摘要
安庆铜矿是长江中下游成矿带中重要的矽卡岩矿床,其矿体绝大部分产在形态复杂的岩体接触带上,对于这种矿体定位特点,本文采用数值模拟的方法探讨了其动力学机制和主要的控矿因素。首先以AutoCAD和GO-CAD为平台构建安庆铜矿岩体及围岩的三维实体模型,并通过C++编程实现到模拟软件的模型格式转换,然后以FLAC3D为平台进行安庆铜矿热液成矿过程的力-热-流耦合数值模拟。结果显示,受控于拉张应力场,岩体大部分位置表现为正的体应变;月山岩体东枝南接触带是扩容最为明显的区域,部分岩石单元的大扩容角对扩容区出现有一定的贡献,岩石物理性质的差异及接触带的复杂形态则是其主要原因;岩石扩容部位成为流体汇集的有利场所,汇流部位与明显扩容区及主矿体产出位置相一致,推断矿体的定位是力-热-流共同作用的结果;运算结果亦指示现有矿体深部存在新的有利找矿靶区。
The Anqing Cu deposit is one of the most important skarn-type deposits in the lower-middle Yangtze metallogenic belt. Most of the orebodies are located in the contact zones of intrusions with complex geometries. Using a numerical modeling approach,this paper studies the geodynamic mechanism and principal ore-controlling factors responsible for the formation of the orebodies （in particular their locations）. Our modelling workflow involves several steps. Firstly,the three-dimensional entity model and computational mesh of the pluton and wall rocks for the Anqing Cu deposit were constructed using a combination of software AutoCAD and GOCAD. The 3D mesh was then converted into a format that can be imported into the modelling software,FLAC3D,by means of C＋＋ programming. Finally,the coupled mechanical-thermal-hydrological numerical modeling of hydrothermal metallogenic processes for the Anqing Cu deposit was performed in FLAC3D. The results show that,controlled by an extensional stress field,the most areas of the pluton show positive volumetric strain,with the maximum dilation localized in the southern contact zone of the eastern intrusion branch. The differences of rock physical properties and the complex geometries of the contact zone are the main reasons for the localization of the maximum dilation while the high dilation angles for skarn and other rock units （T1n-T2y,T1y-T1h） also have roles to play. These areas with the maximum dilation turn to be the favorable sites for fluid flow focusing,consistent with the locations of the main orebodies of the Anqing Cu deposit. It is therefore inferred that mineralization and locations of orebodies at the Anqing Cu deposit reflect the outcomes of the mechanical-thermal-hydrological interactions after magmatic intrusion. The current results are also suggestive of new exploration targets in the deeper contact zone below the existing orebodies.
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2011年第1期128-136,共9页
Geotectonica et Metallogenia
基金
国家自然科学基金项目(40772195)资助
关键词
复杂岩体成矿
矽卡岩矿床
网格模型构建
三维数值模拟
安庆铜矿
complicated pluton ore-formation
skarn-type deposit
construction of grid model
3D-numerical modeling
Anqing deposit
