淮南煤田南缘断层带碳酸盐岩组构特征及其指示意义研究

The fault zone of southern margin of Huainan coalfield, is an important tectonic control of the shape and occurrence of the coal bed. Huainan coalfield is an important coal base in East China, which degree of geological research is high, but the previous research was mainly focused on coal and coal strata, most studies of geological structure were limited to large scale fields such as coal bed or well. Some research knowledge was still lack of outcrop and basis of microscopic structural deformation of rock. The study on the test and analysis of rock fabric of coal periphery fault belt was even less. The main object of this research is carbonate rock of fault zone, using methods of field geological observation and indoor test, macro and micro to get detailed study on composition, structure, microstructure of deformation minerals. At the same time, through a lot of survey and statistics of preferred orientation of mineral crystal axis it can be to discuss stress, strain and the condition of temperature and pressure of deformation in rock mass which made by the tectonic movement, and to provide the basis for micro-deformation properties and further confirmed with deformation environment of main tectonic zone in Huainan coalfield.

淮南煤田南缘断层带，为控制煤田形态和产状的重要地质构造。淮南煤田是我国华东地区重要的煤炭基地，地质研究程度高，但以往的研究成果主要集中于煤及煤系地层，即使是地质构造也只限于煤田、井田等较大尺度范围,一些认识仍缺少露头乃至显微构造尺度的岩石变形特征依据,而开展煤田周缘断层带变形岩石组构方面的测试分析、变形物化条件的研究就显得更少。本次研究以断层带碳酸盐岩为主要研究对象，采用野外地质观察及室内测试、宏观与微观相结合的方法，对断层带碳酸盐岩的成分、结构、变形矿物显微构造等进行详细研究，同时通过对矿物晶体光轴的大量观测及优选方位的统计，来探讨构造运动在岩体内产生的应力、应变特征以及变形时的温压条件，为淮南煤田主要构造带的变形性质和变形环境的进一步确认提供微观依据。

本次研究以断层带碳酸盐岩为主要研究对象，采用野外地质观察及室内测试、宏观与微观相结合的方法，对断层带碳酸盐岩的成分、结构、变形矿物显微构造等进行了详细研究。取得的主要成果有：1）通过节理统计，得到了三期6组节理，其所揭露的主应力方位分别为S-N向、NW-SE向、近E-W向，且具有逆时针变化的特征；2）通过应变测量，研究区应变椭球体为一略有压扁的椭球，其K值为0.8；3）极图所反映的双晶优选方位型式为极密型，通常有多个极密中心，且对称程度低，多为三斜式；4）双晶纹几何特征反应出早期构造运动不强烈，变形温度较低，小于200℃，以机械破碎为主；中期构造运动最强烈，达到顶峰，变形温度高，介于250～300℃，变形伴有塑性变形，局部出现糜棱岩化带；晚期构造运动减弱，整体为脆性变形，但较早期强烈，变形温度总体上为150～200℃。上述研究成果表明，淮南煤田在聚煤期后，主要经历了3次大的构造热事件，其对应时间大致为晚三叠世、中侏罗世以及始～渐新世。以中期规模最大，影响最为强烈。项目研究成果，不仅为淮南煤田主要构造带的变形性质和变形环境的进一步确认提供微观依据，同时对矿山安全开采以及资源远景勘查等也具有重要的参考价值。