运系统耦合，弥散作用发生；?
The metallogenic system is a super complex entirety. It is made up of multi level time scale,manifold ore controlling parameters and multifarious processes.The ore forming process is one expression of dynamic functions of the Earth. It is a complex non linear dynamic process. Dynamics is the key that defines the evolution and final outcome of the system.Dynamic simulation of the shear zone metallogenic system can quantitatively simulate and display its structure and development,so it can reveal the nature of the system. It is a breakthrough of traditional metallogenic theory,and it is of great theoretical and practical significance. The authors put stress on the importance of tectonics and fluid, and apply the percolation theory and mass equilibrium equation to emphatically expound the dynamics of the system. Based on the theory and method of geologic anomaly and tectonic stress field, the authors imitate the processes of shear zone gold ore forming. Mass equilibrium analysis displays that: during the processes of shear and alteration, most elements may migrate in different degrees; volume strain is of extension type during the processes of shear and alteration; Au ore deposits locate in the tensional part of the shear zone, the ratio of fluid to rock is great during the processes of shear and alteration, Au ore bodies locate in the part where the fluids flow is of the greatest one. Dynamic simulation of metallogenic system of shear zone tectonics indicates that: the transformation of tectonodynamic mechanism may give a dynamic guarantee for mineralizing material to react,transport,gather and mineralize; the transformation of tectonic stress field is one of its manifestation, and the mineralization of gold took place on the space time interface where the shear strain deformed structural lithofacies transformed to the shear tension deformed structural lithofacies; the decisive factors are the geochemical characteristics of ore forming elements and the features of ore forming fluids; the temperature gradient belts around the rock body after its intrusion are one of the main dynamics for hydrothermal mineralization; the flow rate of ore forming fluid can accelerate the formation of mixed hydrothermal solution,the shear crushing zone is an advantageous ore forming place with strong transportation and action.The theoretic analysis and computer simulation of the dynamic percolation demonstrate that: the shear zone structure ore forming system is a self similar metamorphic deformation system, under the affection of dynamic system, the ore material system and the ore material transporting system may be coupled up, and the dispersion occurred; it only takes tens of years for finite percolation space to turn to infinite percolation space; different types of shear zones have very different ore forming process,different parts of the same shear zone have different enrichment degree of ore material; the simulation reveals six different types of ore forming parts in the shear zone,which provides an important basis for metallogeny,ore prospecting and predicting.
出处
《地学前缘》
EI
CAS
CSCD
1999年第1期115-127,共13页
Earth Science Frontiers
基金
攀登计划项目
国土资源部"百名跨世纪科技人才培养计划"基金
关键词
剪切带
成矿系统
耦合成矿
点源淀积
动力学模拟
shear zone,metallogenic system,mass equilibrium analysis, coupled ore forming,point source diffusive percolation,fractal percolation theory, simulation of dynamics
