含煤地层中石英组构的成因与意义——实例与实验研究

MECHANISMS AND SIGNIFICANCE OF QUARTZ FABRICS IN COAL BEARING STRATA ——ANALYSIS ON CASES AND EXPERIMENTS

根据我国东部煤田一些实例和高温高压变形实验模拟结果表明，含煤地层中石英Ｃ－轴组构普遍具有稀疏小圆环带型式，其环带轴具有显著的应力指向意义。稀疏小圆环带型式组构的形成与石英底面滑移系的运动有关，是点极密型式的过渡状态，与石英颗粒的塑性应变量较小有关。造成含煤地层中石英颗粒塑性应变量较小的原因，除构造变形强度较小外，还与岩石中普遍存在软弱矿物有关。

According to results of analysis on some cases from coal fields in the eastern China and simulation by deformation expeiments under high temperature and confining pressure,it is indicated that in coal bearing strata quartz C fabric is often of sparse small circle pattern and its axis is of obvious stress directing significance.This type of patterns of quartz C fabrics is related to the activation of basal slip systems of quartz.It is a middle stage pattern of maximum because of less plastic strain in quartz grains.Besides lower intensity of structural deformation,the widespread existence of soft minerals is an other major factor,which is responsible for the less plastic strain of quartz grains in sedimentary rocks,because soft minerals absorbed most of plastic strain.