【作者】 赵义来；

【导师】 刘亮明；

【作者基本信息】 中南大学 ， 地质学， 2012， 博士

【摘要】 成矿系统的结构和动力学过程是认识成矿系统之关键,然而对于复杂的成矿系统而言,要全面而准确地认识和表征其结构和动力学过程却决非易事。计算模拟已成为认识这种复杂成矿系统的有效手段之一。安徽怀宁月山矿田是长江中下游成矿带中最重要的矿田之一,这里的矿床是与月山长英质浅成岩体密切相关的矽卡岩型矿床,是一个非常复杂的成矿系统。本文选择月山矿田为研究对象,在地质背景分析和矿床地质调查的基础上,通过对矿体以及与成矿相关的地质体及地质场的三维形态模拟揭示成矿系统的空间结构和成矿定位的空间规律,通过对岩体冷却过程耦合动力学的计算模拟揭示矿体定位的动力学机制及其控制因素,取得了如下5个方面的主要成果：1)基于形态模拟软件(GoCAD)和模拟对象的特点,发展了一套模拟复杂地质体的建模方法,即：基于连续剖面数据,以Section-TIN法模拟延伸方向稳定的矿体；基于交叉剖面数据,以边界约束下的TIN剖分模拟法向较稳定的地层界面及断层面；基于多组交叉剖面数据,以Section-TIN法及局部约束优化的方法模拟具有分支复合形态的岩体等。这样构建的模型兼具光滑及高度吻合原始数据的特点,达到了理想的模拟效果。2)为解决成矿系统动力学模拟中复杂形态地质体的三维建模和网格剖分的难题,采用C++开发了由GoCAD形态模型转换成FLAC3D可计算的四面体剖分网格模型的转换程序,从而实现了形态模拟和动力学模拟的无缝对接。3)通过矿体及相关地质要素的三维形态模拟揭示出月山岩体成矿的基本规律为：矿体定位受接触带形态控制,岩体接触带成矿主要发生在岩体接触带形态发生急剧变化的部位。4)通过成矿元素空间浓集场的模拟揭示了成矿元素的空间浓集规律与主要断层、岩体接触带形态及褶皱构造有关,成矿元素具有向F1、F6断层、接触带转折部位及褶皱枢纽部位浓集的趋势,表明F1、F6断层不是单纯的错矿体的成矿后断层,对成矿元素的富集也起了重要作用。5)通过月山岩体同构造冷却动力学过程计算模拟实验发现：由力—热—流耦合作用而形成的汇流扩容空间是接触带矽卡岩矿体定位的主要空间,由于岩体接触带形态而造成汇流扩容空间沿接触带不均匀分布是造成接触带上矿体不均匀分布的关键原因,不同来源流体的混合反应和汇流扩容空间流体压力的降低是造成矿石在汇流扩容空间沉淀的主要机制。更多还原

【Abstract】 The architecture and geodynamic processes are critical for understanding the matellogenic system. It is not easy to understand and illustrate the architecture and geodynamic processes of the complex matellogenic systems thoroughtly and accurately. Computational modeling has become one of the most effective means for researching such systems.The Yueshan orefield, located in Huaining, Anhui province, is one of the most important orefields in the lower-middle Yangtze metallogenic belt. The deposits in this orefield, mainly of skarns associated closely to the Yueshan felsic hypabyssal intrusion, are a very complicated metallogenic system. In this thesis, the Yueshan orefield is researched through computastional modeling, based on the analysis of the geological background and investigation of the deposits geology. By the3D shape simulation of the orebodies and related geological factors, the spatial architecture of the matellogenic system and the regularity of orebodies location are revealsed. By modeling the cooling process of the Yueshan intrusion, the dynamic mechanism and controlling factors for ore formation localisation are investigated. The main outcomes in this thesis include the following5aspects.1) On the GoCAD platform, a set of methods for simulating the complex geological bodies are developed according to the features of geological objects. By Section-TIN method and continuous profile data, model of orebodies with constant trending direction is constructed. Based on TIN constrained by curve border and data on crossed profile, surfaces with stable normal direction, such as stratum and fault, are modeled. Based on data on several different directions continuous profile, methods of Section-TIN and local constrained optimization are used to model intrusion with branches. These methods result in the ideal models that are smoothly surfaced as well as constrainted best the the original data.2) A programme is developed by using the C++programming to convert GoCAD solid model to tetrahedron meshed FLAC3D model for dynamic calculation. It absolutely faciliates model construction and grid discretization of complex geological bodies that are general difficult for the modeling the geodynamics of the complex metallogenic systems3) The3D shape modeling of the orebodies and related geological factors demonstrates that the shape of contact zone of the intrusion controls the orebodies location. It is discovered that the orebodies were generally localised in the specific sites where the shape of contact zone has sharp change.4) The modeling of spatial distribution of ore-related elements demonstrates that the concentration is related to the main faults, the shape of contact zone and the fold. The ore elements are concentrated toward the fault F1and F6, the turning positions of the contact zone and the fold hinge, suggesting that F1and F6can not only cut the orebodies, but also play an important role in ore enriching.5) Computational modeling experiments on the syn-tectonic cooling dynamics process of Yueshan intrusion are carried out, and the results are as follows. Fluid-focusing dilation spaces resulted from coupled mechano-thermo-hydrological processes are the favorable positions for the skarn orebodies locating on the contact zone. The uneven distributiong of fluid-focusing dilation spaces related to the shape of the contact zone is the main cause for the uneven distributiong of orebodies on the contact zone. The mixing reaction of fluids from different origin and the decrease of fluid pressure in the fluid-focusing dilation spaces are the main reason for ore precipitation.更多还原