320矿床微晶石英硅质岩的成因

320矿床微晶石英硅质岩具独特的岩石学特征和特定的微量元素组合;产于栖霞组灰岩与当冲组硅质页岩界面的层间破碎带的上盘。按硅化强弱可分为石英质岩、微晶石英岩和硅化硅质岩3类,与铀矿化关系最密切的是黑色石英质岩和黑色微晶石英岩。根据P·尼格里的岩石化学计算法类比,笔者认为该岩石的原岩为粘土-石灰岩混合物类型。微晶石英硅质岩的形成是受区域构造应力影响的,是在一定温度、压力和裂隙溶液的共同作用下溶液中SiO_2围绕石英、方解石和生物碎屑颗粒重新结晶沉淀形成的。岩石重结晶时没有外界成分的参与。

THE GENESIS OF THE BLACK MICROLITIC QUARTZITE IN DEPOSIT NO. 320

The black microlitic quartzite in deposit No.320 has specific petrological features and assemblage of microelements. It is located in the upper wall of the interformational crush belt within the interface between the limestone of Qixia formation and the siliceous shale of Dangchong formation. According to the degree of silicification, the quartzite can be classified into three kinds: quartzose rock, microlitic quartzite and silicified silicalite. Black quartzose rock and black microlitic quartzite have the most intimate relationship with the uranium mineralization. The original reck of quartzite was determined to be the mixing type of clay and limestone by using P. Niggli's lithochcmical, calculation and analogy. The process of formation of the microlitic quartzite is that SiO_2-solution was recrystallized and precipitated around the surface of quartz,calcite and bioclastic grains under the influence of regional tectonic stress and crack solution and at a cer tain. temperature and pressure. There is no external composition added during the reerystallization of the rock.